Turtles of the World: A Guide to Every Family 9780691229034

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TURTLES

OF THE WORLD

TURTLES

OF THE WORLD

A GUIDE TO E V E R Y FA M I LY Je ffr e y E. Lovich and Whit Gibbons

PRINCETON UNIVERSITY PRESS PRINCETON AND OXFORD

Published by Princeton University Press 41 William Street, Princeton, New Jersey 08540 6 Oxford Street, Woodstock, Oxfordshire OX20 1TR press.princeton.edu Text copyright © 2021 by Jeffrey E. Lovich and Whit Gibbons Design and layout copyright © 2021 by Quarto Publishing plc Conceived, designed, and produced by The Bright Press an imprint of The Quarto Group The Old Brewery, 6 Blundell Street, London N7 9BH, United Kingdom T (0) 20 7700 6700 www.QuartoKnows.com All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage-and-retrieval system, without written permission from the copyright holder. Library of Congress Control Number: 2021937966 ISBN: 978-0-691-22322-3 Ebook ISBN: 978-0-691-22903-4 Publisher James Evans Editorial Director Isheeta Mustafi Art Director James Lawrence Managing Editor Jacqui Sayers Publishing Manager Kathy Turtle Project Editors Joanna Bentley, Caroline Earle Design Kevin Knight Picture Research Jane Smith Illustrations John Woodcock Cover photos: Front cover, clockwise from top left: Alamy Images/BIOSPHOTO (1, 2), SPL/MYN/Paul Marcellini/ Nature Picture Library, Alamy Images/ Anat Chantrakool, Alamy Images/Matthijs Kuijpers, Alamy Images/BIOSPHOTO (6, 7, 8), Alamy Images/MARKA, SPL/ Clay Bolt/MYN/Nature Picture Library. Back cover: Shutterstock/fivespots. Printed in Singapore 10 9 8 7 6 5 4 3 2 1

DEDICATION To our friend and colleague Carl Ernst (1938–2018) who wrote the first comprehensive book on the biology of turtles of the world with systematically organized species accounts (Turtles of the World Carl Ernst and Roger Barbour, 1989) and to our wives, Sharon and Carolyn, for their continued support of our pursuits of turtles for decades.

6

Introduction

CONTENTS 46

The Turtle Families

48

Suborder Cryptodira

186

Suborder Pleurodira

230 232 234 235 236 239 240

Appendices Glossary Resources Turtle Classification Index Picture Credits Acknowledgments

INTRODUCTION Turtles are arguably the most successful vertebrates to have ever lived. These iconic animals have been symbolized, memorialized, utilized, and revered by cultures throughout the world for thousands of years. They have changed little in appearance over 200+ million years due to the origin and retention of a morphology and lifestyle unique among vertebrates but which has endured the test of time. Instantly recognizable by their trademark bony shell, turtles are the only vertebrates, living or extinct, to have their limb girdles (hips and shoulders) inside the shell formed by their rib cage. On the one hand, the turtle shell appears to be an ingenious form of protective armor against many predators and the elements, while on the other the shell 6

Introduction

would appear to be a liability from the standpoint of mobility and other life functions. Turtles have a variety of traits humans consider to be of interest. The sex of hatchlings is often determined by incubation temperatures of eggs in the nest, not genetically by X or Y sex chromosomes. Some female turtles have the ability to store viable sperm for several years after one mating, and embryos can have multiple sires in the same clutch. In northern latitudes, turtles basically “hold their breath” for several months during hibernation under ice. Some species have the ability to breathe through their cloaca as if it were a gill. The longevity of some turtles is widely recognized. Turtles are truly amazing animals!

above | The beautiful Diamond-backed Terrapins of North America live only in brackish water habitats and are the only members of their subfamily with spots instead of stripes.

Interest in turtles is growing rapidly as measured by popular and scientific publications (Lovich and Ennen 2013). Unfortunately, this rise in curiosity is paralleled by dramatic declines in turtle populations and extinctions of turtle species around the world. Turtles are unquestionably under siege on local, regional, and global scales, with a growing number of species threatened with extinction. More than half of the world’s turtles require some form of conservation action to protect them – the proportion of turtles in trouble eclipses virtually all other major vertebrate groups except primates. They survived the extinction of dinosaurs, “drifting” continents, and numerous ice ages punctuated by rising sea levels. Whether they will survive humans remains to be seen.

A major purpose of this book is to increase appreciation for these successful creatures, largely unchanged since the mists of time, and expand awareness of their plight in the modern world. We provide a broad overview of general biology, fossil history, and distribution patterns of turtles. We also give details of the ecology and behavior of each of the 14 living families and 95 genera, highlighting some of the remarkable adaptations of selected species. Despite their antiquity, biological knowledge of many turtle species remains incomplete, but we have gleaned material for this book from a large and growing scientific literature base. We provide a list of suggested references for anyone interested in pursuing further details of particular species. 7

WHAT IS A TURTLE? TURTLES VS. TERRAPINS VS. TORTOISES

Simply put, all tortoises and terrapins are turtles, but not all turtles are tortoises or terrapins. Common names of turtles vary regionally and we have adhered mostly to those recommended in “Turtles of the World Annotated Checklist and Atlas of Taxonomy, Synonymy, Distribution, and Conservation Status (8th edition; 2017).” Scientific names of turtles are generally reliable for distinguishing between species but are in a state of flux because of phylogenetic reinterpretations and descriptions of new species. We use the classification system for families, genera, and species accepted internationally by the majority of turtle biologists at the time of writing, as specified in the checklist mentioned

People call turtles by various names including tortoises and terrapins. Technically, all animals with a bony shell and a backbone are turtles, even tortoises and terrapins. Just like foxes are dogs and lions are cats, tortoises and terrapins are turtles. Tortoises are decidedly terrestrial turtles with club-like hind feet. The word terrapin is derived from a Native American word meaning turtle. | Species diversity of non-marine turtles found on six continents and their associated island systems, based on the Turtle Taxonomy Working Group, 2017. The exact numbers change every year as new species are described but general continental relationships remain comparable, with the highest diversities being in North America and Asia.

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CONTINENTAL SPECIES DIVERSITY OF TURTLES

❺

❸ ❶

❹

1 North America 99 species

❷ ❻

2 South America 58 species 3 Europe 8 species

8

4 Africa 59 species

What is a turtle?

5 Asia 95 species

6 Australasia 39 species

above. We have augmented the list by including several species undescribed at the time of that publication. Taxonomy is an everchanging field, with more changes forthcoming. Turtles have not changed for centuries, but what we call them continues to be a moving target. TURTLE BIODIVERSITY

The greatest concentrations of turtle biodiversity in the world are in the southeastern USA and southern Asia. Buhlmann et al. (2009) listed the total number of non-marine species for the USA as 53, while Asia has 77 species. The Mediterranean region of Europe has 14 native species, Australia 35, Africa 48, and Central and South America 51 and 48 respectively but includes overlap of some species among these regions. Notable concentrations of non-marine turtle species also occur in the Galapagos Islands (13) and on Madagascar (nine). These estimates vary from more recent compilations, including ours (see map opposite), due to recognition of new species and taxonomic disagreements. The number of kinds of turtles recognized by the scientific community has steadily increased for

above | The Pig-nosed Turtle of Australia and New Guinea is the only species in its family and the only freshwater turtle with flippers.

decades as new species have been discovered in previously understudied regions. For example, the number of new species described per year worldwide has been almost ten times greater in recent years than in the USA where turtle research and descriptions of new species have been in progress much longer (Gibbons and Lovich 2019). Species diversity in Australia is also now better understood and unlikely to change much compared to Asia or Africa where extensive research programs are becoming established. In addition, our knowledge of turtle phylogenetic relationships continues to change due to scientific advances, often providing recognition that the diversity of species or genera is greater than previously perceived. Turtle biologists have made numerous efforts to report on the fast-growing body of information on turtle taxonomy in various books and technical publications. 9

TURTLE EVOLUTION, SYSTEMATICS, AND TAXONOMY Turtles are distinctive. Living species can be recognized and distinguished from all other animals by the presence of a bony carapace and plastron attached on the sides by a bony or ligamentous bridge. Turtles do not have movable ribs like other vertebrates. Instead the ribs are fused to form the structure of the carapace, providing shell integrity and armor. To breathe, turtles use elongate muscles in the abdomen, whereas most other reptiles breathe by moving the ribs to expand and contract the lungs. A common feature of all living turtles, whether Cryptodira (hidden-neck) or Pleurodira (side-neck), is the presence of eight neck vertebrae. During their long evolutionary history turtles passed through two major extinction events, at the ends of the Triassic and Cretaceous periods. However, not all survived as there are over 700 species of extinct turtles known, double the

right

number of living species. The basic turtle body plan changed little, overall, but no modern turtle has teeth, although several ancient fossil turtles or turtle ancestors did; for example, Pappochelys had marginal teeth (Middle Triassic, Germany), Odontochelys had marginal teeth (Late Triassic, China), and Proganochelys had no marginal teeth but small teeth on the vomer, palatine, and pterygoid bones (Late Triassic, Germany, Thailand, Greenland). The phylogenetic relationship of these various proto- or stem-turtles (page 13) to modern turtles continues to be debated among paleontologists. All possess some skeletal traits characteristic of today’s turtles, but none appear to be a direct ancestor of all modern turtles. Nonetheless, the case is clear that the lineage of turtles in the broadest sense began eons ago as they plodded alongside the Jurassic dinosaurs.

|

Paleontologists have proposed numerous evolutionary relationships of turtles based on fossils, such as this Odontochelys from China, preserved over eons.

10

Turtle evolution, systematics, and taxonomy

THE EARLIEST TURTLES AND THE FOSSIL RECORD

Numerous hypotheses have been proposed about the evolutionary origin and phylogenetic relationships among living and extinct turtles. Original interpretations were based solely on comparative morphology of modern turtles with those in the fossil record. During recent decades, DNA analyses have resolved many of the relationships among the 14 living families, although total agreement among authorities is yet to be achieved. All cryptodire and pleurodire turtles are encompassed within the Testudines and may be descended from a common ancestor in the Jurassic, or earlier, before the two major groups of modern turtles diverged. The oldest known fossil turtle to be a cryptodire was described from Late Jurassic deposits in China. Pleurodires and

above | Turtles have a rich fossil record because their bony shell, skull, and appendages are easily fossilized.

cryptodires are hypothesized to have diverged at an earlier time. Among the 11 families of cryptodires, the softshell turtles (Trionychidae) and pig-nosed turtles (Carettochelyidae) constitute a separate evolutionary branch from the other nine of those 11 families. WHAT WERE THE LARGEST TURTLES?

The largest turtles known have been extinct species found as fossils, with estimations that body sizes of some may have approached 10 feet (3 meters) in carapace length. However, precise linear measurements are often difficult on fossil specimens and can only be estimated. The largest confirmed sizes are those of Stupendemys 11

above | Leatherback Sea Turtles (center) are larger than humans, but intact fossils of some ancient sea turtles, such as Archelon (left), were even larger.

geographicus, a freshwater species from the Miocene of South America, and the comparably sized Archelon ischyros found in marine sediments in North America. Stupendemys was a side-necked turtle in the family Pelomedusidae. Archelon was not a direct line ancestor of any modern turtles although their phylogenetic position is debated. Based on a few fossil specimens, both were larger than the still extant Leatherback Sea Turtles. PHYLOGENETIC RELATIONSHIPS

One statement that all turtle biologists and paleontologists will agree on is that no presentation of phylogenetic relationships among fossil and modern turtles is accepted by everyone. In making phylogenetic trees, biologists refer to stem versus crown groups of organisms. Living species are referred to as the crown group because they are positioned at the top, or in the tips of the branches of the phylogenetic tree. However, the crown group also contains all extinct species, moving down the tree to the oldest common ancestor of all the living species in the crown. Extinct species that did not directly give rise to those living today are referred to as stem species because they are lower in the tree. Research by Shaffer et al. (2017) resulted in a “backbone tree” (see opposite) showing the phylogenetic 12

relationships of the 14 families of crown turtles we recognize and serving as a hypothesis of family relationships for future research and evaluation. Based on their molecular clock analyses they estimated that archosaurs (extinct dinosaurs and their modern relatives, birds and crocodilians) split off from primitive turtles 322 million years ago (MYA) during the Carboniferous Period. The oldest common ancestor of crown turtles has been estimated by some researchers to be 220 MYA during the Late Triassic Period. CLASSIFICATION OF MODERN TURTLES

The advent of modern DNA analyses has unquestionably provided valuable information on patterns of ancestry and relationships among species. Grouping species into families is a comfortable concept for virtually all non-scientists. In fact, most people like schemes that maintain a prescribed order, even though the system for any large group of entities is seldom perfect. For the practical aspect of sorting out the 95 genera and 354 species of living turtles for discussion, we group them according to families. A finer distinction of relationships among genera in some families is the category of subfamilies. We list on page 235 the subfamilies currently recognized but do not dwell on them in detail in the remainder of the text because the situation is fluid. Continued studies will lead to new interpretations of phylogenetic relationships that will result in reassortments among families, genera, and species as well as proposed name changes. But the fundamental phylogenetic relationships are unlikely to change the current basic classification. Recognizing all living and certain extinct turtles as belonging to the order Testudines within

Turtle evolution, systematics, and taxonomy

the class Reptilia also seems like a rational approach to maintain a system that has worked well for more than two centuries. We will leave for academic consideration the issue of how to shift public perception regarding the esoteric

conundrum that birds should be incorporated into the Reptilia as “modern dinosaurs.” For our purposes, everyone would agree that turtles have had their distinctive line of identity across geologic time by any phylogenetic interpretation.

PHYLOGENETIC RELATIONSHIPS AMONG LIVING TURTLES

Acanthochelys spixii Phrynops hilarii Erymnochelys madagascariensis Podocnemis sextuberculata Pelomedusa subrufa Pelusios subniger Carettochelys insculpta Dogania subplana Pelodiscus sinesnsis

Chelidae (partial) Podocnemididae Pelomedusidae Carettochelydidae Trionychidae

Lissemys scutata Chelonia mydas Eretmochelys imbricata Dermochelys coriacea Chelydra serpentina Macrochelys temminckii Dermatemys mawii Kinosternon baurii Staurotypus triporcatus

Cheloniidae Dermochelyidae Chelydridae Dermatemydidae Kinosternidae

Chrysemys picta Emys blandingii

Emydidae

Emys marmorata Platysternon megacephalum Cuora galbinifrons Rhinoclemmys punctularia Kinixys erosa Manouria emys emys

Platysternidae Geoemydidae Testudinidae

above | This chart shows one hypothesis of the phylogenetic relationships among genera and families of living turtles, based on Shaffer et al. (2017).

13

ANATOMY AND PHYSIOLOGY A turtle’s trademark is its bony shell. No other vertebrate, living or extinct, shares this body plan enclosed in a “box” of bone. All of the internal organs and systems (e.g., skeletal, circulatory, respiratory, excretory), which are comparable to those of other vertebrates, are enclosed within the space between carapace and plastron. Because of the shell, over 80 percent of the dry weight of some turtles is bone. SHELL MORPHOLOGY

The nomenclature used to describe various elements of the carapace and plastron vary greatly from source to source. We use the system of Ernst and Lovich (2009). The typical turtle has a carapace with about 50 bones arranged like an intricate geometric design. Included are 11 small peripheral bones around the edges of each side. A nuchal bone divides the right and left peripherals over the neck region and a pygal bone divides them over the tail. Moving inward, there are two rows of eight costal bones divided down the midline by a series of neural bones attached to the neural arches of the vertebrae. These are followed by two suprapygals. The other bones, including the nuchal, pygal, and suprapygals, are articulated to their neighbors but not the vertebral column. Many exceptions and variations on this generalized arrangement exist among species. The typical turtle plastron has nine bones including, from anterior to posterior, a pair of epiplastron bones, a single entoplastron bone, and pairs of hyoplastra, hypoplastra, and xiphiplastra bones. Side-necked (Pleurodira) turtles of the genera Pelusios, Pelomedusa, and Podocnemis have a pair of mesoplastra between the hyoplastra and 14

Anatomy and physiology

hypoplastra. This condition is seen, although rarely, in some hidden-necked (Cryptodira) turtles like the sea turtle Lepidochelys and the Pancake Tortoise Malacochersus. Several genera have hinged plastrons, which in Cuora, Terrapene, and Kinosternon allow complete or nearly complete retraction of their head, limbs, and tail into the safety of a tightly closed shell. Tortoises of the genus Kinixys have a hinge on the posterior of their carapace. The bony shell elements of softshell turtles differ greatly from those of hard-shelled species. For example, peripheral bones are absent. Instead the carapace is a bony disk composed of a nuchal, neurals, and costals covered with leathery skin. The plastron of softshells is reduced and modified anteriorly (no entoplastron) allowing more flexibility when the head is retracted. Another exception to the “typical” turtle body plan is

above | Some turtles, like this Red-eared Slider, shed their epidermal scutes intermittently or annually, replacing them with new ones.

SHELL SHAPE AND STRUCTURE peripheral (p) nuchal

epiplastron

p

costal (c)

p

neural (n)

n n n n n s

suprapygal (s)

p

c

n n

hyoplastron

c

p

c

p

c c p

mesoplastron hypoplastron

p

c c

entoplastron

p p

xiphiplastron peripheral (p)

pygal Above: Shell bones of typical turtle (carapace left, plastron right) nuchal

preplastron costal (c)

epiplastron

neural (n) c

hyoplastron

hypoplastron

n

c

n

c

n

c

n n n

c c

xiphiplastron

Above: Shell bones of softshell turtles (plastron left, carapace right) cervical

marginal (m) m

vertebral (v)

m

gular humeral

pleural (p)

m

axillary pectoral

m

v

p

m

v

abdominal

m p

v p

v m

m

inguinal

m

femoral

m m

anal

Above: Scutes covering a typical hard-shelled turtle (carapace left, plastron right)

15

seen in Leatherback Sea Turtles, which have lost all shell bones except for the nuchal and those rimming the plastron. Instead, they have what is referred to as a “mosaic” of bony plates called osteoderms embedded in the leathery skin of the carapace. Most hard-shelled turtles also have a covering of large scales, called scutes and made of keratin, over the carapace and plastron. Although the arrangement of scutes is roughly analogous to those of bony elements, the contact seams on the scutes do not align with the underlying bony sutures, but instead are offset, which presumably increases structural strength. Overlying the

peripheral bones of the carapace are 12 marginal scutes on each side (11 in the Kinosternidae). The costal bones are covered by four pleural scutes on each side, divided by a row of five or more vertebral scutes over the neurals, depending on the species. Additional scutes are present on the bridge including axillary, inguinal scutes, and inframarginals on some species. Seams between adjoining carapace scutes may disappear with age in the monotypic family Dermatemydidae. The plastron of most hard-shelled turtles has six pairs of scutes including gular, humeral, pectoral, abdominal, femoral, and anal. Members of the family Kinosternidae have variations on this arrangement (e.g., in Kinosternon a single scute replaces the paired gular scutes of most other turtles). Pleurodiran (side-necked) turtles have an intergular scute between the paired gulars. Three families of turtles lack scutes altogether (Carettochelyidae, Dermochelyidae, and Trionychidae), having shell bones covered with skin instead. Scutes of some species (e.g., Chrysemys picta and Trachemys scripta) are shed periodically in a process known as ecdysis. left | No modern turtles have teeth, but many have jaws with sharp edges and pointed tips.

CRYPTODIRA AND PLEURODIRA NECK RETRACTION

above | Whether the neck is pulled into the shell straight (Cryptodira, left) or is in an S-shape (Pleurodira, right) differentiates the two main evolutionary lines of modern turtles.

16

Anatomy and physiology

SKULL AND NECK MORPHOLOGY

Turtle skulls lack temporal openings, and this previously resulted in their being classified in evolutionary trees with the most primitive reptiles in a group known as anapsids. However, discovery of the Middle Triassic stem-turtle Pappochelys, with temporal openings in the skull, suggests that turtles evolved from more recent diapsids and reverted to the anapsid condition seen in modern or crown turtles. Although modern turtles lack teeth, their jaws are sheathed in keratin coverings called rhamphothecae, like a bird’s beak. The sheaths can be sharp for cutting or broad for crushing hard food items like mollusks. A turtle’s neck has eight relatively long cervical vertebrae, and most can be withdrawn into the shell to varying degrees. The neck retraction mechanism varies between Cryptodira and Pleurodira. The cryptodirans pull their necks into their shells, folding them in a vertical fashion, making them appear S-shaped when viewed from the side. In contrast, a pleurodiran folds

above | Some sea turtles patrol a coral reef in search of sponges and other marine invertebrates.

its neck and head under the shell horizontally, so it is S-shaped when viewed from the top or bottom—two solutions to the same problem of protecting the head. LIMB MORPHOLOGY

Turtle limb girdles are unique in being located inside the rib cage instead of outside as in all other tetrapods. This presents locomotory limitations for terrestrial turtles as the limbs are not directly below the body, but it has not kept turtles from plodding along for over 200 million years. Tortoises have modified hindlimbs that are columnar, like elephant legs, to help support them. Sea turtles and Carettochelys have flippers to help them row and glide through the water. Many freshwater species have varying degrees of webbing on their feet to help them swim. 17

TURTLE PHYSIOLOGY

As reptiles, turtles are “cold-blooded” meaning that they generally regulate body temperature through behavior. If they get too hot, they move to a cooler location. If they get too cold, they move to a warmer area. The term cold-blooded thus becomes a misnomer for a “hot” turtle basking on a log in full sunlight during the summer. Herpetologists (scientists who study reptiles) more correctly refer to this kind of metabolism as ectothermy in reference to the fact that heat comes from outside the animal. This contrasts with endothermy, or heat generated within an organism through metabolic processes, as is the case in birds and mammals. One turtle, the Leatherback Sea Turtle (Dermochelys) has been documented to maintain body temperatures significantly above those of cold ocean waters when they forage in high latitudes. Internally generated heat is conserved by several adaptations including thick layers of fat. In addition, their circulatory system has counter-current blood flow that places arteries and veins next to each other in the flippers to help retain body heat. Their massive size further retains heat through a phenomenon biologists call gigantothermy which, with other adaptations, allows maintenance of body temperatures more than 20 °F (11 °C) higher than surrounding sea water. Leatherbacks have other circulatory adaptations that allow females to remain cool while nesting on tropical beaches. Being ectotherms, turtles have slow metabolisms compared to “warm-blooded” endotherms. The amount of metabolic energy expended by a 6½-pound (3-kg) desert tortoise in a full year has been estimated to be able to sustain a 3-kg mammal for only three and a half days! Such low metabolism helps turtles survive during periods of resource scarcity and contributes to the 18

Anatomy and physiology

ability of populations to maintain very high densities and total biomasses (see page 40). Another metabolic trait of turtles is anhomeostasis or the ability to greatly relax their physiological parameters. This contrasts with homeostasis as exhibited by humans and other endotherms. For example, humans must maintain parameters like body temperature and blood sugar within very narrow and stable values to remain healthy. In contrast, turtles like Agassiz’s Desert Tortoise (Gopherus) can allow physiological processes to vary across a wide range of values that would kill an endotherm (bird or mammal) that must maintain

right | Basking on logs or shorelines is a common behavior in many species of turtles, usually for thermoregulation.

| Hauling itself onto a beach and digging a body pit to lay eggs costs an enormous amount of energy for a female Leatherback Sea Turtle.

below

19

homeostasis. The ability to relax homeostasis or temporarily abandon it allows turtles to survive in harsh environments for relatively long periods without access to critical resources like food, water, and, in some situations, atmospheric oxygen. Some temperate zone turtles deal with harsh environmental conditions by brumating (known as hibernating in endotherms) during winter. Cold weather dormancy can involve spending months at the bottom of frozen water bodies, sometimes under anoxic conditions while buried in mud. Collectively, over half of the life span of some turtles can be spent in a state of overwintering. Lowering their metabolism is one way they are able to withstand long periods without access to atmospheric oxygen. Another mechanism involves using carbonate buffers in the shell and bones to neutralize accumulations of lactic acid, which build up under anoxic conditions, and store them as lactate in the skeleton. Still other turtles are able to extract dissolved oxygen from clear flowing water through the lining of the buccopharyngeal 20

Anatomy and physiology

above | Many tortoises living in arid habitats dig burrows and are capable of water retention.

mucosa of the mouth or through the cloaca. The adaptability of turtles to environmental extremes is phenomenal. All animals, including turtles, need to balance body water content and ionic concentrations of salts like sodium and potassium through osmoregulation, similar to human athletes who maintain vital electrolyte levels through consumption of sports drinks. Turtles do so with a variety of adaptations, depending on species and the environment they live in. When fresh water is placed in a semipermeable membrane surrounded by salt water, the water inside flows across the membrane until salinities on both sides are equal. Thus, turtles in marine or brackish habitats must control the loss of body water, which has a lower salt concentration and is continually being lost to the surrounding, saltier waters. Freshwater turtles have the opposite problem as water in their bodies is saltier than the water in

which they live. As a result, they must regulate the problem of continually gaining body water. Turtles in both situations deal with this osmoregulatory challenge, in part, by having skin that is extremely impermeable to water and salts. In addition, eating prey and drinking in their aquatic environment brings in water and salts that must be regulated within physiologically acceptable limits. Sea turtles have well-developed salt glands near their eyes that help them excrete salts like sodium and potassium. The glands produce and eliminate large volumes of fluid that can be twice as salty as sea water. Diamond-backed Terrapins (Malaclemys) also have lachrymal glands that contribute to salt excretion in the brackish estuaries where they live. However, they actively avoid high salinities and

can drink the thin film of freshwater at the surface of estuaries after rains. Tortoises living in arid environments have a variety of adaptations for conserving water lost during the elimination of nitrogenous wastes and excess salts. For example, Desert Tortoises (Gopherus) store water in bilobed bladders, concentrating nitrogenous waste as solid urates and retaining water, which can be high in potassium, as long as possible. When winter or monsoonal rains fall, these tortoises void the concentrated contents of their bladders and drink up to 33 percent or more of their body mass to rehydrate for the long seasonal dry spell to come.

| Diamond-backed Terrapins, which live at the interface of salt and fresh water, must constantly adjust body salinity levels.

below

21

GLOBAL AND REGIONAL DISTRIBUTION Turtles have a nearly worldwide distribution, inhabiting almost all temperate and tropical continental land masses, islands, and oceans. Some marine turtles even make occasional visits to sub-Arctic waters, including Alaska, although none are found in the Antarctic other than Eocene fossils. According to an analysis of the global distribution of non-marine turtles (Buhlmann et al., 2009), they occur from above latitude 56 degrees north for Emys orbicularis in Europe (Latvia), to latitude 42 degrees south for Chelonoidis chilensis in South America (Argentina). The average geographic range for all non-marine species of turtles is slightly more than 386,100 square miles (1,000,000 sq km), which is larger

22

Global and regional distribution

than the combined area of France and Germany. The largest range of a genus, Pelomedusa, at 6,254,855 square miles (16.2 million sq km) in southern Africa, encompasses an area slightly smaller than South America. However, some have restricted distributions. The modern species (or subspecies) with the smallest estimated range was Pelusios castaneus seychellensis (now extinct) at 59 square miles (154 sq km; Mahé, Seychelles). The smallest range for a living species, Chelodina mccordi, is 472 square miles (1,223 sq km), approximately half the size of Luxembourg.

| Some sea turtles have limited geographic ranges whereas others inhabit most warm marine environments.

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HABITATS

Turtles live in virtually every habitat including oceans, rivers, estuaries, lakes, ponds, swamps, marshes, deserts, and forests. Most turtles occupy areas with warm, moist climates and have a fully aquatic or semi-aquatic existence in freshwater systems. North American species richness increases in areas with high precipitation, stream diversity, and an undulating topography (Ennen et al., 2016). Overall species diversity is generally higher toward the equator. Exceptions to this trend include temperate zone “hotspots” in the southeastern USA and southern Asia with their extraordinarily high turtle species diversity. Most turtles thrive in lower elevation habitats below 3,300 ft (1,000 m), although records of the Leopard Tortoise (Stigmochelys pardalis) in Africa occasionally exceed 10,000 ft (3,000 m). The global distribution of turtles is widespread, but some habitats are off limits. High mountains like the Rockies, Himalayas, and Andes, and tablelands like the Tibetan and Colorado plateaus, are inhospitable barriers devoid of turtles except in some situations close to their periphery.

above | Tortoises are found on many oceanic islands and on every continent except Australia and Antarctica.

Similarly, turtles are not found in extremely low elevation regions below sea level like Death Valley in North America and the Dead Sea region in the Middle East. Similarly, turtles avoid extremely arid regions in the interiors of the world’s driest deserts including the Sahara, Atacama, Australian, Gobi, Arabian, and Taklamakan. However, Agassiz’s Desert Tortoise (Gopherus agassizii) is found in portions of the Mojave and Sonoran deserts, and Morafka’s Desert Tortoise (G. morafkai) lives in the Sonoran Desert, both in North America. Overall, few turtle species are endemic to a desert ecosystem. Exceptions other than Gopherus include some members of the genus Kinosternon in southwestern North America and the Padloper (Chersobius solus) in the Namib Desert in Africa. Basically, turtles are like Goldilocks in the English fairytale: animals that do not like it too hot, too cold, too high, or too dry, but all have found a place that is “just right.” 23

BEHAVIOR BASKING

Turtles are usually shy and retiring creatures that remain inconspicuous for much of their lives. However, many aquatic species have well-developed basking habits and dozens may be seen sunning themselves on rocks and logs in wetlands on a warm spring day. Turtles bask for a variety of reasons. First and foremost, as ectotherms, basking allows them to elevate their body temperature to levels that sustain activities such as feeding. A quick dip in the water is all that

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Behavior

is needed if they get too hot. Basking may also help rid turtles of algae growing on their shell or ectoparasites like leeches that are frequently attached in the limb sockets or shell of aquatic species. An additional benefit of basking may be related to vitamin D synthesis, essential for maintenance of calcium homeostasis, an important consideration for turtles given the bone mass in their shells. Basking turtles are extremely wary and drop into the water at the first sign of potential danger.

Aggregations of basking turtles suggest a social gathering, but one common reason is the relative scarcity of elevated basking sites away from shore and close to good escape routes into deeper water. Some turtles interact while basking and have been documented engaging in aggressive behavior to secure or maintain a favorable position on a preferred rock or log. Such behaviors include biting, open mouth threat gestures, and rocking to dislocate a turtle that has climbed on top of another.

above | Many aquatic turtles have a covering of algae on the top of the shell that normally does them no harm.

above | Leeches are found on the shell and appendages of both freshwater and marine turtles.

left | Slider Turtles often bask communally in locations with instant access to deep waters or safe havens beneath banks.

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MIGRATION

Sea turtles are among the champions of migration in animals, often moving staggering distances among oceans and continents. One Loggerhead Sea Turtle (Caretta caretta) traveled a roundtrip from Australia to Africa’s eastern coast over two years, a distance of 22,000 miles (35,405 km)! A Leatherback Sea Turtle (Dermochelys coriacea) was tracked by satellite on a route that stretched for 12,774 miles (20,557 km). Long-distance migrations by female leatherbacks sometimes take them from cold ocean waters in higher latitudes where they feed on jellyfish to warm tropical beaches where they nest. These are not random movements, as turtles know where they are going. Female sea turtles appear to be capable of returning to the beaches of their birth year after year. How they manage 26

Behavior

above | Sea turtle females may travel hundreds of miles between feeding grounds and nesting beaches.

to find their way in the vastness of the world’s oceans is a subject of great interest to biologists. Scientists suspect a combination of mechanisms, including following magnetic fields or ocean currents, using sun-compass orientation, or detecting odors associated with landmarks such as estuaries or nesting beaches. Shorter, but equally important, “migrations” happen when freshwater turtle species leave the aquatic environment to nest in the terrestrial environment surrounding rivers, ponds, and lakes, sometimes moving more than 0.6 miles (1 km). When their habitats dry up, many freshwater turtles migrate to other nearby wetlands.

right | In contrast to most females, adult male Eastern Box Turtles (Terrapene) of North America often have red eyes.

TURTLE SENSES AND VOCALIZATION

How do the senses of vision, hearing, and smell in turtles compare to those of humans and other animals? Turtles have all these senses, but they vary in acuity and importance. VISION

Diurnally active turtles are highly visual animals possessing elaborate and efficient eyes and mechanisms for registering images. Turtle retinas contain rod cells for discriminating shades of gray and cone cells for color detection. Research on Slider Turtles (Trachemys scripta) suggests that color

above | Turtle eyes come in many colors, including blue in the pond turtles (Mauremys) in the Sahara Desert.

vision is well-developed, and their eyes are especially sensitive to red light. Although not documented empirically, perception of color by turtles is tangentially supported by the dramatic coloration of some species like Western Painted Turtles (Chrysemys picta bellii) that have bright yellow and red markings on the shell, limbs, and head. Furthermore, males of some species undergo dramatic changes in color during the breeding season as exemplified by Asian river terrapins of the genus (Batagur), such color dimorphism being indicative of the sexes being able to distinguish between each other. These and other examples support the importance of color perception by some turtles. Nocturnally active species may have monochromatic vision, an area of research needing further study. For example, snapping turtles (Chelydridae) have no coloration on the shell or body parts that would aid the sexes in differentiating between each other during courtship, and they often live in murky aquatic habitats where color detection would be less advantageous. 27

right | The exact functions of chin barbels are among the many biological mysteries about turtles. They may be used for prey detection, possibly by sensitivity to touch, chemical, or bioelectrical signals.

HEARING

Possessing a sense of hearing and an ability to produce meaningful sounds to both sender and recipient are required to facilitate communication by sound. Contrary to popular belief, many species of turtles are capable of producing sounds (e.g., many tortoises) that some scientists have concluded involve communication among individual turtles, but more research is needed to verify certain details related to the hypothesis. The sense of hearing is impeded by the primitive simplicity of the turtle ear in comparison to mammals. Turtles have no external ear pinnae but rather have a patch of skin (tympanum) on both sides of the head that acts like the skin of a drum to transmit sounds toward the brain. The middle ear has a long, straight bone called the columella that attaches to the tympanum and then to the opening of an auditory tube in the internal ear. Turtles that have been studied show sensitivity at the low end of the auditory spectrum (about 300–500 Hz) with sharp declines in sensitivity at higher frequencies. In contrast, human ears are most sensitive to sounds with frequencies 2,000–5,000 Hz, about ten times greater than turtles. 28

Behavior

SMELL

Olfaction has been suggested to be important for female freshwater turtles to locate suitable nest sites and for marine turtles to find foraging areas and nesting beaches. In the wild and in captivity, turtles are frequently observed “sniffing” food items. The behavior of sniffing the cloaca in some turtles is possibly related to detection of pheromones or other chemical signals through their vomeronasal organ. As in other vertebrates, olfaction is closely linked with the sense of taste. Electron microscopy of Slider Turtle (Trachemys scripta) taste buds shows them to be similar to those found in other vertebrates. Tactile senses may be enhanced in some turtles by the presence of protuberances called barbels on their chin (e.g., Kinosternidae, Pelomedusidae, and Podocnemididae).

FEEDING HABITS Turtle mouths have been modified through evolutionary time to accommodate generalized and specialized diets. The edges of both jaws of most turtles are not unlike a dull knife blade, whereas in some the jawline is relatively sharp-edged and capable of slicing through soft plant material or removing chunks from items being preyed upon or scavenged. Examples of turtles that eat live prey or scavenge dead animals, requiring a cutting edge, include Claudius and Chelydra. Species having diets of mollusks or crustaceans (e.g., female map turtles [Graptemys]; Diamond-backed Terrapins [Malaclemys terrapin], and some populations of musk turtles [Sternotherus]) have lower jaws with flat surfaces for crushing and grinding shells. In some turtles, females have broader crushing surfaces than males. Some turtles have a sharp beak at the end of the upper jaw and can kill or subdue larger prey. Hawksbill Sea Turtles specialize on siliceous sponges, using their hooked beaks to grasp and bite off the equivalent of shards of glass. Aquatic turtles commonly use their front feet to hold and manipulate both plant and animal food, but Leatherback Sea Turtles (Dermochelys coriacea) swim open-mouthed in ocean waters to procure one of their major food items, jellyfish. Softshell turtles living in sandy or silty habitats are sit-and-wait predators, camouflaging themselves beneath the substrate with only eyes and nose visible, waiting to make a deadly strike at an unsuspecting invertebrate or fish. Most turtles have powerful

jaw muscles that function effectively not only for particular dietary choices but also for defense. Many turtle biologists can attest to the damage caused by a bite from a large snapping turtle (Chelydra) or softshell (Trionyx; Amyda). Some hapless handlers are missing a finger or two if the assailant was an alligator snapper (Macrochelys). A few turtles have special feeding behaviors, a notable one being the North American Wood Turtle (Glyptemys insculpta). When feeding terrestrially, a Wood Turtle will eat berries, fruits, and any invertebrates it can catch. In habitats where earthworms occur, a Wood Turtle stomps and drums its feet and bumps its plastron on the

| Marine sponges, a favorite food of Hawksbill Sea Turtles, contain needle-sharp spicules, making them unpalatable to most animals.

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above | Male Alligator Snapping Turtles, North America’s largest freshwater turtle, never leave the water.

| South America’s Matamatas have one of the most unusual feeding mechanisms among all animals, vacuuming up their prey.

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Feeding habits

ground. The soil vibrations bring earthworms to the surface, prey for the waiting Wood Turtle. Two highly specialized methods of acquiring prey are rapid underwater suction, used by Chelus species, and tongue luring, used by Macrochelys species, which are discussed in the genus accounts (see pages 54 and 192). Many turtles eat virtually any plants, animals, or fungi they can find or capture. Some are primarily herbivorous; others are strictly carnivorous. Most are omnivores, feeding opportunistically on what is available in the habitat seasonally. The omnivorous and globally ubiquitous Red-eared Slider Turtle (Trachemys scripta) will eat any animal it can catch alive, scavenge on dead animals when available, or can thrive solely on plant material. Its ability to subsist on virtually any organic material is one reason for their being the most successful introduced turtle species in aquatic habitats worldwide.

left | An Eastern Box Turtle eats an earthworm, one of their many invertebrate prey. In addition, box turtles eat mushrooms, fruits, and berries as part of their natural diet.

right | The release of pet Red-eared Slider Turtles and their omnivorous diet have resulted in their widespread occurrence.

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REPRODUCTION Obtaining reproductive data from wild populations of turtles has been challenging, and little detailed information is known for most species, especially in Asia and Africa. Turtles, like all other reptiles, birds, and mammals, are amniotes, meaning the embryo develops within an envelope composed of a membrane (amnion) surrounded by an outer layer (chorion) with an allantois to facilitate respiration and store wastes. All turtles lay eggs with an additional mineral covering (shell) of aragonite (CaCO3 + magnesium). The eggs of other amniotes are covered with calcite (CaCO3). The outer shell can be thick and rigid or thin and flexible, depending on the species. What constitutes a suitable nesting site differs among species based on a variety of factors, including sunlight and moisture levels required for incubation. Female turtles typically dig a cavity in dirt or sand in which they deposit a clutch of eggs. The female turtle covers the nest and departs, leaving eggs and future hatchlings on their own. A few (Gopherus and Manouria) defend their nests for short periods after laying. As noted earlier, females that store viable sperm are capable of laying clutches with eggs fertilized by more than one male. Temperate zone turtles generally lay eggs during spring and early summer. Tropical and subtropical turtles may lay eggs year-round but may be governed by wet–dry seasons characteristic of the region.

left | Leaving the aquatic habitat to nest on land is one of the most vulnerable periods for many turtles because of exposure to predators.

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Reproduction

COURTSHIP

Prior to mating, physical combat occurs in males of some species, especially if males are larger than females. Head-on charges and occasionally overturning occurs in some tortoises. The outcome is typically retreat by the loser. Ritualized courtship behavior occurs in many emydids in which males are smaller than females. For example, male Slider Turtles (Trachemys scripta) and Painted Turtles (Chrysemys picta) develop noticeably longer foreclaws upon reaching maturity. During a ritualized courtship display called titillation, the male approaches a female underwater, holds its front feet together back to back, and vibrates the long claws directly in front of her face. The male swims backward, and the receptive female follows. Copulation occurs by the male climbing onto the female’s carapace and curling his tail (usually longer than the female’s) under hers until their cloacas are aligned and then inserting his penis.

| Sea turtles mate underwater while swimming in an open ocean setting.

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above | The long claws of some male emydid turtles are used in a courtship ritual seen by few humans.

