Marine Mammals and Reptiles 9780648323297

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Contents Credits

5

Chapter 1 Introduction

6

Mammals

6

Types of Marine Mammals

8

Ungulates and Carnivores

8

Reptiles

9

Types of Marine Reptiles

9

Characteristics of Marine Reptiles

9

Chapter 2 Aquatic Ungulates

11

Order Cetacea

11

Habitat and distribution

11

Physical characteristics and physiology

12

Digestion

13

Reproduction

13

Behaviour

13

Echolocation

14

Significance to man

14

The Order Cetacea

15

Suborder Mysticeti (Baleen Whales)

15

Suborder Odontoceti (Toothed Cetaceans)

15

More Information about the Suborder Mysticeti (Baleen Whales)

16

More Information about the Suborder Odontoceti (Toothed Cetaceans)

22

Dolphins

23

Whales

34

The Order Sirenia

35

Chapter 3 Marine Carnivores

38

Pinnipeds

38

Walrus

38

True Seals and Fur Seals

38

Marine and Sea Otters

41

Polar Bear

42

Chapter 4 Marine Reptiles

43

Sea Turtles

43

Taxonomy (Classification)

44

Extinct Marine Turtles

51

Crocodiles

52

Differences Between Gharials, Alligators, and Crocodiles

53

Extinct Marine Crocodiles and Crocodile-Like Groups

56

Marine Lizards

57

Modern Marine Iguanas

57

Extinct Marine Lizards

59

Marine Snakes

60

File Snakes

61

Extinct Marine Snakes

68

Further reading and study

69

More ebooks available

69

Courses available

69

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The information in this book is derived from a broad cross-section of resources (research, reference materials and personal experience) from the authors and editorial assistants in the academic department of ACS Distance Education. It is, to the best of our knowledge, composed as an accurate representation of what is accepted and appropriate information about the subject, at the time of publication. The authors fully recognise that knowledge is continually changing, and awareness in all areas of study is constantly evolving. As such, we encourage the reader to recognise that nothing they read should ever be considered to be set in stone. They should always strive to broaden their perspective and deepen their understanding of a subject, and before acting upon any information or advice, should always seek to confirm the currency of that information, and the appropriateness to the situation in which they find themselves. As such, the publisher and author do not accept any liability for actions taken by the reader based upon their reading of this book. Published by: ACS Distance Education P.O. Box 2092, Nerang MDC, Queensland, Australia, 4211 [email protected] www.acsbookshop.com UK & European Representative: ACS Distance Education UK P O Box 4171, Stourbridge, DY8 2WZ, United Kingdom [email protected] www.acsebooks.com

ISBN: 978-0-6483232-9-7

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Credits Photos: John Mason Layout: Stephen Mason Editorial Contributors: Kara Wight B.Sc., HND (Animal) Dr Maria L. Schmitz Fontes PhD, MSc, BA Peta Jinnath Abdul B.Sc.Grad.Dip.Ed. Jacinda Cole BSc, M.Psych

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CHapter 1 INTRODUCTION We are more familiar with land animals, quite naturally, because that is where humans live. Marine environments may not be as familiar to most people, but they do contain as great a diversity of animals as are found on land. Marine animals can vary from tiny single celled organisms through to the largest animals on earth. Fish and crustaceans are obvious to us. There are more complex animals than fish and crustaceans though which also inhabit marine environments; including birds (e.g. seagulls and penguins), mammals and reptiles. While the birds are never exclusively confined to the water; there are reptiles and mammals which spend almost all, or even all of their time in the water.

MAMMALS Marine mammals are mammals that have adapted to the marine environment. This means that they share the same characteristics as all other mammals: ●● birthing live young

The most familiar marine mammals include seals, sea lions, dolphins, and whales. Each of these mammals, however, is specially adapted to live in an aquatic environment. For example, both dolphins and whales are born with a smattering of hair; many lose these quickly during the first few days of life. Some, like adult humpback whales, have hair follicles along the skin.

●● suckling young from mammary

glands or adapted mammary patches

●● endothermic ●● four-chambered hearts ●● air-breathing ●● hair and/or fur at some stage in the

lifecycle

Marine mammals are found throughout the world. Research suggests that around 40% of marine mammals live around 40 degrees north and south of the equator. page 6

Australian fur seal

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Indo Pacific humpback Dolphin

Many marine mammals have lost the ability to move about efficiently on land. Pinnipeds, such as seals, live parts of their lives on land, but hunting and food gathering behaviours are generally performed in a marine environment. All marine mammals, even those which live entirely in the sea, must breathe air. This means that animals such as dolphins and whales must surface regularly. Generally, they do not need to bring the entire body – or even the entire head – above water. Other marine mammals, like whales, dolphins, and porpoises, have lost their fur-covering and developed streamlined bodies. This reduces drag when swimming, allowing them to slice quickly through the water. Lungs are also specialised, and lungs and muscles can store oxygen, allowing them to stay underwater. Many marine mammals also have layers of thick blubber or fat to help maintain body heat in cold environments. Colder environments can also affect blood flow, which means many marine mammals have enlarged veins to help transfer blood to vital organs. Limbs are also adapted, with flippers, flukes, and fins assisting in movement through a more viscous environment. page 7

Other species such as polar bears have thick layers of fat and fur to help them maintain their body heat in cold climates, a large body to help keep them warm and disperse their body heat, thick curved claws for gripping the ice and predators, sharp teeth and strong jaws for tearing apart prey and powerful muscles for fighting and attacking. Although polar bears do not live their whole lives in the water, they are considered marine mammals due to their dependence on the water for food and living environment. Polar bears are the only bears considered marine, and to live in such extreme environs.

A whale skeleton showing its ungulate characteristics

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Some scientists group sea otters and polar bears together into a group called fissipeds (split toes).

Ungulates and Carnivores Marine mammals can also be divided into two main groups: the ungulates and carnivores. Ungulates are “hoofed” mammals, while carnivores are meat eaters. Marine Ungulates Most ungulates are land animals, such as goats and camels. Recent research, however, suggests that some marine mammals are descended from a common ungulate ancestor. These include the cetaceans and sirenians. Cetaceans Toothed whale skeleton (Odontoceti)

Types of Marine Mammals There are several distinct marine mammal groups. It is important to note, however, that classification is an ongoing process – as scientists learn more about the genetic makeup of different animals’ species are reclassified, with some higher-ranking groups added or moved. Overall, marine mammals are divided into five distinct groups: ●● pinnipeds ●● cetaceans ●● sea otters ●● sirenians ●● polar bears

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●● whales ●● dolphins ●● porpoises

Sirenians ●● manatees ●● dugongs

It is important to note, however, that many researchers still do not class cetaceans as ungulates, especially since they lack many other ungulate characteristics. Moreover, cetaceans are carnivores, while the majority of ungulates are either herbivorous or omnivorous. In most cases, “marine ungulate” refers to the sirenians, all of which are herbivorous.

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Sea Snake

REPTILES There are some major characteristics of marine reptiles – characteristics they share with land reptiles. The major difference is that marine reptiles have adapted to aquatic or semi-aquatic environments.

Types of Marine Reptiles Although there are many marine reptiles in the fossil record, there are only a handful of groups that are true living (extant) marine reptiles. Although some people call crocodiles marine reptiles, it is important to note that “marine” refers to the sea, and with the exception of the saltwater crocodile, crocodiles are adapted for freshwater. In the context of this book, marine can also include brackish and estuarine environments, though this is also specifically noted throughout. ●● sea snakes ●● sea turtles ●● marine lizard (marine iguana) ●● crocodilians page 9

Characteristics of Marine Reptiles ●● ectothermic ●● some keratinous scaling ●● lung-based respiration

(as opposed to gills)

Marine reptiles are an important – and fascinating – group. There is great diversity among marine reptiles, and many kinds are found all over the globe. While many people think of all reptiles as egg-laying (oviparous), many reptiles are in fact viviparous, giving birth to live young. This is seen in almost all true sea snakes (elapids) and is quite possibly an adaptation to the marine environment. Most likely due to the complexity of in vivo gestation, sea snake litters are relatively small – ranging up to around 40 young. By contrast, oviparous snakes, which lay eggs, may lay up to 100 eggs at a time, usually in a single clutch. Marine reptiles, such as the crocodilians and sea turtles, are some of the oldest animals on earth. This group has welladapted hunting behaviours, and in

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the case of crocodilians and turtles, protective coverings and strong swimming adaptations that help in both attack and

Green turtle

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defence. This has made them successful enough to outlive many other species.

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CHAPTER 2 AQUATIC UNGULATES Typical ungulates are animals with hoofs including horses and cattle. Cetaceans may not appear as obvious candidates to be “artiodactyls” (or ungulates) but molecular analysis has shown them to be more closely related to ruminant artiodactyls than what ruminants are to pigs. Over 80 species of whales, porpoises and dolphins populate the world’s oceans. There are also four species of dolphin which inhabit freshwater rivers and estuaries in regions of Asia and Central and South America. The Order Cetacea is divided into two main groups (or suborders) – Baleen whales (Mysticetes) and toothed whales (Odontocetes). Dolphins, Orcas and Porpoises fall into the Odontocetes group. In general, the Baleen whales are much larger than the toothed whales. They also differ in that they use Baleen plates to filter food from water. Odontocetes form a much larger group of species than the Mysticetes.

Order Cetacea Cetaceans include Dolphins, Porpoises and Whales. Characteristics of the Order are: ●● Aquatic, hairless mammals ●● Front limbs modified into flippers,

absent hind limbs, apart from internal remnants

●● Skull adapted so that the nostrils

open on top of the head through a blow hole

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●● Eyes and ears are relatively small ●● No vocal apparatus but can

produce distinctive sounds for communication with other whales or echolocation.

●● Mammary glands either side of

the vaginal opening feeding into a single teat.

Habitat and Distribution All species are fully aquatic, whilst most are pelagic and roam through the open oceans, although some species prefer to roam nearer coastlines. Cetacean species can be found in the oceans worldwide, and some within freshwater rivers of North and South America and Asia. Orcinus orca can be found roaming through all oceans across the globe, while other species are restricted to one hemisphere. Some Cetaceans form movement patterns which can vary from vast migrations to short distance travels. Generally, the short journeys occur when they are foraging for food or when it is mating season. Many species will travel annual migrations travelling thousands of kilometres, and with Whales most will travel to warm temperate or tropical waters in winter. It is usually here that they will breed and give birth. In summer, whales will either migrate to the Artic or Antarctica waters where it is calmer seas in this season.

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Some Cetacean species do not show clear migratory paths but are seasonal migrators. This is the case with the Atlantic Bottlenose Dolphin which seems to migrate when food sources decrease. Cetacean species can travel at fast speeds with great bursts, and the Blue Whale has been recorded travelling at 50km/h. Cetaceans can also stay under water for long periods of time, varying between species, which assists in these long migratory travels.