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Adult males of terrestrial and some semi-aquatic turtles have an indentation on the plastron that conforms to the curvature of the female’s carapace, allowing for a safer balancing act when on land. Male mud turtles (Kinosternidae) have a claw at the end of the tail that may aid in grasping the female during copulation.

EGG QUALITIES

Turtle eggs are white or cream-colored. None have the color variation seen in bird eggs. Smaller turtles generally have oblong eggs whereas as in larger species the eggs are more spherical. The texture of the eggshell, which may range from hard and brittle to leathery and pliable, is consistent within a species.

CLUTCH SIZE AND FREQUENCY

Clutch size in turtles varies from as few as one or two in some genera (e.g., Platysternon; Siebenrockiella; Pyxis) to 100 or more in some sea turtles and softshells. Leatherbacks have been recorded to have clutch sizes of more than 200. Clutch size is usually correlated with female body size within and among species. Larger species lay larger eggs, their size varying relatively little within a species. Some turtles lay only one clutch of eggs per year, but others may lay two to six or more times. In most species reproductive traits are poorly known and data are often based on captive animals.

above | Almost all turtles bury their entire clutch of eggs together before covering them with sand or dirt.

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Reproduction

EGG RETENTION AND INCUBATION

When a female turtle ovulates egg follicles from her ovaries into her oviduct, the shelling process typically takes only a few days. Once an egg has been laid, the incubation periods until hatching are among the best-known facts for turtle species worldwide. The time from egg laying to when the hatchling uses its egg tooth to slice open the egg from the inside is around two to three months for most species. The time from hatching to leaving the nest varies from hours to months, depending on the species and environmental conditions.

above | The egg tooth of a hatchling map turtle allows it to escape from inside the egg by cutting through the shell.

above | Baby sea turtles leaving the nest en masse are easy prey for gulls, crabs, and other predators before reaching the surf.

Some turtles on every continent exhibit delayed emergence from the nest, known as “overwintering” in cold and warm temperate regions but related to wet–dry seasons in the tropics. The sudden appearance of baby turtles in a pond in spring or during the rainy season is often the product of eggs laid months earlier. Chicken turtles (Deirochelys) are known to stay in the nest for up to 18 months. Sea turtles, softshells, and several others leave the nest en masse no more than a few days after hatching, often at night. Mother turtles are not insensitive, uncaring parents as first perceived. Females equip each developing hatchling with a large yolk sac full of fat and nutrients to last for up to a year. In consideration of the full reproductive cycle, turtles are good parents.

SEX DETERMINATION

A turtle’s sex is determined in two dramatically different ways. Softshells and some other species have sex chromosomes that determine the sex of the offspring. But most turtles studied have temperature-dependent sex determination (TSD), aka environmental sex determination (ESD), whereupon hatchling sex is determined by the temperature of the egg during incubation. Usually, eggs incubated at warm temperatures produce females whereas cooler temperatures produce males. In other species, intermediate temperatures produce males while higher and lower temperatures produce females. Thus, the sex ratio of eggs laid in a sunny open area during a hot summer will likely be different from those by the same species laid in a cool, wet wooded habitat. Researchers continue to unravel complexities of TSD, with exceptions being rampant. 35

GROWTH AND LONGEVITY GROWTH RATES

ANNULI TECHNIQUE

Like other reptiles, the growth rates of individual turtles, in both weight and length, are slower than most endotherms—mammals and birds. Nonetheless, some turtles respond dramatically in response to different environmental conditions and feeding opportunities. The fastest growth rates are of turtles in captivity and, like virtually all animals, they grow most rapidly as juveniles. Once maturity is reached, growth rates slow appreciably. Adult turtles continue growing at a diminished rate, often for several years, before reaching maximum size. Within a species, a turtle’s size is not always a good indicator of its age because of the many environmental factors resulting in variability in growth patterns throughout an individual’s life. Included are temperature, food availability and quality, and population density.

One feature of many tortoises and hard-shelled freshwater turtles is that growth rings, analogous to those of a tree, can be used to determine periods of slow or rapid growth or, in some situations, estimate the age of individuals. These rings, called annuli, are visible grooves laid down on individual scutes during a period of dormancy. In the temperate zones, turtles become dormant during winter, creating a narrow growth ring discernible from the wider ring created during the growing season of spring and summer. The annuli technique is confounded in regions with more than one wet or dry season or periodic droughts because multiple annuli may be produced in a

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Growth and longevity

| A set of calipers is a common tool used by biologists for measuring carapace length of turtles.

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| This Wood Turtle is estimated to be about ten years old based on the rings visible on each scute.

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single year. However, the technique is useful in determining when and how fast juvenile turtles grow. The technique becomes less effective in most species once maturity is reached. Being able to estimate the ages of many turtles in a population has been a useful tool for turtle biologists interested in the survivorship of individuals from one time period to another and for determining the demographic makeup of the population. The greatest mortality for most turtles, as much as 100 percent in some years, is the period between the time eggs are laid until the hatchlings reach the habitat where they will live as adults. Juveniles typically have a steady rate of survivorship from year to year that is relatively high (more than 70 percent in some well-studied species), which compensates for low nest survival but varies with levels of predation, weather extremes, and other natural environmental or human-caused factors. BODY SIZES

Determining the largest or smallest species within any large taxonomic group is often difficult because of differing interpretations of how size should be measured. Body weight or length seem straightforward, but various factors can influence either. Recent consumption of food or water (or presence of eggs in females) can affect weight. In turtle research, carapace length has been reported in some studies and plastron length in others. Whether the measurement of an individual was made as a straight line or over the curvature of the

carapace can also affect the outcome. Some turtle length measurements have even been reported based on the distance from the tip of the nose with neck outstretched to the tip of the tail. The Leatherback Sea Turtle (Dermochelys coriacea) is incontestably the largest living species of turtle in the world, their maximum body sizes rivaling those of the largest fossil turtles yet discovered. However, some extinct turtles probably reached larger sizes than the largest Leatherback swimming in today’s oceans, because length measurements of fossil turtles are often only estimates as complete shells are seldom recovered. In addition, in contrast to Leatherbacks, for which thousands of adults have been measured, comparatively few large adult specimens of any fossil species have been 37

THE LARGEST LIVING TURTLE SPECIES

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1 North America Macrochelys temminckii 249 lb (113 kg) 31½ in (80 cm)

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2 South America Podocnemis expansa 200 lb (90 kg) 35½ in (90 cm) 3 Galapagos Chelonoidis porteri 882 lbs (400  kg) 51 in (130  cm)

4 Europe Testudo marginata 11 lb (5 kg) 14 in (35 cm)

5 Africa Centrochelys sulcata (heavier) 220 1b (100 kg) 34 in (86 cm) Trionyx triunguis (longer) 132 lb (60 kg) 47 in (1.2 m)

above | The map shows the living non-marine turtle species with the largest individuals on continental land masses.

discovered, leaving no certainty of what size the largest individuals might have attained. The smallest turtle in the world appears to be the Speckled Padloper Tortoise (Chersobius signatus) of South Africa, although Bog Turtles (Glyptemys muhlenbergii) and some members of the Kinosternidae vie for that title. SURVIVORSHIP AND LONGEVITY

Turtles have a venerable reputation worldwide for extended longevity, and individuals of some species have been scientifically documented to live for several decades in the wild, although most longevity records have been from captive turtles 38

Growth and longevity

6 Asia Chitra sp. 335 lb (152 kg) 45¼ in (115 cm)

7 Australia Carettochelys insculpta 48½  lb (22 kg) 22½ in (57 cm)

that may not be representative of free-living longevity. Many turtles unquestionably can live for over 50 years based on carefully kept records by field biologists, zookeepers, and pet owners. However, many of the oldest reported records have been challenged and must be viewed warily and considered carefully as some people tend to overstate turtle ages due to inaccurate bookkeeping or a desire to hold a record. Claims of century-old Eastern box turtles (Terrapene) have been made but, because of chain of custody uncertainties, most have been called into question. One of the most remarkable records for longevity for a freshwater turtle is a Blanding’s Turtle (Emydoidea blandingii) in Minnesota known to be more than 75 years old when it laid a clutch of fertile eggs, supporting observations that some turtles do not become

left | Individually tagged tortoises have documented that some adults can survive more than 50 years in the wild.

| Visitors to Riverbanks Zoo (South Carolina, USA) watch some of the oldest confirmed turtles in the world, Galapagos tortoises.

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reproductively senile. Several Galapagos tortoises known to have been adults before 1933 were still alive at Riverbanks Zoo in Columbia, South Carolina, and the San Diego Zoo in 2020. All are unquestionably more than 90 years old and probably passed the century mark long ago. Claims that some turtles can live for centuries are not supported with ironclad, scientifically credible proof. Some of the oldest reliable longevity records have been of tortoises, many of which have been confirmed to have lived more than 50 years as pets or zoo animals, which is a remarkable feat. 39

ECOLOGICAL IMPORTANCE Turtles have underappreciated but important ecological roles (Lovich et al., 2018). Before humans greatly reduced turtle numbers, many species had phenomenal natural abundances. Ecologists sometimes measure an organism’s impact in ecosystems using biomass, or simply weight of a given type of organism per unit area, such as pounds per acre. This measure reflects the amount of available and stored energy in organisms in a given habitat. High biomass results in a greater impact on ecosystem processes and turtles have some of the highest values ever reported. Some turtles attain biomasses of over 700 pounds per acre (800 kg per hectare) and population densities of up to 890 individuals per acre (2,200 per hectare)! Turtles are also important in energy transfer from aquatic to terrestrial ecosystems. For example, sea turtles can produce millions of eggs on a given stretch of beach during nesting season, moving minerals and nutrients from the marine environment to land. Only about one-quarter of the energy in those eggs returns to the ocean as

hatchlings, with the remainder staying on land as nutrients in decomposers and the stomachs of terrestrial predators. With a bony shell, a large percentage of turtle weight involves the elements calcium and phosphorus, making them a potentially important link in the geochemical cycle of some ecosystems, especially those deficient in calcium or phosphorus. Consumption of tortoise carcass bones by grazing animals in some areas has been attributed to phosphorus deficiencies in the local environment. Many turtles also play important roles in seed dispersal and germination enhancement of numerous plant species. Turtles not only disperse seeds but also enable them to germinate after the seed coat is scarified or weakened via digestive processes. For example, Galapagos tortoises (Chelonoidis) can transport seeds long distances and deposit an average of more than 400 seeds per defecation event, an act that even provides fertilizer. Leopard Tortoises (Stigmochelys pardalis) in South Africa eat and defecate seeds from as many as 75 different plant species. Several other species of tortoises are known to perform similar ecological services with germination efficiency of seeds being enhanced by 17 percent after passage

left | In addition to over 70 species of plants, Leopard Tortoises have been documented to eat hyena feces to obtain calcium for bone and egg shell development.

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Ecological importance

through a turtle’s gut. Seed dispersal of aquatic turtles (Rhinoclemmys) in Costa Rica has also been linked to the establishment of certain riparian plant species and the floral composition of tree gaps in the rainforest. Some turtles function as keystone species that influence their environment, as with the burrowing habit of some tortoises, especially those in the genus Gopherus. The burrows of some can be up to 33 ft (10  m) long, resulting in mixing of soil layers and allowing water and gas diffusion into the surrounding soil horizons. The large mounds of dirt excavated at the entrance affect environmental heterogeneity and plant species diversity in the area. Equally important, their burrows are known to be used by over 350 other species, including some endangered species.

| Clear streams with no industrial, agricultural, or urban pollution are essential for the long-term survival of some turtles.

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above | Semi-aquatic turtles often deposit seeds as they move overland between wetlands, enhancing native vegetation.

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CULTURAL IMPORTANCE Turtles have played prominent roles in diverse cultures throughout the world for thousands of years. What is it about turtles that makes them so culturally endearing? Is it their unique morphology? The turtle is universally recognizable for its shell, a distinctive adaptation that no other animal, living or extinct, has developed to the degree of turtles. Perhaps it is their slow and steady behavior, an attribute often admired in humans. Or maybe their extreme longevity and wizened countenance symbolic of wisdom has appeal. Whatever the reason, turtles exert a powerful influence on culture from ancient times to this day.

| Basking turtles are appreciated by visitors to parks or nature reserves worldwide as watchable wildlife.

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Cultural importance

Religious veneration of turtles is neither a thing only of the ancient past nor restricted to a particular religion. In Bangladesh, a population of Black Softshell Turtles (Nilssonia nigricans) continues to enjoy complete religious protection at an Islamic shrine. The turtles in Buddhist temple ponds in Bangkok, Thailand show yet another connection between turtles and religion. Although Christianity might appear to claim a connection to turtles through a verse in the King James version of the Bible (Song of Solomon 2:12) concerning “the voice of the turtle,” the reference is actually to a bird, the turtle dove (Streptopelia turtur). Some Native American tribes have creation stories of the earth that involve turtles. Turtles figure prominently in modern culture from Dr. Seuss’s book Yertle the Turtle and Other Stories to the movies based on Teenage Mutant Ninja Turtles.

above | Introduced Red-eared Sliders are probably observed and appreciated by more people on every continent every year than native turtles. right | Children and adults of many cultures enjoy stories and cartoons featuring turtles.

Research by Lovich and Yamamoto (2017) found a connection between the colors of toy turtles manufactured in Japan and the replacement of their native turtles over time by the introduced Red-eared Slider (Trachemys scripta). After World War II toy turtles manufactured in Japan were colored with muted earth-tones, a reflection of the coloration of most native Japanese turtles. As brightly colored Slider Turtles increased in abundance in Japan, toy turtle colors emphasized red, green, and yellow, colors characteristic of juvenile Sliders. The transformation was an example of art imitating life. Further details of the rich panoply of turtles in popular culture, myths, legends, and religion are found in Gibbons and Greene (2009) and Pryke (2021). Ironically, although turtles have been valued and appreciated by human societies worldwide

for millennia, today’s global consumer culture places turtles at risk. Many turtles have a distinctive biological formula beyond their protective shell that includes a co-evolved suite of traits (high nest mortality, delayed maturity, and essential extended longevity of reproductive females). These traits served turtles admirably for literally eons in a pre- and post-asteroid world. However, a life history strategy once effective in response to natural predators and environmental vagaries has become less adaptive in the modern world. Turtles did not evolve to withstand unsustainable removal from the wild for food or pets, widespread wetland pollution, and massive habitat loss. Turtles have joined the ranks of countless animal groups for which global cultural attitudes must change significantly if they are to survive modern human impacts. 43

CONSERVATION Turtles and tortoises are in trouble. That declaration was the title of an article we published in a scientific paper with colleagues in 2020. Did this situation come about only recently? The answer is no. The plight of declining sea turtle populations and the Galapagos tortoises was recognized decades earlier in the mid-twentieth century due to their near global familiarity status and the writings of influential researchers. Recognition of the “turtle conservation problem” came relatively late for reasons not easily explained but related to economic growth in Asia. Widespread recognition that most turtle species are declining globally has its roots in events that started in the 1990s. In 1993, over 200 of the world’s turtle biologists from about 25 countries assembled at the State University of New York for several days of presentations on the status of turtles. The upshot of the introductory material in the published proceedings was that turtles “were facing the greatest challenge of their evolutionary history.” The birth of the journal Chelonian Conservation and Biology also occurred in 1993. Another international meeting of turtle specialists in Phnom Penh, Cambodia in 1999 concluded that the regional turtle fauna of Asia was at risk of elimination due to human overexploitation for food and other cultural uses. The phenomenon became known as the “Asian Turtle Crisis” and was documented in the “Proceedings of a Workshop on Conservation and Trade of Freshwater Turtles and Tortoises in Asia” in 2000. Although previous books on turtles emphasized conservation, the first book titled Turtle Conservation was published in 2000. These events contributed substantially to the

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Conservation

1 Kinosternon hirtipes megacephalum Viesca mud turtle ca. 1970 Mexico 2 Chelonoidis abingdonii Pinta giant tortoise June 24, 2012 Chelonoidis niger Floreana giant tortoise ca. 1850 Galapagos Islands

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3 Pelusios castaneus seychellensis Seychelles mud turtle ca. 1950 Aldabrachelys gigantea daudinii Daudin’s giant tortoise ca. 1850 Seychelles

development of the modern turtle conservation movement and the foundation of various non-profit organizations dedicated to protecting turtles (see page 233). Why are turtles so threatened? A publication focusing on all reptiles (Gibbons et al., 2000) noted that threats faced by almost all species included habitat destruction, unsustainable overexploitation for food and the commercial pet trade, and climate change (many turtles have environmental sex determination). Disease has also contributed to the rapid decline and near extinction of some turtle species (see Myuchelys

LOCATIONS OF EXTINCT MODERN TURTLES

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4 Cylindraspis inepta Mauritius giant domed tortoise ca. 1735 Cylindraspis peltastes Rodrigues domed tortoise ca. 1800

Cylindraspis triserrata Mauritius giant flat-shelled tortoise ca. 1735 Cylindraspis vosmaeri Rodrigues giant saddlebacked tortoise ca. 1800 Mauritius

account). By 2020, over 50 percent of all turtle species were threatened with extinction. The emergence of turtle conservation came too late to save seven species and three subspecies that became extinct between the years 1500 and 2012. Extinction is an ongoing threat to turtles, as is clearly demonstrated with two recent examples. The last known purebred tortoise from Pinta Island (Chelonoidis abingdonii) in the Galapagos died in 2012. “Lonesome George” was removed from the wild in 1972 with the expectation that he might breed with other tortoises kept at the Charles Darwin Research Station in the

5 Cylindraspis indica Reunion giant tortoise ca. 1840 Réunion Island

Galapagos. Unfortunately, that never happened but hybrids of Pinta Island tortoises have been found on Isabella Island, raising hopes for the future. The last known female Yangtze Giant Softshell turtle (Rafetus swinhoei) died on April 19, 2019 at a zoo in China after international efforts to encourage her to produce viable eggs. However, a wild female was discovered in a lake in Vietnam in October 2020. With at least one male surviving at a zoo in China, there is renewed hope that the species will survive through captive propagation. It remains to be seen whether future turtle extinctions can be prevented.

45

T

he following accounts are organized evolutionarily into the two modern suborders of turtles and their living families (14). Within each family we summarize basic biological information on living genera (95) of turtles recognized at the time of writing. Our focus is on modern turtles, although now extinct families existed more than 200 MYA. Extinct families are known from the Triassic (Proganochelyidae), Jurassic (Glyptopsidae, Plesiochelyidae), and Cretaceous (Baenidae, Protostegidae, Toxochelyidae) geological periods. The Meiolaniidae, characterized by giant horned turtles, became extinct in the Late Holocene (as recently as the sixth century) due to human exploitation (Turtle Extinction Working Group, 2015). In the accounts that follow, we provide species lists and descriptions of their habitats and collective geographic ranges. Fossil records when known, morphological characteristics, and intriguing facts

THE TURTLE FAMILIES

T

he following accounts are organized evolutionarily into the two modern suborders of turtles and their living families (14). Within each family we summarize basic biological information on living genera (95) of turtles recognized at the time of writing. Our focus is on modern turtles, although now extinct families existed more than 200 MYA. Extinct families are known from the Triassic (Proganochelyidae), Jurassic (Glyptopsidae, Plesiochelyidae), and Cretaceous (Baenidae, Protostegidae, Toxochelyidae) geological periods. The Meiolaniidae, characterized by giant horned turtles, became extinct in the Late Holocene (as recently as the sixth century) due to human exploitation (Turtle Extinction Working Group, 2015). In the accounts that follow, we provide species lists and descriptions of their habitats and collective geographic ranges. Fossil records when known, morphological characteristics, and intriguing facts

THE TURTLE FAMILIES

are also given. The lengths of the accounts vary, in large measure due to the amount of scientific information available, which is limited for some, extensive for others. Many species of turtles remain under-investigated and poorly known. We generally follow turtle classification of the Turtle Taxonomy Working Group (2017), but turtle taxonomy has been particularly fluid in recent years and future nomenclatural changes are to be expected. Conservation concerns are a common thread throughout the book, as the plight of turtles is a consequence of human activities on a global scale. One or more species in every family is currently threatened with extinction. The need for conservation action cannot be overstated for this admired, revered, and captivating group of animals. We hope the following accounts will add to their being appreciated even more.

left | Female Olive Ridley Sea Turtles ascend a beach to lay their eggs. Highly synchronized nesting occurs in Ridley turtles.

CRYPTODIRA

The suborder Cryptodira (hidden-neck turtles) contains 11 turtle families, characterized by their ability to retract the head into the shell by folding the neck vertically in an S-shape. Two families, Dermochelyidae (Leatherback Sea Turtle) and Cheloniidae (sea turtles), inhabit all of the world’s oceans between the Arctic and Antarctic. Three families— Dermatemydidae (Central American River Turtle), Platysternidae (Big-headed Turtle), and Carettochelyidae (Pig-nosed Turtle)—each has only a single genus and relatively small geographic ranges. Chelydridae (snapping turtles) and Kinosternidae (mud and musk turtles) are in both North and South America. The Geoemydidae (geoemydid turtles) is the largest family of turtles. Most are native to Asia, southern Europe, or northern Africa, with some also in Mexico, Central and South America. Emydidae (semi-aquatic pond and marsh turtles) are found primarily in North and South America and also southern Europe, extreme western Asia, and northern Africa. Testudinidae (tortoises) range from southern North America through Central and South America, and also occur in Europe, Africa, and Asia, but not Australia. Trionychidae (softshell turtles) are found in North America, Africa, and Asia.

49

left | Female Olive Ridley Sea Turtles ascend a beach to lay their eggs. Highly synchronized nesting occurs in Ridley turtles.

CRYPTODIRA

The suborder Cryptodira (hidden-neck turtles) contains 11 turtle families, characterized by their ability to retract the head into the shell by folding the neck vertically in an S-shape. Two families, Dermochelyidae (Leatherback Sea Turtle) and Cheloniidae (sea turtles), inhabit all of the world’s oceans between the Arctic and Antarctic. Three families— Dermatemydidae (Central American River Turtle), Platysternidae (Big-headed Turtle), and Carettochelyidae (Pig-nosed Turtle)—each has only a single genus and relatively small geographic ranges. Chelydridae (snapping turtles) and Kinosternidae (mud and musk turtles) are in both North and South America. The Geoemydidae (geoemydid turtles) is the largest family of turtles. Most are native to Asia, southern Europe, or northern Africa, with some also in Mexico, Central and South America. Emydidae (semi-aquatic pond and marsh turtles) are found primarily in North and South America and also southern Europe, extreme western Asia, and northern Africa. Testudinidae (tortoises) range from southern North America through Central and South America, and also occur in Europe, Africa, and Asia, but not Australia. Trionychidae (softshell turtles) are found in North America, Africa, and Asia.

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FAMILY: CHELYDRIDAE SNAPPING TURTLES

T

he family Chelydridae has two genera, Chelydra (common snapping turtles) with three species and Macrochelys (alligator snapping turtles) with two. Fossil records for the family extend back 90 million years to the Late Cretaceous of North America. Species in both genera have been introduced into Asia where thousands are produced annually in commercial turtle farms from which individuals have escaped into the wild. Both genera have become established in the wild in Japan. Members of the snapping turtle family inhabit virtually every freshwater habitat. Except for nesting activities, alligator snappers are totally aquatic and usually restricted to large streams or rivers, whereas

common snappers inhabit all aquatic habitats as well as traveling overland between wetlands. The members of this family are the largest freshwater turtles in North America and some of the largest in the world. All have powerful, cutting jaws, strong claws, large heads, and heavy carapaces. Their defense against predators includes their armored carapace and powerful jaws. Adult males are larger than females, but sexual size dimorphism is less dramatic in Chelydra than in Macrochelys. The plastron is greatly reduced in size compared to the carapace. Both genera were formerly a major source of commercial turtle meat and continue to be eaten in some regions of the USA and Asia.

right | Even though the head of this common snapping turtle is withdrawn, it can lunge its neck and bite with impressive speed.

North America, Central America, and South America distribution

genera

Chelydra, Macrochelys habitats

All freshwater habitats whether permanent or temporary, including large rivers, streams, lakes, marshes, and small seasonal wetlands

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size

reproduction

CL 19½ in (49.4 cm) in Chelydra and 31½ in (80 cm) and 249 lb (113 kg) in male Macrochelys

Usually 1 clutch per year; 4–109 eggs per clutch; spherical eggs with leathery shells

activity

Primarily diurnal with some nocturnal movements in Macrochelys; bask less frequently than most other turtles in the same habitat

CRYPTODIRA—Hidden-neck turtles

diet Omnivorous, including aquatic plants, fruit, nuts, and aquatic animals, dead or alive

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CHELYDRIDAE: CHELYDRA

SNAPPING TURTLES

C

helydra has three species: C. serpentina (North American Snapping Turtle), C. rossignonii, (Central American Snapping Turtle), and C. acutirostris (South American Snapping Turtle). All were previously considered to be subspecies of C. serpentina along with C. serpentina osceola, the latter still recognized by some sources as either a subspecies or a full species. The most abundant and widespread species, C. serpentina, is native to

left | Common snapping turtles defend themselves from many predators with their large heads and powerful jaws with sharp edges. above | Due to the longevity of common snapping turtles, healthy populations are often composed of various age groups.

distribution

size

North America, Central America, and South America

CL 19½ in (49.4 cm)

species

Primarily aquatic, seldom basking; mostly diurnal; may hibernate underwater in mud

Chelydra acutirostris, C. rossignonii, and C. serpentina habitats

All permanent and temporary freshwater habitats including large rivers, streams, swamps, marshes, lakes, ponds, and ephemeral wetlands

52

CRYPTODIRA—Hidden-neck turtles

activity

lifespan

Over 50 years in the wild

southern Canada and most of the USA east of the Rocky Mountains. The others occur sporadically through Mexico to Honduras (C. rossignonii) and Central America to Ecuador (C. acutirostris). North American fossils of Chelydra have been discovered from as far back as the Pliocene. Snappers can live in any freshwater habitat, and frequently move overland between wetland habitats. They do not occur in large congregations but remain solitary reproduction

One clutch a year in spring; 4–109 (average 26–55) spherical eggs with leathery shells per clutch (C. serpentina); incubation period of 55–125 days; females may travel long distances overland for nesting and return to same aquatic habitat diet

Omnivorous on aquatic plants and animals, including carrion

most of their lives. Snappers vary little in appearance geographically, most having a dark gray or brownish carapace and a greatly reduced, lighter-colored plastron. The mouth has a hooked beak and all feet have strong claws. The long tail has a saw-toothed appearance on top. Their defensive response to humans and terrestrial predators when on land is to position themselves by facing the threat and hissing. If approached from behind, they arch the head and long neck rapidly backward over the front of the carapace with mouth open in an attempt to bite. They will bite underwater if grabbed but will attempt to escape if possible. River otters will prey on hibernating snapping turtles in colder climates, and alligators are predators in warm regions. Parasitic leeches (Placobdella parasitica) are often attached to the soft parts and shell. 53

CHELYDRIDAE: MACROCHELYS

ALLIGATOR SNAPPING TURTLES

above | The alligator snapping turtle is the largest freshwater turtle in North America and one of the largest in the world.

M

acrochelys has two species: M. temminckii (Western Alligator Snapper) and M. suwanniensis (Suwanee Alligator Snapper). They were originally considered a single species until genetic distinctions were recognized between them. The genus is found only in the USA. Western Alligator Snappers are found in midwestern US states centered on the Mississippi River Valley and southern states with rivers flowing into the Gulf of Mexico. Suwanee Alligator Snappers are confined to a few Gulf Coast river systems further east.

Based on fossils from as far back as the Miocene, alligator snappers once had a much more extensive geographic range in North America. Alligator snappers inhabit large rivers and associated permanently aquatic habitats including river swamps and oxbow lakes. They are less abundant than most other turtles. After entering the water as hatchlings, males never move overland and females do so only to lay eggs. Basking occurs rarely in both juveniles and adults. Both species of these enormous turtles are similar in appearance, with

distribution

size

North America

CL females 18 in (46 cm ); males 31½ in (80 cm ); up to 249 lb (113 kg), the largest freshwater turtle in North America

species

Macrochelys suwanniensis, M. temminckii habitats

Rivers, reservoirs, large lakes, and swamp floodplain forests

activity

Completely aquatic except for nesting females and hatchlings returning to the water; seldom bask out of water; diurnal and nocturnal lifespan

Over 70 years in captivity

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CRYPTODIRA—Hidden-neck turtles

above | Alligator snapping turtles are secretive animals that rarely leave the water. Left alone, they do no harm to humans.

reproduction

Usually no more than one clutch a year; 9–61 round, flexible eggs per clutch; incubation period 78–142 days diet

Omnivorous; primarily fish but aquatic plants, including nuts and fruits of trees growing alongside river systems

a dark carapace that is jagged posteriorly and has three prominent longitudinal keels. The tail is smooth, unlike those of Chelydra. Adult males grow much larger than females. The mouth has a prominently hooked beak and its crushing strength is among the most powerful of all turtles. Records exist of alligator snappers biting off human fingers. Both species lie beneath riverbanks or logs with an open-mouthed posture and wiggle an appendage on their tongue. The appendage serves as an underwater lure to attract fish as prey. Alligator snappers are the only animals in the world with this morphology and behavior.

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FAMILY: CHELONIIDAE SEA TURTLES

T

he family Cheloniidae (sea turtles) has two subfamilies, Cheloniinae and Carettinae. The former has two genera: Chelonia (Green Sea Turtle) and Natator (Flatback Sea Turtle). The latter has three genera: Caretta (Loggerhead Sea Turtle), Eretmochelys (Hawksbill Sea Turtle), and Lepidochelys (Ridley Sea Turtles). Each genus has a single species except Lepidochelys, which has two. Collectively, sea turtles are inhabitants of virtually all warm temperate and tropical oceans (Atlantic, Indian, and Pacific) and major embayments, including the Mediterranean Sea, Caribbean Sea, South China Sea, and Gulf of Mexico. Fossils of one or more have been found from the Holocene epoch back to the Late Cretaceous. The habitat of adult sea turtles is saltwater from open ocean to near-shore coastal areas. Only the females come onto land to lay eggs on sandy beaches,

although Green Turtles are fond of basking in Hawaii. All Cheloniidae have a streamlined hard carapace and front flippers for swimming. They possess salt glands in the head region to continually excrete salt from the body. Adult males and females migrate from ocean feeding areas to coastal waters near nesting beaches, where mating occurs. Some species migrate thousands of miles, many returning to the same beach region where they previously nested or even where they entered the sea as a hatchling. After nesting for one year is completed, females usually return in two to three years. Most species of Cheloniidae are protected internationally by a variety of conservation laws enacted by many countries. Nonetheless, exploitation continues in some regions by illegal removal of nesting females and their eggs.

right | Green Sea Turtles are herbivorous and are important in regulating sea grass communities in shallow marine habitats.

distribution

size

diet

Indian, Atlantic, and Pacific oceans

Up to CL 49 in (124 cm) and weight 440 lb (200 kg) for Caretta

Omnivorous, herbivorous, spongivorous, or carnivorous, depending on genus

genera

Chelonia, Natator, Caretta, Eretmochelys, and Lepidochelys

activity

habitats

reproduction

All species prefer tropical and warm temperate zone marine habitats, although several species occasionally migrate as far north as Alaska; they often enter bays, tidal creeks, and estuaries

1–8 clutches per year; 50–238 round eggs per clutch, highly variable among and within genera; females dig nests on sandy beaches

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Active year-round

CRYPTODIRA—Hidden-neck turtles

57

CHELONIIDAE: CARETTA

LOGGERHEAD SEA TURTLE

T

he genus Caretta has a single species, C. caretta, which occurs in all tropical and warm temperate seas globally, often entering cooler waters in temperate regions. Individuals have been reported in ocean waters around Alaska, Norway, eastern Russia, Chile, and South Africa. In addition to open ocean, Loggerhead Sea Turtles are found in tidal creeks and rivers, estuaries, connecting seas, and other major marine habitats around the world. Fossil C. caretta are known from Pleistocene and Pliocene deposits. Adult Loggerhead Sea Turtles get larger than other species of the Carettinae and have a disproportionately larger head. The carapace is thick and is broader in adult males than females. Shell color ranges from dark reddish or olive to dark brown. Males hold onto the females during

courtship with a large claw on each front flipper. Hatchlings have three keels down the length of the carapace. The Loggerhead Sea Turtle is the only sea turtle for which the majority of nesting beaches are in the temperate zone instead of in the tropics. Upon leaving the nest, baby Loggerhead Sea Turtles hatching on the Atlantic coast of North America migrate more than 1,000 miles (1,600 km) to the Sargasso Sea where they spend their first year or more foraging on marine life associated with the floating mat of plants. C. caretta has temperature-dependent sex determination. Eggs incubated above 90 °F (32 °C), produce females while those at lower temperatures, below 79 °F (26 °C), produce males. C. caretta is a threatened or endangered species worldwide.

right | Nesting Loggerhead Sea Turtles dig a body pit on the beach, in addition to the nest cavity, before laying eggs.

distribution

size

Indian, Atlantic, and Pacific oceans

CL up to 49 in (124 cm) and weight 440 lb (200 kg)

species

Caretta caretta habitats

Tropical and warm temperate zone marine habitats; estuaries, saltwater lagoons, bays, tidal creeks, and rivers; in contrast to other sea turtles, female Caretta commonly nest on sandy beaches in temperate zone areas

58

CRYPTODIRA—Hidden-neck turtles

activity

Primarily diurnal except for nocturnal nesting More than 33 years in captivity lifespan

reproduction

2–8 clutches per season at 2–3-year intervals; 7–220 eggs per clutch diet Omnivorous on extensive array of marine animals, including horseshoe crabs and other invertebrates; marine plants

above | The highly modified flippers of sea turtles, like this Loggerhead Sea Turtle, allow them to glide through the water with ease.

59

CHELONIIDAE: ERETMOCHELYS

HAWKSBILL SEA TURTLE

T

he genus Eretmochelys has a single species, E. imbricata, and can be found globally in all tropical and subtropical ocean habitats, from open ocean to any associated marine environments. Some turtle biologists recognize two subspecies, one in the Atlantic and the other in the Indian and Pacific oceans. Hawksbill Sea Turtles are most prevalent in shallow, near-shore habitats, especially coral reefs. They have been reported to enter rocky

underwater habitats, water around mangroves, and estuaries, whether the bottom is muddy or sandy. Hawksbills are distinctive from other sea turtles in both morphology and behavior. The carapace is the most colorful of all sea turtles, being tortoiseshell: a mottled mix of orangish-yellow and black. The head is narrow with crushing jaws and a noticeable sharp beak unlike any other sea turtle. Each front flipper has two claws.

distribution

activity

Indian, Atlantic, and Pacific oceans

Primarily diurnal, except for nocturnal nesting

species

Eretmochelys imbricata habitats

Tropical and subtropical marine habitats, near-shore lagoons, and coral reefs size

CL up to 45 in (114 cm)

60

CRYPTODIRA—Hidden-neck turtles

More than 20 years in captivity lifespan

reproduction

2–6 clutches at 2+ year intervals; 26–250 eggs in each clutch

left | Hawksbill Sea Turtles were formerly killed in large numbers to remove their scutes for ornamental tortoise-shell trinkets.

above | Coral reefs are home to Hawksbill Sea Turtles, which feed on the sponges and other organisms that grow there in profusion.

diet Omnivorous; adults often carnivorous, preying on invertebrates, primarily sponges, living in coral reefs, also jellyfish and Portuguese Man-o-War; plants include mangrove leaves and shoots, and sea grasses; algae

Like other sea turtles, Hawksbills migrate to nesting beaches but females are mostly solitary nesters now, a possible result of historical overharvest. Hawksbill Sea Turtles are notable not only for their appearance but for their diet. Much of their food is unpalatable to other marine predators by being toxic or because of the presence of glass-like sponge spicules. Hawksbills have endured the plight of other sea turtles in that both adults and eggs have been sought after for food. But a major threat has been their slaughter worldwide for their ornamental shells. E. imbricata is listed as endangered wherever it occurs. Commercial sale of Hawksbill shells is illegal, but black-market transactions occur in many areas.

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CHELONIIDAE: LEPIDOCHELYS

RIDLEY SEA TURTLES

T

he genus Lepidochelys has two species: L. kempii (Kemp’s Ridley) and L. olivacea (Olive Ridley). The origin of the word “Ridley” is unknown. Olive Ridley Sea Turtles travel to all oceans in tropical and subtropical areas and will venture as far north as Nova Scotia and the Gulf of Alaska. The range of Kemp’s Ridley Sea Turtles is centered around the Gulf of Mexico, with forays into the Atlantic. Fossils from the Pliocene of Florida may be Lepidochelys. Feeding grounds are usually in shallow coastal areas with mud or sand bottoms. Both

species are smaller than any other sea turtles. They differ from each other in body color and carapace shape. L. kempii is grayish green with a nearly rounded carapace that is wider than long in adults. L. olivacea is more olive or brownish with a heartshaped carapace. Despite their small size, both species are capable of migrating more than 3,000 miles (4,800 km). Ridley Sea Turtles sleep on the bottom in shallow ocean areas and can remain underwater for as long as four hours at a time. Kemp’s Ridley Sea Turtles nest primarily during the day whereas Olive Ridley Sea Turtles nest mainly at night. One of the most remarkable features of Ridley Sea Turtles is their communal nesting behavior, called an arribada, in which tens of thousands of females previously came ashore to nest at a single location. The numbers today are greatly reduced. L. kempii is protected as endangered under the US Endangered Species Act. L. olivacea is threatened but breeding colonies on the Pacific coast of Mexico are classified as endangered. left | Kemp’s Ridley is the smallest of the seven species of sea turtles, and like Natator, has a restricted distribution.

distribution

activity

Indian, Atlantic, and Pacific oceans

Primarily diurnal

species

lifespan

Lepidochelys kempii, L. olivacea

More than 29 years in captivity

habitats

reproduction

Tropical and warm temperate zone marine habitats; saltwater lagoons and bays; females nest on sandy beaches

1–4 clutches per nesting year, usually at intervals of 1–3 years; 9–185 eggs per clutch; both species nest communally in arribadas when females come ashore on particular beaches, although some females have solitary nests

size

CL up to 30 in (75 cm)

62

CRYPTODIRA—Hidden-neck turtles

diet

Omnivorous, eating a large variety of marine invertebrates and algae

above | Although graceful in the water, female Olive Ridley Sea Turtles struggle ashore to lay their eggs before returning to the sea.

63

CHELONIIDAE: CHELONIA

GREEN SEA TURTLE

T

he genus Chelonia has a single species, C. mydas, which occurs in all tropical and warm temperate seas globally. Green Sea Turtles in the Atlantic and Pacific oceans differ slightly genetically but are still placed in the same species. They are called Green Sea Turtles because fat deposits in the body are greenish in color. Fossils are known from as far back as the Late Cretaceous in Europe. In addition to the ocean, Green Sea Turtles are found in connecting seas, bays, and other major marine habitats around the world. The carapace is broad anteriorly, tapering posteriorly. Adults have olive, brown, or black carapaces whereas juveniles are lighter in color. Males get slightly larger than females. C. mydas can be distinguished from most other sea turtles by the presence of two large prefrontal plates between the eyes. Green Sea Turtles nest in more than 80 countries worldwide and inhabit marine waters around more than 140. Two of the largest Green Sea Turtle nesting populations in the world are found on the Great Barrier

Reef in Australia (Raine Island) and Costa Rica (Tortuguero) in the Caribbean where more than 20,000 nest each year. Green Sea Turtles were first protected under the US Endangered Species Act in 1978 and are now listed as either threatened or endangered depending on their location. CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) also considers them in need of protection worldwide, but illegal exploitation of eggs and adults continues in many areas.

right | Green Sea Turtles can be identified by two prefrontal scales between their eyes in contrast with hawksbills, which have four.

distribution

species

Indian, Atlantic, and Pacific oceans

Chelonia mydas

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habitats

size

reproduction

Tropical and warm temperate zone marine habitats; saltwater lagoons and bays; females nest on sandy beaches

CL up to 60¼ in (153 cm); weight 838 lb (380 kg)

1–8 clutches laid during a nesting year at 2–4 year intervals (usually 3 years); 3–238 (typically 100–120) per clutch

activity

Primarily diurnal lifespan

More than 31 years in captivity

CRYPTODIRA—Hidden-neck turtles

diet Omnivorous during some life stages; ranging from carnivorous on marine animals as juveniles to becoming mostly herbivorous on marine plants as adults

CHELONIIDAE: NATATOR

FLATBACK SEA TURTLE

N

atator has a single species, whose closest living relative is the Green Sea Turtle (Chelonia mydas). In contrast to all other sea turtles, Flatback Sea Turtle nesting beaches are restricted to a single country, Australia. Some migrate more than 1,000 miles (1,600 km) to return to nest along the northern perimeter of Australia. Natator hatchlings do not migrate from the nesting beaches into the deeper ocean waters but remain in the area where they hatched.

distribution

Indian Ocean, Timor Sea, Coral Sea of coastal Australia, eastern Indonesia, and Papua New Guinea species

Natator depressus habitats

Tropical to subtropical marine habitat, including near-shore

above | Although once placed in the same genus as Green Sea Turtles, Flatbacks have a greatly reduced geographic range.

The Flatback Sea Turtle has a shell that is noticeably flatter and thinner than those of Chelonia. The head, body, and carapace are gray, greenish, or a combination. The plastron is pale yellow. Hatchlings are distinctive in being up to twice as large as C. mydas hatchlings.

lagoons and bays with soft bottoms; nests on sandy beaches size

CL up to at least 39¾ in (100 cm); weight 198½ lb (90 kg) activity

Primarily diurnal lifespan

reproduction

4 clutches each nesting year at intervals of 2+ years; 18–80 eggs per clutch; individual females usually nest on the same beach each time diet

Primarily carnivorous on marine invertebrates

More than 30 years in the wild

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FAMILY: DERMOCHELYIDAE LEATHERBACK SEA TURTLE

T

he family Dermochelyidae has one genus and one species, Dermochelys coriacea, the Leatherback Sea Turtle. These turtles range throughout the oceans of the world, entering permanently cold northern waters near the southern edge of the Arctic Ocean, and cold southern waters around Tasmania. In addition to being more than twice the size of any other modern turtle in the world, D. coriacea has a distinctive suite of morphological characteristics. Scutes on the shell are absent in adults, which have a leathery, black carapace with lighter markings and seven prominent longitudinal ridges. D. coriacea has a bony skeleton but proportionally more cartilage than other sea turtles. It does not have claws on either the front or back flippers, but it

does have projecting spines that point backward in the mouth and throat to hold and guide captured prey such as jellyfish. Leatherback Sea Turtles are capable of diving deeper than 3,000 ft (1 km) and staying underwater for 1.5 hours. They are able to tolerate such cold, deep waters by generating their own body heat, an unusual trait in turtles. A unique reproductive feature near the top of each nest cavity is shelled eggs filled only with albumin but no yolk or embryo. The function of these yolkless eggs is unknown. The species is endangered globally as populations are declining throughout their range from various forms of human impacts, including dietary complications from ingesting floating plastic bags that resemble jellyfish.

right | Another name for the Leatherback is the “luth” because its shell shape is similar to the musical instrument the lute.

activity

Dermochelys coriacea

Active both day and night

habitats

lifespan

Open ocean and connecting marine habitats including the Mediterranean Sea

Over 19 years confirmed in the wild but presumably much longer

size

distribution

World’s oceans as far south as Tasmania and Chile and north to Iceland and the Barents Sea

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species

CL 96 in (243.8 cm); weight 2,016 lb (916 kg)

CRYPTODIRA—Hidden-neck turtles

reproduction 1–14 clutches per nesting season at 2–4 year intervals; 23–166 round eggs in each

clutch; nest on sandy beaches diet

Carnivorous on a variety of marine invertebrates, especially jellyfish

67

FAMILY: DERMATEMYDIDAE CENTRAL AMERICAN RIVER TURTLE

T

his family has one species, Dermatemys mawii, found in southern Mexico, much of Belize, and northern Guatemala. Formerly more widespread, almost 20 extinct fossil genera of the Dermatemydidae have been described from the Jurassic and Cretaceous to Miocene of Europe, North America, and eastern Asia. However, no fossils of D. mawii have been found to date. Central American River Turtles occur in large rivers, oxbow lakes, and possibly some mangrove swamps. This is a large species with thin scutes covering the brownish to grayish carapace. Males have golden pigment on the top of their heads. Highly aquatic and not known to bask, Dermatemys are able to extract some oxygen from water through the mucosal lining of their mouths

and throats, allowing them to remain submerged without surfacing to breathe for long periods of time. Males do not leave the water and females only do so to nest short distances of less than 10 ft (3 m) from their aquatic habitats. They nest so close to the water’s edge during the rainy season that nests are often inundated for up to six weeks. However, they still have high hatching success. When placed on land, Dermatemys are very clumsy and have difficulty elevating their heads and necks. However, they are strong swimmers and extremely wary of humans. Dermatemys are herbivorous, feeding at night on rising tides. During the rainy season they swim into flooded forests to forage. Overharvesting for human consumption has reduced populations, making Dermatemys one of the most endangered turtles in the world.

right | Central American River Turtles are sexually dichromatic, with males (a male shown here) having different colors from females.

distribution

activity

Mexico, Belize, Guatemala

Feeding occurs mostly at night

species

lifespan

Dermatemys mawii

Over 11 years in captivity, likely much longer in the wild

habitats

68

Freshwater systems, often under tidal influence; large rivers, lakes, oxbows, possibly some mangrove swamps

reproduction

size

diet

25½ in (65 cm); weight 55 lb (25 kg)

Entirely herbivorous with a diet of tree leaves, grass, and fruits

CRYPTODIRA—Hidden-neck turtles

1–4 clutches per year; 10–24 eggs per clutch

69

FAMILY: KINOSTERNIDAE MUD AND MUSK TURTLES

T

he family Kinosternidae is divided into two subfamilies, Kinosterninae and Staurotypinae, with four genera and 30 species, including K. vogti, described in 2018. The subfamilies listed here have been proposed as separate families by some taxonomists. A fifth genus, Cryptochelys, has been proposed to differentiate six species traditionally listed in the genus Kinosternon. Kinosternids are confined to the New World, ranging from Canada to South America. Most species are found in Mexico and Central America. They live in a diversity of habitats from temperate regions in the eastern USA, to southwestern deserts, through the southern tropics to the Amazon Basin. Fossils are known from as early as the Paleocene. Except for Staurotypus, which is much larger, most kinosternids are small, apple-sized turtles. Most have some degree of hinging on the plastron that enables some species to close their shells for protection.

Males of many species have a claw at the tip of their tail, which presumably functions during courtship activities to hold on to females. Several species have environmental sex determination in which females are produced at cool and warm incubation temperatures whereas males are produced at intermediate temperatures. In contrast, Claudius and Staurotypus have genetic sex determination. Eggs of some Kinosternon undergo embryonic diapause and do not hatch for about one year after oviposition. Embryonic development may be delayed 265 days until triggered by changing temperatures during incubation. Kinosternon living in ephemeral streams and ponds in southwestern deserts and the Great Plains of North America have variable abilities to estivate during the dry season. If conditions dictate, some species can stay underground for up to two years.

right | Although few members of the mud and musk turtle family have a tendency to bask, this yellow mud turtle defies convention.

distribution

size

diet

North, Central, and South America

CL just over 4 in (10 cm) in Kinosternon vogti to 15¾ in (40 cm) and weight 22 lb (10 kg) in Staurotypus

Both omnivorous and carnivorous species on fish and other aquatic animals, including carrion; Staurotypus triporcatus eats mollusks and is also “cannibalistic” on some species of Kinosternon

genera

Claudius, Kinosternon (including Cryptochelys), Staurotypus, and Sternotherus

activity

Primarily diurnal

habitats

reproduction

Rivers, streams, swamps, springs, lakes, ponds, stock tanks

Up to 6 clutches a year; 1–12 hard-shelled, elliptical eggs per clutch

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CRYPTODIRA—Hidden-neck turtles

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KINOSTERNIDAE: KINOSTERNON

MUD TURTLES

right | This hatchling Striped Mud Turtle has stripes on the head and carapace as is typical in the southern portion of the range.

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he genus Kinosternon has 21 species and is found from the northeastern, central, and western USA southward to below the Amazon region of South America. Six species occur in the USA, three in South America, and the rest are found in Mexico and Central America, with some overlapping distributions. Fossil Kinosternon are reported from as far back as the Miocene of North America and the Pleistocene of South America.

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Most mud turtles are relatively small, brownish, typically nondescript turtles that seldom leave the water except to lay eggs or bask. Some species have yellow stripes or other patterns on the head. The sparsity of distinguishing features renders species classification difficult without locality data or careful measurement of shell dimensions and ratios. Several species live in ephemeral wetlands in the Sonoran and Chihuahuan deserts of North

distribution

habitats

Northeastern and central USA to South America

Lakes, rivers, streams, ponds, stock tanks, and swamps

species

size

Kinosternon abaxillare, K. acutum, K. alamosae, K. angustipons, K. baurii, K. chimalhuaca, K. creaseri, K. dunni, K. durangoense, K. flavescens, K. herrerai, K. hirtipes, K. integrum, K. leucostomum, K. oaxacae, K. scorpioides, K. sonoriense, K. steindachneri, K. stejnegeri, K. subrubrum, and K. vogti

CL 4 in (10 cm) for K. vogti to over 7¾ in (20 cm) in some species

CRYPTODIRA—Hidden-neck turtles

lifespan

49 years in captivity (K. baurii); 50 years in the wild (K. subrubrum)

above | In the northern portion of their range, Striped Mud Turtles may or may not have yellow stripes on the head and carapace.

reproduction

Typically 1–3 (as many as 6) clutches a year; 1–12 eggs depending on species; eggs are oval-shaped with brittle shells; eggs do not hatch for months, with hatchlings overwintering in the nest and emerging a year later in several species

America, including K. durangoense, K. hirtipes, K. sonoriense, and K. stejnegeri. This is unusual as comparatively few of the world’s turtles live in deserts. Turtles of all kinds prefer moist environments. Mud turtles deal with egg development in arid environments by delaying embryonic development in the egg. After a desertdwelling female mud turtle deposits her eggs, during the summer rainy season, the embryos remain dormant for months. Hatching occurs about a year later after changes in environmental temperatures trigger the completion of embryonic development and signal the return of seasonal rains. The ability to estivate for months during dry times is another crucial adaptation for desert-dwelling mud turtles.

diet

Most eat aquatic plants and animals, including carrion

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KINOSTERNIDAE: STERNOTHERUS

MUSK TURTLES

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he genus Sternotherus has six species including S. intermedius, described in 2018 based on genetic evidence. The most common and widespread species, S. odoratus, is found from southern Canada and throughout most of eastern North America, whereas the others have much smaller ranges restricted to the southeastern USA. Fossil Sternotherus are reported from as far back as the Pliocene. Musk turtles produce a foul-smelling yellowish liquid from Rathke’s glands located on the bridge of their shells when disturbed, which may discourage

| Although small, musk turtles like this stinkpot have foul dispositions to match their foul odor and will bite vigorously.

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distribution

size

Southern Canada and most of eastern USA

CL 5 in (12.5 cm) for S. depressus to 7 in (17.5 cm) for S. carinatus

species

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Sternotherus carinatus, S. depressus, S. intermedius, S. minor, S. peltifer, and S. odoratus

lifespan

habitats

reproduction

Lakes, rivers, streams, ponds, and swamps

Typically 1–3 (as many as 5) clutches per year; 1–5 (maximum 13) eggs per clutch, depending on species; eggs are oval-shaped and have brittle shells;

CRYPTODIRA—Hidden-neck turtles

54 years in captivity; 28 years in the wild (S. odoratus)

left | If a turtle drops into a boat on a southern USA river, it may be a Loggerhead Musk Turtle that was basking in the branches.

above | Razor-backed Musk Turtles are aptly named for their strongly keeled carapace that may be adapted for swift-flowing streams.

certain predators. All are small, mostly nondescript brownish turtles that seldom leave the water except to lay eggs or bask. The latter behavior is welldeveloped in S. carinatus, S. minor, and S. odoratus. The Common Musk Turtle (S. odoratus) is distinctive in having two yellow stripes on each side of the head. A musk turtle plastron is noticeably

incubation 45–122 days; most eggs are laid in late spring and early summer; many hatchlings overwinter in the nest and emerge in the spring diet

Most eat aquatic plants and animals, including carrion

smaller than the carapace and has an anterior hinge. Some musk turtles are noted for their atypical egg-laying behavior in which females do not dig nests but may deposit eggs near water or under logs or stumps. Also reported are communal nests in which several females deposit eggs in the same spot. Imperiled from stream degradation caused by coal mining, S. depressus has one of the smallest geographic ranges of any North American turtle, living in a single river system in central Alabama. The shell is depressed, allowing an individual to squeeze into rock crevices. The species has threatened status under the US Endangered Species Act.

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KINOSTERNIDAE: CLAUDIUS

NARROW-BRIDGED MUSK TURTLE | Known as chopontils in Mexico, Narrow-bridged Musk Turtles will readily bite when threatened by a predator, including humans.

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C

laudius is a genus with only one species, C. angustatus, and a small geographic range in southern Mexico and western Central America. Adults are dark-colored, but juveniles can be strikingly patterned, including starburst markings on the carapace. Unlike other kinosternids, Claudius lacks a hinged plastron. Instead, the extremely narrow bridge connecting plastron to carapace has a flexible articulation, allowing the entire plastron to tilt on its long axis. This allows for retraction of the huge head

distribution

size

Southern Mexico, Guatemala, and Belize

CL 6½ in (16.5 cm)

species

Diurnal

Claudius angustatus habitats

Ponds, flooded fields, forests, marshes, shallow lakes, and other intermittently flooded wetlands

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with the mouth wide open in a defensive posture. The pugnacious behavior of Claudius begins upon emergence from the egg. The beak has a pointed cusp on each side to puncture and grasp crustaceans. What causes a hatchling to be a male or a female is unknown as sex determination is not a result of incubation temperature and sex chromosomes are absent. Eggs are laid in the rainy season and embryonic development is delayed until drying conditions trigger development. They estivate during the dry season.

CRYPTODIRA—Hidden-neck turtles

activity lifespan

Over 16 years in captivity reproduction

1–8 eggs per clutch; eggs oblong and brittle

diet Opportunistic carnivore on invertebrates including insects, crabs, and some snails, including carrion

KINOSTERNIDAE: STAUROTYPUS

GIANT MUSK TURTLES

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he genus Staurotypus contains two species, S. salvinii (Pacific Coast Giant Musk Turtle) and S. triporcatus (Northern Giant Musk Turtle), both with small geographic ranges in southern Mexico and western Central America. Their ranges are divided by the highlands separating the Caribbean and Pacific lowlands in the vicinity of the Isthmus of Tehuantepec in Mexico. Miocene fossils have been found in Panama. S. salvinii lives in coastal lagoons, marshes, and temporary pools, including polluted ones. S. triporcatus, the largest kinosternid, prefers permanent water habitats and achieves greatest abundance in shallow, slow-moving rivers. Adults are dark-colored, but juveniles, especially hatchlings, can be strikingly patterned with contrasting light and dark markings on the carapace or plastron. Three longitudinal keels are present on the carapace, and the plastron has an anterior hinge. Members of the genus are not known to bask but may estivate during the dry season. Staurotypus is not pugnacious like Claudius but exudes pungent musk from

Rathke’s glands when disturbed. Juveniles appear to be clumsy on land and adults are poor swimmers. Sex is determined genetically by XX/XY sex chromosomes. S. triporcatus produces one to six clutches of 42 or more eggs per season. S. salvinii lays up to three clutches per year. Based on examination of enlarged follicles, clutch size ranges from six to ten eggs. Nesting in S. salvinii is thought to occur in October, near the end of the rainy season. S. triporcatus nests from September to March and hatching is coincident with thunderstorms in June. Reproductive differences are thought to result from variation in precipitation patterns between the Caribbean and Pacific coasts. | The genus name for the Pacific Coast Giant Musk Turtle is Staurotypus, which refers to the reduced, cross-shaped plastron.

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distribution

size

reproduction

Southern Mexico, Guatemala, El Salvador, Honduras, and Belize

CL up to 10 in (25 cm) in S. salvinii to 15¾ in (40 cm) in S. triporcatus

species

activity

1–6 clutches per year of 4–18 oblong, brittle eggs per clutch (S. triporcatus); 1–3 clutches of 6–10 eggs (S. salvinii)

Staurotypus salvinii, S. triporcatus

Some estivate during the dry season

habitats

lifespan

Rivers, coastal lagoons, ponds, oxbow lakes, mangrove swamps, and marshes

Over 26 years in captivity (S. salvinii); over 33 years in captivity (S. triporcatus)

diet

Opportunistic omnivore; seeds, fruit, mollusks, insects, fish; S. triporcatus is known to eat Kinosternon leucostomum and other turtles

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FAMILY: EMYDIDAE SEMI-AQUATIC POND AND MARSH TURTLES

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ith 12 genera and 53 species, the Emydidae is one of the largest families of turtles, although the taxonomy of some species and genera is still debated. It is divided into two subfamilies, Emydinae and Deirochelyinae. With one exception, emydids are confined to the New World, ranging from southern Canada to southern South America. Several species of Trachemys are found on various Caribbean islands and it is the only genus in the family found in South America. European pond turtles (Emys) are found in Europe, extreme western Asia, and North Africa. Emydids are believed to have arisen in the Eocene. Habitats range from fully aquatic to semi-aquatic to terrestrial, depending on species and sometimes season. One species, the Diamond-backed Terrapin (Malaclemys terrapin) is restricted to brackish estuaries and salt marshes. Most other members of the family

live in rivers, lakes, marshes, and ponds. Box turtles (Terrapene) are terrestrial. Most species in the family have a relatively low carapace that streamlines them for living and swimming in aquatic habitats. The majority have inflexible plastrons, but Blanding’s Turtles (Emydoidea blandingii), European pond turtles (Emys), and box turtles (Terrapene) have hinged plastrons that allow members of the latter genus to pull into their shells when threatened. Many species exhibit sexual size dimorphism with adult females being larger than adult males. This is especially prominent in map turtles (Graptemys). Because of the popularity of colorful hatchling Red-eared Slider Turtles (Trachemys scripta elegans), they have been introduced on all continents but Antarctica and persist in many of the world’s temperate and tropical islands, often competing with native turtles.

right | Like hatchlings and juveniles of many turtle species, this Painted Turtle is more vividly colored than most adults.

distribution

size

diet

Europe, western Asia, North, Central, and South America

CL from 4½ in (11.5 cm) in Bog Turtles (Glyptemys muhlenbergii) to over 16 in (40 cm) in Pseudemys and some Trachemys

Pseudemys are strongly herbivorous, especially as adults; Malaclemys are carnivorous, eating snails, crabs, and bivalves; Trachemys are more carnivorous as juveniles, becoming more herbivorous/ omnivorous as adults

genera

Actinemys, Chrysemys, Clemmys, Deirochelys, Emys, Emydoidea, Glyptemys, Graptemys, Malaclemys, Pseudemys, Terrapene, and Trachemys habitats

Rivers, streams, lakes, ponds, estuaries, salt marshes, and forests

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activity

Primarily diurnal reproduction

Up to 6 clutches a year in some species; up to 35 eggs per clutch

CRYPTODIRA—Hidden-neck turtles

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EMYDIDAE: CHRYSEMYS

PAINTED TURTLES

| Adult Painted Turtles lose some of the bright coloration of juveniles but are still some of the most beautiful turtles.

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his genus has two species, Chrysemys picta (Painted Turtle) and C. dorsalis (Southern Painted Turtle), the former with three subspecies. This arrangement has not yet gained universal acceptance since all four taxa were long recognized as subspecies. Hypotheses about the evolution and taxonomic diversification of this genus are based on glacial advances during the Pleistocene that

pushed northern populations into isolation in southern refugia. This is the only turtle genus in North America with a range that extends from the Atlantic coast to the Pacific and is one of only two genera of emydids (including Actinemys) found on the Pacific coast of the continent. Isolated populations are found in the Desert Southwest and into Mexico.

distribution

size

Canada, USA, and Mexico

CL 6 in (15.3 cm) for males; 10 in (25.4 cm) for females

species

Chrysemys dorsalis, C. picta habitats

Most freshwater habitats; ponds, lakes, marshes, swamps, oxbows, and other slow-moving water bodies

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CRYPTODIRA—Hidden-neck turtles

activity

Diurnal although nesting may be completed after dark lifespan

Possibly up to 61 years in the wild but typically 30–40 years

Painted Turtles are fond of shallow wetlands like ponds, lakes, marshes, and even slow-moving rivers. They prefer permanent aquatic habitats with soft bottoms, aquatic vegetation, and plentiful basking sites. Painted Turtles are some of the most beautiful turtles in the world with smooth green to dark carapaces with bright red markings on the marginal scutes and limbs, and yellow stripes and blotches on

reproduction

Up to 5 clutches per year and 1–23 eggs per clutch (C. picta); C. dorsalis 1–11 eggs per clutch diet

Omnivorous, eating many plants and animals found in their habitat, including scavenging

above | Males of some species like this Painted Turtle have very long foreclaws that play a role in the courtship ritual.

the head and neck. The Western Painted Turtle (C. picta bellii) has a bright reddish plastron with intricate, black, concentric vermiculations. Males have long claws used in courtship. Hatchling sex is determined by incubation temperature. Painted Turtles are very conspicuous by virtue of their fondness for basking, and large numbers can be observed in some habitats on warm sunny days. A great deal has been published about Painted Turtles because of their wide distribution and abundance in some areas.

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EMYDIDAE: DEIROCHELYS

CHICKEN TURTLES

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he genus Deirochelys contains a single species, D. reticularia (Chicken Turtle), with three subspecies. The geographic range of D. reticularia is mostly in southern states of the USA that border the Atlantic Ocean and Gulf of Mexico, with an extension slightly north in the Mississippi River Valley. Fossil D. reticularia have been found in

Pliocene and Pleistocene deposits and an extinct species is known from the Miocene, but none are outside the current range. Chicken Turtles frequent a variety of wetland habitats such as swamps, ponds, and small streams, as well as seasonal wetlands that may dry completely. The species is almost exclusively

distribution

Southern USA

species

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size

CL up to 10 in (25.4 cm) in females; 6½ in (16.5 cm) in males

Deirochelys reticularia

activity

habitats

Active in the morning and evening hours

Heavily vegetated seasonal wetlands; edges of swamps, marshes, ponds, lakes, and slow-moving streams

lifespan

CRYPTODIRA—Hidden-neck turtles

13 years in captivity and maximum 21 years in the wild

left | Chicken Turtles are characterized by a single broad yellow stripe on each forelimb, while the hindlimbs mimic striped pants.

above | Like other turtles in the family Emydidae, Chicken Turtles are fond of basking on sunny days to regulate their temperature.

reproduction

1–4 clutches per year; 1–19 oval-shaped eggs per clutch diet

Carnivorous on aquatic invertebrates: insects, snails, crayfish, and spiders; tadpoles of many species of frogs and toads

carnivorous, typically eating only live, mostly invertebrate prey. Males tend to hibernate on land whereas females remain in the water if available. Adults have a smooth, oval-shaped carapace that is widest posteriorly. The basic color is brownish with a yellowish reticulated pattern on the carapace. The plastron is yellow and has no hinge. In proportion to body length, the neck of D. reticularia is extremely long. Females are much larger than males. The species is also distinctive in having one of the shortest lifespans ever documented for a turtle species. The Chicken Turtle is one of the very few North American turtles that lays its eggs in fall and winter rather than spring and summer. In Florida they may nest year-round. Individual females sometimes carry a clutch of eggs from fall to late winter before depositing them. Hatchlings emerge from the nest in spring, some clutches spending almost a year and a half underground. 83

EMYDIDAE: GRAPTEMYS

MAP AND SAWBACK TURTLES

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raptemys is one of the most diverse genera in the Emydidae with 14 species, two of which have subspecies. Despite widespread acceptance of the high species diversity, some taxonomists think too many species are recognized. They are commonly called map turtles or sawbacks, due to map-like patterns on their carapaces and distinctly knobbed or pointed vertebral keels present on some.

Map turtles are restricted to the eastern USA and southeastern Canada, where most species live in river systems and large creeks. All species occur in rivers that ultimately drain into the Gulf of Mexico apart from G. geographica (Northern Map Turtle) which also occurs in some tributaries to the Atlantic Ocean. A few fossils are known from Pleistocene deposits.

distribution

habitats

Eastern USA and southeastern Canada

Rivers, creeks, and lakes

species

size

Graptemys barbouri, G. caglei, G. ernsti, G. flavimaculata, G. geographica, G. gibbonsi, G. nigrinoda, G. oculifera, G. ouachitensis, G. pearlensis, G. pseudogeographica, G. pulchra, G. sabinensis, and G. versa

From CL 4 in (11 cm) for male G. flavimaculata to 13 in (33 cm) for female G. barbouri activity

Primarily diurnal lifespan

Over 45 years in captivity; over 30 years in the wild

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CRYPTODIRA—Hidden-neck turtles

left|

The intricate yellow and black markings illustrated on this Black-knobbed Sawback turtle are typical of the genus.

left | Like many Graptemys, Yellow-blotched Sawbacks of the Pascagoula River are restricted to a single river drainage.

right | Mississippi Map Turtles are distinguished by a curved yellow stripe behind each eye in addition to linear neck stripes.

Map turtles in the southeastern USA exhibit “drainage-specific endemism” in which adjacent river systems often have different species because rising and falling sea levels during glacial–interglacial periods connected and isolated river systems at various times. Ancestral species became separated and eventually evolved into different species. Map turtles are highly aquatic, leaving the water only to bask or lay eggs. They exhibit strong sexual size dimorphism with adult females becoming much

reproduction

1–22 eggs, depending on species; incubation 52–85 days diet

Most species are omnivores; typical foods include insects, worms, fish, aquatic vegetation; species with broader jaws also consume mollusks and snails

larger than adult males. In addition, females of some species exhibit disproportionately larger heads than males and favor hard-shelled prey like freshwater mollusks that need to be crushed whereas the males eat soft-bodied prey like insects. Other species have narrower heads reflecting dietary preferences. No more than three species occur together in a river system; a large-headed species often co-exists with a narrow-headed one. Nesting typically occurs during the daytime from April to July. 85

EMYDIDAE: MALACLEMYS

DIAMOND-BACKED TERRAPIN

left | Some Diamondbacked Terrapin populations often have bulbous or knobby projections on the carapace like some Graptemys.

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he genus Malaclemys contains a single species, M. terrapin (Diamond-backed Terrapin.) Seven subspecies have been described but only four were supported in the most recent review of variation. Individual variability in appearance is high and assignment to a particular subspecies is often difficult unless the locality is known. Diamondbacked Terrapins occur along the Atlantic and Gulf coasts of North America from New England to Texas. An isolated population of unknown origin is in Bermuda. Fossil Malaclemys have been found in Pleistocene deposits along southern coasts within the current geographic range of the species.

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Diamond-backed Terrapins are distinctive among the world’s turtles in being the only species to spend their entire life from hatchling to adult in brackish waters. Individuals occasionally venture into the ocean for short periods and into freshwater adjacent to brackish water but are not permanent residents of either extreme. Some populations persist in impoundments that remain brackish due to periodic flooding by sea water. Terrapins are variable in appearance, ranging from a carapace color of light gray to black and occasionally brown or tan, sometimes with yellowish spots. Conspicuous concentric annual growth rings are obvious on

distribution

size

Northeastern to southern coastal margin of USA; Bermuda

CL to 5½ in (14 cm) in males and to 9¼ in (23.8 cm) in females

species

activity

Malaclemys terrapin

Diurnal

habitats

lifespan

Restricted to brackish water in coastal estuaries; salt marshes, tidal creeks and rivers, mangrove thickets, and impoundments

At least 33 years in the wild

CRYPTODIRA—Hidden-neck turtles

each carapace scute. Females are much larger and have proportionally larger heads. Malaclemys was the turtle most extensively exploited commercially for food in North America until the early twentieth century, resulting in rapid depletion of populations throughout the range and efforts to cultivate the species in captivity. The species is given various levels of protection in different coastal states but is not protected under the US Endangered Species Act.

reproduction

Up to 5 clutches a year (usually 1–2); 1–23 oval-shaped, leathery eggs; clutch sizes are greater in northern populations, but eggs are larger in the southern portion of the geographic range

| Diamond-backed Terrapins are unlike other members of their subfamily in not having yellow or red head and limb stripes.

top

above | Diamond-backed Terrapins have a more bewildering array of color decorations among individuals than most turtles.

diet

Carnivorous, capturing live aquatic invertebrate prey, especially crustaceans and mollusks. Plant matter is occasionally eaten, perhaps incidentally

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EMYDIDAE: PSEUDEMYS

COOTERS

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he genus has eight currently recognized species. Collectively these turtles are called cooters (presumably derived from the word “kuta” that means turtle in the African Bambara and Malinké languages). Found only in the USA and Mexico, Pliocene and Pleistocene fossils are known for several species. Cooters are some of the largest members of the family Emydidae. Adult females are larger than males in all species. Shell shape varies according to the aquatic habitat. Cooters living in large streams and rivers have more streamlined carapaces than those in still-water habitats. Some species are known to hybridize and the taxonomic relationships of species in the genus are controversial and unresolved.

Three species of “red-bellied turtles” (P. alabamensis, P. nelsoni, and P. rubriventris) have reddish plastrons, especially as hatchlings, and notched upper jaws with tooth-like cusps on either side. Cusps are also visible on P. texana. The range of P. gorzugi extends into northeastern Mexico.

right | Cooters are herbivorous as adults and their diet includes algae, which cover rocks in some aquatic habitats.

distribution

USA and northern Mexico species

Pseudemys alabamensis, P. concinna, P. floridana, P. gorzugi, P. nelsoni, P. peninsularis, P. rubriventris, and P. texana

activity

Rivers, oxbow lakes, large streams, ponds, and isolated wetlands

Up to 25 years in the wild

habitats

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size CL up to 17¼ in (43.7 cm) in females of some species

CRYPTODIRA—Hidden-neck turtles

Diurnal although nesting may be nocturnal lifespan

above | Northern Red-bellied Cooters live farther north than any other Pseudemys, with an isolated population in New England.

reproduction

Typically 1–2 (maximum 6) clutches per year; up to 35 elongated eggs per clutch; P. concinna suwanniensis, P. floridana, and P. peninsularis dig a satellite nest on each side of the main chamber and lay eggs in those as well diet

Adults are mostly herbivorous to somewhat omnivorous with juveniles being more carnivorous

Pseudemys alabamensis, P. rubriventris, and P. concinna suwanniensis have restricted geographic distributions. All species are characterized by bright-yellow stripes on the head and limbs. These highly aquatic turtles usually leave the water only to lay eggs or bask on rocks and logs. The nests of some are often characterized by a central chamber with smaller satellite chambers. The reasons for the side chambers are unknown, but they possibly distract egg predators from the main nest chamber. P. nelsoni sometimes deposits eggs in American Alligator (Alligator mississippiensis) nests. The sex of hatchlings of some species is determined by incubation temperature. P. alabamensis is protected under the US Endangered Species Act.

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EMYDIDAE: TRACHEMYS

SLIDER TURTLES

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rachemys has 15 species, more than any other genus in the family Emydidae. The genus also has one of the widest geographic ranges of any New World genus of turtles: one or more species of slider turtle is native from the US Midwest to Mexico, the West Indies, Central America, and South America to eastern Brazil, Argentina, and Uruguay. Fossils are known from the Pleistocene and Miocene of North America. Although T. scripta is not native outside North America, the Red-eared Slider subspecies (T. scripta elegans) has been introduced and become established

in aquatic habitats throughout the world because of the sale of millions of hatchlings by the pet trade. It is found in dozens of countries and often considered an invasive species competing with native turtles. Slider turtles inhabit virtually every freshwater aquatic habitat, whether permanent or temporary, within their extensive natural range. They openly bask on logs and shorelines. Slider turtles are similar in general appearance throughout their range in having a greenish, olive, brown, or black carapace with yellow markings. Yellow stripes are usually present on the head and legs. The most

left | Male sliders in North America become melanistic as they get older and larger, losing their formerly colorful markings.

distribution

Central and southeastern USA, Central America, Caribbean, and South America species

Trachemys adiutrix, T. callirostris, T. decorata, T. decussata, T. dorbigni, T. gaigeae, T. grayi, T. nebulosa, T. ornata, T. scripta, T. stejnegeri, T. taylori, T. terrapen, T. venusta, and T. yaquia habitats

Almost all freshwater habitats; rivers,

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CRYPTODIRA—Hidden-neck turtles

streams, ponds, lakes, swamps, and temporary wetlands size

CL greater than 19¾ in (50 cm) in some species activity

Primarily diurnal lifespan

More than 41 years in captivity

widespread species, the Common Slider (T. scripta), has a distinctive yellow or red blotch or stripe behind the eye. Females get much larger than males in most northern species, and in much of the USA adult males often become melanistic, with black pigment on the carapace, head, and limbs. Like Painted Turtles, adult male Common Sliders in most of the USA develop elongated foreclaws used in courtship behavior. Males of some neotropical species have shorter claws but elongated and upturned snouts and different courtship behavior.

above | Trachemys, the genus represented by this Big Bend Slider, has more species than any other genus in the family Emydidae.

| Because of their beauty and popularity in the pet trade, Red-eared Slider Turtles have been introduced all over the world.

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reproduction

Highly variable due to widespread geographic area and high number of species. In T. scripta, one of the most thoroughly studied turtles in the world, 1–5 clutches each year; 1–30 flexible, elongate eggs per clutch diet Carnivorous as juveniles becoming omnivorous after first year; many aquatic plants, animals, and carrion

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EMYDIDAE: CLEMMYS

SPOTTED TURTLE

T

he genus contains only one species, Clemmys guttata, although Actinemys (two species) and Glyptemys (two species) were formerly included in Clemmys. Spotted Turtles are found in the eastern USA and southeastern Canada. Their range is divided into two major regions, one generally east

of the Appalachian Mountains from Maine to Florida, and another around the Great Lakes where they live in shallow wetlands. They prefer habitats with clear water, soft bottoms, and aquatic vegetation. As wetlands dry up during the summer, Spotted Turtles estivate in adjacent terrestrial habitats. They return to wetlands in the spring. Limited fossil remains are known only from the Pleistocene of the USA, including in Louisiana and Wisconsin, outside their current range. These small, jet-black turtles have attractive yellow spots on the head and carapace. Hatchlings are born with one spot on each major carapace scute. Spots increase in number as the animal matures and have been suggested to mimic the floating aquatic plant duckweed (Lemna; Spirodela), providing a form of camouflage. Incubation temperature determines the sex of hatchlings. Most hatchlings emerge the same year as nesting after 50–90 days of incubation, but some overwinter in the nest and emerge

distribution

size

Canada and USA

CL 5¾ in (14.3 cm)

species

activity

Clemmys guttata

Diurnal; most active in the spring during cool temperatures on sunny days, but timing varies geographically

habitats

Marshes, fens, bogs, swamps, and other shallow, sometimes ephemeral, wetlands

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CRYPTODIRA—Hidden-neck turtles

lifespan

Over 30 years in the wild

left | Spotted Turtles, like other US species pushed south during ice ages, reinvaded northern regions after the glaciers melted.

above | Because of their beauty, Spotted Turtles are overexploited by illegal collectors and this has decimated populations.

reproduction

1–2 clutches per year; 1–14 elliptical eggs per clutch; eggs are sometimes laid in tussocks of emergent vegetation or hummocks of moist sphagnum moss in wetland habitat

the following spring. Hybridization has been noted between this species and Glyptemys muhlenbergii. Destruction of wetland habitats and road mortality are continuing threats to this species. In addition, Spotted Turtle populations have declined in many parts of the range due to their popularity in the pet trade and subsequent unsustainable removal from the wild.

diet

Omnivorous on various plants, invertebrates, and carrion

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EMYDIDAE: EMYS

EUROPEAN AND SICILIAN POND TURTLES

T

he genus Emys has two species, E. orbicularis (European Pond Turtle) and E. trinacris (Sicilian Pond Turtle). E. trinacris is endemic to the island of Sicily, but E. orbicularis has a wide geographic range from Africa to extreme western Asia and displays extensive regional variation. Turtle taxonomists have proposed as many as 7–14 subspecies for E. orbicularis.

| European Pond Turtles have a massive distribution with a range including parts of three continents.

below

distribution

size

North Africa, Europe, and western Asia

CL 6½ in (16.5 cm) in males and 8 in (20 cm) in females

species

Emys orbicularis, E. trinacris habitats

Most freshwater habitats; ponds, lakes, marshes, swamps, canals, and other slow-moving water bodies

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CRYPTODIRA—Hidden-neck turtles

activity

Diurnal, but nesting may start at nightfall lifespan

70 years in captivity (an unsubstantiated record of 120 years has been reported)

Emys is the only Old World genus in the family, occurring in North Africa, Europe, and western Asia. European Pond Turtles range farther north than any freshwater or terrestrial turtle in the world, up to about latitude 58 degrees north. Much of its morphological variation resulted from glacial advances forcing populations into southern refugia where they differentiated. This was followed by Holocene expansion into its modern distribution. Fossils are known from the Miocene of central Asia. Pond turtles are found in shallow wetlands like ponds, lakes, marshes, and slow-moving rivers. They prefer permanent aquatic habitats with soft bottoms and aquatic vegetation. They bask frequently, preferring small islets surrounded by water rather than on shorelines. The olive to dark carapace, head, and neck are often patterned with a profusion of spots and radiating patterns remarkably similar to the North American turtles of the genus Actinemys and Emydoidea. However, Emys and Emydoidea have an anteriorly hinged plastron and a bridge connecting the carapace and plastron with ligaments.

Hatchling sex is determined by incubation temperature. Populations are considered to be threatened in Europe due to habitat loss, pollution, and introduced Red-eared Sliders (Trachemys scripta) that compete for basking spaces and food.

reproduction

3–20 eggs per clutch diet

Omnivorous tending toward carnivory

| Turtles of the genus Emys have a moderately developed hinge between the pectoral and abdominal scutes of the plastron.

above right

95

EMYDIDAE: ACTINEMYS

PACIFIC POND TURTLES

V | Pacific pond turtles in the arid Mojave Desert have declined dramatically in recent years due to human overuse of water.

below

ariously placed in the genera Clemmys, Actinemys, and Emys since the 1900s, debate continues about whether these turtles should be classified as Actinemys or Emys. Regardless of generic classification, two species of Pacific pond turtles are currently recognized. The northernmost species, A. marmorata, ranges from Washington state into parts of southern California. A. pallida ranges from southern California into Baja California, Mexico. Actinemys and Chrysemys (painted turtles) are the only emydid turtle genera in North America whose distributions include the Pacific coast. The name pond turtle is a misnomer as Actinemys most frequently occur in streams and rivers. Populations in southwestern Canada were extirpated in the mid-1960s. Relict populations of Pacific pond turtles are found in several drainages emptying into the Great Basin and Mojave deserts. Miocene to Pleistocene fossils have been reported from many sites throughout their modern range, mostly along the Pacific slope. Pleistocene fossils, tentatively referable to A. pallida, have been collected near southern Death Valley, California, a location too extreme for Actinemys survival now.

distribution

size

Western USA and northwestern Mexico; formerly southwestern Canada

CL 9½ in (24.1 cm)

species

Diurnal; semi-aquatic

Actinemys marmorata, A. pallida habitats

Streams and rivers (draining into the Pacific Ocean); deserts (Great Basin and Mojave; scattered relict populations)

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CRYPTODIRA—Hidden-neck turtles

activity

lifespan

Over 27 years in captivity; possibly over 50 years in the wild

above | Pacific pond turtles are one of the few species of freshwater turtles found west of the Rocky Mountains in North America.

reproduction

Up to 2 clutches per year; 1–13 elliptical hard-shelled eggs per clutch diet

Omnivorous; mostly algae, aquatic plants, invertebrates, and small vertebrates, including carrion

These relatively small brownish turtles often have attractive, lighter-colored starburst patterns on their carapace. The plastron lacks a hinge. Pacific pond turtles hibernate on land in some areas, often great distances from water. Populations living in ephemeral streams estivate during drought. Even prior to their recognition as two separate species, Pacific pond turtles were considered for protection under the US Endangered Species Act. Populations in southern California have declined dramatically due to habitat destruction. Drought and fire in particular take their toll on populations of A. pallida.