Physical Characteristics and Physiology Cetaceans, in general, are aquatic species which are large, streamlined, and hairless. Their front limbs are modified to have either flippers or fins and exhibit no external hind legs, although there are internal remnants. They lack an external ear and only have a vestigial ear pinnae. They have adapted to have nostrils on the top of the head known as a blowhole, and this assists in their locomotion underwater. They have very small eyes which are positioned far back on the side of their heads, allowing for excellent binocular vision. Their tails are long which expands in to two horizontal lobes or flukes which is flattened laterally and moves up and down allowing for fast thrusts of movement. The size of a cetacean varies between species and this order comprises of the largest mammal on the planet, the blue whale (Balaenoptera musculus), which is thought to be the biggest mammal ever to have existed. Weighing up to 140 tonnes and can reach up to a length of 34 meters, with flippers reaching to about three to four meters in length. page 12

Most species are sexually dimorphic with variation; male blue whales are smaller than the females, and it is the opposite for bottlenose dolphins, with the males being larger in size than the females. Cetacean species have very large brains are thought to be highly intelligent. The skin is thick, and contains a subcutaneous layer filled with fat and oil which assists in regulating their body temperatures. Cetacean species do lack sweat glands, although they have very efficient and complex circulatory and respiratory systems. Smaller species contain a modified heat exchange system within their flippers and flukes which allows warmth from the arterial blood to heat up venous blood which is returning to the heart. This is very complex and assists in their habitat diversity. Cetaceans have large, elongated bodies which assists in their torpedo speeds and also enables them to breach out of the water. This is a common sight with dolphins (which have slicker bodies) but can also be seen with baleen whales. Their reproductive organs are held internally which assists in their locomotion underwater to be more streamlined and efficient. This is probably another reason for the modified ears and nose structures. Some cetacean species have completely lost teeth within their jaws. This group, the Mysticetes, have modified structures which acts by filtering tiny plankton from the water for feeding. Other species have still retained their teeth on both the upper and lower jaw and these are known as odontocetes species. Cetaceans are able to produce distinct sounds for communication, mating and

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echolocation and are specific to the individual and can be heard for over a kilometre. Dolphins are a good example of the use of echolocation and, like bats, use it to identify prey and other objects. They produce sound as clicks which bounces off objects or potential prey, and ricochets back providing them with information about the location, distance and size.

Digestion Digestion and feeding habits vary between species, and this is one of the reasons for the split into suborders. Mysticetes, or the baleen, species lack the presence of teeth instead have developed hair fringed plates, known as baleen plates, which are made up of keratin. These modified structures act like a sieve, filtering out tiny organisms and plankton for feeding. Odontocetes species (toothed species) will thrive on fish, crustaceans, squid, aquatic birds and mammals, even other smaller cetaceans. Cetacean species also have a chambered stomach to aid in their digestion. The first compartment is referred to as a forestomach, and this acts much like a crop in birds. The second compartment is known as the glandular stomach and it is here which the chemical breakdown takes place. The third compartment which is referred to as the pyloric stomach is a muscular organ which control flow into the intestinal tract.

Reproduction The reproductive strategies and courtship can be quite difficult to study due to their location but it is believed most species are polyandrous (one page 13

female with various males), polygynous (one male and variant females) and polygynandrous (strategy that a number of males mate with a number of females). Northern Atlantic Right Whales exhibit courtship behaviour at the surface which shows various number of male individuals circling one female, who may mate with several of these males. Most cetacean species have a mating season once a year, with the females giving birth to one offspring every one to six years depending on the species. Reproduction, gestations and nursing varies between species, but all females incubate the young inside their bodies and give birth to live young. Calves are born tail first and must swim the moment they are born. Cetacean mothers are attentive who provide milk to their young calf, protect from predators and will accompany the young to the water surface for their first breath of air. Males are believed to have very little to parental care; however, it has been observed that some male species will bring food to their young.

Behaviour All cetaceans are fully aquatic therefore have to be able to swim from the moment they are born. They do this by pumping their tail in an up and down motion, whilst using their flippers for stability. This allows them to reach high speeds, with baleen species reaching 26km/hour and toothed species reaching over 30km/hour. Toothed species (odontocetes) are able to gain extra speed form riding waves which can be exhibited when they follow the waves created by boats. Prior to diving,

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all cetacean species will inhale then they may remain underwater for a few seconds to over an hour. The social structure of cetacean species varies greatly, and some species live single, solitary life, while others form unstable groups, and others form large herds made up of hundreds of individuals. The bottlenose dolphin, for example, will form bonds to last a lifetime, and orcas will form dominance hierarchy pods. Many species form migratory patterns, whilst others remain within the same area for life. The humpback whale is known for its extensive migratory route to temperate feeding grounds, and tropical breeding grounds.

Echolocation Echolocation is common among some the odontocetes (toothed whales). Sound carries through water well, so the ability to send out sounds to improve hunting and navigation behaviours is a useful adaptation for a low-light environment. Odontocetes transmit sound from their foreheads (also called melons). The melon focusses the sound as it transmits. Special tissues located in the head (around the lower jawbone and ear) receive the echoes formed by the sound “bouncing back”. Scientists do not have enough information to definitively state where the transmitted sound comes from. Similarly, there is no consensus on how many odontocetes use echolocation.