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EMYDIDAE: EMYDOIDEA

BLANDING’S TURTLE

T

he genus Emydoidea contains a single species, E. blandingii, and no subspecies. The species was formerly placed in the genus Emys and some have argued that it should remain there. E. blandingii ranges from southeastern Canada through the US Midwest with isolated populations in New England and Nova Scotia. Fossil Emydoidea have been discovered in numerous Miocene,

Pliocene, and Pleistocene deposits. Fossils found in Mississippi and South Carolina, far to the south of their current distribution, indicate the species once had a very different geographic range. Preferred habitat of Blanding’s Turtles varies throughout the range, but it is commonly found in marshes, lakes, and small ponds with abundant aquatic vegetation as well as in slow-moving creeks and sloughs. Individuals of both sexes are often found terrestrially moving from one wetland to another. Blanding’s Turtle has a black shell, usually with yellow dots that may mimic duckweed (Lemna; Spirodela) providing camouflage. The plastron is yellow with large dark blotches and an anterior hinge

left | Blanding’s Turtles are the only species in North America with a yellow chin and throat, and a notched upper jaw.

distribution

activity

Northeastern USA and southeastern Canada

Primarily diurnal with peaks in the morning and afternoon; nesting often completed after dark

species

Emydoidea blandingii habitats

Most wetlands; marshes, lakes, ponds, small creeks, and fens size

CL up to 11¼ in (28.4 cm)

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CRYPTODIRA—Hidden-neck turtles

lifespan

83 years in the wild reproduction

1 clutch in a year (or less frequently); 3–22 elongated, hard-shelled eggs; females capable of laying eggs at over 50 years of age

above | Female Blanding’s Turtles have been documented to reach up to 86 years and still continue to reproduce.

diet

Mostly carnivorous on aquatic insects, mollusks, crayfish; dead fish; occasionally aquatic vegetation

allowing it to close up and hide its head. A distinctive feature of Blanding’s Turtles is that both adult males and females have a bright yellow chin and throat. The function is unknown but the yellow color can be seen from far away as the turtle sits on the surface with its body underwater with only the yellow throat visible. Blanding’s Turtles bask out of water on logs and muskrat lodges but not in large numbers. They are long-lived, usually taking up to 15–20 years to reach maturity and commonly laying eggs after 50 years of age. They are docile creatures that seldom bite when handled.

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EMYDIDAE: GLYPTEMYS

WOOD AND BOG TURTLES

above | Wood Turtles today are found no farther south than northern Virginia, USA, but in the Pleistocene they occurred in Georgia.

T

he genus Glyptemys contains only two species, the Wood Turtle (G. insculpta) and Bog Turtle (G. muhlenbergii). Both were formerly placed in the genus Clemmys which was later separated into multiple genera (Actinemys, Clemmys, and Glyptemys) due to morphological and molecular differences among species. Wood turtles occur in the eastern portion of North America. Bog Turtles have disjunct populations extending from New England into some

southeastern states. The fossil record for Glyptemys extends to the Miocene, and the genus was pushed far to the south of its current distribution during glacial maxima in the Pleistocene. The two species usually occupy different habitats that vary geographically. In the eastern portion of the range, Wood Turtles are more terrestrial in the summer season but are found near streams in which they hibernate in winter. Wood Turtles around the

distribution

Eastern USA and southeastern Canada species

Glyptemys insculpta, G. muhlenbergii habitats

Rivers, creeks, marshes, bogs, and fens size

CL 4½ in (11.5 cm) for Bog Turtles (one of the smallest turtles in the world) to 9¼ in (23.4 cm) for Wood Turtles

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CRYPTODIRA—Hidden-neck turtles

activity

Primarily diurnal; some evidence of nocturnal behavior lifespan

Bog Turtles live over 30 years in the wild. Wood Turtles live over 40 years in the wild and 58 years in captivity

left | Wood Turtles have been reported to receive and even solicit symbiotic cleaning by small fish while occupying streams.

| Living in widely scattered, shallow wetlands comprised of small numbers of individuals places Bog Turtle populations at risk.

below

Great Lakes region are more aquatic, also living in or near streams and rivers. Bog Turtles sometimes co-occur with Wood Turtles but prefer marshes, bogs, fens, and other shallow wetlands. Unlike many turtles, sex in Glyptemys is not determined in the egg by incubation temperatures but rather genetically through XX/XY chromosomes. Wood Turtles nest in holes dug by the female in soil like most turtles. In contrast, Bog

reproduction

1 clutch per year of 1–6 eggs (Bog Turtles); 1 clutch per year of 3–20 eggs (Wood Turtles) diet

Omnivorous on insects, aquatic vegetation, fruits, fungi, some vertebrates (probably as carrion). Wood Turtles “stomp” on the ground to bring earthworms to the surface to eat

Turtles often nest in tussocks of marsh grasses, sometimes not even covering the eggs. Hatchlings of both species usually emerge in the fall of the year that the eggs were deposited. Both species are threatened by habitat destruction and overcollection for pets. Bog turtles are protected under the US Endangered Species Act.

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EMYDIDAE: TERRAPENE

BOX TURTLES

F

our species in the genus Terrapene are currently recognized and one, T. carolina (Eastern Box Turtle), has six subspecies, some of which have been considered as full species. Box turtles formerly ranged from Canada, where they are extirpated, southward in the USA and into southern Mexico. The ranges of the species are largely discontinuous

except for overlap between T. carolina and T. ornata in the USA. Two species, T. nelsoni and T. coahuila, are restricted to narrow distributions in northwestern and northeastern Mexico respectively. Across this wide range, Terrapene is adapted to diverse habitats that also vary seasonally. Most box turtles are largely terrestrial, but they are often found

distribution

size

Canada, USA, and Mexico

CL 9¼ in (23.5 cm)

species

activity

Terrapene carolina, T. coahuila, T. nelsoni, and T. ornata,

Diurnal except for some nesting females

habitats

Over 100 years reported in the wild

Moist temperate zone woodlands and grasslands in the USA; a unique wetland system (Cuatro Ciénegas) in the Chihuahuan Desert; subtropical and tropical forests in Mexico

102

CRYPTODIRA—Hidden-neck turtles

lifespan

in or near shallow water like streams, swamps, and marshes, making habitat generalizations difficult. T. carolina is primarily a turtle of moist woodland throughout most of its range, in deciduous forests and pinelands in the eastern half of the USA. However, subspecies occur in subtropical and tropical forests of eastern Mexico (T. carolina mexicana) and Yucatan (T. carolina yucatana). In contrast, T. ornata prefers prairie grasslands and semidesert habitats from the central and southwestern USA into Mexico. In Mexico, T. nelsoni is found in the dry oak savannas on the Pacific slope of the Sierra Madre Occidental, and T. coahuila is a mostly aquatic species living in a wetland complex in the Chihuahuan Desert. Box turtles have domed shells with a hinged plastron that allows them to withdraw completely into their shells when threatened. Most species have bright-yellow markings on the shell, neck, and head. Male T. carolina often have red eyes.

| Eastern Box Turtles, once abundant, have been diminished by road mortality and removal of large numbers for the pet trade.

far left

above | Box turtles no doubt got their name because they can retract into their shells, like closing a box, when threatened.

reproduction

1–5 clutches per year;1–11 elliptical eggs per clutch diet

Omnivorous on many plants and animals, including carrion

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FAMILY: PLATYSTERNIDAE BIG-HEADED TURTLE

T

he family Platysternidae has one genus and species, Platysternon megacephalum, (Big-headed Turtle), with three subspecies. The geographic range is restricted to the region of Hong Kong and southern mainland China, extending into the Indochina Peninsula to southern Myanmar, northern Cambodia, and Vietnam. The fossil record of platysternids is questionable, and detailed re-examination of specimens is needed. A prime habitat is clear, rocky streams or rivers. This unusual turtle is remarkable when compared with other turtle groups anywhere in the world, hence its placement in a family of its own. The Big-headed Turtle has a dark head and carapace ranging from brown to olive and a yellowish plastron. Their morphology is one of disproportionate body parts including an enormous

head, long tail, and a flattened hard-shelled carapace. The head is covered by a single, solid plate rather than a combination of scales characteristic of most turtles. The head cannot be retracted into the shell. The large mouth, powerful jaws, and hooked beak are an effective defense against most predators. The tail is as long as the carapace and can be used as a prop for climbing. Juveniles have been found crawling up the undersides of waterfalls by using their tails to assist their movements. They are basically aquatic although they will venture onto land alongside streams. A highly distinctive feature is their occasional vocalization during periods of stress, presumably as a form of defense against a perceived threat. Juveniles make a squeaking sound. Adults are able to make a low-pitched, primordial-sounding roar.

right | The Big-headed Turtle is reported to be a good climber, ascending rocks, vegetation, and even waterfalls in mountain streams.

distribution

activity

Myanmar, Cambodia, Thailand, Laos, Vietnam, and China (including Hong Kong and Hainan)

Mostly nocturnal

species

Platysternon megacephalum habitats

Fast-moving streams and rivers with rocky or gravelly substrate size

CL up to 7¼ in (18.5 cm)

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CRYPTODIRA—Hidden-neck turtles

lifespan

Over 27 years in captivity reproduction

1–2 large, oval eggs are laid per clutch; little other information known diet

Carnivorous on a variety of stream invertebrates, fish, and carrion

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FAMILY: GEOEMYDIDAE ASIAN AND AMERICAN POND AND RIVER TURTLES

T

he family Geoemydidae, formerly called Bataguridae, has two subfamilies (Geoemydinae and Rhinoclemmydinae), 19 genera, and 71 species, making it the most diverse family of turtles. Representatives are found in Asia, Europe, and northern Africa, with the exception of one genus, Rhinoclemmys, found in the New World. Many geoemydids have remarkably convergent morphology and ecology with members of the Emydidae, with which they were once classified, and both families occupy similar habitats. For example, shell morphology in Pangshura is remarkably similar to the emydid genus Graptemys, and both are river turtles. Most geoemydids are aquatic, occurring in a wide range of wetlands from lakes, ponds, and marshes, to streams, rivers, and estuarine habitats. In contrast, Vijayachelys and some Rhinoclemmys are terrestrial.

They range in body size from very large turtles like Orlitia to relatively small species like Geoemyda. Some species exhibit spectacular sexual dichromatism during the breeding season with males undergoing a dramatic transformation of head and shell coloration (e.g., Batagur). Some, like Cuora, have hinged plastrons and bear a striking morphological similarity with emydids of the genus Terrapene. Others have the plastron firmly attached to the carapace with a strong bony bridge. Unlike emydids, some geoemydids produce small clutches of rather large eggs. The high diversity of geoemydids contributes measurably to the status of Southeast Asia as a biodiversity hot spot for turtles. Of the 25 turtles in the world at highest risk of extinction, 13 are geoemydids, threatened by overexploitation for food and for purported but unproven medicinal benefits.

right | Geoemydid turtles, like this Crowned River Turtle, were formerly placed in the superficially similar family Emydidae.

distribution

Asia, Europe, northern Africa, Mexico, Central America, and South America genera

Batagur, Cuora, Cyclemys, Geoclemys, Geoemyda, Hardella, Heosemys, Leucocephalon, Malayemys, Mauremys, Melanochelys, Morenia, Notochelys, Orlitia, Pangshura, Rhinoclemmys, Sacalia, Siebenrockiella, and Vijayachelys

106

habitats

activity

Depending on the species, most aquatic habitats; standing, flowing, and ephemeral water; rivers, streams, ponds, marshes, swamps, and even estuarine environments. Some species are terrestrial or semi-aquatic

Most are diurnal but some species are crepuscular or even nocturnal

size

CL 4 in (just over 10 cm) in Geoemyda spengleri to 31½ in (80 cm) in Orlitia

CRYPTODIRA—Hidden-neck turtles

reproduction

1–43 eggs, depending on species diet

Herbivorous, carnivorous, and omnivorous, depending on species

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GEOEMYDIDAE: BATAGUR

ASIAN RIVER TERRAPINS

T

he genus Batagur currently includes six species, some of which were previously placed in the genera Callagur or Kachuga. They range from east India and Bangladesh to Borneo with largely disjunct distributions. Two species, B. dhongoka and B. kachuga, are found in much of the Ganges River Basin of India and Nepal. Another, B. trivittata, is found in large rivers in Myanmar. The others are found in the lower reaches of various Asian rivers and their tidally influenced estuaries. Salinity tolerance varies among species. The more estuarine species are characterized by massive shells that make up to 33 percent of their body mass. One notable feature of Asian river terrapins is the dramatic sexual dichromatism exhibited by males of some species during the breeding season that borders on clownish. Male B. borneoensis change from their normally drab brown to gray coloration to a cream-colored carapace and pure white head with a bright red patch

| A Hindi common name for breeding males of the Red-crowned Roofed Turtle is “one with red marking on forehead.”

below

distribution

size

Bangladesh, Cambodia, India, Indonesia, Malaysia, Myanmar, Nepal, Singapore, Thailand, and Vietnam

CL 19 in (48 cm) in B. dhongoka to 24.5 in (62.5 cm) in B. affinis

species

Diurnal but nesting occurs at night in B. affinis

Batagur affinis, B. baska, B. borneoensis, B. dhongoka, B. kachuga, and B. trivittata habitats

Large rivers and, in some species, their estuaries

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CRYPTODIRA—Hidden-neck turtles

activity

lifespan

21 years in captivity

on top. Breeding male B. affinis develop a jet-black head and striking white irises. Such coloration may be important for species recognition in areas where both species occur or for sexual recognition. The head of male B. kachuga looks like they are painted with dramatic red and yellow stripes. Females of at least two species, B. baska and B. borneoensis, migrate downriver to nest on ocean beaches and islets, with sea turtles. B. affinis go upriver during the dry season to nest on exposed sand bars. Populations of most Batagur species have been dramatically depleted due to overharvesting of eggs and adults for human consumption.

reproduction

1–3 clutches of 20–43 eggs per clutch. Like some Pseudemys species, B. affinis sometimes splits clutches between 2–4 nest cavities, all within about 20 ft (6 m) of each other

| The Burmese Roofed Turtle was almost extinct before captive colonies were established in Myanmar by conservationists.

below left

above | The red coloration of male Painted Terrapins during the breeding season is a result of extensive changes in epidermal cells.

diet

Mostly herbivorous but some species are more omnivorous

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GEOEMYDIDAE: CUORA

ASIAN BOX TURTLES | The Southeast Asian Box Turtle, like the North American Box Turtle, can retract into its shell when threatened by predators.

below

C

uora has more currently recognized species, 13, than any other genus in the family Geoemydidae. The taxonomy of this group has been especially fluid and controversial due in part to description of some species later found to be captive-produced or natural hybrids, including hybrids with other turtle genera (Mauremys, Ocadia, Sacalia). In addition to the taxonomic turmoil, the

natural ranges of some species of Asian box turtles are unknown because they were described to science based on specimens with faulty locality data, including live animal markets in Asia. Members of this genus have sometimes been placed in the genera Cistoclemmys or Pyxidea. Cuora has a wide range that extends from India and Bangladesh, south and east through southern

distribution

habitats

India, Brunei, Indonesia, Malaysia, Philippines, Singapore, Thailand, Laos, Myanmar, Bangladesh, Bhutan, Nepal, Cambodia, China, Taiwan, Japan, and Vietnam

Depending on the species, moist woodlands and evergreen forests, ponds, marshes, swamps, rice paddies, irrigation ditches and canals, and streams

species

Cuora amboinensis, C. aurocapitata, C. bourreti, C. cyclornata, C. flavomarginata, C. galbinifrons, C. mccordi, C. mouhotii, C. pani, C. picturata, C. trifasciata, C. yunnanensis, and C. zhoui

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CRYPTODIRA—Hidden-neck turtles

size

CL up to 12 in (30 cm) activity

Some are nocturnal; others unknown lifespan

Over 38 years in captivity (C. amboinensis)

China and Indochina, to Indonesia, Malaysia, the Philippines, Hainan, and the Ryukyu Islands of Japan. Some species have very small distributions. C. amboinensis has the largest range and is the only species of non-marine turtle that occurs naturally on both sides of Wallace’s Line, an invisible but biologically important boundary between Asian and Australian faunas. Holocene remains of various Cuora are reported from Pleistocene deposits in Asia. Cuora can be aquatic, semi-aquatic, or largely

reproduction

3 clutches of 2–3 eggs (rarely 5) per clutch in captive C. amboinensis; 4–8 eggs per nesting season in multiple clutches for C. flavomarginata; 1–7 eggs per clutch for C. mouhotii. Information on clutch and egg size is unknown for wild populations of most species

terrestrial, depending on species, but most occur in association with moist forested habitats and associated wetlands. These are small turtles, some of which are remarkably convergent in morphology with North American box turtles (Terrapene), which also have hinged plastrons. They can be colorful with yellow stripes and markings on the head. Some, such as C. galbinifrons, have attractive patterns on the carapace. The natural history of most species is unknown.

above | The Chinese Three-striped Box Turtle, also known as the Golden Coin Turtle, was once abundant but is now rare in the wild.

diet

Omnivorous to carnivorous

111

GEOEMYDIDAE: CYCLEMYS

LEAF TURTLES

above | Leaf Turtles, such as this Cyclemis dentata, are mostly nondescript. They eat a wide variety of invertebrates, carrion, and plants, such as figs.

C

yclemys includes seven poorly studied species found in Southeast Asia. Some Leaf Turtles are similar in appearance and cannot easily be differentiated. As adults, all species of Cyclemys are brownish and nondescript except C. pulchristriata which has an attractive yellow head and neck stripes. Some have dark plastrons and others are yellow. Some with yellow plastrons also have a striking pattern of radiating fine, black lines on

112

their plastron scutes. Adult leaf turtles have rounded carapaces. The anterior portion of the plastron is hinged, allowing flexibility. Survivorship of this genus is low in lowland ponds, likely due to the ease of capture for human consumption. C. oldhamii is commonly sold for food in Asian markets. In Myanmar, C. fusca and C. oldhamii are seldom taken as food because of their strong smell.

distribution

habitats

India, Brunei, Indonesia, Malaysia, Philippines, Singapore, Thailand, Myanmar, Bangladesh, Bhutan, Nepal, Cambodia, China, and Vietnam

On the island of Borneo, Malaysia, and in Myanmar they inhabit small rocky streams and plunge pools in the highlands; small streams, rivers, and ponds in lowland areas

species

size

Cyclemys atripons, C. dentata, C. enigmatica, C. fusca, C. gemeli, C. oldhamii, and C. pulchristriata

activity

CRYPTODIRA—Hidden-neck turtles

CL 9½ in (24 cm) Activity periods of C. dentata are primarily dawn and dusk;

adults are said to be more terrestrial than juveniles lifespan

Over 14 years in captivity reproduction

2–3 large, oblong eggs in C. dentata; 7 eggs have been reported in C. fusca diet

Omnivorous

GEOEMYDIDAE: GEOCLEMYS

SPOTTED POND TURTLE | The reportedly shy Spotted Pond Turtle rarely bites but is said to utter a low croak with its mouth open when threatened.

below

T

his genus contains a single species, Geoclemys hamiltonii, which occurs in a broad band across the sub-Himalayan lowlands of the Indian subcontinent from Pakistan to Bangladesh, in the Indus, Ganges, and Brahmaputra river basins. Fossils of the species are known from the Pliocene– Pleistocene boundary of India. Not much is known of the habitats of Spotted Pond Turtles, but they seem to prefer still, shallow

waters, including lakes and oxbows. Some may occur in rivers. Adults have mostly black carapaces and skin with contrasting white markings. Juveniles are strikingly patterned with numerous white to yellow spots and markings on the skin and shell. The carapace is domed with three keels. The hingeless plastron is yellow with dark radiations. Threats to the species include the pet trade and use for traditional medicine and food.

distribution

size

diet

Pakistan, India, Bangladesh, and possibly Nepal

CL to 16 in (40.5 cm)

Carnivorous including snails and other invertebrates

species Geoclemys hamiltonii

Primarily crepuscular but they are fond of basking

habitats

lifespan

Rivers, lakes, oxbows, and other aquatic habitats, especially those with abundant aquatic vegetation

reproduction

activity

Over 19 years in captivity 1–2 clutches; up to 36 eggs per clutch; laid December to March

113

GEOEMYDIDAE: GEOEMYDA

BLACK-BREASTED LEAF TURTLES

T

here are two species in this genus, Geoemyda japonica (Ryukyu Black-breasted Leaf Turtle) and G. spengleri (Black-breasted Leaf Turtle). Like many turtles, this genus has a history of being classified in several different genera currently or formerly assigned to both Old World and New World turtle species. G. spengleri ranges from eastern China (including Hainan Island) to Laos and Vietnam. G. japonica is restricted to some of the Ryukyu Islands of Japan. Fossils of the genus are known from the Pleistocene of Japan, but they differ slightly from G. japonica and are described as a separate species.

Both modern species are essentially terrestrial, preferring moist forests and occasionally entering streams. Several modern references repeat a 1930s claim by Clifford Pope that G. spengleri prefers “wild, wooded, mountainous country,” which in Vietnam includes montane bamboo forests with steep terrain. These are small turtles (G. spengleri is the smallest geoemydid species) with relatively flattened carapaces with three keels. The posterior margin of the carapace is serrated with tooth-like marginal scutes. The unhinged plastron is mostly black, hence their common

left | The Ryukyu Black-breasted Leaf Turtle from southern Japan gets its name from the black plastron, as seen here.

right | The brown coloration, small size, and flattened carapace allow Black-breasted Leaf Turtles to hide on the forest floor.

distribution

size

China (including Hainan Island), Japan (Ryukyu Islands), Laos, and Vietnam

CL up to 4¼ in (10.7 cm) in G. spengleri; up to 6¼ in (15.5 cm) in G. japonica

species

activity

Geoemyda japonica, G. spengleri

G. spengleri is active mid-day in Vietnam, especially after rainstorms when the sun comes out

habitats

Moist forests. In Vietnam they occur in montane forests, including bamboo thickets, especially near streams and rocky terrain with caves

114

CRYPTODIRA—Hidden-neck turtles

lifespan

18 years in captivity for Geoemyda sp.

left | Black-breasted Leaf Turtles can be differentiated from other species in the genus by the shape of their nostrils.

reproduction

G. japonica 4–6 eggs; G. spengleri 1–2 eggs diet

Omnivorous

name, and rimmed with a yellowish margin. Research has demonstrated that the eyes of G. spengleri are highly movable and normally operate independently. However, when they focus on bait in a laboratory setting, the eyes are locked together in their focus, even if one eye is blocked experimentally. Both traits are similar to those demonstrated for chameleons. 115

GEOEMYDIDAE: HARDELLA

CROWNED RIVER TURTLE

T

above | Crowned River Turtles are aquatic, but when moving overland during droughts are subject to aerial and terrestrial predators such as vultures and jackals.

he only species in this genus is Hardella thurjii, which ranges in a broad band across the sub-Himalayan lowlands of the Indian subcontinent from Pakistan to Bangladesh, in the Indus, Ganges, and Brahmaputra river basins. Formerly described eastern and western subspecies are no longer recognized based on genetic analysis. Fossils are known from the Pliocene–Pleistocene boundary of northern India. Crowned River Turtles prefer still or slowmoving waters like ponds and lakes. When ponds dry up, they move overland in search of water but can survive for brief periods buried in the mud. The frequent attachment of leeches and egg masses of aquatic insects speaks to their aquatic disposition. It is a large species and females can have carapace lengths up to three times greater than males. The dark-colored, keeled carapace is thick and firmly attached to the hingeless plastron by a strong bridge. Females have fontanelles in their bony carapace up to a length of about 12 in (30 cm), at which point they begin to close. The plastron is yellow and there is a large dark blotch on each scute. Yellow markings on the head and neck or the orangish margin around the carapace perhaps give the appearance of a “crown” to some, and may be responsible for their common name.

distribution

activity

Pakistan, India, Nepal, Bangladesh, and possibly western Myanmar

Mostly diurnal except for wanderings by nesting females

species

lifespan

Hardella thurjii

At least 18 years in captivity; probably longer in the wild

habitats

Canals, ponds, marshes, lakes, and other still or slow-moving aquatic habitats size

CL up to 8 in (20 cm) for males and 25½ in (65 cm) for females

116

CRYPTODIRA—Hidden-neck turtles

reproduction

Multiple clutches per year; 8–16 eggs per clutch; up to 100 eggs per season diet

Herbivorous

The snout is pronounced. Because of its large size and former abundance, this species was heavily exploited as a source of human food resulting in population declines. They are said to have a non-aggressive disposition.

above | Juvenile Crowned River Turtles are more brightly patterned than adults and must conceal themselves from predators.

117

GEOEMYDIDAE: HEOSEMYS

FOREST, TEMPLE, POND, AND SPINY TURTLES

H

eosemys has four species that are found in various parts of Southeast Asia. The Spiny Turtle (H. spinosa) has the widest distribution of the four species, occurring from Myanmar and southern Thailand, into peninsular Malaysia, several Indonesian islands, and the southern Philippines. Genetic evidence suggests that H. spinosa should be divided into more than one species over the wide geographic range. No fossils of the genus have been discovered, but Holocene archaeological remains of H. annandalii and H. grandis are known from Thailand. Habitats range from terrestrial to semi-aquatic. Some spend considerable time on land, sometimes buried in leaf litter. H. depressa live in evergreen tropical forests and bamboo thickets near streams. Yellow-headed Temple Turtles (H. annandalii) occur in swamps, rivers with slow current, and flooded fields. Spiny Turtles prefer high humidity forests, often hiding in leaf litter. Shell morphology varies among species, with H. annandalii being the largest semi-terrestrial geoemydid species. Juveniles have keeled carapaces. Carapace color ranges from

| Although giant Asian Pond Turtles are abundant in temple ponds and zoos, they are reportedly not as common in the wild.

below

distribution

size

Myanmar, Thailand, Malaysia, Singapore, Indonesia, Cambodia, Laos, Vietnam, Brunei, and Philippines

CL up to 19 in (48 cm) for H. grandis and 19¾ in (50 cm) or more for H. annandalii

species

Some crepuscular activity reported but little is known about the biology of Heosemys

Heosemys annandalii, H. depressa, H. grandis, and H. spinosa habitats

Evergreen tropical forests. H. depressa also inhabits bamboo thickets

118

CRYPTODIRA—Hidden-neck turtles

activity

lifespan

Over 29 years in captivity

above | The protective spines so obvious on a juvenile Spiny Turtle are greatly diminished in adults through growth and abrasion.

reproduction

Up to 3 clutches per year in captive H. spinosa; 1–10 large eggs per clutch for genus diet

Mostly herbivorous

light to dark brown, sometimes with radiating black markings. Plastrons are yellowish with attractive patterns of radiating dark lines in juveniles. The head of the Giant Asian Pond Turtle (H. grandis) can have yellow or orange vermiculations and markings. Female Spiny Turtles have a flexible rear plastron, facilitating passage of the relatively large eggs. Juvenile Spiny Turtles look like weapons called “throwing stars,” with exaggerated serrations on their marginal scutes. The spines become much less pronounced as adults. H. annandalii and H. grandis are sometimes released in Buddhist temple ponds in Thailand, hence the name “temple turtles.”

119

GEOEMYDIDAE: LEUCOCEPHALON

SULAWESI FOREST TURTLE

right | Sulawesi is a land of odd endemic animals including a pygmy buffalo, the anoa, the babirusa, and this poorly-known turtle.

O

riginally discovered and described to science in 1995 as a member of the genus Geoemyda, this species was elevated to its own monotypic genus Leucocephalon in 2000. Known only from central and northern Sulawesi, Indonesia, this is one of just two species of geoemydids (including Cuora amboinensis) occurring east of Wallace’s Line, the invisible but biologically important boundary between Asian and Australian faunas. Observations of wild Sulawesi Forest Turtles occur mostly at night in streams flowing through dense secondary forests bordered by agricultural plantations. They reportedly forage on land near streams during daytime and return to streams at night to rest and feed. Local turtle hunters claim they remain in streamside habitats during full moons.

distribution

activity

diet

Sulawesi, Indonesia

Some activity both day and night

Mostly herbivorous as adults; juveniles eat some insects

species

Leucocephalon yuwonoi habitats

Evergreen tropical forests and streams size

CL to at least 11 in (27.8 cm) in males and 9½ in (24 cm) in females

120

The carapace is brown, relatively flat, and with three moderate keels. Posterior marginal scutes are serrated, especially in juveniles. The unhinged plastron is yellowish, sometimes with brown smudges and markings. Head color varies between the sexes after 7–8 years of age, one of the few instances of color differences between the sexes in turtles. The head is cream colored in males and dark brown in females. Juveniles will eat insects; adults eat leaves and possibly fruits. They are reportedly good climbers. When disturbed they bite and void large quantities of feces. Very little else is known about the natural history of this species. Habitat destruction and overexploitation for human consumption threaten the continued survival of this enigmatic turtle.

CRYPTODIRA—Hidden-neck turtles

lifespan

Unknown reproduction

Multiple clutches per year; 1–2 large, hard-shelled eggs per clutch

GEOEMYDIDAE: MALAYEMYS

SNAIL-EATING TURTLES | Malayan snail-eating turtles are adapted to eating hard-shelled prey such as snails and mussels.

below

T

hree species of Malayemys are currently recognized. Divergence among the species appears to have been driven by Pleistocene climate fluctuations and tectonic rearrangements of river drainages. The range of the snail-eating turtles is focused on Indochina with all three species occurring in various parts of Thailand including Holocene archaeological remains. In addition to snails, snail-eating turtles are reported to eat other aquatic invertebrates. These turtles apparently prefer still-water habitats with soft

substrates and aquatic vegetation. They also occur in rice fields and urban wetlands, including the khlongs (canals) of Bangkok. This is a small turtle with a moderately domed carapace and three keels. Carapace color ranges from dark brown to light chocolate with a yellowish border. The plastron is unhinged and yellowish with dark markings on the scutes. Prominent white or yellow stripes are present on the head and neck. Snail-eating turtles are eaten and may be released into temple ponds in Thailand.

distribution

size

diet

Laos, Thailand, Malaysia, Cambodia, Indonesia (Java and Sumatra—possible human translocation)

CL 8¼in (21 cm)

Carnivorous on snails, insects, mussels, worms, and shrimp

species

Malayemys khoratensis, M. macrocephala, and M. subtrijuga habitats

Marshes, rice fields, ponds, canals, slow-moving rivers

activity

Some activity both day and night lifespan

At least 14 years in captivity reproduction

3–6 hard-shelled eggs

121

GEOEMYDIDAE: MAUREMYS

OLD WORLD POND TURTLES

N

ine species are currently placed in the genus Mauremys. Several were formerly classified in other genera. The range of the genus is vast, stretching discontinuously from northwestern Africa and southern Europe, across the Mediterranean region to the Caspian Sea. There is a large gap in central Asia before they appear again in China, Southeast Asia, and Japan; a distance of almost 7,500 miles (12,000 km)! The large gap in central Asia has been attributed to extinctions due to Pleistocene glaciation.

Some turtle biologists question the use of the genus for all nine species based on genetic analyses and instead support the existence of four welldefined groups: one in eastern Asia, another in Southeast Asia, and two in Europe and Africa combined, with one of the latter containing only M. leprosa, the Mediterranean Pond Turtle. Other researchers report greater differentiation among east Asian species than between eastern (Asia) and western (Europe, Africa) groups. Fossils of Mauremys are known from as early as the Miocene of Italy. right | Populations of Mediterranean Pond Turtles in the Sahara have blue eyes whereas those elsewhere have yellow eyes like the one in this photograph.

above | The local name of the Japanese Pond Turtle, “ishigame,” means stone turtle, referring to their prevalence in rocky streams.

distribution

habitats

Northwestern Africa, Mediterranean Europe, Caspian region of western Asia, eastern China, Japan, and Vietnam

Ponds, marshes, irrigation canals, rice paddies, rivers, lakes, streams, some brackish estuaries, oases, and coastal lagoons; habitat varies with species and location

species

Mauremys annamensis, M. caspica, M. japonica, M. leprosa, M. mutica, M. nigricans, M. reevesii (introduced in Japan), M. rivulata, and M. sinensis

size

Up to at least 11¾ in (30 cm) in M. reevesii activity

Mostly diurnal

122

CRYPTODIRA—Hidden-neck turtles

Old World pond turtles live in both still and flowing waters including some brackish oases and estuaries in arid regions. They are small to mediumsized turtles with relatively flattened carapaces with one or three keels. Carapace color is olive, brown, or darker, sometimes with lighter-colored markings. The black, yellow, or red (in juvenile M. nigricans)

unhinged plastron is firmly attached to the carapace. Conspicuous red or yellow stripes are present on the head and limbs of some species. M. leprosa in the Sahara Desert of Morocco are one of only a few turtle species known to have blue eyes. Hybrids have been reported between various Mauremys and other genera (see Cuora pages 110–11).

lifespan

Over 24 years in captivity (M. leprosa) reproduction

1–4 clutches per year; 1–14 eggs per clutch, depending on species. Female M. nigricans deposit portions of each clutch in two nest cavities diet

Omnivorous

123

GEOEMYDIDAE: MELANOCHELYS

TRICARINATE HILL TURTLE AND INDIAN BLACK TURTLE

left | The Indian Black Turtle will eat carcasses of large mammals, including elephants, and nest in rhinoceros dung piles.

M

elanochelys has two species, with a range divided into two widely separate regions. Tricarinate Hill Turtles (M. tricarinata) and some subspecies of Indian Black Turtles (M. trijuga) occur in a broad band across the sub-Himalayan lowlands in the Ganges and Brahmaputra river basins, then eastward into Myanmar and Thailand. Remaining subspecies of M. trijuga occur in southern India and Sri Lanka. Tricarinate Hill Turtles are entirely terrestrial and occur mostly in hilly, moist forested habitats. In contrast, the Indian Black Turtle is more of a lowland species found in streams and ponds in both

distribution

habitats

activity

Bangladesh, India, Nepal, Myanmar, Sri Lanka, Thailand, with questionable records in eastern Pakistan and southwestern China. Possible introductions to various small Indian Ocean islands (e.g., Diego Garcia, Maldives)

Moist forests (M. tricarinata); ponds, rice paddies, rivers, streams, brackish marshes (M. trijuga)

Crepuscular to nocturnal

species

Melanochelys tricarinata, M. trijuga

124

forested areas and those created by humans like waterholes and rice paddies. Melanochelys have moderately domed carapaces with three keels. Overall carapace color of M. tricarinata is reddish brown, olive, or gray-black with yellowish bands along the keels. The plastron is yellow and joins the carapace with a partial ligamentous connection allowing flexibility for oviposition of large eggs. The head and neck are gray-black, sometimes with a yellow or red stripe through the eyes. Indian Black Turtles vary in color among the six recognized subspecies, but carapace and plastron color are typically brown or black.

CRYPTODIRA—Hidden-neck turtles

size

CL 6¾ in (17.4 cm) in M. tricarinata and 9¾ in (25 cm) in M. trijuga

lifespan

Over 40 years in captivity (M. trijuga) reproduction

1–6 large eggs (M. tricarinata); 1–16 eggs (M. trijuga) diet

Omnivorous

GEOEMYDIDAE: MORENIA

EYED TURTLES

M

orenia has two species: M. ocellata (Burmese Eyed Turtle) and M. petersi (Indian Eyed Turtle). The former is found in Myanmar and possibly western China based on specimens observed for sale in local markets. The latter is widely distributed in the lowlands of the Ganges and Brahmaputra rivers in India and Nepal, southward to Bangladesh. Fossils are unknown. Eyed turtles occur in standing or slow-moving aquatic habitats including weed-choked pools in riverbeds, oxbow lakes, and other stagnant water bodies. M. ocellata inhabits water bodies that may dry up seasonally. Both species have a slightly domed greenish to dark olive carapace and yellow plastron. A distinctive feature of both species is the presence of pale ocelli surrounding darker coloration on the pleural scutes of the carapace giving the appearance of “eyes.” The eye spots are especially prevalent in juveniles. Both species have bright yellow stripes on the head and neck, including a V-shaped marking on the top of the head. M. ocellata has a longer snout than M. petersi. Females are larger than males. M. petersi produces two clutches during the egg-laying season from November to February. Nesting occurs at night in agricultural fields, the elevated banks of

above | Eyed turtles of the genus Morenia (and Sacalia) have markings that look remarkably like eyes that may startle predators.

canals, and along roadsides. All are characterized by sparse vegetation. Incubation takes 76–148 days. Nest temperatures range from 81.5–86 °F (27.5–30.0 °C.) Hatching success may be as low as 57 percent. Predators of eggs and hatchlings include monitor lizards, mongooses, crows, kites, and red ants. Eyed turtles are considered to be threatened by unsustainable removal from the wild for human consumption.

distribution

size

reproduction

India, Nepal, Bangladesh, Myanmar, and possibly western China

CL 8¾ in (22 cm) in M. ocellata and 7¾ in (20 cm) in M. petersi

1–2 clutches per nesting season in M. petersi; 5–15 eggs per clutch in both species

species

activity

diet

Morenia ocellata, M. petersi

Diurnal, although nesting occurs at night in M. petersi

Omnivorous tending toward herbivory on aquatic plants

habitats

Pools in seasonal rivers, oxbow lakes, and other slow-moving water bodies

lifespan

Unknown

125

GEOEMYDIDAE: NOTOCHELYS

MALAYAN FLAT-SHELLED TURTLE

N

otochelys platynota is the only species in this monotypic genus. Little scientific information is known of the ecology or behavior of this species, and some of the limited biological information is contradictory. The range of the Malayan Flat-shelled Turtle is centered in a biogeographical region known as Sundaland, a large equatorial land mass that is now partially submerged as the shallow continental shelf of Southeast Asia. The area was exposed during the lower sea levels of previous ice ages but is now largely comprised of portions of mainland

Southeast Asia and various Malaysian and Indonesian islands including Borneo, Sumatra, and Java. Late Pleistocene fossils are known from caves in Borneo. Malayan Flat-shelled Turtles have been reported to live in shallow wetlands in lowland rainforests. The carapace is flattened, as reflected in both the common and scientific names. While most turtle species have five vertebral scutes, Notochelys typically has six, seven, or, rarely, eight. The carapace is brownish in adults. According to most references, the yellowish plastron has dark markings and a weak hinge. Others claim the plastron is purple, and in Thailand this species is known as the “purple-bellied terrapin.” In contrast to the drab coloration of adults, juveniles have a variety of color variations ranging from apple-green to bright-yellow carapaces with dark spots. They also have yellow to red stripes on the side of the head. Like some other turtle species, when handled, Notochelys defecates frequently. It is commonly used for food by local people in peninsular Malaysia and Borneo. left | Although the carapace of hatchlings can be brightly colored, Malayan Flat-shelled Turtles become brown as they age.

distribution

size

diet

Brunei, Indonesia, Malaysia, Myanmar, Singapore, and Thailand

CL up to 14¼ in (36 cm)

Omnivorous based on observations in the wild and in captivity

species

Notochelys platynota habitats

Marshes, swamps, ponds, and streams

126

CRYPTODIRA—Hidden-neck turtles

activity

Unknown lifespan

Over 18 years in captivity reproduction

3 large hard-shelled eggs have been reported

GEOEMYDIDAE: ORLITIA

MALAYSIAN GIANT TURTLE

O

rlitia borneensis is the only species in this monotypic genus. The range of the Malaysian Giant Turtle is equatorial Southeast Asia in the biogeographical region known as Sundaland. Pleistocene fossils are known from Java where the species no longer occurs. Habitat includes large rivers and some lakes, and occasionally in vegetation-choked ponds. The carapace is dark, almost black. The yellowish

above | It is amazing that in the 21st century so little is known about an animal as large as the Malaysian Giant Turtle.

plastron has dark smudges and is firmly attached at the bridge. The head is relatively large. Very little is known of the ecology or behavior of this large riverine species. Because of its large size, it is heavily exploited for human consumption.

distribution

activity

diet

Malaysia, Indonesia (including Sumatra and Borneo)

Unknown

species

Unknown

Omnivorous based on observations in the wild and in captivity

Orlitia borneensis habitats

Large rivers and lakes

lifespan reproduction

12–15 large brittle eggs have been reported

size

CL 31½ in (80 cm)

127

GEOEMYDIDAE: PANGSHURA

ROOFED AND TENT TURTLES

T

he genus Pangshura contains four species, all of which were formerly placed in the genus Kachuga. Pangshura occur in the Ganges, Brahmaputra, and Indus rivers from Pakistan eastward along the base of the Himalaya Mountains in India and Nepal to Bangladesh. Some species have more disjunct ranges in other river systems farther east and south on the subcontinent. Late Pliocene to Pleistocene fossils are known from Pakistan. Although their morphology appears to be adapted to living in fast-flowing waters, Pangshura reportedly occupy a variety of habitats including small streams, large rivers, oxbows, and marshes, depending on species.

above | Brown Roofed Turtles are among the few turtles in the world with blue eyes.

right | Turtles in the genus Pangshura bask frequently in groups on logs in lakes and rivers, but will rapidly retreat into deep water when disturbed.

distribution

activity

Pakistan, India, Nepal, and Bangladesh

Diurnal; fond of basking

species

lifespan

Pangshura smithii, P. sylhetensis, P. tecta, and P. tentoria

Over 13 years in captivity (P. smithii)

habitats

3–12 eggs

Streams, rivers, oxbows, marshes, and lakes size

CL up to 10½ in (26.5 cm)

128

CRYPTODIRA—Hidden-neck turtles

reproduction diet

Omnivorous, herbivorous, or carnivorous according to species, sex, and age class

These are small to medium-sized turtles characterized by a brownish, keeled carapace. The keels include rearward-facing low spines on some of the vertebral scutes. In this regard, they bear a striking resemblance to the North American genus Graptemys which have species known locally as “sawbacks.” This convergent morphology may have a hydrodynamic purpose enabling these streamlined turtles to better negotiate powerful currents in flowing streams and rivers. In adults, the unhinged plastron is dark or has dark blotches. Hatchling Indian Roofed Turtles (P. tecta) have lime-green carapaces with a yellow-orange border and a broken scarlet mid-dorsal stripe. Adult

above | Members of the genus Pangshura inhabit both flowing and still water habitats.

females are larger than males in Pangshura, sometimes considerably so. Several species also have attractive white or yellowish striped patterns and colorful markings on the head and neck, and the Brown Roofed Turtle (P. smithii) has blue eyes. Jackals and hyenas are some of the egg predators of Indian Tent Turtles (P. tentoria). Much more remains to be learned about the biology of these interesting turtles. 129

GEOEMYDIDAE: SACALIA

BEALE’S EYED AND FOUR-EYED TURTLES below

T

he two species of Sacalia have partially overlapping ranges, mainly in southern China. The range of the Four-eyed Turtle (S. quadriocellata) extends south to Hainan Island and Vietnam. Both species are reported to live in streams in forested mountains. These small turtles have a brownish carapace sometimes with radiating dark lines. The plastron is unhinged, and females are larger than males. Their most remarkable feature is the presence of conspicuous ocelli that look like eyes on the back of the neck. S. quadriocellata typically has four ocelli that are green in males and yellow in females. The Beale’s Eyed Turtle (S. bealei) has only two ocelli. Both species have neck stripes that are red in males and yellow in females. The function of the unusual eyespots and color difference in neck stripes between the sexes is unknown.

| Female Four-eyed

Turtles lack thin lines outlining the eye spots in comparison to males shown on the next page.

distribution

activity

China, Laos, and Vietnam

Unknown; presumed diurnal

species

lifespan

Sacalia bealei, S. quadriocellata

Over 27 years in captivity

habitats

reproduction

Streams in forested mountains; below 1,640 ft (500 m) elevation for S. quadriocellata

2–6 hard-shelled eggs; female S. quadriocellata are very selective and only about 4 percent of male courtship attempts result in mating

size

CL 6 in (15 cm) in S. quadriocellata and 7½ in (19 cm) in S. bealei

130

CRYPTODIRA—Hidden-neck turtles

diet

Reportedly omnivorous to carnivorous

above | The plastron of male Beale’s Eyed Turtles (shown) usually has a stippled pattern of black spots while the female has dark blotches.

left | Eyed turtles of the genus Sacalia have “eye” markings on their neck. More than two “eyes” may suggest safety in numbers.