Significance to Man Cetacean species play a vital role within our ecosystem and they assist page 14

in stabilizing the aquatic food chain. Without these species, our oceans would quickly become overrun with many smaller aquatic species, and microorganisms such as plankton. Many whales are hunted for meat and blubber; this is known as whaling. Commercial whaling and the trade of whale products has been banned by most countries; the anti-whaling laws were set in place in 1986 due to a decline in the population of whales. However, there are still a few countries use scientific research as a reason to hunt whales; it is suggested that much of this whaling is part of the meat trade. Whales which are affected by this trade is the Humpback Whale, Sei Whale, Right Whales, Common Minke Whale, Fin Whale, Antarctic Minke Whale and the Sperm Whale. Many cetacean’s species are kept in captivity for entertainment purposes at resorts and marine parks. Their high intelligence means they appear very trainable. Sadly, these animals are kept in small pools which do not allow them to exhibit their natural behaviours. Dolphins and orcas tend to be the species which are most affected, however, times are beginning to change for these creatures with many organisations pledging to not capture anymore from the wild. Dolphin hunting is also a concern for many environmentalists and researchers. Dolphins are hunted around the world, including countries in West Africa, the Caribbean, the South Pacific, and parts of Asia. The reasons for hunting are varied; some groups cite dolphin hunting as part of a traditional practice and culture, while others hunt for meat and to sustain the local diet.

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THE ORDER CETACEA Order Cetacea includes two suborders: Mysticeti and Odontoceti. Within these suborders includes a variety of families and subfamilies.

Suborder Mysticeti (Baleen Whales) This suborder includes four families: Family Balaenidae includes four species; three of them are Right Whales and one Bowhead Whale. Family Balaenopteridae includes eight species which are split up over two subfamilies; Megaptera which includes one species, the Humpback Whale, and Balaenopterinae including two species of Minke Whale, Fin, Blue, Sei and Brydes Whales.

Suborder Odontoceti (Toothed Cetaceans) This suborder includes ten families: Family Delphinidae includes up to forty species including Dolphins, Orcas and Pilot Whales. It is impossible to give an exact number of species due to a lack of consensus in the scientific community. Family Physeteridae includes one species, the Sperm Whale. Family/Subfamily Kogiidae includes two species, the Pygmy Sperm Whale and the Dwarf Sperm Whale. Some classifications believe this is family is a subfamily of Physeteridae.

Family Neobalaenidae includes only one species, the Pygmy Right Whale.

Family Ziphiidae includes around twenty specie. Four species belong to the family Ziphiidae, and the rest in the subfamily Hyperoodontidae. The families include Beaked and Bottlenose Whales.

Family Eschrichtiidae also includes only one species, the Gray Whale.

Family Platanistidae includes two species of Indian River Dolphin. Family Iniidae includes species of the Amazon River Dolphin. Family Lipotidae includes the critically endangered species of Chinese River Dolphin. Family Pontoporiidae includes the Franciscana Dolphins. Family Monodontidae includes two species, the Narwhal and Beluga.

Beluga Whale (Delphinapterus leucas)

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Family Phocoenidae includes the six species of Porpoise.

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More information about the Suborder Mysticeti (Baleen Whales) Family Balaenidae The whales within this family are distributed through the northern and southern hemisphere, and the names of the three right whales are related to their geographic locality. Eubalaena australis (Southern Right Whale) can be found roaming the Southern hemisphere in the South Pacific and South Atlantic Oceans. Eubalaena glacialis (North Atlantic Right Whale) can be found roaming the North Atlantic Oceans, and Eubalaena japonica (North Pacific Right Whale) can be found roaming the North Pacific Oceans. These three right whale species all thrive in habitats near land masses, which make them great for whale spotters. Balaena mysticetus (bowhead whale) used to inhabit oceans throughout the northern hemisphere, however population depletion occurred due to commercial whaling. They are now found roaming the oceans and seas around the Arctic Ocean. Balaena mysticetus can be split in to five geological groups: the Spitsbergen group (North Atlantic Ocean); the David Strait and Hudson Bay group (North-West Atlantic); the Bering Sea group (Bering Sea); and the Okhotsk group (Okhotsk Sea). Family Balaenidae consists of large whale species. These whales have large heads which are around a third in size of their bodies. Balaena mysticetus (bowhead whale) is the third largest mammal in the world reaching to 600 feet/~ 183 m in length and weighing over 100 tons, with the blue whale being larger in size. Right whales are generally smaller reaching around 18 page 16

m in length. Females are slightly larger than males within this family. No dorsal fin is present in this family and they have rounded short flippers. This family contains no throat grooves which are present in some other mysticete species; instead the area is made up of smooth skin. The rostrum is high, narrow and arched with a curved fontal. They have approximately 300 or more long, narrow baleen plates on each side of their upper jaw, and Balaena mysticetus is thought to have the largest baleen plates within mysticetes suborder. The three species of right whales are all dark in colour and have white callus markings around the head area. These calluses are unique to each individual whale, and the largest callus sits upon the anterior position of the head and is referred to as the bonnet. Right whales also have a distinguished v-shaped blowhole and have a well-developed dermis layer. Balaena mysticetus is defined by its bow shaped lower jaw which sits around the upper jaw. The lower jaw is covered in white spots. This species does not hold the dermis layer but has a 2 feet/ 61 cm thick blubber layer. Species within this family thrive on zooplankton, such as copepods, and epibenthic organisms, and some benthic organisms. They will swim slowly with their mouths wide open, allowing organisms to enter and filter through the baleen plates. Any food trapped within the plates is removed with their tongue. They will feed near or on the water’s surface. Balaena mysticetus have been observed swimming in a V-shape group when feeding. Although not greatly studied, this family has been observed displaying

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polygamous behaviour, with individual females mating with up to seven males. Courting is generally calm, and no aggression has been observed, and this is probably due to the mating system and sperm rivalry once excreted into the females reproductive tract. All species within this family typically give birth to one offspring which is fed milk from their mother. Right whale species usually have a gestation period of around a year, with weaning occurring from four to six months. Sexual maturity is reached around five to ten years of age. Balaena mysticetus (Bowhead Whale) typically have a gestation period of twelve to sixteen months, with weaning occurring around nine to fifteen months. It can take twenty years for this species to reach sexual maturity. Behavioural patterns are not well studied with this family, although all species form migratory paths. Balaena mysticetus do exhibit migratory paths which are related to feeding and the polar ice cap depression and can be seen in small groups. The group tends to split into three smaller groups for migration. Eubalaena australis (Southern Right Whale) migrate to southern latitudes in summer months for feeding and migrate north of the southern hemisphere during winter months. This species has been observed head standing vertically rocking back and forth. This is thought to be a courting behaviour, although it has not been well studied. Both Eubalaena glacialis (North Atlantic Right Whale) and Eubalaena japonica (North Pacific Right Whale) migrate north to cooler waters in the summer, and south to warmer waters in the winter. The three species of right whales may form very page 17

small groups of two or three individuals, and Eubalaena glacialis is thought to be the most social within this family.

Baleen plates inside the mouth of a Humpback Whale – physical feature of a baleen whale

Family Balaenopteridae This family is split into two subfamilies: a. Megaptera and b. Balaenopterinae. Subfamily Megaptera This subfamily consists only of one species, Megaptera novaeangliae the Humpback Whale. This species has a geographical range reaching from polar to tropical regions. They mainly roam in the Pacific, Atlantic and the Arctic Oceans although also range through the Bering Sea down to the waters of Antarctica. Through migration they tend to be deep oceanic swimmers, only really come into coastal regions at Long Island and New York. Megaptera novaeangliae populations, like the bowhead whale, is divided into geographical regions. There are several populations of the humpback whale within the southern hemisphere,

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two known populations within the North Atlantic Ocean and two populations within the North Pacific Ocean. Megaptera novaeangliae is a large whale with a sturdy body which holds a distinct hump, hence the name, humpback whale. They can grow to 53 feet/16 m in length and weigh between thirty and fifty tons. Females are larger than males. This species has a thick blubber layer and the ventral pleats are present running from the neck to halfway down the body. These pleats or groves allow for expansion of this area during feeding, meaning the mouth can

hold more during feeding. Baleen plates are back in this species. The dorsal fin is black in colour and is small, with the pectoral fins measuring up to a third of the body length. These are mostly white in colour with knobbly areas along the edges. On the underside of the tail there is a distinct pattern of black and white which is believed to be used in identification of individuals. The tail has a wavy edge and is resemblance to the shape of wings. The olfactory senses are reduced, and the eyes are very small, with a very narrow auditory passage.

A Humpback Whale (Megaptera novaeangliae) seen during whale watching - an example of baleen whale, Order Mysticeti

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The humpback whale is an opportunistic feeder and will thrive on plankton and small fish which is dependent on the location of the whale. They swim slowly with their mouth open wide, allowing water and prey to enter. Once their mouth is full, they will close it allowing the food to filter through the baleen plates. The vertical grooves long the neckline allow for expansion during feeding. Breeding usually takes place in the winter months where Megaptera novaeangliae spends time in the tropical waters of their regions. Males will compete for the female and can become quite aggressive. Many males will surround the female, and will compete by tail flicking, flipping, rolling head lifting. Copulation has not been well studied but is thought to involve rolling, line swimming, body flipping and close proximity of ventral surfaces. Gestation usually takes a period of eleven to twelve months, with the calves born within the warmer waters of the tropics. Calves suckle milk from their mother. Weaning will usually start when the calf reaches around five months of age. Sexual maturity is reached around four to five years of age and breeding usually takes place every two years. Megaptera novaeangliae live in groups, which appear to be larger groups in the summer months when they are on their feeding grounds of the cooler waters. These group numbers seem to reduce as migration starts. This species are seasonal migrators who will migrate from the cool water of their feeding range in summer, through deep oceanic waters to their breeding range of the warm tropical regions. It is believed they reach up to 27 km/hour during migration. page 19

During spring, summer and autumn they will spend their time feeding, and during winter they do not feed but spend their time in the warmer waters for breeding and giving birth. Aggressive behaviour is exhibited during breeding season between males and can also be seen in defence. When a calf is born, certain members of the group become escorts for the calf; these escorts can become extremely aggressive towards other humpback whales and predators. Subfamily Balaenopteridae There are six species within this rorqual family; ●● Balaenoptera acutorostrata –

Common Minke Whale

●● Balaenoptera bonaerensis –

Antarctica Minke Whale

●● Balaenoptera borealis – Sei Whale ●● Balaenoptera edini – Bryde’s Whale ●● Balaenoptera musculus – Blue

Whale

●● Balaenoptera physalus – Fin Whale

Balaenoptera acutorostrata (the Common Minke Whale) is generally distributed throughout the northern hemisphere. Balaenoptera bonaerensis (the Antarctica Minke Whale) is distributed in the southern hemisphere. Balaenoptera acutorostrata can be observed swimming through estuaries and bays. Balaenoptera borealis (Sei Whale) prefer to thrive in temperate and subpolar regions during summer