131

GEOEMYDIDAE: SIEBENROCKIELLA

BLACK MARSH AND PALAWAN FOREST TURTLES

T

he two species of Siebenrockiella have disjunct ranges. Black Marsh Turtles (S. crassicollis) are found in Sundaland from Laos south to Sumatra and western Borneo. Palawan Forest Turtles (S. leytensis; formerly placed in the genus Heosemys) are found only on Palawan and Dumaran islands in the Philippines. Holocene remains of S. crassicollis are known from Thailand. Both species live in a variety of freshwater habitats although S. leytensis is mainly found in

pristine forest wetlands. S. crassicollis is often found in human-modified environments. Both species are rather nondescript with brown to black carapaces and unhinged plastrons but with distinctive species-specific lighter-colored head and neck markings. S. crassicollis has XX/XY genetic sex determination.

distribution

size

reproduction

Cambodia, Indonesia, Malaysia, Laos, Myanmar, Thailand, Singapore, Vietnam, and Philippines

CL 8 in (20 cm) in S. crassicollis and 11¾ in (30 cm) or more in S. leytensis

3–4 clutches per year in S. crassicollis; 1–2 brittle eggs per clutch

species

Nocturnal

Siebenrockiella crassicollis, S. leytensis habitats

Streams, small rivers, ponds, marshes, swamps, and flooded rice fields

132

above | Siebenrockiella leytensis is now threatened by exploitation for the pet trade and food. Most specimens are darker than the one shown.

CRYPTODIRA—Hidden-neck turtles

activity lifespan

Over 16 years in captivity (S. crassicollis)

diet

Omnivorous to carnivorous

GEOEMYDIDAE: VIJAYACHELYS

COCHIN FOREST CANE TURTLE

V

ijayachelys silvatica is the only species in this genus, and is restricted to the Western Ghats region of southwestern India. Fossils have not been described. Cochin Forest Cane Turtles live in evergreen (rainforest) and semi-evergreen forests where they are entirely terrestrial. Much of their time is spent buried beneath leaf litter or hiding under logs and vegetation. It is the smallest turtle species in India. The flattened brownish carapace has three keels. Females develop a plastron which is movable where it connects to the carapace. Male eyes have a scarlet or white iris surrounded by a scarlet sclera. Female eyes, while colorful, are usually not as vivid. Until its rediscovery in 1982, the biology of Vijayachelys went unreported for over 70 years after its initial description. Habitat loss and subsistence hunting by indigenous people are serious threats to this turtle.

| The rare and diminutive Cochin Forest Cane Turtle has many predators including wild dogs, leopards, and other carnivores.

below

distribution

activity

diet

Southwest India

Crepuscular to nocturnal; especially active during rain

Mainly carnivorous on earthworms, insects, and millipedes; some fruits

species

Vijayachelys silvatica habitats

Rainforest and other tropical forests, especially those with heavy undergrowth

lifespan

Unknown reproduction

1–2 clutches; 1–4 brittle eggs per clutch

size

CL up to 5½ in (13.9 cm)

133

GEOEMYDIDAE: RHINOCLEMMYS

NEOTROPICAL WOOD TURTLES

R

hinoclemmys, the only genus in the family Geoemydidae in the western hemisphere, contains nine species. Their geographic range is extensive, from northwestern and southeastern coastal Mexico and the Yucatan Peninsula, through all Central American countries, the Caribbean island nation of Trinidad and Tobago, through South America to Brazil and Ecuador. Neotropical wood turtles occur in a wide variety of both freshwater aquatic, semi-aquatic, and terrestrial habitats, ranging from large rivers to thorn scrub areas and tropical forests, depending on species and regions. Some are important seed dispersers. Some species are dramatically affected by the wet–dry seasons characteristic of many areas, being especially obvious during rains but dormant and well hidden during dry periods. Most adults have dark-colored, nondescript carapaces, many with a longitudinal ridge down the middle of the back. The Painted Wood Turtle

distribution

habitats

Mexico, Central America, Brazil, and Ecuador

Terrestrial or aquatic depending on species and region; freshwater marshes, streams, rivers, pine woods, broadleaf woodlands, and agricultural areas

species

Rhinoclemmys annulata, R. areolata, R. diademata, R. funerea, R. melanosterna, R. nasuta, R. pulcherrima, R. punctularia, and R. rubida

size

CL up to 9 in (23 cm) activity

Often active in the morning; some nest at night

134

CRYPTODIRA—Hidden-neck turtles

(R. pulcherrima), has a colorful carapace with concentric yellowish markings. Yellow, orange, and, occasionally, red stripes, spots, or other markings are on the head and neck of most species. The plastron is yellowish, with some species having a large dark blotch covering some or most of the underside. Rhinoclemmys do not have plastral hinges, but the posterior junction of the carapace and plastron is flexible. This anatomical feature is critical to reproduction because they lay enormous eggs, which have a brittle shell and would be unable to pass through a rigid connection of carapace and plastron. Only one or two eggs are laid in most clutches and are among the largest eggs relative to body size of the world’s turtles.

| Spot-legged Turtles found in northern South America have a pointed head and projecting snout.

below

| Brown Wood Turtles feed on the fruits of tropical plants and distribute seeds, maintaining distinctive flora in treefall areas.

opposite

right | Painted Wood Turtles, found from northwest Mexico to Central America, are among the most beautiful turtles in the world.

lifespan

Over 20 years in captivity reproduction

1–4 eggs per clutch; most species lay one or two very large, oblong brittle eggs diet

Omnivorous on seeds, fruits, terrestrial plants, insects, and other invertebrates; also carrion and animal scats

135

FAMILY: TESTUDINIDAE TORTOISES

T

he tortoise family Testudinidae is second only to the Geoemydidae in diversity, with 18 genera and 65 species in modern times, some now extinct. The largest genus, Chelonoidis, has 17 species, two of which are extinct. This genus includes all Galapagos tortoises and their three South American relatives. Tortoises are found in parts of Africa, Asia, Europe, North America, and South America. Some oceanic islands are home to giant species, most notably, the Galapagos Islands and various Indian Ocean islands. Most tortoises have relatively small distributions. The range of habitats occupied by species in this family is almost as diverse as the tortoises themselves, from temperate and subtropical deserts and grasslands to tropical rainforests. Fossil tortoises of this family are known from the early Eocene. Tortoise legs are adapted for walking on land or digging and have no webbing between the toes.

Their shells are generally domed but the pancake tortoise of Africa (Malacochersus) is flattened with a poorly ossified, flexible shell allowing them to hide from predators in rock crevices. Some species, like Kinixys, have hinged rear carapaces, and spider tortoises (Pyxis) and some Testudo have different types of hinging on the plastron. The first Earthlings to orbit the Moon and return safely to Earth were Central Asian tortoises (Testudo horsfieldii) in a Russian spacecraft launched in 1968. The most recent extinction of a tortoise occurred with the death of Lonesome George, the last known Pinta Island (Galapagos) tortoise (Chelonoidis abingdonii), in 2012. The discovery of hybrids of his species on another Galapagos island, have raised hope for possible recovery. In addition, a female Chelonoidis phantasticus, thought to have been extinct on Fernandina Island (Galapagos) for over 100 years, was rediscovered in 2019 and genetic tests in 2021 confirmed her identity.

right | Some tortoises, like this Star Tortoise, are strikingly patterned, making them a target for the illegal wildlife trade.

distribution

habitats

activity

Africa, Asia, Europe, North America, South America, Galapagos Islands, Madagascar, and Seychelles (Aldabra Atoll)

Most species prefer subtropical, tropical, and warm temperate zone habitats. Some tortoises inhabit desert ecosystems, but none are found in regions with the most extreme aridity. Other tortoises live in rainforest habitats in Africa, Asia, and South America

Primarily diurnal, but see account for Gopherus

genera

Aldabrachelys, Astrochelys, Centrochelys, Chelonoidis, Chersina, Chersobius, Cylindraspis (extinct), Geochelone, Gopherus, Homopus, Indotestudo, Kinixys, Malacochersus, Manouria, Psammobates, Pyxis, Stigmochelys, and Testudo

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size

Diminutive CL 4 in (10 cm) in Chersobius signatus to 51 in (130 cm) and weight of 882 lb (400 kg) in the gigantic Chelonoidis porteri (in captivity)

CRYPTODIRA—Hidden-neck turtles

reproduction

1–6 clutches per year depending on species; 1–51 eggs per clutch (51 eggs is for Manouria in captivity) diet

Most species are herbivorous, some omnivorous, and others fungivorous

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TESTUDINIDAE: ALDABRACHELYS

ALDABRA GIANT TORTOISES

A

ldabrachelys, formerly Geochelone, has a single species and four subspecies once considered full species. One of these is extinct. All lived on the small Indian Ocean islands including Aldabra Atoll in the Republic of the Seychelles. Tortoise populations, once present on most islands in the region, were extirpated or translocated by early seafarers. Reintroductions to some islands have been successful, and in the 1970s more than 150,000 Aldabra Giant Tortoises were estimated to be present. According to some reports, the collective tortoise biomass was the highest density of any grazing animal in the world, including hoofed mammal herds. Aldabra is a coral reef habitat with low-lying ground vegetation of grasses and shrubs that vary in species composition among small islands of the atoll. Depending on an island’s plants, the inhabitants graze on grasses, known as tortoise turf, and other low-lying vegetation, or browse on shrubs to the point of determining the vegetative structure. The tortoises are active during cooler periods of the early morning and late afternoon, seeking shade or soaking in freshwater or saline pools of water during the hottest period of the day. As reported for certain other tortoise species, Aldabrachelys drinks collected rainwater through its nose.

| Aldabra Giant Tortoises are the second largest tortoises in the world after the large Galapagos tortoises.

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distribution

size

Seychelles islands (Aldabra Atoll; extirpated or introduced on other islands)

CL up to 41½ in (105 cm); weight up to 683 lb (310 kg) but usually less than 265 lb (120 kg)

species Aldabrachelys gigantea habitats

Grasslands, open scrub, and occasionally mangrove swamps

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CRYPTODIRA—Hidden-neck turtles

lifespan

Over 63 years confirmed in captivity; unverified claims of a century or more activity

Diurnal; active early morning and late afternoon, seeking shade during mid-day or soaking in wet areas

above | Aldabra Giant Tortoises have a head that is more pointed than that of the otherwise similar Galapagos Giant Tortoises. right | The body form of Aldabrachelys gigantea is domed or saddle-backed.

reproduction

1+ clutch per year; 4–17 round brittle eggs per clutch diet

Mostly herbivorous on low-lying grasses and sedges; woody plants such as shrubby fig trees

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TESTUDINIDAE: ASTROCHELYS

RADIATED TORTOISE AND PLOUGHSHARE TORTOISE | Radiated Tortoises continue to be illegally poached at unsustainable levels in Madagascar for food and the pet trade.

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A

strochelys has two species, A. radiata and A. yniphora, both formerly placed in the genus Geochelone with numerous other species. Both species have restricted, non-overlapping geographic ranges on the southern tip and central-western coast of the island of Madagascar. One or both species also occur on some of the Mascarene Islands as the result of maritime trade.

Astrochelys occupy arid habitats including dry scrublands and bamboo stands, where they graze on ground vegetation. No fossils of the genus have been reported. Astrochelys are the quintessential tortoises in appearance with remarkably high, domed shells and large columnar legs. The Radiated Tortoise has a striking color pattern with a dark carapace, yellow starburst markings on each scute, and yellow legs.

distribution

lifespan

Madagascar, Mascarene Islands (Mauritius, Réunion, Rodrigues, and Round islands; introduced)

Over 32 years in captivity (A. radiata); an age record of 188 years is unconfirmed

species

Diurnal

Astrochelys radiata, A. yniphora habitats

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activity reproduction

Dry bamboo stands, scrub forests, savannas

1–3 clutches per year; 3–6 round eggs per clutch

size

diet

CL up to 19¼ in (48.6 cm); weight 41¾ lb (18.9 kg)

Herbivorous

CRYPTODIRA—Hidden-neck turtles

| The Ploughshare Tortoise is named for the prominent gular scutes on the front of the plastron that resemble a plow to some.

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A reported age record many view as dubious is 188 years for a Radiated Tortoise supposedly collected by Captain Cook in the 1770s. Astrochelys is critically endangered due to a variety of humanmade problems including habitat loss, poaching both for food and the illegal pet trade, and predation on Ploughshare Tortoises by bush pigs introduced from the African continent. Turtle biologists consider the Ploughshare Tortoise to be

one of the most threatened tortoises in the wild because of many years of uncontrolled removal of individual tortoises from their native habitat. The total Radiated Tortoise population was conservatively estimated at 25 million individuals in 2000. Collection of over 45,000 per year for food and the pet trade has greatly reduced populations.

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TESTUDINIDAE: CENTROCHELYS

AFRICAN SPURRED TORTOISE

T

he genus Centrochelys has one species, historically ranging across the Sahel and Sudanian savanna below the Sahara Desert from the Atlantic Ocean in the west to the Red Sea. Whether the genus is native or introduced to Asia, in Saudi Arabia and Yemen, is uncertain. The species has been extirpated in many regions of its original range in Africa, and now only isolated wild

populations persist. Centrochelys was formerly placed in the genus Geochelone with numerous other tortoises. African Spurred Tortoises occupy arid habitats bordering the southern edge of the Sahara Desert. To avoid high daytime temperatures and prolonged droughts during the dry season, African Spurred Tortoises dig burrows that are several meters long. They emerge primarily during the coolest parts of

| African Spurred Tortoises have enlarged scales on their limbs. On the hindlimbs they resemble spurs, hence their common name.

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right | Their popularity in the pet trade stems from the small, cute hatchlings. They quickly grow to less popular sizes.

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distribution

size

West Africa, Central Africa, and East Africa; possibly Yemen and Saudi Arabia

CL up to 34 in (86 cm); weight 220 lb (100 kg) or more

species Centrochelys sulcata

lifespan

habitats

activity

Arid savannas with scattered acacia trees and other shade-providing vegetation

Diurnal; mostly in early morning and late afternoon

CRYPTODIRA—Hidden-neck turtles

Over 54 years in captivity

the day, shortly after dawn and before dusk, except during dry seasons when they may spend months in their burrows. The body overall is sand-colored, ranging from a yellowish to light brown carapace to yellowish or beige plastron and limbs. reproduction

2–4 clutches per year in wild, (up to 6 clutches in captivity); up to 40 round, hard-shelled eggs per clutch diet

Herbivorous on ground vegetation

These are the largest tortoises in the world not restricted to oceanic islands and are exceeded in size only by Galapagos and Aldabra tortoises. Natural populations of Centrochelys are on the decline due to habitat modification and other human-caused impacts. Ironically, they are common in captivity. Because of their impressive size, hardy nature, and propensity to readily breed in captivity, they are a popular display animal at zoos and nature parks and are kept personally by turtle enthusiasts in many parts of the world. Consequently, African Spurred Tortoises are scattered across much of the world outside of Africa.

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TESTUDINIDAE: CHELONOIDIS

SOUTH AMERICAN AND GALAPAGOS TORTOISES

T

he genus Chelonoidis, formerly Geochelone, has 17 species, 14 of which are giant tortoises found on the Galapagos Islands, the largest tortoises in the world. Two of the latter have become extinct in modern times. The three continental species occur collectively in many parts of South America and one, the Red-footed Tortoise (C. carbonarius), has colonized or been introduced to several islands in the Caribbean.

The giant Galapagos species are distributed among the varied volcanic islands in habitats ranging from dry and rocky, to moist montane forests. The continental species occupy both arid and moist savannas and scrublands as well as deciduous and evergreen tropical rainforest. All eat grasses, cacti, and other plants. Fossil Chelonoidis have been found in middle Miocene deposits in Argentina. Most Chelonoidis are large tortoises, including the largest terrestrial species on the South American continent, the Yellow-footed Tortoise (C. denticulatus; maximum carapace length 32¼ in / 82 cm), and the giant Galapagos tortoises (maximum carapace length 51 in / 130 cm). The smallest is the continental Chaco Tortoise (C. chilensis; maximum carapace length 17 in / 43 cm). The domed carapace of the continental Chelonoidis vary from yellowish to black and may have yellow or red coloration on the shell, head, and limbs. The Galapagos island forms have a solid dark gray to black shell, limbs, and neck, which is very long. left | Tortoises in South America, like Red-Footed Tortoises, are related to Galapagos tortoises despite their size differences.

distribution

habitats

Panama, South America, Galapagos Islands, and Caribbean islands (possibly introduced)

Mostly arid, rocky volcanic terrain on the Galapagos Islands; dry and moist savannas and thorn scrub. C. denticulatus is found in tropical rainforests

species

Chelonoidis carbonarius, C. chilensis, C. denticulatus, C. abingdonii (extinct), C. becki, C. chathamensis, C. darwini, C. donfaustoi, C. duncanensis, C. guntheri, C. hoodensis, C. microphyes, C. niger (extinct), C. phantasticus, C. porteri, C. vandenburghi, and C. vicina

144

CRYPTODIRA—Hidden-neck turtles

size

CL up to 51 in (130 cm); weight 882 lb (400 kg) in Galapagos tortoises

lifespan

49 years in captivity for continental species C. carbonarius; over 92 years in captivity for Galapagos species C. porteri; numerous estimates of more than a century are unconfirmed activity

Diurnal

reproduction

1–19 brittle-shelled eggs per clutch; smaller, continental species have oval-shaped eggs whereas Galapagos species lay round eggs

above | Galapagos tortoises look ancient and indeed, some may live 200 years, meaning they were alive when Darwin visited the islands.

diet

Mostly herbivorous on grasses, cactuses, and other ground vegetation

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right | Galapagos tortoises are among the most iconic turtles in the world. Despite their celebrity, some cling to survival.

The carapace is domed but tortoises on some islands have a saddle-backed profile. A male tortoise named Lonesome George from Pinta Island in the Galapagos achieved international significance as a symbol for turtle conservation, being the only remaining member of its species, C. abingdonii. Upon his death in 2012, the species became officially extinct. Over-exploitation by humans and the introduction of invasive species have led to the overall decline of tortoises. There is hope for recovering two species of “extinct” Galapagos tortoises, including C. abingdonii. Researchers discovered that there were both saddle-backed and domed shell tortoises on Wolf Volcano, Isabela Island. Co-occurrence of both shell morphologies is unknown anywhere else in the

right | The volcanic origin of the Galapagos Islands creates a harsh landscape for the survival of many of their famous tortoises.

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CRYPTODIRA—Hidden-neck turtles

Galapagos. The mystery began to be unraveled with the advent of genetic analyses demonstrating that some of the tortoises on Wolf Volcano were hybrids with species from other islands, possibly transported by humans in the past. Some of those hybrids had genes of Pinta Island tortoises. In fact, based on the age of the hybrids and evidence that some had at least one genetically pure parent, it is probable that there are still genetically pure Pinta tortoises on Wolf Volcano. Similar hybrids were found with Floreana Island genes, where tortoises became extinct between 1846 and 1850. Efforts are underway to find genetically pure Pinta and Floreana tortoises on Wolf Volcano. Also, some hybrids have been relocated to the Tortoise Breeding Center on Santa Cruz Island for backcrossing.

above | While no match for Galapagos tortoises, Yellow-footed Tortoises can reach relatively large sizes, more than 31 in (80 cm). left | The Eastern Santa Cruz Giant Tortoise was described as a new species in 2015, proving there are still discoveries to be made.

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TESTUDINIDAE: CHERSINA

SOUTH AFRICAN BOWSPRIT TORTOISE

T

he genus Chersina has a single species with a distribution confined to the arid coastal strip of the southern and southeastern tip of Africa, up to elevations of 4,000 ft (1,200 m). Pliocene fossils have been reported from South Africa. South African Bowsprit Tortoise habitat is typically semi-arid with sandy or rocky terrain with shrubs and grasses. The carapace is elongate and yellowish to black with contrasting patterns of light and dark on each scute and along the marginals a pattern of alternating triangles like a backgammon board.

above | Also called Angulate Tortoises, the South African Bowsprit Tortoise is the only African tortoise with a single gular scute, instead of two, on the plastron.

distribution

lifespan

diet

Namibia and South Africa

32 years in captivity

species

activity

Chersina angulata

Diurnal and active year-round, especially during rainy periods

Omnivorous, eating grasses, mosses, and other ground vegetation; insects and snails, and rabbit feces

habitats

Dry grass and scrub areas inland from the coast size

CL up to 13¾ in (35.1 cm)

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Chersina exhibits a peculiar behavior in obtaining drinking water. When water collects on the carapace during rain, the tortoise pushes its hindlegs up so that water runs down the carapace and collects in front of the head, whereupon the tortoise drinks through its nose.

CRYPTODIRA—Hidden-neck turtles

reproduction

6 clutches per year of 1 (rarely 2) oval, hard-shelled egg

TESTUDINIDAE: CHERSOBIUS

FIVE-TOED PADLOPER TORTOISES

C

hersobius has three species with non-overlapping ranges in southern Africa. All were formerly placed in the genus Homopus. Five-toed padloper tortoises inhabit dry, rocky terrain. Possible fossils have been found in strata of unknown age in South Africa. Individual Chersobius shells may decrease in length, height, and volume during dry weather: an example of shrinking tortoises! C. signatus is referred to as the “world’s smallest tortoise.” Coloration of the carapace, plastron, head, and limbs is highly variable in shades of brown, reddish, and yellowish. Dark dots form geometric patterns on the carapace of H. signatus. Both carapace and plastron are unhinged. C. signatus is adept at climbing up and over large rocks in the habitat. Despite living under normally dry conditions, they have not been observed to drink water, with hydration presumably being achieved by eating a wide variety of plant material including succulents.

Females typically lay a single exceptionally large egg; relative to body size, C. signatus produces the largest egg of any turtle species.

| These tiny tortoises are called padlopers, or path runners in Afrikaans, perhaps because they are seen on paths and roads.

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distribution

lifespan

Namibia and South Africa

No records

species

activity

Chersobius boulengeri, C. signatus, and C. solus

Diurnal

habitats

Up to 4 clutches per year; only one egg per clutch for C. signatus; egg size is positively correlated with the size of the female

Arid, rocky areas size

CL up to 4¼ in (11 cm); smaller during low rainfall periods

Herbivorous on grasses and ground vegetation; occasionally insects diet

reproduction

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TESTUDINIDAE: GEOCHELONE

INDIAN STAR AND BURMESE STAR TORTOISES

G

eochelone has two species with three widely separated geographic ranges. Indian Star Tortoises (G. elegans) occur in northeastern India and bordering Pakistan, a region separated by hundreds of miles from populations in southeastern India and Sri Lanka. Burmese Star Tortoises (G. platynota) have a more restricted range in central Myanmar. No Geochelone fossils have been reported for these species.

Star tortoises occupy a variety of habitat types, depending on the region, including both wet and semi-arid forests, dry savannas, and more moist grasslands. Ground vegetation of a variety of plant species are eaten but members of the genus will capture small animals or consume carrion if attainable. The domed carapace is highly ornamental in appearance, with yellow lines on a dark background. Scutes on the carapace are

right | The Burmese Star Tortoise is considered ecologically extinct in the wild. Captive breeding and releases have been successful.

distribution

Over 24 years in captivity in G. elegans

species

reproduction

Geochelone elegans, G. platynota

1–4 clutches per season; 1–11 oval, brittle eggs

habitats

Tropical deciduous forests and savannas size

CL up to 15 in (38 cm) in G. elegans activity

Diurnal

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liifespan

India, Myanmar, Sri Lanka, and Pakistan

CRYPTODIRA—Hidden-neck turtles

diet

Omnivorous; mostly herbivorous but opportunistically carnivorous

sometimes elevated in the center, the point from which yellow radiating lines start. The head and limbs have yellow or tan markings. These are medium-sized tortoises, typically reaching adult carapace lengths of 7¾ to 11¾ in (20 to 30 cm). Sexual dimorphism is evident, with females reaching larger body sizes than males. Despite the starburst and other intricate markings all over the shell making them physically attractive,

these benign tortoises have been eaten historically by native peoples throughout their range. As many as 100,000 per year have been sold in markets in India. In addition, widespread habitat loss from human development (agricultural as well as urban) and the illegal removal of wild animals for the international pet trade have been major threats to both species in the genus. The Burmese Star Tortoise is critically endangered.

| There are subtle differences in body size and coloration of Indian Star Tortoises across their fragmented range.

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151

TESTUDINIDAE: GOPHERUS

NORTH AMERICAN TORTOISES

G

opherus has six species, all restricted to southern USA and northern Mexico. Only two have modern ranges that include both countries, G. berlandieri and G. morafkai. G. flavomarginatus occurred in the USA during the Pleistocene and a colony has been re-established in New Mexico, the only US population. Gopherus fossils are numerous and date to the Oligocene of North America. Habitats vary widely among species but generally favor those characterized by hot and arid to semi-arid climates. Going from west to east, G. agassizii is found in the Mojave and western Sonoran deserts, extremely arid ecosystems, with some winter, but little summer, rainfall. G. morafkai occurs in the rest of the Sonoran Desert where both winter and summer rains occur, hybridizing with G. agassizii where their ranges narrowly overlap in Arizona. Farther to the south, G. evgoodei occurs in tropical deciduous forests with very distinct dry and rainy seasons. G. flavomarginatus is found in a small portion of the northern

| Agassiz’s Desert Tortoise is found in the Mojave Desert, home also to iconic plants such as the Joshua Tree.

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distribution

size

Mexico and USA

CL up to 9 in (22.8 cm) in G. berlandieri and up to 15¾ in (40 cm) in G. flavomarginatus

species

Gopherus agassizii, G. berlandieri, G. evgoodei, G. flavomarginatus, G. morafkai, and G. polyphemus Desert, semi-arid grassland, and shrubland in southwestern and southcentral USA and northern Mexico; sandhill habitats in southeastern USA habitats

152

CRYPTODIRA—Hidden-neck turtles

activity

Diurnal but G. flavomarginatus emerges from deep burrows at night during rainstorms lifespan

Over 80 years in captivity for G. agassizii; over 56 years for G. polyphemus

above | Berlandier’s Tortoise is the smallest tortoise native to North America, found only in Texas and northeastern Mexico.

Chihuahuan Desert, another arid region and is the largest terrestrial reptile in North America. In Texas and Mexico, G. berlandieri is found in arid to semi-arid grasslands and shrublands. The easternmost species, G. polyphemus, while living in the humid southeastern USA, is generally confined to sandhill habitats that are xeric in comparison to surrounding habitats. Like all tortoises, Gopherus have no webbing between their toes and they are primarily terrestrial. Most have forelimbs adapted for digging deep burrows that protect them from environmental extremes. Their shells are domed in comparison with most aquatic turtles.

reproduction

1–3 clutches per year; typically 1–12 eggs per clutch for G. agassizii and most species. Gopherus eggs are very large, relative to body size, in comparison to aquatic turtles diet

Herbivorous on annual and perennial grasses and forbs

above | The burrows of Gopher Tortoises are known to provide shelter for over 350 species of vertebrates and invertebrates.

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TESTUDINIDAE: HOMOPUS

FOUR-TOED PADLOPER TORTOISES

right | It would take about 2,000 padlopers (average weight ½ lb/200 g) to equal the weight of one large Galapagos tortoise.

T

he genus Homopus has two species with adjacent ranges in South Africa. Fossils have been described from unknown strata in South Africa. The primary habitat is dry scrublands, and savannas where they often shelter under rocks. The domed carapace of these small tortoises varies greatly in color depending on species and sex, including yellowish, brown, olive, reddish,

distribution

lifespan

diet

South Africa

More than 28 years in captivity

Herbivorous

species

activity

Homopus areolatus, H. femoralis

Diurnal; H. femoralis hibernates during the winter

habitats

reproduction

Coastal areas, arid scrub habitat, and savanna

1–2 clutches per year; 1–4 eggs per clutch

size

CL up to 6¾ in (16.8 cm) in H. femoralis

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orangish, or greenish. The plastron is yellowish, often with dark markings. They have four toes on each foot. Both carapace and plastron are unhinged. The Common Padloper (H. areolatus) is distinctive in being one of the few species of turtles that change color during the breeding season, at which time the front part of the face (prefrontals) of males turns orange. A major threat to four-toed padloper tortoises is road mortality.

CRYPTODIRA—Hidden-neck turtles

TESTUDINIDAE: INDOTESTUDO

INDIAN AND SOUTHEAST ASIAN TORTOISES

I

ndotestudo has three geographically isolated species, I. elongata, I. forstenii, and I. travancorica. The Travancore Tortoise is restricted to the Western Ghats of southeastern India, and Forsten’s Tortoise is found only on Sulawesi, Halmahera, and the Maluku islands in Indonesia. An earlier suggestion that Forsten’s Tortoises were introduced to Indonesia by humans has been dismissed by later studies, which, if true, makes it the only native tortoise found east of Wallace’s Line. In contrast, the Elongated Tortoise has an extensive geographic range from northern India and Nepal through much of Southeast Asia. All modern species are forest-dwelling, often in association with streams and marshes. The shell is noticeably elongate, the carapace being about twice

as long as wide. The unhinged carapace and plastron ranges from light brown or olive to darker brown, often with large, darker blotches on each scute. The eyelids and area around the eyes and nose, which are normally pinkish, turn bright red during the breeding season, especially in males. An unusual behavior has been observed in Travancore Tortoises in captivity in which individuals make audible calls at night and have even been heard in choruses making croaking sounds during rain. Although not studied in the wild, the sound production is presumed to be some form of social behavior, possibly related to reproduction. Indotestudo is severely threatened in many parts of its range by collection of wild tortoises for Asian food markets, in addition to habitat destruction.

right | The calls of Indotestudo tortoises have been likened to “whimpers” or “bellows” and may be a form of communication.

distribution

size

reproduction

India, Indonesia, and Southeast Asia

CL up to 13 in (33.1 cm) for I. travancorica) and up to 14 in (36 cm) for I. elongata

1–10 eggs per clutch

species

Indotestudo elongata, I. forstenii, I. travancorica habitats

Moist, evergreen, and deciduous forests, including bamboo thickets, often near streams and marshes

activity

Mostly crepuscular in early morning and late evening

diet

Omnivorous on forest plants, fruits, invertebrates, vertebrates, and carrion

lifespan

Over 32 years in captivity for I. forstenii

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TESTUDINIDAE: KINIXYS

HINGE-BACK TORTOISES

T

he genus Kinixys has eight species distributed over much of central and southern Africa. Populations of K. zombensis inhabiting a small region on Madagascar were possibly a result of human introductions. Kinixys fossils are known from the Miocene of Kenya, Uganda, Sudan, Congo, and Chad. Living species occupy a variety of habitats, ranging from tropical forests to savannas. The carapace is flattened or slightly depressed. The carapace and plastron range from dark brown to yellowish, often with dark or light blotches and patterns on the scutes. These are the only turtles to have a hinge on the carapace, allowing them to close the rear portion of their shell when threatened. Hinge-back tortoise populations have numerous threats, including habitat destruction and removal of animals from the wild for food and the pet trade.

| Home’s Hinge-back Tortoises are found in lowland evergreen rain forest habitat near water in west Africa.

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distribution

size

Most sub-Saharan countries in West, Central, and Southern Africa; Madagascar

CL up to 6¼ in (16 cm) for K. natalensis to 15¾ in (40 cm) for K. erosa

species

lifespan

Kinixys belliana, K. erosa, K. homeana, K. lobatsiana, K. natalensis, K. nogueyi, K. spekii, and K. zombensis

Over 26 years in captivity

habitats

Humid forests, in or near marshes, and swamps as well as savanna/grasslands, depending on the species

156

CRYPTODIRA—Hidden-neck turtles

activity

Some species crepuscular and nocturnal; others diurnal during rainy periods

above | Speke’s Hinge-back Tortoise was named in 1863 after Captain John Speke, credited with discovery of the source of the Nile. right | The hinge on the rear of the carapace is better developed in some species and size classes of Kinixys than in others.

reproduction

Several clutches a year of 1–6 elongate eggs with hard shells diet

Omnivorous

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TESTUDINIDAE: MALACOCHERSUS

PANCAKE TORTOISE

| Pancake Tortoises acquire their flexibility by having permanent openings (or fenestrae) between carapace bones.

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T

he genus Malacochersus has a single species in East Africa. Their preferred habitat is rocky terrain with abundant crevices. The carapace is typically yellow to tan with black-bordered scutes having radiating lines of black and yellow. The distinctive morphological feature is a relatively supple shell that is flatter than that of any other tortoise. The carapace has no keels, and both

distribution

lifespan

diet

Kenya, Tanzania, and Zambia

Over 25 years in captivity

species

activity

Malacochersus tornieri

Diurnal

Herbivorous on grasses, succulents, and sometimes carrion

habitats

reproduction

Rocky areas with crevices suitable for hiding

2–3 clutches of 1 (occasionally 2) oval, hard-shelled egg laid in a nest dug in sandy soil

size

CL up to 7 in (17.7 cm)

158

carapace and plastron are unhinged. The scutes are thinner and the shell is more pliable than in other tortoises. Pancake Tortoises are noted for crawling into rock crevices and wedging themselves in to escape predators and avoid being trampled by hoofed mammals. The greatest threat to the species throughout its range is illegal collection for the pet trade.

CRYPTODIRA—Hidden-neck turtles

TESTUDINIDAE: MANOURIA

ASIAN GIANT TORTOISE AND IMPRESSED TORTOISE | The Impressed Tortoise is most active during the wet season when mushrooms are available, a primary food in the wild.

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M

anouria has two species, including the largest tortoise in Asia, the Asian Giant Tortoise (M. emys). The genus is found sporadically from extreme northeastern India and Bangladesh through Southeast Asia to Borneo and Sumatra. Fossils of an extinct species of Manouria have been found in Pleistocene deposits in the Ryukyu Islands, Japan. Both species occupy forest habitat, including wet, mountainous areas, especially juvenile M. emys.

The carapace and plastron are unhinged with color ranging from light brown to dark brown or black. Manouria lay their eggs in an above-ground nest mound built by the female, who then stays near the nest or sits on top after the eggs are deposited. The female protects the nest and will defend it against potential predators for several days afterward. Nest-guarding behavior is rare in turtles.

distribution

size

reproduction

India through Southeast Asia

CL 11¾ in (30 cm) for M. impressa to 23½ in (60 cm) for M. emys

30–60 round eggs laid in nest mound and guarded up to 21 days by female M. emys; M. impressa lay 17–20 eggs

species

Manouria emys, M. impressa habitats

Wet, forested areas, often near streams (M. emys) or more arid tropical areas including bamboo forests (M. impressa)

activity

Mostly inactive during the dry season; M. impressa are crepuscular lifespan

Over 19 years in captivity for M. emys

diet

Herbivorous on forest plants, bamboo shoots; mushrooms and other fungi

159

TESTUDINIDAE: PSAMMOBATES

GEOMETRIC AND TENT TORTOISES

left | In 2012, a wildfire burned up most of the remaining habitat of Geometric Tortoises, killing much of the world’s population.

T

he genus Psammobates has three species in southern Africa. Fossils are known from the early Pleistocene of South Africa. The preferred habitat varies greatly from arid, sandy areas and dry scrublands to open savanna depending on the species and region. The highly domed carapace of these small tortoises has intricate cross-hatching designs of yellowish to orange on a dark-brown or black carapace. Scutes on the carapace are elevated

distribution

size

reproduction

Namibia, South Africa, Botswana, and Zimbabwe

CL up to 8 in (20 cm)

species

Probably more than 30 years in the wild

Up to 6 clutches per year; 1–5 elongate, hard-shelled eggs per clutch

Psammobates geometricus, P. oculifer, and P. tentorius habitats

Range of habitats including desert, dry shrubland, rocky outcrops, and savanna, depending on species and locality

160

in the tent tortoises (P. oculifer and P. tentorius) giving them their tent-like appearance. The carapace and plastron are both unhinged. Psammobates are one of the few turtles to be preyed upon by ostriches. Aside from the hard shell, their primary means of protection is camouflage among ground vegetation with their intricate color pattern. The Geometric Tortoise (P. geometricus) is critically endangered.

CRYPTODIRA—Hidden-neck turtles

lifespan

activity

Diurnal; estivate during dry seasons or remain dormant during winter, depending on the species and locality

diet

Mostly herbivorous but will eat some animal matter

TESTUDINIDAE: PYXIS

SPIDER AND FLAT-TAILED TORTOISES

T

he genus Pyxis has two species with nonoverlapping ranges on the southern tip and west-central coast of Madagascar. Fossils have been reported from the Quaternary of Madagascar. The primary habitat is dry, deciduous woodlands and dry coastal forests and scrublands. Pyxis are among the world’s smallest tortoises. The carapace and marginals are yellow to beige with dark marking on each scute, sometimes forming a spider-web appearance of star-shaped yellow patterns. The plastron is yellowish, often with dark markings. A distinctive morphological feature of the genus, possessed by no other tortoise, is that the Spider Tortoise has a hinge on the anterior plastron with variable flexibility among populations. The genus is threatened by habitat destruction and illegal collecting in the wild for food and the pet trade. Populations have declined greatly.

| Spider and Flat-tailed Tortoises in the genus Pyxis are sometimes called “Pixies” because of their diminutive stature.

below

distribution

lifespan

diet

West-central and southern Madagascar

Unknown. Estimated 70 years, but unconfirmed

species

activity

Omnivorous on vegetation, fruits, invertebrates, and mammal feces

Pyxis arachnoides, P. planicauda

Diurnal; primarily active during the rainy season

habitats

reproduction

Arid deciduous forests

Typically lays one oval egg

size

CL up to 6¼ in (16 cm) for P. planicauda

161

TESTUDINIDAE: STIGMOCHELYS

LEOPARD TORTOISE

T

he genus Stigmochelys has a single species, found in much of eastern and southern Africa. The genus has been variously placed in other genera including Geochelone. The species has one of the most extensive geographic ranges among African tortoises. Leopard Tortoises occupy arid savannas and grasslands including rocky terrain to elevations above 9,500 feet (2,900 m). They mainly eat grasses and shrubby ground vegetation but have also been recorded eating bones, presumably as a source of calcium. Fossil Stigmochelys have been found in Pliocene deposits in Tanzania. Leopard Tortoises commonly reach large adult body sizes and are among the largest terrestrial turtles in the world. Most individuals have a yellowish to brown carapace and limbs with black markings on most scutes although some

above | Leopard Tortoises constituted 76% of tortoises exported from Africa for the pet trade from 1987 to 1991, harming populations. right | Although terrestrial like all tortoises, Leopard Tortoises regularly enter water when it is available, and float like corks.

right | The Leopard Tortoise has the largest latitudinal distribution of tortoises in Africa: from the Horn to the Cape Region.