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and spend their time in warmer waters during winter. This species is pelagic and will not usually swim too near the coastlines. Balaenoptera edini (Bryde’s Whale) is distributed across the Pacific, Atlantic and Indian oceans from tropical to subtropical regions. Some individuals are pelagic, thriving in open waters, while others are more sedentary. Balaenoptera musculus (the Blue Whale) and Balaenoptera physalus (the Fin Whale) roam in all open oceans across the globe, although the latter species can be found nearer coastal waters. These species range in size from the small Balaenoptera acutorostrata (Common Minke Whale), which is about 8 to 10 m in length, to the large Balaenoptera musculus (Blue Whale) which is approximately 28 m in length. Balaenoptera borealis (Sei Whale) can reach from 12 to 20 m in length. Balaenoptera edini (Bryde’s Whale) can reach to around 12 to 14 m in length, and Balaenoptera physalus (Fin Whale) is the second largest mammal on earth reaching approximately 20 m in length, the largest being Balaenoptera musculus. Balaenoptera acutorostrata and Balaenoptera bonaerensis both are dark across the dorsal section of the body with a white ventral section, and the dorsal fin is curved. Both species hold a pointy head with a small rostrum, although Balaenoptera bonaerensis has a larger skull. Balaenoptera acutorostrata species have a distinctive white band across the dorsal side of their pectoral fin, and this is not present in Balaenoptera bonaerensis species. Both Balaenoptera borealis and Balaenoptera edini have dark grey dorsal section on their body, and the ventral area is white. Balaenoptera page 20

musculus is slate grey to blue in colour and may have mottled spots across shoulder area. Balaenoptera physalus is brown to grey in colour across the dorsal section of the body and white ventral side. Balaenoptera edini also has a pointed rostrum, while Balaenoptera musculus has a blunt rostrum. Balaenoptera physalus holds more of a flatter head. Balaenoptera edini pectoral fins are short and narrow with a hooked dorsal fin whilst Balaenoptera musculus dorsal fin in short. Balaenoptera physalus has a distinctive long lean body, with a raised base of the tail. All species within this subfamily hold the vertical grooves across their chest which expand during feeding time. These are baleen species, so they filter feed through baleen plates held within their mouths. All species feed on plankton, copepods, krill, and small vertebrates according to locality. All species usually give birth to one offspring at a time, although twin calves have been reported. The females all nurture the young once born and provide milk for suckling. Most of the courtship and copulation is not well studied as it can be quite difficult to observe. Both Balaenoptera acutorostrata and Balaenoptera bonaerensis tend to breed and give birth in the warmer waters of their regions and will breed close to the water’s surface. They have a gestation period of around ten to eleven months, with weaning occurring around five months. Calves will spend much more time with their mothers and will reach sexual maturity around six years of age. Balaenoptera borealis species within the northern hemisphere will most likely breed from November to February, and

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species within the southern hemisphere will breed from May to July. They have a gestational period of around ten to twelve months and will reach sexual maturity at around ten years of age. Balaenoptera edini pelagic species will breed in the months of the fall, while sedentary species will breed throughout the year. The gestational period will last eleven to twelve months, weaning will take place around six months of age and sexual maturity is reached at ten to thirteen years. Balaenoptera musculus tend to breed and give birth in the warmer waters and have a short gestational period for the species size of eleven to twelve months. Weaning takes place around seven to eight months of age, and sexual maturity is reached at around five years. Balaenoptera physalus is believed to be a monogamous species and the male is the one to chase the female. Breeding and birth also occur in warmer waters during the late fall and winter. The gestational period is around eleven months, with weaning taken place around six to seven months and sexual maturity is reached around four to eight years of age. Balaenoptera acutorostrata and Balaenoptera bonaerensis are exceptioannly good divers and can be seen in small groups of two to four individuals, although many are seen living solitary. If food is of abundance, then you can see these species in larger feeding groups. Some populations migrate and this greatly depends on feeding and breeding. Balaenoptera borealis, although not greatly studied, is thought to mainly live in groups of two to five individuals. When migration occurs, or feeding, this species can be seen in groups of thousands. They page 21

are not as good at diving as the Minke Species; however, they are exceptionally fast swimmers reaching speeds of up to 50km/hour. Balaenoptera edini have been observed living more solitary lives with the exception of mother and calf. They do tend to feed in groups, with up to thirty individuals at a time sighted offshore. In winter, they tend to migrate towards the equator, and species who populate the northern hemisphere will migrate at different times to the species in the southern hemisphere due to the difference in seasonal changes, therefore they will never meet. This is the same with all species who populate the different hemispheres. Balaenoptera musculus can live solitary or pods of two to three individuals, although larger groups have been observed. They follow migratory routes of low latitudes in the winter months for breeding and birth, then migrating to higher latitudes in summer months for feeding. Balaenoptera physalus is the most sociable species within this family forming groups of six to ten individuals, reaching up to two hundred and fifty individuals during migration or feeding. They to follow migratory paths of feeding in the summer months in the cooler waters and migrate to warmer waters in the winter to breed or give birth. Family Neobalaenidae There is only one species within this family, Caperea marginata, the Pygmy Right Whale. It is the smallest whale within the baleen group reaching only six meters in length. A small dorsal fin is present, and they are grey in colour with a white oral cavity and tongue. Caperea marginata is a pelagic species distributed across a narrow area of the