162

distribution

lifespan

East Africa and Southern Africa

30 years in captivity

species

activity

Stigmochelys pardalis

Diurnal

habitats

reproduction

Dry savannas, open plains, thorn scrub, and rocky areas in mountainous regions

3–7 clutches per year; 6–15 (rarely 30) round, hard-shelled eggs per clutch

size

diet

CL up to 27½ in (70 cm); weight 119 lb (54 kg)

Mostly herbivorous on grasses and other ground vegetation

CRYPTODIRA—Hidden-neck turtles

older adults become more uniform with less patterning. Juveniles have dark, leopard-like spots on a yellowish shell. The carapace is domed, and a nuchal bone is absent, which allows for extension of the neck during swimming—in contrast to most members of the Testudinidae, Leopard Tortoises are able to swim if necessary. During mating, males make a grunting sound. Among the greatest conservation threats to some populations are removal from the wild by humans for food and perceived medical purposes, and the conversion of natural habitat to agriculture. In some areas additional removal is to prevent crop damage by foraging Leopard Tortoises. They are also popular in the pet trade, especially the brightly colored and patterned juveniles, so illegal poaching is a problem in some countries.

163

TESTUDINIDAE: TESTUDO

SPUR-THIGHED, HERMANN’S, EGYPTIAN, MARGINATED, AND HORSFIELD’S TORTOISES

T

he genus Testudo has five species in three subgenera, Agrionemys, Chersine, and Testudo, although their taxonomy is unsettled. Its vast geographic range extends across southern Europe and the northern coast of Africa through the

Middle East to western China. Fossil Testudo have been found in the Miocene of Greece. Testudo occupies mostly semi-arid and arid habitats with sparse vegetation and often rocky terrain, ranging from sea level to 6,560 ft (2,000 m).

distribution

Europe, North Africa, Middle East, and Asia species

Testudo (Testudo) graeca, T. (Testudo) kleinmanni, T. (Testudo) marginata, T. (Agrionemys) horsfieldii, and T. (Chersine) hermanni habitats

Mostly arid, sparsely vegetated areas from sea level to higher elevations; dry savannas,

164

CRYPTODIRA—Hidden-neck turtles

rocky hillsides, and dry thornscrub plant communities size

CL up to 12 in (30.5 cm) for T. graeca activity

Diurnal; hibernate in cold regions and estivate during hot, dry periods lifespan

123 years in captivity in T. graeca, report not verified

The diet consists of a wide range of plant material, including grasses and leaves, flowers, and fruits of shrubs. T. graeca plays a role in seed dispersal. T. hermanni feeds opportunistically on terrestrial invertebrates and carrion. left | The genus Testudo has a geographic range that includes three continents and encircles the Mediterranean Sea.

above | Horsfield’s Tortoise lives in a hostile environment on the Steppes of central Asia with extreme temperature fluctuations.

reproduction

1–4 clutches per year; 1–12 oval to round brittle-shelled eggs per clutch diet

Mainly herbivorous on ground vegetation

Testudo are small to medium-sized tortoises ranging from T. kleinmanni (maximum CL 5¼ in / 13.5 cm) to T. graeca (maximum CL 12 in / 30.5 cm). All but one species, T. horsfieldii, have a posteriorly hinged plastron. The domed carapace of members of this genus varies from yellowish brown or gray with dark markings to dark brown or black with yellow blotches. The head and limbs are usually dark gray. The plastron is mostly black in some forms. In 1758, T. graeca was the first species of tortoise described by the founder of binomial nomenclature, Carl Linnaeus. He selected the epithet “graeca” because the ornate black and yellow markings on the carapace of the original type specimen he had reminded him of a Grecian frieze, even though the nominate subspecies does not occur in Greece. Habitat loss and uncontrolled collection of hundreds of thousands of wild tortoises for the pet trade have led to significant declines in some regions. 165

FAMILY: CARETTOCHELYIDAE PIG-NOSED TURTLE

T

he family Carettochelyidae has one genus and one species, Carettochelys insculpta. The Pig-nosed Turtle, also known as the Fly River Turtle in Papua New Guinea, is found only in southern New Guinea and the Northern Territory of Australia. Its presence in Australia was not generally recognized until its scientific discovery there in 1970, despite its depiction in Aboriginal rock paintings estimated to be 7,000 years old. The family was more widely distributed during the Paleogene, more than 23 MYA, and Neogene geological periods based on fossils in North America, Europe, and Asia. Interestingly, Carettochelys are not known from Queensland, the closest portion of Australia to New Guinea. In Papua New Guinea they sometimes inhabit estuarine habitats in contrast to those in Australia. The Pig-nosed Turtle has morphological features setting it apart from most other turtles.

They have no epidermal scutes on the shell, which is covered instead with skin. They have paddleshaped forelimbs bearing a resemblance to those of sea turtles. Like softshell and side-necked turtles, they have smooth muscle erectile tissue in their nostrils allowing them to dilate or contract them. The sex of embryos is determined by incubation temperature, with the warmest nests producing females. Hatchlings delay emergence until the beginning of the wet season. Populations are declining throughout their range due to overharvest of both eggs and adults by the commercial pet trade and for food in New Guinea. Habitat degradation and trampling of nesting beaches by introduced large mammals is also a problem for Pig-nosed Turtles. This species has been projected to have a significant portion of its range affected by sea level rise due to climate change (Agha et al., 2018).

right | Pig-nosed Turtles were erroneously thought to be allied with softshelled turtles when first discovered by scientists in the 1880s.

distribution

lifespan

West Papua, Papua New Guinea, northern Australia

Over 38 years in captivity

species

2 clutches every second year; 7–26 hard-shelled eggs; incubation period 64–107 days; hatchlings emerge with onset of rainy season; females nest communally at night

Carettochelys insculpta habitats

Rivers, lagoons, swamps, billabongs, lakes, and estuaries size

CL 22½ in (57 cm); weight 48 lb (22 kg) activity

Active both day and night; highly aquatic

166

CRYPTODIRA—Hidden-neck turtles

reproduction

diet

Omnivorous tending toward being herbivorous on fruits, leaves, stems, mollusks, and crustaceans

167

FAMILY: TRIONYCHIDAE SOFTSHELL TURTLES

T

he family Trionychidae has 13 genera and 32 species. Their overall range is generally confined to the northern hemisphere including Africa, Asia, and North America. Fossil trionychids date as far back as the Jurassic or Cretaceous, and the occurrence of fossils in Europe, South America, and Australia, as recently as the Pliocene, demonstrates a much wider past distribution. All species of softshells are highly aquatic, leaving the water only to bask or lay eggs. They live in rivers, streams, lakes, swamps, and other mostly permanent water bodies. Several species are known to enter brackish estuaries and even near-shore marine environments, especially Pelochelys of Southeast Asia and New Guinea, and Trionyx along the eastern Mediterranean coast. Softshells are arguably the least “turtle-like” of all turtles as they have a skin-covered, relatively

flat shell without scutes that is flexible near the edge. The Indian Flapshell Turtle (Lissemys punctata) is able to estivate during dry periods by burrowing in the mud and using the pliable shell to cover its limbs. The bony disks forming the superstructure of the carapace and plastron beneath that covering of leathery skin are greatly reduced in size in comparison to typical hard-shelled turtles. The Trionychidae also have very long necks, strongly webbed feet, a very pronounced tubular proboscis, and a generally irascible temperament. The penis of softshell turtles is unusual for having five distinct lobes, like fingers on a hand. Females are larger than males. Softshells do not have temperature-dependent sex determination like many other turtles. Ironically, perhaps, softshells produce hard-shelled eggs.

right | The snorkel-like nose is one of many features that differentiate softshelled turtles from their hard-shelled cousins.

distribution

habitats

reproduction

Africa, North America, and Asia (and reported from Turkey and Greece in Europe); southern hemisphere only for species with equatorial range

Some temporary but mostly permanent freshwater habitats; large rivers, streams, lakes, swamps, coastal estuaries, and some near-shore marine environments

Up to 7 clutches per year; 3–193 spherical eggs, depending on species; eggs have brittle shells

genera

size

Cyclanorbis, Cycloderma, Lissemys, Amyda, Apalone, Chitra, Dogania, Nilssonia, Palea, Pelochelys, Pelodiscus, Rafetus, and Trionyx

CL up to 10 in (25 cm) for Pelodiscus and to at least 39½ in (100 cm) for Chitra and Pelochelys

Mostly carnivorous but some are omnivorous; fish, amphibians, crustaceans, mollusks, and insects, including carrion

activity

Diurnal and nocturnal activity, depending on species

168

CRYPTODIRA—Hidden-neck turtles

diet

169

TRIONYCHIDAE: CYCLANORBIS

NUBIAN AND SENEGAL FLAPSHELL TURTLES

C

yclanorbis has two African species. The Nubian Flapshell Turtle (C. elegans) has a fragmented range due in part to the encroachment of the Sahara Desert on the Sahel region of Africa. Overgrazing by livestock and competition for limited water resources drive the desertification of the Sahel. The Senegal Flapshell Turtle (C. senegalensis) is more widespread than C. elegans, but both are restricted to a band across central Africa, north of the equator. Fossils are known from the Miocene, Pliocene–Pleistocene, and Quaternary of Africa.

Both members of the genus live in slow-moving rivers as well as lakes, though C. senegalensis is also often observed in ephemeral pools throughout their range. These are medium to large turtles with somewhat domed shells and tubercles on the anterior portion of the carapace. The carapace is brown to olive gray, often mottled, and with a light border in C. senegalensis. Numerous light yellow or greenish spots are present around the periphery of the carapace in C. elegans. Plastron color can be white, cream, or yellowish, sometimes with dark markings (particularly in young juveniles). The head and neck are brown with light green or yellow spots. Coloration varies with body size and hatchlings are more strikingly patterned than adults. Being “flapshell” turtles in this subfamily of softshells, Cyclanorbis have the ability to hide and protect their hindlimbs and tail with semicircular flaps that they close when threatened. Both species of Cyclanorbis co-occur in some places. Large softshell turtles like these are consumed by humans throughout their range.

left | African flapshell turtles are remarkably convergent with Asian flapshell turtles but have a flatter carapace.

distribution

size

reproduction

Discontinuous geographic range across tropical Africa

CL 26½ in (67.6 cm) in C. elegans and 13¾ in (35 cm) in C. senegalensis

Several clutches per season; up to 12 eggs per clutch for C. senegalensis

Cyclanorbis elegans, C. senegalensis

activity

diet

Presumed diurnal

habitats

lifespan

Rivers, streams, backwaters, marshes, ponds, and lakes

Unknown

Omnivorous on small aquatic animals, fruit, some carrion. Broad crushing surfaces on the jaws of C. elegans suggest a diet of hard-bodied prey

species

170

CRYPTODIRA—Hidden-neck turtles

TRIONYCHIDAE: CYCLODERMA

AUBRY’S AND ZAMBEZI FLAPSHELL TURTLES

right | Eating the meat of Zambezi Flapshell Turtles is reportedly taboo in some communities in coastal regions of Mozambique.

left | Aubry’s Flapshell Turtles have lateral extensions on the upper jaw that overlap the lower jaw giving them the appearance of jowls.

C

ycloderma has two African species with disjunct distributions. Fossils are known from the Miocene and Pliocene–Pleistocene of Africa. Aubry’s Flapshell Turtles (C. aubryi) leave rivers during the wet season to forage in flooded areas. Zambezi Flapshell Turtles (C. frenatum) are found in lakes and rivers. C. aubryi has a brown carapace and a long dark-colored neck with a dark stripe running from

the nose through the eyes and along the neck. C. frenatum can have several neck stripes and a pale- to dark-olive carapace with darker blotches. Plastrons of both species are pale with welldeveloped callosities present in adults. Cycloderma have semicircular flaps that protect the hindlimbs. They can also pull in the head, tail, and forelimbs, deforming the edge of the carapace to cover and protect those areas too. Humans are a major threat.

distribution

size

reproduction

Discontinuous range in sub-equatorial tropical Africa

CL up to 22 in (56 cm) for C. frenatum; CL 24 in (61 cm) and weight 39½ lb (18 kg) for C. aubryi

2+ clutches per year; 15–35 spherical hard-shelled eggs per clutch in C. aubryi, and possibly C. frenatum

activity

diet

Feeding occurs at night

Carnivorous on crabs, shrimp, fish, frogs, aquatic insects, and other invertebrates

species

Cycloderma aubryi, C. frenatum habitats

Swamps, marshes, flooded rainforests, rivers, and lakes

lifespan

Unknown

171

TRIONYCHIDAE: LISSEMYS

INDIAN, SRI LANKAN, AND BURMESE FLAPSHELL TURTLES | Juvenile Indian Flapshell Turtles are more dramatically colored than adults, with bright yellow spots on the carapace.

below

T

he genus Lissemys contains three species, all with ranges confined to, or adjacent to, the Indian subcontinent, including Sri Lanka and Myanmar. This wide range encompasses portions of four major drainage basins (Ayeyarwady, Ganges, Brahmaputra, and Indus) as well as many other river systems in the region. Flapshell turtles occupy a wide range of aquatic

habitats including both natural and human-created wetlands. Their shells are somewhat more domed than most softshells and oval in adults. The carapace ranges from brownish to green or olive, often with dark spots or yellow blotches, depending on subspecies, in the Indian Flapshell Turtle (L. punctata). The plastron is pale colored and has flaps to cover the rear limbs like other members of this subfamily.

distribution

activity

Bangladesh, India, Myanmar, Nepal, Pakistan, and Sri Lanka

Nesting occurs at night; bury themselves in mud or soil to hibernate during cold periods or estivate during hot and dry periods; overland movements are possible during rain; fond of basking

species

Lissemys ceylonensis, L. punctata, and L. scutata habitats

Rivers, streams, ponds, oxbow lakes, rice fields, canals, and salt marshes size

CL 13¾ in (35 cm) for L. punctata

172

CRYPTODIRA—Hidden-neck turtles

lifespan

Over 17 years in captivity reproduction

2–14 spherical, brittle eggs per clutch in L. punctata; 7–9 eggs per clutch in L. scutata

left | Like some other species of softshell turtles, Sri Lankan Flapshell Turtles are fond of basking on riverbanks and vegetation.

| The Irrawaddy River system of Myanmar has several endemic turtle species like the Burmese Flapshell Turtle.

below

In addition, L. punctata has an anterior hinge on the plastron, allowing it to close and protect the head and forelimbs. L. punctata produces a vile-smelling yellowish fluid from Rathke’s glands on the underside of the shell. In contrast, the Burmese Flapshell Turtle (L. scutata) shoots jets of liquid from the same glands that are odorless and mild tasting to humans.

diet

Omnivorous, tending toward carnivory; mollusks, fish, amphibians, crustaceans, snails, and insects. Plants; seeds, flowers, stems, and leaves. Cannibalism has also been reported.

As of 2014, populations of L. punctata were considered to be stable since many occur in protected areas, such as wildlife sanctuaries and national parks where hunting is prohibited. That status is surprising in light of the fact that populations of these turtles are thought to sustain high levels of natural predation, and Lissemys is heavily exploited for food throughout Asia today, and for 5,000 years, based on prehistoric evidence.

173

TRIONYCHIDAE: AMYDA

ASIATIC SOFTSHELL TURTLES

A

myda has one, or possibly two, species, depending on taxonomic assignments. Some authorities consider A. ornata to be a subspecies of A. cartilaginea whereas others classify it as a full species. The discontinuous geographic range extends from northeastern India and Bangladesh through Southeast Asia to Malaysia and Borneo. Confirmed fossils of the genus are unknown. Asiatic softshell turtles inhabit streams and rivers and adjacent aquatic habitats, including in

agricultural areas. The smooth, oval carapace is olive green to gray, and the head is dark green or grayish with a smattering of yellowish markings. The plastron is light gray or white. Field research has been limited and few detailed ecological studies have been conducted. Consequently, despite their reaching enormous body sizes, the maximum size is undetermined. Tigers have been reported to be predators.

left | Because of their large size and relative abundance, Asiatic Softshell Turtles are heavily exploited for food and are declining.

distribution

Bangladesh, India, Brunei, Indonesia, Malaysia, Cambodia, India, Laos, Myanmar, Thailand, and Vietnam species

Amyda cartilaginea, A. ornata habitats

Rivers, streams, and associated aquatic habitats including lakes

174

CRYPTODIRA—Hidden-neck turtles

and swamps; upland streams with waterfalls

activity

size

reproduction

CL up to 33½ in (85 cm); weight 143¼ lb (65 kg) confirmed; heavier individuals reported but not documented

Multiple clutches possible each year: 3–28 round, hard-shelled eggs per clutch

lifespan

Omnivorous on aquatic insects, crustaceans, fish, and plant materials

Over 25 years in captivity documented but undoubtedly lives much longer

Active both day and night

diet

TRIONYCHIDAE: APALONE

NORTH AMERICAN SOFTSHELL TURTLES

A

palone has three species: A. ferox (Florida Softshell), A. mutica (Smooth Softshell) with two subspecies, and A. spinifera (Spiny Softshell) with six subspecies. The genus is found in extreme southern Canada and through the central and southeastern portion of the USA to the northeastern states of Mexico. Scattered populations are in the eastern coastal US states. Fossil Apalone are reported as far back as the Miocene of North America. Softshell turtles are distinctive from all other North American turtles in having smooth, flattened carapaces without scutes and with pliable margins. All are brownish or tan, often matching the color of bottom sediments. Dark spots are present on males and juveniles of some species. The unhinged plastron is lighter in color, usually gray or white, sometimes with a yellowish tinge. The feet are webbed for swimming with comparatively great speed in open water and for chasing prey. Adult female Apalone are larger than males. The nose is noticeably longer than that of other turtles within their geographic range and they have long necks. A common behavior is for Apalone to sit camouflaged on the bottom in shallow water and

distribution

Southern Canada, USA, and Mexico species

Apalone ferox, A. mutica, and A. spinifera habitats

Moving or still waters (depending on species) with muddy, gravelly, or sandy bottoms with or without aquatic

above | Juvenile Florida Softshell Turtles are much more colorful than the more muted earth tones exhibited by adults.

extend the neck and long nose, which functions as a snorkel, to breathe. They are also able to remain under cold water for days by using cloacal breathing. Sex of hatchlings is controlled by a ZZ/ZW genetic sex determination system as seen in birds, not incubation temperature as in many turtle species.

vegetation; big rivers with sandbars, oxbow lakes size

CL 26½ in (67.3 cm) for A. ferox activity

Mostly diurnal; some nocturnal activity reported

reproduction

2–7 clutches per year; 1–40 round, hard-shelled eggs per clutch diet

Mostly carnivorous on aquatic invertebrates, especially crayfish and fish

lifespan

36 years in captivity for A. ferox

175

TRIONYCHIDAE: CHITRA

NARROW-HEADED SOFTSHELL TURTLES

O

nly one species of Chitra was recognized until 1986 but now three species are described, one of which (C. chitra) has two subspecies. They range from Java, Sumatra, and Peninsular Malaysia to India, Pakistan, and Nepal. All inhabit large rivers with sandy bottoms, including the Ganges in India and Ayeyarwady in Myanmar. Narrow-headed softshell turtles are among the largest of freshwater turtles and some individuals are

| The Burmese Narrow-headed Softshell Turtle, like others in the genus Chitra, has a tiny head and an enormous neck.

below

distribution

size

Indonesia (Java, Sumatra), Thailand, Peninsular Malaysia, India, Bangladesh, Nepal, Pakistan, and Myanmar

CL 45¼ in (115 cm); weight 335 lb (152 kg)

species

habitats

Diurnal; nesting occurs mostly at night in C. indica; totally aquatic except during terrestrial nesting

Large rivers with sandy or muddy bottoms

lifespan

Chitra chitra, C. indica, and C. vandijki

176

CRYPTODIRA—Hidden-neck turtles

activity

Unknown

left | An Asian Narrow-headed Softshell Turtle displays the intricate patterns seen on the carapace of these turtles.

| The drab carapace coloration on this Indian Narrow-headed Softshell Turtle may serve as camouflage on the river bottom.

below

enormous, more than 1¼ yards (just over a meter) long. The flat, round, leathery carapace is olive to gray with intricate pale markings. The name of the genus is derived from a Hindi or Bengali word meaning “picture” in reference to these patterns. The plastron is yellowish or cream colored and the limbs are grayish. The extended neck is long and thick, but the head is small and narrow with a short nose, and the eyes are located near the tip. The head is olive in color with pale stripes. They are powerful swimmers with webbed feet and are totally aquatic except for nesting females and hatchlings returning to the water. All are sit-and-wait predators, lying camouflaged on sandy substrates to capture aquatic animals. Like many

reproduction

60–193 round eggs per clutch diet

Carnivorous on fish, mollusks, and crustaceans

other softshell turtles, they can remain submerged underwater for long periods, presumably acquiring oxygen by pharyngeal respiration. Large Chitra have a reputation of being capable of delivering a blow by rapidly extending the head and neck or delivering serious bites when handled. Chitra are among the most endangered turtles in the world due to river pollution in some locations and commercial exploitation for food.

177

TRIONYCHIDAE: DOGANIA

MALAYAN SOFTSHELL TURTLE

D

ogania has a single species, Dogania subplana, found from Myanmar and Thailand to Java, Borneo, and the Philippines. The species is aquatic and primarily inhabits clear streams and associated water bodies in forested habitats. These medium-sized turtles have a flat, leathery, brownish carapace with a black line running down the center. Four black eyespots encircled by yellow are on the carapace of young individuals. The head

above | Malayan Softshell Turtles are the smallest softshell turtles in Southeast Asia and the Indonesian archipelago.

distribution

size

diet

Brunei, Indonesia, Malaysia, Philippines, Singapore, Myanmar, and Thailand

CL up to 13¾ in (35 cm)

Omnivorous on fish, crustaceans, crabs, and fruit

species

Dogania subplana habitats

Clear, fast-flowing streams in forests

178

is also brownish with a configuration of black lines on top. The snout is relatively short for a softshell. Muted yellow markings may be visible on the limbs. Collection of Malayan Softshell Turtles in the wild for local consumption and sale in markets has been a threat for many years.

CRYPTODIRA—Hidden-neck turtles

activity

Crepuscular/nocturnal lifespan

Unknown reproduction

3–7 round eggs per clutch

TRIONYCHIDAE: NILSSONIA

PEACOCK AND INDIAN SOFTSHELL TURTLES

N

ilssonia has five species. N. formosa occurs in the Ayeyarwady and other large rivers in Myanmar. Four other species are found in India and several bordering countries. Nilssonia inhabit most large rivers, including the Indus, Ganges, and Brahmaputra, on the Indian subcontinent. Due to their omnivorous diet, which includes carrion, India once had a captive breeding program for N. gangetica in order to release hatchlings into the Ganges River to clean organic trash, including partially burned human corpses. The carapace and body are olive, brown, or black. The plastron is cream colored or whitish gray. A distinctive feature of Nilssonia juveniles is four or more black and yellow circles on the back,

resembling ocelli on peacock tails. The circles fade in adults, and the adaptive significance is unknown. Juvenile N. hurum are preyed upon by the Checkered Keelback snake, Xenochrophis piscator. N. nigricans was once thought to survive only in a pond associated with an ancient shrine in Bangladesh but was later discovered in India.

above | Burmese Peacock Softshell Turtles, especially juveniles, have distinctive “eyespots” on the carapace that will fade with age. left | In captivity Indian Softshell Turtles are said to be cannibalistic on other members of the species and their eggs.

distribution

size

reproduction

Afghanistan, India, Bangladesh, Nepal, Pakistan, and Myanmar

CL 31½ in (80 cm); possibly to 39½ in (100 cm)

1–3 clutches per year; 8–38 round eggs per clutch

activity

diet

species

Nocturnal nesting; N. hurum in ponds migrate to other waters when ponds dry up

Omnivorous

Nilssonia formosa, N. gangetica, N. hurum, N. leithii, and N. nigricans habitats

Large rivers, lakes, reservoirs, and ponds

lifespan

Over 12 years in captivity

179

TRIONYCHIDAE: PALEA

WATTLE-NECKED SOFTSHELL TURTLE

right | The massive collection of wattles at the base of the neck distinguishes this species from all other softshells.

P

alea has a single species, P. steindachneri, native to southern China and Vietnam. Populations have been introduced and become established in Hong Kong, Hawaii, and Mauritius. Wattlenecked Softshell Turtles are aquatic and inhabit rivers, streams, and associated habitats, some at elevations to 4,500 ft (1,500 m). Fossils are unknown. These medium-sized turtles have a mostly smooth carapace as adults, often with tubercles. Color ranges from brownish gray to brown.

distribution

size

diet

China and Vietnam; introduced to some of the Hawaiian islands, Mauritius, and Hong Kong

CL up to 17½ in (44.5 cm)

Carnivorous on fish, mollusks, and crustaceans

species

Over 41 years in captivity

Palea steindachneri habitats

Streams, rivers, and adjoining lakes; marshes and canals in Hawaii

180

The plastron is lighter gray, yellow, or olive colored. Yellow markings on the head and paler-yellow stripes on the neck are prominent in juveniles but more obscure in adults. Females reach larger sizes than males. Palea is a vulnerable turtle in many areas of its native range because of pollution and human modifications of waterways, as well as uncontrolled poaching for Asian food markets.

CRYPTODIRA—Hidden-neck turtles

activity

Presumed diurnal lifespan

reproduction

2–28 round, hard-shelled eggs per clutch

TRIONYCHIDAE: PELOCHELYS

ASIAN AND NEW GUINEA GIANT SOFTSHELL TURTLES

P

elochelys has three species of which one, the Asian Giant Softshell Turtle (P. cantorii) is found widely in India and throughout the Sundaland region of Southeast Asia; two, P. bibroni and P. signifera, are confined to the island of New Guinea. Fossils are unknown. This genus is indicative of how little we know about turtles. For example, the first two species were described about 10 years apart while almost a century and a half expired before the third species was described. Pelochelys are among the largest freshwater turtles and even more remarkable sizes and weights have been reported but not fully confirmed. The shell is somewhat flattened and olive green to brown. P. bibroni can have wide, dark lines on the neck and radiating from the vertebrals of the carapace.

The plastron is cream colored. The head is extremely small in proportion to the rest of the body, the proboscis is short, and the neck is wide. Their extensive distribution throughout the islands of Sundaland and their occurrence in both fresh and ocean waters suggests an ability to cope with exposure to widely varying salinities.

right | Despite the enormous size of species in this genus, relatively little is known of their ecology and behavior in the wild.

distribution

habitats

reproduction

Bangladesh, Cambodia, China, India, Indonesia, Laos, Malaysia, Myanmar, New Guinea, Thailand, Vietnam, and possibly Philippines

Lakes, rivers, estuaries, and coast

24–70 round eggs per clutch. Sometimes nest on ocean beaches with sea turtles, approaching nest sites from the river or from the sea

species

Unknown

Pelochelys bibroni, P. cantorii, and P. signifera

size

CL to at least 39½ in (100 cm) activity

lifespan

Over 10 years in captivity but possibly longer in the wild

diet

Omnivorous on fish, shrimp, crabs, mollusks, and plants

181

TRIONYCHIDAE: PELODISCUS

HUNAN, CHINESE, NORTHERN CHINESE, AND VIETNAMESE SOFTSHELL TURTLES

P

elodiscus has four species, with most of the geographic range confined primarily to China and Vietnam but extending to Russia and the Korean peninsula. Fossils attributable to Pelodiscus are unconfirmed. The habitats include a variety of flowing and still aquatic habitats including lakes and marshes associated with rivers and streams. Carapace, head, and limbs are olive to gray. The plastron ranges from white to yellowish. P. sinensis is noted not only for obtaining oxygen underwater by pharyngeal breathing but also for excreting most urea through the mouth instead of the kidney. The species has ZZ/ ZW genetic sex determination like birds. P. sinensis is one of the world’s most common commercial species, with hundreds of Chinese turtle farms producing millions of turtles each year.

| The snorkel-like snout of Asian and other softshell turtles allows them to breathe while keeping the rest of their head and body underwater.

below

distribution

size

diet

China, Vietnam, North Korea, Russia, South Korea; introduced to Hawaii and Japan

CL up to 13¾ in (35 cm)

Carnivorous on aquatic insects, crustaceans, and fish

species

Pelodiscus axenaria, P. maackii, P. parviformis, and P. sinensis habitats

Lakes, ponds, and slow-flowing streams and rivers; may enter brackish waters

182

CRYPTODIRA—Hidden-neck turtles

activity

Presumed diurnal lifespan

Unknown reproduction

Typically lays 10–35 round, hard-shelled eggs per clutch

TRIONYCHIDAE: RAFETUS

EUPHRATES AND YANGTZE RIVER GIANT SOFTSHELL TURTLES

R

afetus has two widely separated species; one in southwest Asia in the Tigris and Euphrates rivers, and the other in eastern China and Vietnam. They share morphological similarities with North American softshells (Apalone). Miocene fossils of the genus are reported from Europe. The Euphrates Softshell Turtle (R. euphraticus) prefers shallow water in oxbows along rivers with muddy or sandy shores with dense reed thickets. They are not found in river gorges. The carapace is flattened and grayish, olive green, dark brown, or black. The head has light-colored spots. Only one male and one female R. swinhoei are known to survive as of October 2020. Habitat destruction, pollution, and bycatch by fishermen all contributed to the decline of these species.

above | Found in the Tigris and Euphrates rivers, this species lives in the Fertile Crescent where western civilization began.

| The Yangtze River Giant Softshell Turtle may be the rarest turtle in the world, and is not likely to survive without management.

below

distribution

size

reproduction

Iran, Iraq, Syria, Turkey, China, and Vietnam species

CL of 26¾ in (68 cm) or more for R. euphraticus; 39½ in (100 cm) or more for R. swinhoei

Rafetus euphraticus, R. swinhoei

activity

1–3 clutches per year and 60 eggs per clutch in R. swinhoei; 17–37 eggs per clutch in R. euphraticus

habitats

Sluggish portions of rivers, streams (especially backwaters and confluences), lakes, and temporary pools formed by spring floods in the case of R. euphraticus

Primarily diurnal; some nocturnal activity in R. euphraticus lifespan

diet

Omnivore; carrion, crabs, insects, and plants including some fruits

Unknown

183

TRIONYCHIDAE: TRIONYX

AFRICAN SOFTSHELL TURTLE

T

rionyx, which once included many species of softshell turtles now placed in other genera, has a geographically wide-ranging single species in Africa and the Middle East. Fossils are known from as early as the Oligocene of Germany. African Softshell Turtles are powerful swimmers with large webbed feet and live in large rivers and lakes. They can even run rapidly for short distances on land. They occasionally enter ocean waters and are known to nest on beaches with sea turtles.

| Both the genus (Trionyx) and the species (triunguis) names refer to “three claws,” one in Greek and the other in Latin.

below

distribution

activity

West Africa, Central Africa, East Africa, and the eastern Mediterranean coast

Diurnal; fond of basking

species

Over 50 years in captivity

Trionyx triunguis habitats

Large rivers, streams, lakes, and swamps; will enter brackish or ocean waters size

CL up to at least 39½ in (100 cm); weight 132¼ lb (60 kg)

184

CRYPTODIRA—Hidden-neck turtles

lifespan

reproduction

25–100 round, hard-shelled eggs per clutch diet

Omnivorous on insects, crustaceans, mollusks, fish, aquatic plants, fallen nuts from palm trees, and carrion

The leathery carapace is drab olive, gray, or dark brown. The plastron is usually white or cream colored. The head and limbs are olive with yellow or white markings. White spots are visible on the chin and throat. The African Softshell Turtle is one of the few reptiles in which play behavior with non-food objects has been documented in captivity. The species is rare or absent from portions of its northern distribution on the lower Nile and in the Mediterranean.

above | Occasional records of this species in Mediterranean Greece, constitute the only occurrences of softshell turtles in Europe.

185

left | With few exceptions, side-necked turtles are found in the Southern Hemisphere, a relict distribution from evolution on Gondwanaland.

PLEURODIRA

The suborder Pleurodira (side-necked turtles) contains three families—Chelidae (Australasian and South American side-necked turtles), Pelomedusidae (African side-necked turtles), and Podocnemididae (Madagascar and South American side-necked turtles)—19 genera, and 93 species. Members of current-day Pleurodira occur primarily in the southern hemisphere, with Australia having only genera in the Chelidae and mainland Africa having only those in the Pelomedusidae. Both the Chelidae and the Pelomedusidae have representatives in South America. Pleurodiran turtles are characterized by being able to fold the neck sideways under the front of the carapace for protection instead of retracting it straight into the shell by folding it vertically like the cryptodires. Other anatomical features of pleurodires that differ from cryptodires are the presence of a pair of mesoplastron bones between the anterior and posterior sections of the bony plastron and the presence of an intergular scute on the anterior of the plastron. Pleurodires rarely have hinges on the plastron or carapace, which is a common trait of many cryptodiran species. Another morphological attribute of side-necked turtles is that the pelvic girdle is fused to the plastron in a manner that restricts movement while walking, a partial explanation for why most species are semi-aquatic or aquatic. 187

FAMILY: CHELIDAE AUSTRALASIAN AND SOUTH AMERICAN SIDE-NECKED TURTLES

T

he family Chelidae has four subfamilies, 14 genera, and 58 species. The family occupied Gondwanaland, which split during the Mesozoic, ultimately resulting in seven genera in South America and an equal number in Australia. Representatives are also found on the island of New Guinea. Genetic studies on turtles on both continents have resulted in numerous taxonomic rearrangements within the subfamilies and several genera. Fossils are known from the Paleocene of Australia and from the Pleistocene, Pliocene, and Miocene from several localities in South America. Because of the wide diversity of several genera and species, as well as their being geographically widespread over most of two continents, a variety of

habitats are occupied by members of the family. All species are aquatic or semi-aquatic, living in association with watercourses, from small streams to large rivers, as well as lakes and swamps in tropical rainforests and more temperate regions. Brackishwater habitats are frequented by some species. Included among the distinctive representatives of the Chelidae are the Australian snake-necked turtles, one of which is known to lay its eggs underwater. Several Australian genera are also noted for being able to obtain oxygen through the cloaca while underwater. One of the most critically endangered turtles in the world, Pseudemydura umbrina of western Australia, belongs in its own subfamily, Pseudemydurinae.

right | Although most side-necked turtles have drab coloration on their head, limbs, and shells, Red-bellied Short-necked Turtles are an exception.

distribution

habitats

size

South America, Australia, Papua New Guinea, Indonesia (West Papua and Roti Island), and Timor-Leste

Varies with genus, species, and region; swamps, marshes, billabongs, oxbow lakes, ponds, lakes, small streams, fast- and slow-moving rivers, blackwater streams through rainforests, rocky, fast-moving streams, brackish-water lagoons, coastal estuaries, and near-shore marine environments

CL to over 19½ in (50 cm) for Chelus

genera

Acanthochelys, Chelodina, Chelus, Elseya, Elusor, Emydura, Hydromedusa, Mesoclemmys, Myuchelys, Phrynops, Platemys, Pseudemydura, Rheodytes, and Rhinemys

188

PLEURODIRA—Side-necked turtles

activity

Mostly diurnal reproduction

1–5 clutches per year; 1–30 eggs per clutch diet

Omnivorous, herbivorous, or carnivorous, depending on genus and species

189

CHELIDAE: ACANTHOCHELYS

SOUTH AMERICAN SIDE-NECKED SWAMP TURTLES

A

canthochelys has four species, all once assigned to the genus Platemys. The geographic range is confined to a region in southeastern Brazil, Uruguay, the Chaco region of Paraguay, Argentina, and Bolivia. Fossil Acanthochelys are known from the Pliocene of Argentina and the Miocene of Bolivia. The genus is semi-aquatic, occasionally going onto land, and is typically associated with shallow, still-water habitats including ditches, ponds, and larger shallow lakes. The Pantanal Swamp Turtle (A. macrocephala) is known to inhabit brackish lagoons in addition to freshwater habitats. The four species of this medium-sized turtle range in maximum carapace length from 6½ to 11¾ in (17 to 29.5 cm). The carapace generally varies in color from light brown to dark brown or black. Yellow markings are sometimes present around the carapace margins. The plastron is yellowish or light brown. The neck and limbs are mostly drab gray or brownish, although the chin and underside of the neck may be lighter in color. Most Acanthochelys respond to the wet–dry seasons of the region, migrating between bodies of water as necessary, relying on suitable terrestrial habitat for travel. Consequently, a major

| The prominent pointed neck tubercles on Black Spiny-necked Turtles have an unknown function but may have a sensory role.

below

distribution

size

Argentina, Bolivia, Brazil, Paraguay, and Uruguay

CL to 11¾ in (29.5 cm) for A. macrocephala

species

Unknown

Acanthochelys macrocephala, A. pallidipectoris, A. radiolata, and A. spixii habitats

Swamps, marshes, small streams, and slow-moving rivers with heavy vegetation, and brackish-water lagoons (A. macrocephala)

190

PLEURODIRA—Side-necked turtles

lifespan

activity

Diurnal and nocturnal; mostly aquatic but some species venture onto land reproduction

4–9 hard-shelled eggs per clutch, round to slightly elongate, depending on species

conservation issue for most Acanthochelys is the deforestation of natural habitats, primarily for agricultural purposes, which has led to fragmentation of the landscape. Many populations of species in the genus are small and can be readily extirpated by local habitat modifications. The preservation of both terrestrial and aquatic habits is viewed by conservationists as essential for the long-term survival of many populations of these and other turtles.

diet

Carnivorous on fish, frogs, tadpoles, and aquatic invertebrates, worms, dragonfly larvae, and snails

| The Pantanal Swamp Turtle occasionally travels between freshwater wetlands and will even enter brackish habitats.

top

above | The Chaco Side-necked Turtle is one of the southernmost turtle species in the world, occurring to almost 35º south latitude.

191

CHELIDAE: CHELUS

MATAMATA

C

helus has two species: C. fimbriata and newly described C. orinocensis (both known as Matamata). Matamatas are found in northern South America from eastern Colombia, Ecuador, and Peru to the Atlantic Ocean. Fossils of extinct Chelus species are reported as far back as the Miocene of Brazil, Venezuela, and Colombia. The habitat of the Matamata is a variety of

| The odd shapes and outlines of a Matamata on the muddy bottom of a waterway can camouflage them from both predators and prey.

below

distribution

habitats

Northern South America: eastern Colombia, eastern Ecuador, northern and eastern Peru, Bolivia, Brazil, Venezuela, the Guianas, and Trinidad; Amazon, Orinoco, and other river basins

Quiet waters of streams, swamps, marshes, and lakes, often with silty conditions and low visibility

species

Chelus fimbriata, C. orinocensis (described in 2020)

192

PLEURODIRA—Side-necked turtles

size

CL to over 19¾ in 50 cm activity

Both diurnal and nocturnal

freshwater habitats including swamps, marshes, flooded forests, lakes, and slow-moving streams. The water is often murky. Matamatas are distinctive in appearance and behavior, resembling no other turtle in the world. The carapace is dark, with prominent keels and knobs. Adults almost invariably have a coating of algae, several barbels on the chin and jaw, and dark, flap-like extensions along the sides of the neck. The head is wide and flat. Collectively, the morphological features result in an animal looking like a piece of old wood. The yellowish or brown plastron is narrow with no hinge. A long nose operates like a snorkel

and allows the turtle to breathe while sitting on the bottom in shallow water. The feet are webbed for swimming, but most locomotion is by walking along the bottom. Matamatas have one of the most remarkable feeding behaviors of any turtle. Relying on their superb camouflage from both predators and prey, they remain stationary much of the time. As small fish or aquatic invertebrates approach, the turtle rapidly opens its mouth, creating suction and consuming everything within several inches. The water is expelled, but the prey is retained and swallowed.

right | The Matamata is one of the strangest looking turtles in the world with its unusual head shape and heavily sculpted shell.

lifespan

Over 35 years in captivity reproduction

12–28 round, hard-shelled, brittle eggs per clutch diet

Carnivorous on aquatic invertebrates and fish

193

CHELIDAE: MESOCLEMMYS

TOAD-HEADED TURTLES

M

esoclemmys has ten species, but the genus has been fraught with taxonomic confusion and controversy. Seven of the recognized species were previously placed in the genus Phrynops, with which they share many similarities. The taxonomic issue is further exacerbated by a 2019 scientific paper documenting that eggs from a single female produced hatchlings with characteristics of two different species, M. raniceps and M. heliostemma.

Further taxonomic studies will be needed to resolve the true phylogenetic relationships among these South American turtles. The geographic range of the toad-headed turtles encompasses much of tropical and temperate South America east of the Andes Mountains, including large portions of the Orinoco and Amazon river basins. An extinct species of the genus has been discovered in the fossil record from the middle-

distribution

Venezuela, Guyana, Trinidad, Colombia, Ecuador, Peru, Bolivia, Paraguay, Argentina, and Brazil species

Mesoclemmys dahli, M. gibba, M. heliostemma, M. hogei, M. nasuta, M. perplexa, M. raniceps, M. tuberculata, M. vanderhaegei, and M. zuliae habitats

Depending on species, almost all freshwater

194

PLEURODIRA—Side-necked turtles

aquatic habitats; streams, rivers, swamps, ponds, and blackwater streams through rainforests size

CL to 13¾ in (34.7 cm) for M. hogei lifespan

Over 27 years in captivity (M. dahli) activity

Most movement by individuals occurs during the dry season or during the shift from wet season to dry (M. dahli)

left | The Gibba Turtle is a poorly-studied turtle genus, with most information on their ecology and behavior published in the 21st century. above | Some South American toad-headed turtles, like this one from Peru, are aptly named for their large head and widely-spaced eyes.

reproduction

Some lay several clutches per year, depending on the species; 1–14 oblong or round, hard-shelled eggs per clutch diet

Carnivorous or omnivorous depending on the species on aquatic plants, invertebrates, fish, and tadpoles

Miocene of Colombia. Virtually all freshwater aquatic habitats are inhabited by toad-headed turtles, including both flowing and still waters, such as ponds, swamps, and marshes. The body and carapace are usually dark olive, brown, gray, or black depending on the species. The large, unhinged plastron is usually yellow, sometimes with darker blotches. Some species have a keel down the middle of the carapace. The name “toadheaded turtles” is a consequence of the thick, wide head and short neck, which make them proportionately shorter relative to the carapace than is true of most turtles. Yellow markings are evident on some species, but, overall, most are drab in appearance. They are small to moderate in size, ranging from 8½ to 13¾ in (21.5 to 34.7 cm) in maximum carapace length.

195

CHELIDAE: PHRYNOPS

SOUTH AMERICAN SIDE-NECKED TURTLES

P

hrynops has four species, although several that were formerly placed in the genus are now assigned to Mesoclemmys, and another to Rhinemys. The geographic range encompasses much of tropical and temperate South America east of the Andes Mountains, with the exception of large parts of the Amazon River Basin. Fossils of P. geoffroanus

| Like many turtles, Saint-Hilaire’s Side-necked Turtle likes to bask, however, basking frequency decreases in the austral summer.

below

are known from the Pliocene–Miocene boundary of Argentina and Uruguay. Three of the species live in still–water habitats with soft, muddy bottoms and heavy vegetation. Williams’ Side-necked Turtle (P. williamsi) has a more restricted geographic range and occurs in rocky streams. These moderately large turtles have a dark brown, olive, gray, or black carapace with a maximum length ranging from 13 in (33 cm) in P. williamsi to 15¾ in (40 cm) in Saint-Hilaire’s Side-necked Turtle (P. hilarii). The head and carapace may have striking yellow markings. The head of most Phrynops is large and wide compared to other turtles. The jaw is not hooked, but the snout has a noticeable point. Two barbels are on the chin. The plastron is yellowish, often with darker markings, and has a distinct notch on the posterior end. P. williamsi is an exception from the other three species in having a much narrower head, a shorter neck, and a distinctive light-colored lower jaw with well-defined black stripes. The carapace sometimes has a yellowish rim. The general ecology and behavior of Geoffroy’s Side-necked Turtle (P. geoffroanus) have been relatively well-studied, but more research is needed, especially on the biology of the other species.

distribution

size

Much of South America east of the Andes

CL up to 15¾ in (40 cm) for P. hilarii

species

activity

Phrynops geoffroanus, P. hilarii, P. tuberosus, and P. williamsi

Primarily diurnal; more study needed

habitats

Over 37 years in captivity (P. hilarii)

Heavily vegetated backwaters of rivers, oxbow lakes, ponds, swamps (not P. williamsi); rocky, fast-moving streams in forested habitat (P. williamsi)

196

PLEURODIRA—Side-necked turtles

lifespan

above | Geoffroy’s Sidenecked Turtle achieves high population densities and biomass in polluted rivers with abundant sewage. right | When feeding, Saint-Hilaire’s Side-necked Turtle visually locates stationary prey followed by olfactory examination.

reproduction

9–23 eggs per clutch; round eggs in P. geoffroanus and P. hilarii; eggs more elongate in P. williamsi than in other species diet

Mostly carnivorous on fish and aquatic invertebrates, including mollusks; occasionally aquatic plants

197

CHELIDAE: PLATEMYS

TWIST-NECKED TURTLE

P | The Twist-necked Turtle has a wide groove down the midline of the carapace bordered by a lateral keel on each side.

below

latemys has a single species, although four closely related species formerly placed in the genus are now assigned to Acanthochelys. The geographic range includes most of northern South America, including basins of the Orinoco and Amazon rivers. Fossils unambiguously referable to be Platemys are unknown. The species is semi-aquatic and noted for entering shallow, still-water habitats but not for its

distribution

habitats

Most of northern South America from the Orinoco River Basin in Venezuela to the Amazon River Basin in Brazil, Guyana, French Guiana, Suriname into Colombia, Ecuador, Peru, and Bolivia

Small streams and rainforest pools but not large rivers. Terrestrial areas adjacent to aquatic habitats in rainforests where it may estivate during the dry season

species

CL up to 7 in (18 cm)

Platemys platycephala

size

activity

Diurnal and nocturnal; spends time both in the water and foraging on land

198

PLEURODIRA—Side-necked turtles

| The species name (P. platycephala) of the Twist-necked Turtle is derived from the Greek words that describe a flat head.

below

swimming ability, much of its time being spent on land, buried in leaves. This small- to medium-sized turtle has a noticeably flat carapace. The head is relatively flat and smooth on top compared to other Chelinae. In contrast to many turtles with a ridge down the middle of the back, the Twist-necked Turtle instead has an obvious furrow with the sides

lifespan

20 years in captivity reproduction

Multiple clutches are possible; 1 large, hard-shelled, elongate egg covered with fallen leaves and sometimes soil diet

Carnivorous on fish, amphibian eggs and tadpoles, and aquatic invertebrates, including worms and mollusks

of the carapace being higher. The carapace has a combination of yellow, brown, and black, creating a camouflage appearance when in shallow water with dead leaves, or on the forest floor. The plastron is dark brown or black, encircled by yellow along the margins. The head and neck are yellow or orange above with a light-brown blotch down the center. The legs and tail are black. It twists its head when withdrawing into its shell. An unexplained genetic peculiarity of the species has been discovered in individuals from Suriname in which some cells in the body have triploid or tetraploid chromosomes rather than the normal diploid condition found in other parts of the geographic range. This condition differentiates Platemys from Acanthochelys.

199

CHELIDAE: RHINEMYS

RED SIDE-NECKED TURTLE

R

hinemys has a single species, which was previously placed in the genus Phrynops. The geographic range is limited to the northwestern portion of South America, east of the Andes Mountains in the upper Amazon River Basin of Brazil and Colombia. The species has been conjectured to occur in Venezuela and Peru, but no documentation has been forthcoming. It lives in small, shallow streams flowing through tropical rainforest with dense canopy but has not been found in larger rivers in the same region.

Red Side-necked Turtles (R. rufipes) are somewhat distinctive among South American turtles because of their appearance, having red coloration over many parts of the body from hatchlings to adults. The head and neck are mostly red with a black stripe across the snout and running from the nose to the neck. The legs are also primarily red. The carapace is brownish. The large, unhinged plastron is yellow. Adults have a keel down the middle of the carapace. Females are larger than males.

distribution

activity

Northwestern Brazil and southeastern Colombia

Primarily nocturnal

species

Unknown

Rhinemys rufipes habitats

Small, blackwater streams in closed-canopy tropical rainforest size

CL up to 10 in (25.6 cm)

200

PLEURODIRA—Side-necked turtles

lifespan

reproduction

3–12 round eggs with brittle shells per clutch diet

Omnivorous on aquatic invertebrates, fish, and fallen tree fruits

R. rufipes remains enigmatic in many aspects of its ecology and behavior, although it is suspected by some investigators of being relatively abundant. The species appears to be fully aquatic, seldom if ever coming onto land except, possibly, to lay eggs; sex determination is genetic. However, nests have not been found in the wild. In contrast to most turtle species within its geographic range, it is usually the only species of turtle found in most of the habitats where it occurs.

| As of 2014, scientists had not observed nesting Red Side-necked Turtles under natural conditions.

far left

above | This Red Side-necked Turtle clearly shows the neck retraction mode that gives pleurodirans their common name.

right | The Red Sidenecked Turtle is among the most colorful pleurodirans, with pinkish to red coloration on the head and limbs.

201

CHELIDAE: HYDROMEDUSA

SOUTH AMERICAN AND BRAZILIAN SNAKE-NECKED TURTLES

H

| Australia is home to many species of snake-necked turtles, but South America only has two, including this H. tectifera.

below

ydromedusa has two species, with geographic ranges restricted to southeastern Brazil, Uruguay, and northeastern Argentina. Fossils of an extinct Hydromedusa have been discovered from middle-Eocene deposits in Argentina. The two extant species overlap only in Brazil, but, where both are present in the same region, Brazilian Snake-necked Turtles (H. maximiliani) typically occur at elevations above 2,000 ft (600 m). The habitats vary greatly between the two species. H. maximiliani live in fast-moving, rocky streams, even with waterfalls and sometimes with sandy bottoms. South American Snake-necked

distribution

size

Argentina, Brazil, and Uruguay

CL up to 11¾ in (30 cm) for H. tectifera

species

lifespan

Hydromedusa maximiliani, H. tectifera

Over 12 years in captivity (H. tectifera); estimated longevity of 100 years (H. maximiliani)

habitats

Both species are aquatic; H. maximiliani in clear streams, in rocky, mountainous terrain. H. tectifera in ponds, lakes, and marshes or slow-moving streams and rivers; will enter brackish waters where they can be colonized by barnacles

202

PLEURODIRA—Side-necked turtles

activity

Both species are aquatic, but H. maximiliani has been reported to be sedentary in its movement patterns

left | Brazilian Snakenecked Turtles living in different streams and rivers show substantial genetic variation and may require special management.

Turtles (H. tectifera) prefer still or slow-moving waters with soft bottoms and in coastal areas, they will enter brackish waters. The flat carapace is dark, usually light or dark brown or sometimes dark gray. The head is also dark

reproduction

1–3 oblong, hard-shelled eggs per clutch; may lay eggs along shorelines in leaf litter or under tree roots diet

Carnivorous on a wide variety of aquatic vertebrates including fish and amphibians, and invertebrates such as snails, insects, shrimp, and crabs

with a yellowish lower jaw. The unhinged plastron varies from yellow to brownish. A distinguishing characteristic of Hydromedusa is an extremely long neck which, when extended, is nearly as long as the carapace and similar in appearance to the snakenecked turtles of Australia. They are almost exclusively carnivorous, and the flattened head and long neck function effectively in pursuing aquatic prey beneath rocks or roots. They have been reported to capture live fish. Habitat disruption of aquatic habitats as a result of deforestation is a continuing problem in Hydromedusa conservation.

203

CHELIDAE: CHELODINA

AUSTRALIAN SNAKE-NECKED TURTLES

T

he genus Chelodina has 15 species divided among three subgenera: Chelodina, Macrodiremys, and Macrochelodina. The taxonomy of this genus has been a topic of substantial controversy for many years, which will doubtless lead to future changes. Their various ranges are confined to Australia and the island of New Guinea, with the exception of C. mccordi, found only in the small island nation of Timor-Leste and nearby Roti Island, Indonesia. Fossil Chelodina are known from the Paleocene to Eocene of Australia. Australian snake-necked turtles live in shallow wetlands including swamps, lakes, slow-moving streams, and rivers, sometimes in brackish habitats.

Some species estivate on land or migrate to permanent waters during dry periods. The brownish to blackish carapace is relatively low and oblong with depressed vertebrals. The plastron is unhinged and firmly attached to the carapace. The otherwise drab coloration of adults is occasionally accentuated by neck striping in some species, in contrast to brightly patterned hatchlings in some species. The most amazing feature of their morphology is a neck that can be almost as long as their carapace. Vertebrae in the neck are longer than those under the carapace. Sex in C. longicollis is determined by XX/XY sex chromosomes, not incubation temperature as in many turtles. Other notable characteristics of the genus include documentation in C. oblonga of an underwater vocal repertoire of 17 different sounds including squawks, growls, chirps, and howls, hypothesized to facilitate communication during the breeding season in their murky habitats. Another oddity in the genus is underwater nesting by C. oblonga!

left | Australian Snake-necked Turtles are born with long necks and bright colors that fade as they grow larger.

distribution

Australia, Papua New Guinea, Indonesia (West Papua and Roti Island), and Timor-Leste species

Chelodina (Chelodina) canni, C. (C.) gunaleni, C. (C.) longicollis, C. (C.) mccordi, C. (C.) novaeguineae, C. (C.) pritchardi, C. (C.) reimanni, C. (C.) steindachneri, C. (Macrochelodina) burrungandjii, C. (M.) expansa, C. (M.) kuchlingi, C. (M.) oblonga, C. (M.) parkeri,

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PLEURODIRA—Side-necked turtles

C. (M.) walloyarrina, and C. (M.) colliei habitats

Swamps, marshes, billabongs, ponds, lakes, slow-moving streams and rivers, and some brackish habitats size

CL up to 19 in (48 cm) in C. expansa activity

Diurnal lifespan

Over 36 years in captivity (C. longicollis)

above | This Arnhem Snake-necked Turtle from northern Australia uses its long neck to probe into crevices for prey items.

right | Some snake-necked turtles make overland migrations when it rains to find productive new aquatic habitats.

reproduction

Typically 1–3 clutches per year of up to 30 eggs (C. expansa). C. oblonga lays its eggs underwater diet

Carnivorous on fish, shrimp, tadpole shrimp, crayfish, and other invertebrates

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CHELIDAE: ELSEYA

AUSTRALIA AND NEW GUINEA SNAPPING AND STREAM TURTLES

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E

lseya comprises nine species, which are classified among three subgenera: Elseya, Hanwarachelys, and Pelocomastes. These are tropical turtles found only in northern Australia and various parts of the island of New Guinea.

| White-throated

Snapping Turtles are capable of long dive times, spending up to three hours underwater.

distribution

habitats

Northern Australia and the island of New Guinea

Rivers and streams

species

CL up to 16½ in (42 cm)

Elseya (Elseya) branderhorsti, E. (E.) dentata, E. (E.) flaviventralis, E. (Hanwarachelys) novaeguineae, E. (H.) rhodini, E. (H.) schultzei, E. (Pelocomastes) albagula, E. (P.) irwini, and E. (P.) lavarackorum. E. (P.) irwini was named in honor of TV personality and conservationist Steve Irwin

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PLEURODIRA—Side-necked turtles

size

activity

Diurnal and nocturnal lifespan

Over 21 years in captivity reproduction

6–21 eggs per clutch

left | The Northern New Guinea Stream Turtle, has a restricted geographic range on the northern portion of the island of New Guinea.

| Steve Irwin’s father, Bob, caught the first live Irwin’s Snapping Turtle that was recognized as a new species.

below

Pleistocene fossils of the genus are known from Australia and E. (Pelocomastes) lavarackorum was initially described from these fossils before it was “rediscovered” as a species that was still living! The fossils suggest that E. (Pelocomastes) lavarackorum once attained carapace lengths of 19¾ in (50 cm), larger than those found today. They live in rivers and streams and can acquire oxygen through their cloaca. The carapace ranges

diet

Herbivorous to omnivorous depending on species, mostly on fruits, seeds, leaves, and some invertebrates; juveniles mostly carnivorous

from light to dark brown and in most the color extends onto the plastron to varying degrees. However, E. (Elseya) flaviventralis has a cream-colored plastron. Juveniles have serrated carapace margins and may have geometric patterns of dark markings on the scutes. The head of some species has extensive white coloration.

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CHELIDAE: ELUSOR

MARY RIVER TURTLE

T

he only species in this genus was “discovered” in 1990 and described to science in 1994. Hatchlings were sold in pet shops in Australia for over 25 years before biologists were able to determine where the “pet shop” turtle occurred in the wild. The species is found only in the Mary River in Queensland, Australia, and has numerous unique features that warrant its description as a separate genus. Fossils are unknown. Mary River Turtles appear to prefer flowing sections of the river near riffles, a behavior especially prevalent in juveniles. This is one of the species of “short-neck” turtles in Australia and New Guinea and like most is not very colorful, having a drab brownish-black carapace and gray head. Two chin barbels are present and are longer than those on any other Australian short-neck turtle. What they lack in flashy colors and patterns is more than made up for in the enormous size of their tails that can be up to 70 percent of male carapace length with correspondingly massive bulk. The tail is

left

| The Mary River

Turtle has a very small geographic range and was listed as one of Australia’s most endangered turtles.

distribution

activity

The Mary River and its major tributaries in eastern Australia

Diurnal except during nesting

species

Unknown

Elusor macrurus habitats

Rivers and streams size

CL up to 17 in (43.6 cm)

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| The enormous tail of Mary River Turtles and its bony architecture is unique among turtles and the hallmark of the species.

above right

PLEURODIRA—Side-necked turtles

lifespan

reproduction

1–2 clutches of 5–25 soft, flexible eggs. Mass nesting may have occurred before populations were depleted

laterally compressed with great depth to its form and is supported by vertebrae with haemal arches, allowing increased blood flow, a unique anatomical feature among all the world’s turtles. The adaptive significance of the massive tail is unknown. Like the Australian turtle Rheodytes, Elusor has the ability to extract dissolved oxygen from the water via “cloacal breathing,” essentially using its cloaca like a gill.

diet

Primarily herbivorous on aquatic macrophytes and fruits that fall into the water above | John Cann, the famous Australian biologist, unraveled the mystery that the source of “pet shop” turtles was the Mary River.

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CHELIDAE: EMYDURA

AUSTRALIA AND NEW GUINEA SHORT-NECKED TURTLES

E

mydura comprises four species, two of which, E. macquarii and E. subglobosa, show geographic variation resulting in recognition of several subspecies. All Emydura are found in Australia, the island of New Guinea, or both. Fossils are known from the Paleocene of Australia. Most species live in permanent rivers and streams but some inhabit ephemeral wetlands in arid parts of Australia.

The pear-shaped to oval carapace is moderately domed and tan to dark brownish in color. The plastron is lighter in color (reddish in E. subglobosa) and hingeless. This genus contains some of the most colorful chelids, some with red, yellow, or pale markings on the face that are especially conspicuous in juvenile E. subglobosa. E. subglobosa occasionally lay their eggs in the nest mounds of saltwater crocodiles. | Short-necked species, such as this Red-bellied Short-necked Turtle, contrast with Australia’s numerous snake-necked turtles.

below

distribution

size

Eastern and northern Australia, and island of New Guinea

CL to almost 14½ in (37 cm)

species

Presumed diurnal

Emydura macquarii, E. subglobosa, E. tanybaraga, and E. victoriae habitats

Rivers, streams, lakes, lagoons, and swamps

210

PLEURODIRA—Side-necked turtles

activity

lifespan

Over 25 years in captivity

above | Red-bellied Short-necked Turtles live in northern Australia as well as in the southern part of the island of New Guinea.

reproduction

1–3 clutches per year; 4–35 ellipsoidal, hard-shelled eggs per clutch, depending on species diet

Omnivorous on fish, mollusks, plants, algae, seeds, aquatic and terrestrial insects, and crustaceans, depending on species

above | The Eastern Short-necked Turtle has four subspecies that range in overall coloration from pallid to almost black.

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CHELIDAE: MYUCHELYS

SAWSHELLED TURTLES

M

yuchelys contains four species, all restricted to small and separate ranges in Australia. Some authorities place these species in the genus Wollumbinia; however, the validity of that name is debated. Fossils are unknown. Sawshelled turtles occupy various aquatic habitats from streams and rivers to still waters, depending on the species. The carapace has a brownish color and low profile. The rear marginal scutes are serrated, hence their common name. The plastron can be mostly yellowish in some

| Sawshelled Turtles use cloacal respiration, and hatchlings can obtain almost 30% of their oxygen while underwater.

below

distribution

size

diet

Portions of northern and eastern Australia

CL up to 12 in (30 cm)

species

Diurnal with crepuscular peaks in M. bellii

Omnivorous on aquatic plants, fruits, algae, snails, crustaceans, and benthic macroinvertebrates

Myuchelys bellii, M. georgesi, M. latisternum, and M. purvisi habitats

Mostly rivers and streams, also waterholes, lagoons, lakes, and billabongs (M. latisternum)

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species, black in M. bellii. Tubercles are present on the back of the neck and pale neck stripes are present on some, especially in juveniles and M. purvisi. Sawshelled turtles can obtain some oxygen via cloacal breathing. In 2015 hundreds of M. georgesi died from a possible viral infection, threatening their survival.

PLEURODIRA—Side-necked turtles

activity

lifespan

Over 26 years in captivity reproduction

8–23 eggs per clutch

CHELIDAE: RHEODYTES

FITZROY RIVER TURTLE left | Fitzroy River Turtles, like Mary River Turtles, are physiologically more like fish than other turtles due to their ability to “breathe” underwater.

T

he only species in this genus, Rheodytes leukops, is so distinctive it warrants its own taxonomic status, which has been supported by numerous studies published since its original description to science in 1980. Fitzroy River Turtles are found only in the Fitzroy River and its tributaries in northeastern Australia, preferring fast-flowing riffles in the river and streams where it occurs. Fossils are unknown.

The carapace is brownish, textured with fine ridges, and with a low profile. The pale plastron is unhinged. The silver-blue iris of hatchlings becomes ivory surrounded by a brown ring in adults. Like Elusor, Rheodytes can extract oxygen from the water using heavily vascularized structures in their cloaca, like gills. They can obtain up to 70 percent of the oxygen they need underwater.

distribution

activity

diet

Fitzroy River drainage system in northeastern Australia species

Varies from stream to stream between diurnal, crepuscular, and nocturnal

Rheodytes leukops

lifespan

Primarily carnivorous on aquatic insect larvae in some tributaries; herbivorous in other tributaries

habitats

Unknown

Fast-flowing rivers and streams

reproduction

size

CL to at least 10¼ in (26.2 cm)

3–5 clutches per year; average clutch size is 18 eggs; annual reproductive potential may be up to 59 eggs

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CHELIDAE: PSEUDEMYDURA

WESTERN SWAMP TURTLE

P

seudemydura umbrina, the only species in this genus, has a restricted range near Perth, Australia. Although described in 1901 by European scientists, the species remained unknown to Australian herpetologists until “rediscovered” and given a different name in 1954. When scientists later recognized the earlier description from half a century before was the same species, the original name was adopted. Fossils are not known.

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Remaining habitats in this highly developed region are few in number, consisting of ephemeral swamps with clay bottoms in small nature preserves. The swamps hold standing water for three to six months of the year, and when they dry, usually in October, turtles estivate under leaf litter or in burrows constructed by other animals including goanna lizards. Turtles do not return to the swamps until they start to fill again in May or June.

distribution

size

The few remaining small swamps in the Swan Valley near Perth, Australia

CL up to about 6 in (15.5 cm)

species

Pseudemydura umbrina

Feeding and movement only observed diurnally

habitats

lifespan

Shallow swamps dominated by plants like paperbark (Melaleuca), Banksia, and dense heath (Regelia ciliata)

Unknown

PLEURODIRA—Side-necked turtles

activity

| Western Swamp Turtles persist in only two tiny natural habitats: Ellen Brook and Twin Swamps Nature Reserve near Perth.

below

These relatively nondescript brownish turtles have a straw-colored unhinged plastron and a relatively flattened shell. The head is broad and also flattened with conical tubercles on top of the neck. The Western Swamp Turtle is the only turtle in the world known to excavate a nest cavity with its forelimbs instead of its hindlimbs. Females nest in the daytime during the dry season and remain near the nest for several days before leaving to estivate. The Western Swamp Turtle is Australia’s smallest turtle species; males are larger than females, a condition observed in only one other species of Australian turtle: Elusor macrurus. Its rarity and limited distribution make Pseudemydura Australia’s most vulnerable turtle and one of the most threatened in the world. They are the focus of intensive captive breeding efforts. Introduced Red Foxes (Vulpes vulpes) are predators of adults, juveniles, and nests.

left

| Agricultural

development of the Swan Valley destroyed Western Swamp Turtle habitat and contributed to their decline.

right | Unlike some Australian chelid turtles, Western Swamp Turtle hatchlings, although cute, are drab in appearance like the adults.

reproduction

1 clutch per year of 3–5 hard-shelled eggs diet

Carnivorous on crustaceans, insects, and tadpoles

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FAMILY: PELOMEDUSIDAE AFRICAN SIDE-NECKED TURTLES

T

he family Pelomedusidae has two genera and 27 species. Most species occur in countries of continental Africa below the Sahara Desert, one native to Yemen and Saudi Arabia, four in Madagascar, and three in the Seychelles islands. Collectively, members of the Pelomedusidae are primarily semi-aquatic and occupy most aquatic habitats including rivers, lakes and ponds, watering holes used by large ungulates, and marshes. Some species are associated with freshwater habitats on savannas, others prefer tropical rainforests. Some are forced to estivate when water bodies dry up. Body sizes range from small (maximum carapace 4¾ in / 12 cm) to large (21¾ in / 55 cm). The carapace is slightly domed or flat, depending on the species. Most Pelomedusidae are drab in appearance. The carapace and limbs are a shade of brown or gray. The chin and underside of the neck

may have lighter coloration. Two or three barbels are present on the chin. Yellow or cream-colored markings are present on some species. The plastron is yellow or brownish in most. The two genera differ in morphology with Pelusios having a hinged plastron whereas in Pelomedusa it is unhinged. The conservation status varies greatly among pelomedusid species, with some being geographically wide-ranging and common whereas others have localized distributions and are threatened by habitat loss. The Seychelles Mud Turtle (Pelusios castaneus seychellensis) was declared extinct in the mid-twentieth century. Some Pelomedusidae are eaten by humans and have been for millennia. Archaeologists found Pelusios sinuatus fossils to be by far the most common turtles associated with habitations of human ancestors 1.7 MYA in Olduvai Gorge in Tanzania.

right | Turtles in the family Pelomedusidae formerly included all three genera now placed in the family Podocnemididae.

distribution

size

reproduction

Sub-Saharan Africa, Madagascar, Saudi Arabia, Yemen, and Seychelles islands

CL up to 18¼ in (46.5 cm) for P. sinuatus

6–42 oblong eggs with pliable shells per clutch

genera

Some species estivate for months in mud of drying aquatic habitats during droughts; overland movement between aquatic habitats

Pelomedusa, Pelusios habitats

Most aquatic habitats; standing, flowing, and ephemeral water; in rivers, streams, ponds, watering holes, marshes, savannas, rainforests, depending on the species

216

activity

PLEURODIRA—Side-necked turtles

diet

Carnivorous on carrion, fish, amphibians, and a wide variety of invertebrates

217

PELOMEDUSIDAE: PELOMEDUSA

AFRICAN HELMETED TURTLES | The Sahelian Helmeted Turtle is named for the arid “Sahel” region along the southwestern fringe of the Sahara Desert.

below

T

he genus Pelomedusa, once considered a single species, is now recognized as ten, with a widespread distribution across continental Africa. One species (Pelomedusa barbata) is native to Yemen and southwestern Saudi Arabia. P. subrufa is common in Madagascar and was possibly introduced from the continent by humans prehistorically. Fossil records of the genus are uncertain. African helmeted turtles are semiaquatic and occupy mostly temporary aquatic

218

habitats including marshes and human-made ponds. Some species inhabit arid savannas where seasonal wetlands are found. During the dry season, some species estivate in receding mud and may remain in a dormant state underground for months. African helmeted turtles occur at high elevations in southern Africa (5,200 ft [1,600 m]). Body sizes range from 8¾ to 12 in or more (20 to 30 cm). Males are larger than females in some species.

distribution

habitats

Most sub-Saharan African countries, Madagascar, the Mascarene Islands, Saudi Arabia, and Yemen

Semi-aquatic in permanent and temporary bodies of water, marshes, small streams, and aquatic areas in open savannas

species

size

Pelomedusa barbata, P. galeata, P. gehafie, P. kobe, P. neumanni, P. olivacea, P. schweinfurthi, P. somalica, P. subrufa, and P. variabilis

CL up to 12¾ in (32.5 cm) for P. galeata

PLEURODIRA—Side-necked turtles

activity

Most active during wet season; may estivate for months in temporary aquatic habitats during hot, dry periods

The head is broad, and the carapace is moderately flat and brown or olive in color. The head, neck, and limbs are grayish or brown with lighter coloration on the underside. The plastron is usually yellow and is unhinged. Pelomedusa are noted for being pugnacious when threatened, having musk glands on the sides of the carapace that secrete a foul-smelling liquid. They will also bite, scratch, defecate, and void their bladders on predators or humans if picked up. Pelomedusa has been recorded capturing birds along shorelines and dragging them into the water to drown before eating them. An unusual feeding behavior observed in Pelomedusa is turtles feeding on ticks of large mammals in waterholes. The conservation status of most species is relatively secure with few threats other than habitat loss in localized areas.

above | Unlike many turtles, the Helmeted Turtle has an unpleasant, musky smell, and is reportedly seldom eaten by people.

| Helmeted Turtles prefer temporary wetlands like “pans” but avoid permanent water with predatory crocodiles.

below

lifespan

Over 20 years in captivity reproduction

10–42 oblong eggs with leathery shells per clutch diet

Omnivorous, carnivorous, or herbivorous, depending on species, on carrion, fish, amphibians, doves, wide variety of invertebrates, and occasional aquatic plants

219

PELOMEDUSIDAE: PELUSIOS

AFRICAN MUD TURTLES

T

he genus Pelusios is recognized as having 17 species, together covering much of continental Africa, with representatives on Madagascar and the Seychelles islands. African mud turtles are semi-aquatic but occupy a wide range of permanent aquatic habitats, including large rivers, streams, lakes, reservoirs, and humanmade ponds; swamps and marshes are occupied in some regions, as well as small temporary wetlands.

above | The Okavango Mud Turtle lives in the delta of the Okavango River where juveniles are preyed upon by Shoebill Storks (Balaeniceps rex). right | The Serrated Hinged Terrapin in South Africa is the southernmost member of the genus and also the largest species.

Most sub-Saharan African countries, Madagascar, and Seychelles islands distribution

habitats

species

Habitat of Pelusios is highly variable; permanent aquatic habitats, rivers, streams, lakes, swamps, marshes, farm ponds, and reservoirs, depending on species and locality; some species are found in aquatic habitats in rainforests

Pelusios adansonii, P. bechuanicus, P. broadleyi, P. carinatus, P. castaneus, P. castanoides, P. chapini, P. cupulatta, P. gabonensis, P. marani, P. nanus, P. niger, P. rhodesianus, P. sinuatus, P. subniger, P. upembae, and P. williamsi

size

CL to 21¾ in (55 cm) for P. sinuatus activity

Overland movements during wet season from rivers and lakes to temporary

220

PLEURODIRA—Side-necked turtles

Pelusios are well represented in Miocene and Pleistocene fossils of Africa. They are conjectured to be more abundant as fossils than the closely related genus Pelomedusa because of the propensity of Pelusios to inhabit permanent aquatic habitats, and more likely to have become fossilized in sedimentary deposits. Species of African mud turtles vary in body size from a maximum carapace length in P. nanus of 4¾ in (12 cm) to 21½ in (55 cm) in P. sinuatus. The carapace is flattened in most species and dark, ranging from brown to black. The head, neck, and limbs are also dark, most ranging from dark gray to black with lighter coloration on the underside. The plastron is yellow, brown, or black. The plastron has an anterior hinge allowing the turtle to close the shell to protect its head and limbs. African mud turtles living in watering holes will eat ticks on floating carcasses of large mammals and even on live Cape buffalos. Some species are common with large ranges and are not threatened by human activities whereas localized populations of others are of conservation concern.

| The East African Black Mud Turtle is the only living member of the genus found in Africa, Madagascar, and the Seychelles.

below

wetlands; bask frequently on logs, rocks, and shorelines lifespan

Over 47 years in captivity (P. subniger) reproduction

7–50 oblong, flexible eggs per clutch diet

Omnivorous, but mostly carnivorous on aquatic snails and other invertebrates, nestling birds that fall into water; fallen fruit and aquatic vegetation

above | The Variable Mud Turtle is vulnerable to fire death and scarring when it estivates in reed beds during the dry season.

221

FAMILY: PODOCNEMIDIDAE SOUTH AMERICAN RIVER TURTLES AND BIG-HEADED SIDE-NECKED TURTLES

T

he pleurodiran family Podocnemididae has three genera, two of which, Peltocephalus and Erymnochelys, have one species each. The other genus, Podocnemis, has six species. The family originated in Gondwanaland, which began splitting apart 140 MYA during the Mesozoic Era, ultimately resulting in two genera, Podocnemis and Peltocephalus, in South America and one, Erymnochelys, on Madagascar. All Podocnemididae are highly aquatic, most living in association with large rivers, including in the Amazon and Orinoco basins. In contrast, Podocnemis vogli is not often seen in large rivers, instead preferring to live in ponds or small creeks in the savannas of the Llanos region of northeastern South America. This species attains large concentrations

during the dry season when they take shelter in the remaining water. Peltocephalus in South America and Erymnochelys in Madagascar are superficially similar in appearance in being large turtles, around 20 in (50 cm) in maximum carapace length, with enormous heads and crushing jaws. Most Podocnemis also reach large sizes, with the giant South American Turtle or Arrau (P. expansa) reaching lengths of almost a meter. The Podocnemididae are distinctive in having lower numbers of chromosomes than most other turtles, which have 50 or more. Peltocephalus has the lowest reported number, 26. The Podocnemididae are vulnerable in their native habitats due to a variety of threats, including removal of adults from the wild for food and illegal poaching of eggs.

right | The Giant South American River Turtle is one of the largest freshwater turtles in the world.

savannas, and clear streams with aquatic vegetation, depending on genus, species, and region

lifespan

Northern South America, Trinidad, and Western Madagascar genera

size

Erymnochelys, Peltocephalus, and Podocnemis

CL to 35½ in (90 cm) or more in female P. expansa

16–150 eggs per clutch, depending on species

habitats

activity

Diversity of aquatic habitats; swamps, marshes, large rivers and backwaters, oxbow lakes, flooded forests, lakes, flooded

Some species primarily nocturnal but others diurnal

distribution

222

PLEURODIRA—Side-necked turtles

Over 25 years in captivity (P. expansa) reproduction

diet

Omnivorous, herbivorous, or carnivorous, depending on genus and species

223

PODOCNEMIDIDAE: ERYMNOCHELYS

MADAGASCAN BIG-HEADED TURTLE

T

he genus Erymnochelys has a single species, E. madagascariensis, with a geographic range restricted to western Madagascar. Its primary habitats are associated with large rivers, streams, or lakes in low-lying areas. The species is the only living member of the family Podocnemididae found outside South America. After the breakup

| One of the major threats facing the Madagascan Big-headed Turtle is bycatch in fishing nets and subsequent human consumption.

below

distribution

lifespan

Madagascar

Unknown

species

reproduction

Erymnochelys madagascariensis

1–3 clutches per year, every two years;16–22 eggs per clutch; up to 63 eggs can be produced in a nesting year

habitats

Slow-moving rivers and streams, swamps, marshes, backwaters, and some lakes size

CL up to 19 in (48 cm) activity

Lays eggs at night

224

PLEURODIRA—Side-necked turtles

diet

Omnivorous on reed shoots and snails

of Gondwanaland, ancestors of today’s podocnemid turtles once had a wide distribution in Africa and Europe. For example, fossils of Erymnochelys are known from the Miocene and Pliocene of Kenya, and related extinct genera have been reported from the Eocene of France and Spain. The current disjunct nature of the surviving genus, Erymnochelys, may have resulted from large-scale extinctions leaving the final remnant population in Madagascar. The carapace is usually a drab grayish brown color. The plastron is yellow or yellowish brown. The head is large and wide and is brown or reddish

with conspicuous large plates on the side that may be yellowish or gold in color. Both jaws, chin, and underside of the short neck are yellow. The upper jaw is hooked at the end, and the species is noted for having a strong, crushing bite. Although some individuals reach relatively large sizes, males, which get bigger than females, can be up to 19 in (48 cm) in carapace length. The Madagascan Big-headed Turtle is indisputably one of the most critically endangered turtles in the world. It reportedly is gone from some lakes where it was once common. A major threat is the removal of Erymnochelys from the wild for food.

left | Madagascar’s freshwater turtles, like this Madagascan Big-headed Turtle, are often overshadowed by its four native tortoise species.

225

PODOCNEMIDIDAE: PELTOCEPHALUS

BIG-HEADED SIDENECK TURTLE

T

he genus Peltocephalus has a single species (P. dumerilianus) with a geographic range covering much of the Orinoco and Amazon river basins from Ecuador to French Guiana. Being aquatic, they are found in backwaters and streams associated with rivers. They are primarily nocturnal, omnivorous bottom crawlers that eat fruits, aquatic vegetation, fish, and invertebrates. They have also been reported to eat eggs of their own species, a phenomenon unreported in any other turtle.