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South Pole. They can be found encircling Antarctica both in the Pacific and the Atlantic oceans feeding on copepods. Very little is known about this species as they are quite a rare sight and are distributed across a barren region. They are not known to have a migratory route of any distance but may make short trips for feeding and breeding. Caperea marginata will only give birth to one calf and is believed to have a gestation period of ten to twelve months, with weaning taking place when the calf is around six months of age. Family Eschrichtiidae This family contains only one species, Eschrichtius robustus – the gray whale – which can be found distributed in the North Pacific Ocean with populations in both the east and the west. Eschrichtius robustus can reach up to 45 feet/14 m in length and is mottled grey in colour with no dorsal fin present, instead having a dorsal hump. The tail is ridged with a hump at the base followed by raised, knobbed area. The pectoral fins are relatively small but broad. The lower jaw is shorter than the upper jaw, and the throat grooves are present although not as numerous as in other baleen species. Breeding and copulation is not greatly studied, although breeding groups have been observed. Eschrichtius robustus gestation period is around thirteen to fourteen months, with weaning occurring around six to seven months of age. Sexual maturity is reached at around eight years, although it may occur as young as five. Populations of Eschrichtius robustus inhabit both the east and west Pacific page 22

Ocean. Populations in the east will use arctic feeding regions within the Chukchi and Bering seas in the summer months. They will then migrate south to warmer waters for breeding and birth in the winter months. Popular areas for calving down the west coast of North America are found in California. The western population will spend summer months in cooler waters of Okhotsk Sea along the Russian coast to Korea. They will migrate south for winter months where they will spend time in warmer waters for breeding and calving along the Chinese coast. This species will calve in shallow waters and lagoons. It has also been known for calves to return to the same feeding area as their mother. Eschrichtius robustus thrives as a bottom feeder where they plunge into the sea floor, filling their mouths full of sediment which they then filter through their baleen plates, removing any blocked food with their tongue. They will feed on larvae, amphipods, shrimp, crustaceans and schools of fish.

More information about the SUBORDER ODONTOCETI (Toothed Cetaceans) Family Delphinidae This family consists of the most species diversity with over 30 species within seventeen genera. They range in size from 5 to 33 feet/1.5 m to 10 m in length. All species have a fatty lump on their forehead, which creates a distinctive bulge which is believed to assist in feeding and echolocation. Some have a beak-like rostrum; others have a short, broad and stumpy rostrum. The dorsal fin is present on a streamlined body. The species in this

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family all have teeth which are peg-like and pointed. They thrive in oceans, seas, rivers all over the world, and prefer shallow waters or near surface waters. All species are fast swimmers.

DOLPHINS Genus Cephalorhynchus This genus includes four species of dolphin: ●● Cephalorhynchus commersonii

(Commerson’s dolphin)

●● Cephalorhynchus eutropia

(Black dolphin)

●● Cephalorhynchus heavisidii

(Heaviside’s dolphin)

●● Cephalorhynchus hectori

(Hector’s dolphin)

All four species are relatively small, ranging from 3 to 7 feet/1 to 2 m in length. They have streamlined, torpedo shaped bodies which assist in their high-speed swimming. They all have rounded heads with a distinctive beaklike rostrum, except Cephalorhynchus hectori, whose beak is less distinctive. C. commersonii is mostly white in colour with black markings over the head, blowhole, dorsal fin, pectoral fins and encircling the tail. Calves are born grey; this usually changes around four to six months of age. C. eutropia is dark grey in colour with lighter patches behind the pectoral fins, throat and anal area. C. heavisidii is dark grey in colour with distinctive white patches in the ventral locality, and dark blue shade running from the blowhole to the tail. C. hectori is also grey in colour with white page 23

markings along the ventral surface. All species have rounded pectoral fins. The dorsal fin of C. commersonii and C. hectori both have rounded dorsal fins, and C. eutropia and C. heavisidii both have triangular shaped dorsal fins. Cephalorhynchus commersonii populations are located in the southwest Atlantic Ocean, near Patagonia and the Falkland Islands, and the east coast of South America. A population is also present in the Indian Ocean with individuals being larger in size than their Atlantic cousins. Cephalorhynchus eutropia is distributed along the Chilean coastline, and populations may overlap with the C. commersonii. Cephalorhynchus heavisidii is distributed within the Atlantic Ocean particularly along the southwest African coastline. C. hectori thrive along the coastline of New Zealand with four genetically distinctive regional populations. One population is distributed along the west coast of the north of the island and is known locally as the Maui’s Dolphin. This population appears to have larger skulls than the southern cousins. The other three populations are distributed across the south of the island and are still genetically distinct from one another. All four species prefer to thrive in shallow waters and where tidal currents can be strong, such as bays, river mouths and estuaries. C. eutropia thrive in tidal currents and have been observed entering into river estuaries. C. heavisidii will also thrive in coastlines but may not be as close to land as the other three species. C. hectori will spend their summer months close to shore, then their winter months further offshore. The reproduction of these species is limited, and it is believed to

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copulate using belly to belly rubbing. C. commersonii has been observed mating in the months of September to February, C. eutropia in early winter whilst C. hectori will mate in summer to give birth in the winter months. All have a gestation period of around twelve months and will give birth to only on calf which is born tail first. The mother will feed her calf on milk secreted from her mammary glands. Mating will occur every two to four years. Sexual maturity is reached between five and nine years of age. C. hectori is believed to be polygynandrous, where many males and females’ mate with opposite sexes. The males will go in search of any receptive females. When C. hectori calves reach around two years of age they become independent and have been observed forming young juvenile groups. All four species are social animals which form loose groups of two to three individuals, although larger groups of thirty individuals have been observed. Cooperative feeding may also be involved in these loose social groups. They can reach high speeds and swim against strong waves and currents. C. commersonii has been known for its strong, acrobatic spins through waves. It also socialises with the Lagenorhynchus australis (Peales Dolphin). C. heavisidii has been observed leaping out of the water to height of two metres. C. eutropia has been observed assisting injured individuals within their group. All use echolocation, touch and visual communication. All four species feed on schools of small fish, squid, octopus and crustaceans. C. commersonii also feeds on algae and benthic invertebrates as a more opportunistic feeder. page 24