Both males and females are large turtles, reaching more than 19 in (48 cm) in carapace length. The domed carapace is dark, ranging from gray or olive to brown to almost black, with a central keel down the back that diminishes in older individuals. The plastron is yellow to brown. The head and limbs are drab gray to olive. A notable feature of the Big-headed Sideneck Turtle is an extremely large head and hooked upper jaw that is triangular in shape with large scales. The width of the head can be 20 percent (more than 4 in/10 cm) of the length of the carapace. A single barbel is under the chin. The species is unusual in having the lowest number of chromosomes (26 diploid) reported for any turtle. Some side-necked turtles (suborder Pleurodira) have diploid chromosome numbers as low as 28 to 36, but most of them, as well as the hidden-necked turtles (suborder Cryptodira) have more than 50 chromosomes. The Big-headed Sideneck Turtle is recognized as a vulnerable species, threatened by collection for food by native peoples of the region.

left | The Big-headed Sideneck Turtle of the Amazon basin bears a striking similarity to the Madagascan Big-headed Turtle.

distribution

size

Colombia, Ecuador, Peru, Brazil, Venezuela, and French Guiana

CL to almost 19¾ in (50 cm); weight 33 lb (15 kg)

species

activity

Peltocephalus dumerilianus

Primarily nocturnal aquatically but diurnal in some habitats

habitats

Streams and associated floodplains and backwaters, oxbow lakes, swamps, and clear streams with aquatic vegetation

226

PLEURODIRA—Side-necked turtles

lifespan

Unknown

above | Big-headed Sideneck Turtles prefer rainforest habitats in small blackwater streams and swamps rather than big rivers.

right | The Big-headed Sideneck Turtle reportedly has environmental sex determination, as in many other turtles.

reproduction

7–25 elongate eggs per clutch diet

Omnivorous on fallen tree fruits, plants, and fish

227

PODOCNEMIDIDAE: PODOCNEMIS

SOUTH AMERICAN RIVER TURTLES

T

he genus Podocnemis has six species and a geographic range centered on the Orinoco and Amazon river basins of South America. P. lewyana is found in the Magdalena and nearby rivers of Colombia. Fossils of extinct Podocnemis are known from the Miocene of South America. Podocnemis are relatively large turtles, the two smallest, P. erythrocephala and P. sextuberculata, reaching carapace lengths of more than 12 in (31 cm), and P. expansa (Arrau Turtle) commonly being almost 40 in (100 cm) in length. Males are smaller than females. The oval-shaped heavy carapace is olive, gray, or brown and either somewhat domed or flat, depending on the species. A keel is present on the carapace of some, especially juveniles, and absent in others. The head usually has yellow (reddish in P. erythrocephala) spots or other markings. The

above | Yellow-spotted River Turtles can often be seen basking on logs along the Amazon, Orinoco, and other large South American rivers.

right | Similar to Ridley Sea Turtles, Giant South American River Turtle females sometimes emerge to nest in spectacular numbers.

distribution

habitats

Northern South America. Found in tributaries and main river systems of the Amazon, Essequibo, and Orinoco rivers of Colombia, Ecuador, Peru, Bolivia, Brazil, Venezuela, Suriname, and Guyana; occasionally on Trinidad (P. expansa)

Large rivers and backwaters, oxbow lakes, flooded forests, and swamps

species

Podocnemis erythrocephala, P. expansa, P. lewyana, P. sextuberculata, P. unifilis, and P. vogli

228

PLEURODIRA—Side-necked turtles

size

CL to 35½ in (90 cm) or more for P. expansa activity

Largely diurnal with most nesting at night lifespan

Over 25 years in captivity (P. expansa)

large plastron has no hinge. All have at least one chin barbel and most have two. The most well-known South American river turtle is the Arrau because of its unusual communal nesting habits. Hundreds of Arrau females nest at the same time on sandbars at night. Research on the Arrau in Brazil has suggested an unusual social phenomenon of females in the river communicating vocally with hatchlings as they leave nests on beaches to enter the water. Because they accumulate on land to nest, they are vulnerable to exploitation by locals for food in many parts of their range. Both adults and eggs are prized commodities, hence population sizes of the Arrau have been severely reduced in many areas. The species is protected in several countries, but illegal poaching continues.

right | Unlike many of its relatives, the Savanna Sideneck Turtle is rarely found in large rivers, preferring small streams and ponds.

reproduction

2+ clutches per year of 5–30 hard, brittle, elongate eggs in most species; up to 150 round, leathery eggs in P. expansa diet

Mostly herbivorous on aquatic plants, flowers, fallen tree fruits, and roots; some species are opportunistic carnivores on fish and aquatic invertebrates

229

APPENDICES

GLOSSARY Allantois: extraembryonic membrane of amniotic eggs, which expands in a turtle egg during embryonic development and functions to store waste and facilitate respiration.

phylogenetic tree and containing all extinct species moving down the tree to the oldest common ancestor of all the living species in the lineage.

Amnion: extraembryonic membrane surrounded by the chorion and enclosing the embryo, allantois, and yolk sac inside a turtle egg.

Diurnal: active during the day.

Amniote: a mammal, bird, or reptile (including turtles) in which the embryo develops within an envelope composed of the amnion and chorion.

Ectothermy: metabolism of animals, such as turtles and other reptiles, in which body heat is derived from external sources (e.g., via basking in the sun).

Anhomeostasis: a metabolic trait of ectotherms like turtles to tolerate a wide range of variation in physiological traits, including temperature, osmotic concentration, blood sugar, and oxygen level, in contrast to most homeotherms (birds and mammals) that rely on homeostasis.

Embryonic diapause: temporary pause in embryonic development in the eggs of some turtles.

Ecdysis: periodic shedding of scutes on the shell of some hard-shelled species of turtles.

Endothermic: body heat generated within an organism through metabolic processes, as in birds and mammals.

Annuli (sing. annulus): growth rings, analogous to tree rings, formed as visible grooves on scutes of tortoises and other hard-shelled turtles during alternating periods of growth and dormancy.

Entoplastron: a midline, unpaired bone situated on the anterior plastron of turtles.

Annuli technique: counting growth rings on hard-shelled turtles to determine the number of periods of dormancy, which equates to winter in many temperate-zone turtles, often permitting age of individuals to be estimated.

Estivate: to remain in a dormant state during hot or dry spells.

Anoxic: conditions of depleted oxygen, which are created beneath frozen bodies of water or in mud where many temperate-zone turtles spend winter. Aquatic: refers to turtles inhabiting freshwater or marine habitats during all or some part of their life cycle. Archosaur: the broadest classification of a phylogenetically related grouping that includes modern-day crocodilians and birds and their extinct ancestors, including the dinosaurs. Authorities disagree on whether turtles belong in the archosaur classification scheme. Arribada: communal nesting behavior in which thousands of sea turtles in the genus Lepidochelys historically arrived synchronously at particular beaches, including in the Gulf of Mexico, Pacific Ocean (Costa Rica), and Indian Ocean (Orissa, India). Barbel: protuberance, usually a paired or single sensory organ, on the chin, jaw, or neck of some turtles. Brumation: winter dormancy in turtles and other reptiles; equivalent to hibernation in mammals. Carapace: the bony upper shell of a hard-shelled turtle.

Epiplastron: one of a pair of the most anterior bony plates on the plastron of turtles. Family: taxonomic unit comprising closely related genera and which may be further divided into subfamilies. Fontanelle: a translucent membranous area present between bones in the shell of some turtles, especially during early development. Fungivorous: eating mushrooms or other fungi. Genus (pl. genera): taxonomic unit comprising closely related species. Glacial maxima: periods of greatest global distribution of ice. Gular (scutes): the most anterior scutes on a turtle plastron; usually a pair but singular in some species as an intergular. Herbivorous: eating plants. Herpetology: the study of reptiles and amphibians. Humeral (scutes): pair of scutes on a turtle plastron located between the gular and pectoral scutes. Hyoplastra: pair of bony plates located posterior to the epiplastra and entoplastron and located anterior to the hypoplastra on a turtle’s plastron. Hypoplastra: a pair of bony plates located between the hyoplastra and xiphiplastra on a turtle’s plastron.

Carnivorous: preying on other animals.

Inguinal: a small scute on the posterior portion of the bridge between the carapace and plastron in some species of turtles.

Chorion: extraembryonic membrane of amniotic eggs that is the outer layer within the egg shell enclosing the embryo of a turtle.

Keel: a midline or lateral longitudinal ridge on the carapace of some turtles.

CL (carapace length): one of the measurements of size in living and fossil turtles. Cloaca: the opening at the base of the tail in turtles through which excretory and reproductive products (eggs; sperm) pass. Costal: one of the bones on the carapace of a turtle between the neurals and peripherals. Crepuscular: being active at dusk or dawn in contrast to being nocturnal or diurnal. Crown group: living species positioned at the top of a

232

Glossary

Mesoplastron bones: pair of bony plates located between the hyoplastra and hypoplastra in some turtle genera (e.g., Pelusios, Pelomedusa, and Podocnemis). Molecular clock analyses: determination of the estimated time of divergence of ancestral lines through calculations based on rates of genetic change. MYA: million years ago. Nocturnal: active at night. Nuchal bone: the most anterior bone of the carapace in most turtles, which separates the peripheral bones on either side above the neck.

Ocelli (sing. ocellus): patterns on turtle shells that resemble eyes. Omnivorous: eating both plants and animals. Osmoregulation: process of maintaining the balance of water and salts on both sides of a cell membrane. Osteoderms: bony plates embedded in the leathery skin of the carapace of Leatherback Sea Turtles. Palatine: one of a pair of bones in the roof of the mouth, associated with the upper jaw bone (maxilla) and bearing small teeth in some extinct turtles. Phylogenetic: evolutionary relationship among species or higher systematic classifications. Plastron: the bony lower shell of a turtle. Pleural: one of the scutes of a turtle’s carapace, lying between the midline vertebral scutes and marginal scutes on the side Pterygoid: one of a pair of bones in the roof of the mouth, associated with the upper jaw bone (maxilla) and bearing small teeth in some extinct turtles. Pygal bone: the most posterior bone of the carapace, behind the suprapygals and which separates the peripheral bones on either side above the tail. Rhamphothecae: the outer layers of turtle jaws, composed of keratin. They can be sharp for cutting and slicing plant or animal food or broad for crushing mollusks. Scutes: large scales made of keratin covering the carapace and plastron of most hard-shelled turtles. Semi-aquatic: refers to turtle species inhabiting aquatic habitats but that sometimes spend extensive time on land for purposes other than nesting. Species: traditionally defined as an identifiable and distinct group of organisms capable of interbreeding and producing viable offspring under natural conditions. Closely related species are generally classified as belonging to the same genus.

Stem group/species: extinct species lower on the turtle phylogenetic tree that did not directly give rise to lineages living today. Subfamily: taxonomic unit composed of genera more closely related to each other than to other genera placed in the same family; a subfamily may have only one genus, if it is more distantly related than other genera in the family are to each other. Subgenus: taxonomic unit composed of species more closely related to each other than to other species placed in the same genus; a subgenus may have only one species, if it is more distantly related than other species in the genus are to each other. Subspecies: a taxonomic category of a morphologically distinct group within a species, usually one occupying a geographic range not overlapping with other subspecies. Sundaland: shallow continental shelf of Southeast Asia, periodically above water during glacial maxima, encompassing parts of mainland Southeast Asia and Malaysian and Indonesian islands, including Borneo, Sumatra, and Java. Suprapygal: one of a pair of bones of the carapace, located posterior to the costals and anterior to the pygal bone. Terrestrial: refers to turtles living on land. Tympanum: circular or oval skin on both sides of the head of a turtle that transmits sounds to the brain through the middle ear. Vermiculation: one of the irregular lines or markings that form intricate patterns on the head or shell of some turtles. Vomer: one of a pair of bones in the roof of the mouth, associated with the upper jaw bone (maxilla) and bearing small teeth in some extinct turtles. Vomeronasal organ: part of the olfactory system of some reptiles located in the roof of the mouth and capable of detecting chemical signals. Xiphiplastra: the most posterior pair of bony plates on a turtle’s plastron.

TURTLE CONSERVATION ORGANIZATIONS Chelonian Research Foundation, founded 1992 https://chelonian.org/, publishes Chelonian Conservation and Biology, https://chelonian.org/ccb.

Turtle Conservation Fund, founded 2002 https://turtleconservationfund.org/, provides funding to support turtle research and conservation.

Chelonian Research Institute, founded 1997 https://chelonianri.org/, third largest research collection of turtle specimens in the world.

American Turtle Observatory, founded ca. 2015 http://www.americanturtles.org/, dedicated to the conservation of critical landscapes for American turtles.

Turtle Survival Alliance, founded 2001 https://turtlesurvival.org/, hosts an annual symposium.

The Turtle Room https://theturtleroom.org/, advances survival of the world’s turtles and tortoises through collaborative education, conservation, and research programs.

Turtle Conservancy, founded 2005 https://www.turtleconservancy.org/, publishes The Tortoise magazine. https://www.turtleconservancy.org/magazine.

233

RESOURCES BOOKS (GENERAL) Bonin, F., B. Devaux, and A. Dupré. 2006. Turtles of the World. Johns Hopkins University Press, Baltimore. Branch, B. 2008. Tortoises, Terrapins and Turtles of Africa. Struik Publishers, Cape Town. Cann, J. and R. Sadlier. 2017. Freshwater Turtles of Australia. ECO Wear and Publishing, Rodeo, New Mexico. Das, I. 1991. Colour Guide to the Turtles and Tortoises of the Indian Subcontinent. R&A Publishing Limited, Avon, England. Ernst, C. H., and R. W. Barbour. 1989. Turtles of the World. Smithsonian Institution Press, Washington, D.C. Ernst, C. H., and J. E. Lovich. 2009, Turtles of the United States and Canada, Second Edition. Johns Hopkins University Press, Baltimore. Gibbons, J. W. 1990. Life History and Ecology of the Slider Turtle. Smithsonian Institution Press, Washington, D.C. https://srelherp. uga.edu/SliderBook/sliderbook.htm Gibbons, J. W., and J. L. Greene. 2009, Turtles: The Animal Answer Guide. Johns Hopkins University Press, Baltimore. Klemens, M. 2000, Turtle Conservation. Smithsonian Institution Press, Washington, D.C. Lehrer, J. 1990. Turtles and Tortoises. Mallard Press, New York. Liat, L. B. and I. Das. 1999. Turtles of Borneo and Peninsular Malaysia. Natural History Publications, Kota Kinabalu, Borneo. Obst, F. J. 1988. Turtles, Tortoises and Terrapins. St. Martin’s Press, New York. Orenstein, R. 2012. Turtles, Tortoises and Terrapins: A Natural History. Firefly Books, Ltd, Ontario, Canada. Pritchard, P. C. H. 1967, Living Turtles of the World. T.F.H. Publications, Jersey City, New Jersey. Pritchard, P. C. H. 1979, Encyclopedia of Turtles. T. F. H. Publications, Inc. Ltd., Neptune, New Jersey. Pritchard, P. C. H. 2012. Rafetus: The Curve of Extinction. Living Art Publishing, Ada, Oklahoma. Pryke L. 2021. Turtle. Reaktion Books Ltd, London. Spotila, J. R. 2004. Sea Turtles: A Complete Guide to their Biology, Behavior, and Conservation. Johns Hopkins University Press, Baltimore.

JOURNAL ARTICLES Agha, M., J. R. Ennen, D. S. Bower, A. J. Nowakowski, S. C. Sweat, and B. D. Todd. 2018. “Salinity tolerances and use of saline environments by freshwater turtles: implications of sea level rise.” Biological Reviews 93:1634–1648. Buhlmann, K. A., T. S. B. Akre, J. B. Iverson, D. Karapatakis, R. A. Mittermeier, A. Georges, A. G. J. Rhodin et al. 2009. “A global analysis of tortoise and freshwater turtle distributions with identification of priority conservation areas.” Chelonian Conservation and Biology 8:116–149. Congdon, J. D., A. E. Dunham, and R. C. Van Loben Sels. 1993. “Delayed sexual maturity and demographics of Blanding’s turtles (Emydoidea blandingii): implications for conservation and management of long-lived organisms.” Conservation Biology 7:826–833.

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Resources

Ennen, J. R., M. Agha, W. Matamoros, S. Hazzard, and J. E. Lovich. 2016. “Using climate, energy, and spatial-based hypotheses to interpret macroecological patterns of North America chelonians.” Canadian Journal of Zoology 94:453–461. Ewert, M. A., D. R. Jackson, and C. Nelson. 1994. “Patterns of temperature-dependent sex determination in turtles.” The Journal of Experimental Zoology 270:3–15. Gibbons, J. W., and J. E. Lovich. 2019. “Where has turtle ecology been, and where is it going?” Herpetologica 75:4–20. Gibbons, J. W., D. E. Scott, T. J. Ryan, K. A. Buhlmann, T. D. Tuberville, B. S. Metts, J. L. Greene, T. Mills, Y. Leiden, S. Poppy, and C. Winne. 2000. “The global decline of reptiles, déjá vu amphibians.” Bioscience 50:653–666. Iverson, J. B. 1992. “Global correlates of species richness in turtles.” Herpetological Journal 2:77–81. Lovich, J. E., and J. R. Ennen. 2013. “A quantitative analysis of the state of knowledge of turtles of the United States and Canada.” Amphibia-Reptilia 34:11–23. Lovich, J. E., J. R. Ennen, M. Agha, and J. W. Gibbons. 2018. “Where have all the turtles gone, and why does it matter?” BioScience 68:771–781. Lovich, J. E., and K. Yamamoto. 2016. “Measuring the impact of invasive species on popular culture: a case study based on toy turtles from Japan.” Humans and Nature 27:1–11. Shaffer, H. B., E. McCartney-Melstad, T. J. Near, G. G. Mount, and P. Q. Spinks. 2017. “Phylogenomic analyses of 539 highly informative loci dates a fully resolved time tree for the major clades of living turtles (Testudines).” Molecular Phylogenetics and Evolution 115:7–15. Stanford, C. B., J. B. Iverson, A. G. J. Rhodin, P. P. van Dijk, R. A. Mittermeier, G. Kuchling, K. H. Berry et al. 2020. “Turtles and tortoises are in trouble.” Current Biology 30:R721–R735. Turtle Extinctions Working Group (Rhodin, A. G. J., S. Thomson, G. Georgalis, H.-V. Karl, I. G. Danilov, A. Takahashi, M. S. de la Fuente, J. R. Bourque, M. Delfino, R. Bour, J. B. Iverson, H. B. Shaffer, and P. P. van Dijk). 2015. “Turtles and tortoises of the world during the rise and global spread of humanity: first checklist and review of extinct Pleistocene and Holocene chelonians,” pages 000e.001–066 in A. G. J. Rhodin, P. C. H. Pritchard, P. P. van Dijk, R. A. Saumure, K. A. Buhlmann, J. B. Iverson, and R. A. Mittermeier, ed., Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. Chelonian Research Monographs. Turtle Taxonomy Working Group (Rhodin, A. G. J., J. B. Iverson, R. Bour, U. Fritz, A. Georges, H. B. Shaffer, and P. P. van Dijk). 2017. “Turtles of the World: Annotated Checklist and Atlas of Taxonomy, Synonymy, Distribution, and Conservation Status (8th Ed.)” in Rhodin, A. G. J., J .B. Iverson, P. P. van Dijk, R. A. Saumure, K. A. Buhlmann, P. C. H. Pritchard, and R. A. Mittermeier (eds.), Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. Chelonian Research Monographs 7:1–292.

TURTLE CLASSIFICATION AND PHYLOGENETIC ORDER Based on Turtle Taxonomy Working Group (2017) SUBORDER CRYPTODIRA Family

Subfamily

Genus

Family

Subfamily

Chelydridae

Genus

Family

Subfamily

Cuora Chelydra

Cyclemys

Macrochelys

Geoclemys

Cheloniidae

Genus Cycloderma Lissemys

Trionychinae

Geoemyda

Amyda

Hardella

Apalone

Caretta

Heosemys

Chitra

Eretmochelys

Leucocephalon

Dogania

Lepidochelys

Malayemys

Nilssonia

Mauremys

Palea

Chelonia

Melanochelys

Pelochelys

Natator

Morenia

Pelodiscus

Notochelys

Rafetus

Orlitia

Trionyx

Carettinae

Cheloniinae

Dermochelyidae Dermochelys Dermatemydidae

Pangshura Dermatemys

Sacalia

Kinosternidae Kinosterninae Kinosternon

Family

Vijayachelys

Chelidae

Rhinoclemmydinae

Sternotherus Staurotypinae

SUBORDER PLEURODIRA

Siebenrockiella

Subfamily

Genus

Chelinae Rhinoclemmys

Acanthochelys

Testudinidae

Chelus

Claudius

Aldabrachelys

Mesoclemmys

Staurotypus

Astrochelys

Phrynops

Centrochelys

Platemys

Emydidae Deirochelyinae

Chelonoidis

Rhinemys

Chrysemys

Chersina

Deirochelys

Chersobius

Graptemys

Geochelone

Malaclemys

Gopherus

Chelodina

Pseudemys

Homopus

Elseya

Trachemys

Indotestudo

Elusor

Kinixys

Emydura

Clemmys

Malacochersus

Myuchelys

Emys

Manouria

Actinemys

Psammobates

Emydoidea

Pyxis

Glyptemys

Stigmochelys

Emydinae

Terrapene Platysternidae

Hydromedusinae Hydromedusa Chelodininae

Rheodytes Pseudemydurinae Pseudemydura Pelomedusidae

Testudo

Pelomedusa

Carettochelyidae

Pelusios

Platysternon Geoemydidae

Carettochelys Trionychidae

Geoemydinae

Erymnochelys Cyclanorbinae

Batagur

Podocnemididae

Peltocephalus Cyclanorbis

Podocnemis

235

INDEX A Acanthochelys 190–1 Actinemys 96–7 African helmeted turtles 218–19 African mud turtles 220–1 African side-necked turtles 187, 216–21 African Softshell Turtle 184–5 African Spurred Tortoise 142–3 Agassiz’s Desert Tortoise 18, 23, 152 Aldabra Giant Tortoise 138–9 Aldabrachelys 138–9 alligator snapping turtles 29, 50, 54–5 Amyda 29, 174 anapsids 17 anhomeostasis 18 annuli 36–7 Apalone 175 Archelon 12 Arrau Turtle 228–9 Asian box turtles 110–11 Asian Giant Softshell Turtle 181 Asian Giant Tortoise 159 Asian river terrapins 108–9 Asian Turtle Crisis 44 Asiatic Softshell Turtle 174 Astrochelys 140–1 Aubry’s Flapshell Turtle 171 Australasian side-necked turtles 187, 188–215 Australian short-necked turtles 210–11 Australian snake-necked turtles 188, 204–5 Australian snapping turtles 206–7

B barbels 28 basking 18, 24–5 Batagur 27, 106, 108–9 Beale’s Eyed Turtle 130–1 Berlandier’s Tortoise 153 big-headed side-necked turtles 222–9 Big-headed Sideneck Turtle 226–7 Big-headed Turtle 49, 104–5 biodiversity 9, 23 biomass 40 Black Marsh Turtle 132 Black Softshell Turtles 42 Black-breasted Leaf Turtle 114–15 Blanding’s Turtle 38, 78, 98–9 body size 37–8 body temperature 18–20, 24 Bog Turtle 38, 100–1 box turtles 38, 78, 102–3, 110–11

236

Index

Brazilian Snake-necked Turtle 202–3 breathing 6, 10 Brown Roofed Turtle 129 brumating 20 Burmese Eyed Turtle 125 Burmese Flapshell Turtle 172–3 Burmese Star Tortoise 150–1

C carapace 10, 14, 16, 37, 40 Caretta 26, 56, 58–9 Carettochelyidae 11, 16, 49, 166–7 Carettochelys 17 Central American River Turtle 49, 68–9 Central American Snapping Turtle 52–3 Central Asian tortoises 136 Centrochelys 142–3 Chaco Tortoise 144 Chelidae 187, 188–215 Chelodina 22, 204–5 Chelonia 56, 64 Cheloniidae 49, 56–65 Chelonoidis 22, 40, 45, 136, 144–7 Chelus 30, 192–3 Chelydra 29, 50, 52–3 Chelydridae 27, 49, 50–5 Chersina 148 Chersobius 23, 38, 149 Chicken Turtle 35, 82–3 Chinese Softshell Turtle 182 Chitra 176–7 Chrysemys 16, 27, 33, 80–1 Claudius 29, 70, 76 Clemmys 92–3 cloaca 6, 20, 28, 33 clutch size 34 Cochin Forest Cane Turtle 133 color culture influence 43 dimorphism 27 Common Musk Turtle 75 Common Padloper 154 Common Slider Turtle 91 conservation 44–6, 47 cooters 88–9 copulation 33–4 courtship 33 Crowned River Turtle 116–17 Cryptochelys 70 Cryptodira 10, 11, 14, 17, 48–185 cultural importance 42–3 Cuora 14, 106, 110–11 Cyclanorbis 170 Cyclemys 112 Cycloderma 171

D Deirochelys 35, 82–3 Dermatemydidae 16, 49, 68–9 Dermatemys 68–9 Dermochelyidae 16, 49, 66–7 Dermochelys 18, 26, 29, 37–8, 66–7 Desert Tortoises 21 Diamond-backed Terrapin 21, 29, 78, 86–7 diapsids 17 Dogania 178

E ears 28 Eastern Box Turtle 38, 102 ecdysis 16 ecological roles 40–1 ectothermy 18–20, 24 eggs 32 clutch size 34 energy transfer 40 incubation 34, 35 sea turtles 34, 40 Egyptian Tortoise 164–5 Elongated Tortoise 155 Elseya 206–7 Elusor 208–9 Emydidae 49, 78–103, 106 Emydoidea 38, 78, 98–9 Emydura 210–11 Emys 22, 78, 94–5 energy transfer 40 environmental sex determination (ESD) 35 Eretmochelys 56, 60–1 Erymnochelys 222, 224–5 Euphrates Softshell Turtle 183 European Pond Turtle 78, 94–5 extinctions 7, 10–12, 45–7, 146 eyed turtles 125, 130–1

F feeding 29–31 Fitzroy River Turtle 213 five-toed padloper tortoises 149 Flatback Sea Turtle 56, 65 Flat-tailed Tortoise 161 Floreana tortoises 146 Florida Softshell Turtle 175 Fly River Turtle see Pig-nosed Turtle Forsten’s Tortoise 155 fossil record 10, 11–12, 46 Four-eyed Turtle 130–1 four-toed padloper tortoises 154

G Galapagos tortoises 38, 40, 44–5, 136, 144–7 Geochelone 150–1 Geoclemys 113 Geoemyda 106, 114–15, 120 Geoemydidae 49, 106–35 Geoffroy’s Side-necked Turtle 196–7 Geometric Tortoise 160 Giant Asian Pond Turtle 119 Giant musk turtles 77 gigantothermy 18 global distribution 22–3 Glyptemys 29–30, 38, 93, 100–1 Gopherus 18, 21, 23, 32, 41, 152–3 Graptemys 29, 78, 84–5, 106 Green Sea Turtle 56, 64 growth 36–8

limb girdles 17 Lissemys 168, 172–3 Loggerhead Sea Turtle 26, 56, 58–9 “Lonesome George” 45, 136, 146 longevity 6, 36–9

M

Hardella 116–17 Hawksbill Sea Turtle 29, 56, 60–1 hearing 28 Heosemys 118–19 Hermann’s Tortoise 164–5 hibernation 6, 20 hinge-back tortoises 156–7 Homopus 154 Horsfield’s Tortoise 164–5 Hunan Softshell Turtle 182 Hydromedusa 202–3

Macrochelys 29, 30, 50, 54–5 Madagascan Big-headed Turtle 224–5 Madagascar side-necked turtles 187 Malaclemys 21, 29, 78, 86–7 Malacochersus 14, 136, 158 Malayan Flat-shelled Turtle 126 Malayan Softshell Turtle 178 Malayemys 121 Malaysian Giant Turtle 127 Manouria 32, 159 map turtles 29, 78, 84–5 Marginated Tortoise 164–5 Mary River Turtle 208–9 Matamata 192–3 Mauremys 122–3 Mediterranean Pond Turtle 122–3 Melanochelys 124 Mesoclemmys 194–5 migrations 26 Morafka’s Desert Tortoise 23 Morenia 125 mud turtles 34, 49, 70, 72–3 musk turtles 29, 49, 70, 74–7 Myuchelys 212

I

N

Impressed Tortoise 159 Indian Black Turtle 124 Indian Eyed Turtle 125 Indian Flapshell Turtle 168, 172–3 Indian Roofed Turtle 129 Indian Softshell Turtle 179 Indian Star Tortoise 150–1 Indian Tent Turtle 129 Indian tortoises 155 Indotestudo 155

Narrow-bridged Musk Turtle 76 narrow-headed softshell turtles 176–7 Natator 56, 65 necks 10, 16, 17 neotropical wood turtles 134–5 nests 32 New Guinea Giant Softshell Turtle 181 New Guinea short-necked turtles 210–11 New Guinea Stream Turtle 206–7 Nilssonia 42, 179 North American Snapping Turtle 52–3 North American softshell turtles 175 North American tortoises 152–3 Northern Chinese Softshell Turtle 182 Northern Giant Musk Turtle 77 Northern Map Turtle 84 Notochelys 126 Nubian Flapshell Turtle 170

H

K Kemp’s Ridley Sea Turtle 62 keystone species 41 Kinixys 14, 136, 156–7 Kinosternidae 16, 28, 34, 49, 70–7 Kinosternon 14, 23, 70, 72–3

L leaf turtles 112 Leatherback Sea Turtle 12, 16, 18, 26, 29, 34, 37, 49, 66–7 Leopard Tortoise 23, 40, 162–3 Lepidochelys 14, 56, 62–3 Leucocephalon 120

O Odontochelys 10 Old World pond turtles 122–3 Olive Ridley Sea Turtle 62–3 Orlitia 106, 127 osmoregulation 20–1 “overwintering” 35

P Pacific Coast Giant Musk Turtle 77 Pacific pond turtles 96–7 padloper tortoises 23, 38, 149, 154 Painted Turtle 33, 80–1 Painted Wood Turtle 134–5 Palawan Forest Turtle 132 Palea 180 Pancake Tortoise 14, 136, 158 Pangshura 106, 128–9 Pantanal Swamp Turtle 190 Pappochelys 10, 17 Peacock Softshell Turtle 179 Pelochelys 168, 181 Pelodiscus 182 Pelomedusa 14, 22, 216, 218–19 Pelomedusidae 28, 187, 216–21 Peltocephalus 222, 226–7 Pelusios 14, 22, 216, 220–1 pheromones 28 Phrynops 196–7 phylogenetic trees 12–13 Pig-nosed Turtle 11, 49, 166–7 Pinta Island tortoises 45, 136, 146 plastron 10, 14, 16, 29, 34, 37 Platemys 198–9 Platysternidae 49, 104–5 Platysternon 34 Pleurodira 10, 11, 14, 16, 17, 186–229 Ploughshare Tortoise 140–1 Podocnemididae 28, 187, 222–9 Podocnemis 14, 222, 228–9 pond turtles 49, 78, 94–7 Proganochelys 10 Psammobates 160 Pseudemydura 188, 214–15 Pseudemys 88–9 Pyxis 34, 136, 161

R Radiated Tortoise 140–1 Rafetus 45, 183 Red Side-necked Turtle 200–1 Red-eared Slider Turtle 30, 43, 78, 90 Red-footed Tortoise 144 religion 42

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reproduction 32–5 color dimorphism 27 in old age 38 sex determination 6, 35 see also eggs Rheodytes 213 Rhinemys 200–1 Rhinoclemmys 41, 106, 134–5 Ridley sea turtles 56, 62–3 roofed turtles 128–9 Ryukyu Black-breasted Leaf Turtle 114

S Sacalia 130–1 Saint-Hilaire’s Side-necked Turtle 196 salt glands 21 sawback turtles 84–5 sawshelled turtles 212 scutes 16 sea turtles 14, 17, 35, 49, 56–65 conservation 44 eggs 34, 40 feeding 29 migrations 26 salt glands 21 see also Leatherback Sea Turtle seed dispersal 40–1 Senegal Flapshell Turtle 170 sex determination 6, 35 Seychelles Mud Turtle 216 Sicilian Pond Turtle 94–5 Siebenrockiella 34, 132 skulls 17 slider turtles 27, 28, 30, 33, 43, 78, 90–1 smell 28 Smooth Softshell Turtle 175 snail-eating turtles 121 snapping turtles 27, 29, 49, 50–5, 206–7 softshell turtles 11, 14, 29, 35, 42, 45, 49, 168–85

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South African Bowsprit Tortoise 148 South American river turtles 222–9 South American side-necked swamp turtles 190–1 South American side-necked turtles 187, 188–215 South American Snake-necked Turtle 202–3 South American Snapping Turtle 52–3 Southeast Asian tortoises 155 Southern Painted Turtle 80–1 Speckled Padloper Tortoise 38 Spider Tortoise 136, 161 Spiny Softshell Turtle 175 Spiny Turtle 118–19 Spotted Pond Turtle 113 Spotted Turtle 92–3 Spur-Thighed Tortoise 164–5 Sri Lankan Flapshell Turtle 172–3 star tortoises 150–1 Staurotypus 70, 77 stem-turtles 10, 17 Sternotherus 29, 74–5 Stigmochelys 23, 40, 162–3 Stupendemys 11–12 Sulawesi Forest Turtle 120 Suwanee Alligator Snapper 54–5 swimming 17

T taste 28 temperature-dependent sex determination (TSD) 6, 35 tent tortoises 160 tent turtles 128–9 Terrapene 14, 38, 78, 102–3, 106, 111 terrapins 8, 21, 29, 78, 86–7, 108–9 Testudines 11, 12 Testudinidae 49, 136–65 Testudo 136, 164–5

Index & Picture Credits

titillation 33 toad-headed turtles 194–5 tortoises 8, 14, 17, 18, 21, 23, 39, 40, 49, 136–65 Galapagos 39, 40, 44–5, 136, 144–7 Pinta Island 45, 136, 146 Trachemys 16, 27, 28, 30, 33, 43, 78, 90–1 Travancore Tortoise 155 Tricarinate Hill Turtle 124 Trionychidae 11, 16, 49, 168–85 Trionyx 29, 168, 184–5 Twist-necked Turtle 198–9

V Vietnamese Softshell Turtle 182 Vijayachelys 106, 133 vision 27 vomeronasal organs 28

W Wattle-necked Softshell Turtle 180 Western Alligator Snapper 54–5 Western Painted Turtles 27 Western Swamp Turtle 214–15 Williams’ Side-necked Turtle 196 Wolf Volcano 146 Wood Turtle 29–30, 100–1

Y Yangtze River Giant Softshell turtle 45, 183 Yellow-footed Tortoise 144 Yellow-headed Temple Turtle 118–19

Z Zambezi Flapshell Turtle 171

PICTURE CREDITS The authors and publishers would like to thank the following for permission to reproduce copyright material: l=left; r=right; t=top; b=bottom, c=centre, i=inset. 2–3 Alamy Images/Vivid Photo Visual; 5 Getty Images/Don Farrall; 6–7 Alamy Images/Matthijs Kuijpers; 8 Shutterstock/Evgeniy_D; 9 Getty Images/Istvan Kadar Photography; 10 Paleozoological Museum of China/Jonathan Chen https://creativecommons.org/licenses/by-sa/4.0/deed.en; 11 Alamy Images/ Kevin Schafer; 14 Getty Images/ChristinaPrinn; 15tr&l John Woodcock; 15mr&l Ernst, Carl H., and Jeffrey E. Lovich. Turtles of the United States and Canada. pp. 604, Figures 10.1, 10.2. © 2009 Johns Hopkins University Press. Reprinted with permission of Johns Hopkins University Press; 15br&l John Woodcock; 16 Getty Images/reptiles4all; 17 Shutterstock/Aaronejbull87; 18–19 Nature Pl/ Pascal Kobeh; 19t Shutterstock/Jwass; 20 Shutterstock/Matt Jeppson; 21 Shutterstock/Brittany Mason; 22 Getty Images/M Swiet Productions; 23 Getty Images/Federico Burgos Bauer; 24–25 Alamy Images/Michael Hora; 25t Alamy Images/Molly Marshall; 25b Alamy Images/blickwinkel;26 Getty Images/ Norbert Probst; 27t Getty Images/Jeff Mauritzen; 27b Alamy Images/ BIOSPHOTO; 28 Alamy Images/Anton Sorokin; 29 Image courtesy of Anne Meylan; 30t Nature Pl/Daniel Heuclin; 30b Andre Seale/imagequestmarine.com; 31t Getty Images/David A. Northcott; 31b Science Photo Library/Ken M. Highfill; 32 Shutterstock/David Evison; 33t Getty Images/Alexis Rosenfeld/ Contributor; 33b Jim Harding; 34l Shutterstock/David Evison; 34r Jim Harding; 35 Shutterstock/Jennah Vaughn; 36 Getty Images/Eric VANDEVILLE/ Gamma-Rapho; 37 Robert T. Zappalorti; 38 Shutterstock/Evgeniy_D; 39t Victor Loehr; 39b Scott Pfaff Riverbanks Zoo; 40 Alamy Images/Chris Mattison; 41t Shutterstock/Robert Lessmann; 41b Alamy Images/Leonardo Prest Merçon Rocha; 42 Shutterstock/bcube; 43l Getty Images/Carlos Muina/Contributor; 43r Shutterstock/ZikG; 44–45 Shutterstock/pockygallery; 46–47 Shutterstock/ fivespots; 48 Alamy Images/Brian Overcast; 51 Alamy Images/Peter Steiner; 52 Ardea/John Cancalosi; 52–53 Robert T. Zappalorti; 54 Alamy Images/Matthijs Kuijpers; 55 Alamy Images/Danita Delimont; 57 Getty Images/M Swiet Production; 58 Ardea/Valerie & Ron Taylor; 59 Masa Ushioda/ imagequestmarine.com; 60 Mark Conlin/V&W/imagequestmarine.com; 61 Getty Images/Wild Horizon/Contributor; 62 Michael Patrick O’Neill/Blue Planet Archive/imagequestmarine.com; 63 Alamy Images/Brian Overcast; 64 Carlos Villoch/imagequestmarine.com; 65 Doug Perrine/Blue Planet Archive/ imagequestmarine.com; 67 Getty Images/Rawlinson Photography/E+; 69 R. Wayne Van Devender; 71 Bill Draker/imageBROKER/imagequestmarine.com; 72 FLPA/Michel Gunther/Biosphoto; 73 Parker W. Gibbons; 74t Jim Harding; 74b Ardea/Science Source/Suzanne L. Collins; 75 Ardea/Biosphoto/Bruno Cavignaux; 76 Alamy Images/F1online digitale Bildagentur GmbH; 77 Alamy Images/BIOSPHOTO; 79 Ardea/Danita Delamont/David Northcott; 80 Getty Images/Don Farrall; 81 Ardea/Science Source/Phil Degginger; 82 Alamy Images/National Geographic Image Collection; 83 Alamy Images/George Grall; 84 Getty Images/Ed Reschke; 85t Ardea/Danita Delamont/David Northcott; 85b Alamy Images/Juniors Bildarchiv GmbH; 86 Alamy Images/Matthijs Kuijpers; 87t Getty Images/Paul Starosta; 87b Alamy Images/Brian Kushner; 88 Alamy Images/Nature Picture Library; 89 Alamy Images/John Cancalosi; 90 Alamy Images/WaterFrame; 91t Alamy Images/Bill Gorum; 91b Alamy Images/ Imagebroker; 92 Jim Harding; 93 Dave Collins; 94 Alamy Images/jack perks; 95 Getty Images/Life On White; 96 Jeff Lovich; 97 Ardea/Science Source/Dan Suzio; 98 & 99 Jim Harding; 100 Shutterstock/fivespots; 101t Alamy Images/ Jason Ondreicka; 101b Robert T. Zappalorti; 102 Alamy Images/Phil Degginger; 103 Ardea/Jim Zipp; 105 Alamy Images/Joe Blossom; 107 Alamy Images/ Dominic Robinson; 108 Indraneil Das; 109l Kaylar Platt; 109r Paul Freed; 110 Alamy Images/Juniors Bildarchiv GmbH; 111 FLPA/Emanuele Biggi; 112 Alamy Images/dwi putra; 113 Alamy Images/Life on white; 114 Alamy Images/ Photononstop; 115t & 115b Alamy Images/Juniors Bildarchiv GmbHv; 116 Alamy Images/VPC Animals Photo; 117 Alamy Images/CTK; 118 FLPA/David Massemin/Biosphoto; 119 Alamy Images/Matthijs Kuijpers; 120 Shutterstock/ fivespots; 121 Alamy Images/dwi putra; 122 Ardea/Biosphoto/Matthijs Kuijpers; 123 Getty Images/Valter Jacinto; 124 Alamy Images/Ariadne Van Zandbergen; 125 Indraneil Das; 126 Alamy Images/Eng Wah Teo; 127 Alamy Images/VPC

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ACKNOWLEDGMENTS We thank the following individuals for providing information and suggestions regarding turtles: Grover Brown, Kurt Buhlmann, Vince Burke, Kristy Cummings, Indraneil Das, Josh Ennen, Nancy Fitzsimmons, Oscar Flores-Villela, Arthur Georges, Parker Gibbons, Kim Gray, Cris Hagen, Jim Harding, John Iverson, Rod Kennett, Dwight Lawson, Peter Lindeman, Pearson McGovern, Scott Pfaff, Steve Platt, Pam Plotkin, Shellie Puffer, Frank Slavens, Jim Spotila, Scott Thompson, Tracey Tuberville, Tony Tucker, Margaret Wead, and George Zug. We thank the staff at Ivy Press and Bright Press for their assistance during the global COVID-19 pandemic. We thank Natalia Price-Cabrera, Tom Kitch, Jacqui Sayers, Richard Green, and Caroline Earle at Ivy Press for launching the project and Joanna Bentley of Bright Press for ultimately coordinating all aspects. We appreciate Frances Cooper for providing editorial comments and Jane Smith for acquiring photographs. We especially thank Caroline Earle for editorial suggestions during the final stages of the book. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

ILLUSTRATION REFERENCES Illustrations on page 15 of shell bones of typical turtle, shell bones of softshell turtles, and scutes covering a typical hard-shelled turtle redrawn from Ernst, Carl H., and Jeffrey E. Lovich. Turtles of the United States and Canada. © 2009 Johns Hopkins University Press. Redrawn with permission of Johns Hopkins University Press.

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Acknowledgments