Genus Delphinus This genus contains two species: ●● Delphinus delphis (Short-beaked

common dolphin)

●● Delphinus capensis (Long-beaked

common dolphin)

Delphinus delphis is found widely distributed across both the Atlantic and Pacific Oceans. They have been known to swim up the Gulf Stream to cooler waters, and can be seen living in the Black Sea, Red Sea, Gulf of Mexico, Mediterranean Sea and even as far as the Indian Ocean. They thrive in coastal and open seas. Delphinus capensis is believed to have two subspecies dependants on distribution: Delphinus capensis capensis and Delphinus capensis tropicalis, the latter being found in in the Indo-Pacific Ocean. D.capensis have a scattered distribution and can be found in warm, shallow coastal waters of South and West Africa, Latin America, Madagascar, Peru, Japan and Korea. D. delphinus is the smaller of this genus and share most similarities. Both have a high triangular dorsal fin, with small pectoral fins and flukes. Their rostrum is beak shaped with a groove separating this from the forehead. The main difference is their beak size. D. capensis has a longer beak which can be up to 10% of their own body size. D. capensis has a sleeker body shape. They are both dark grey to brown in body colour, with a lighter coloured underside, separated by a crisscross pattern along their flanks, although D. capensis patterns are less distinct. D. delphinus has dark markings encircling

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the orbital area, compared to D. capensis has a dark stripe leading from the eye to their beak. Courtship consists of fast swimming, rubbing of fins, swimming alongside each other, and males will chase the females. Copulation occurs when the bell to belly motion is formed. Gestation is approximately ten to twelve months, and sexual maturity is reached at around twelve to fifteen years of age. Calves are immediately accepted into groups, and their mothers will feed their young milk from their teats. Other members of the group assist in protecting the calves and accompanying them for air. This genus is extremely sociable and can live in groups ranging from 100 to 100,000 individuals. These large groups are probably formations of smaller, social pods. These groups will eat, play, travel and breathe at the same time. They show acrobatic displays of flips and jumps and will swim behind the waves created by boats and whales. The species within this genus are very vocal and playful and will also help care for sick individuals and share responsibilities. All species will feed on small fish such as herring, sardines, pilchards, squid, and octopus. Group members will round up a school of fish, then each individual will swim at high speeds through the school of fish, catching their prey. They have been observed feeding with Tursiops truncates (bottlenose dolphin) and Lagenorhynchus obliquidens (Pacific white-sided dolphin) species.

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Genus Grampus This genus includes one species: ●● Grampus griseus (Risso’s dolphin)

Grampus griseus is a widely distributed species raging in oceans across the globe, including temperate, tropical and subtropical waters. They tend to be a pelagic species which chooses their habitat of steep slopes including marine canyons and slopes. One of the key features of this species is the blunt shape of the skull and absence of the beak shaped rostrum. G. griseus anterior body is robust and solid, which decreases to narrow tail end. Their dorsal fin is high and curved in shape, with long pectoral fins which are pointed in shape. Adults are generally around two to four meters in length. Another feature, which is unique to this species, is there is a slight groove along the melon area and runs along the body axis. G. griseus is dark grey in colour to almost black and is white on the ventral side. This coloration usually fades with age, becoming lighter as they become older and usually covered in pigmentation scars. G. griseus lacks teeth in their upper jaw, only present in the lower jaw. G. griseus can often be confused with Tursiops truncates (bottlenose dolphin), Orcinus orca (killer whale) and Pseudorca crassidens (false killer whale) due to the shape of the skull, rostrum and dorsal fin. Studies are limited on G. griseus and it is thought that they may be polyandrous or polygynous. Courtship, copulation and birth is most likely similar to other cetaceans of this size. It has been observed that mothers with calves will

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form female pods with each other and assist each other in finding food. Only the mother will feed her young calf with her milk. G. griseus are an extremely social species and tend to develop stratified social groups in which individuals are ranked by age, sex, and strength. Female mothering pods exist and are believed to form the largest pods to ensure protection and assist each other in daily activities. This species has been observed in groups of up to 4000 individuals but are believed to form tighter pods of eight to thirty individuals. G. griseus spend most of their time travelling from their summer and wintering grounds and will migrate dependant to on their geographical location. For example, species living within the cooler waters of the North Atlantic Ocean in summer will migrate south to warmer waters of the North Atlantic Ocean for winter. The rest of their time is spent feeding, resting and socialising. This species can be seen attacking other species of dolphins and killer whales, although they have also been observed socialising with other species, in particular Tursiops truncates (bottlenose dolphin). Genus Lagenodelphis This genus includes one species: ●● Lagenodelphis hosei (Fraser’s

dolphin)

Lagenodelphis hosei is found more abundantly in the Pacific Oceans, but there have been sightings in both the Indian and Atlantic Oceans. The species prefers tropical to subtropical waters and prefers to live at depths. page 26

L.hosei is grey to brown in colour with a cream line running from the eye to the anus across the flanks, followed by a black stripe. The ventral side is white in colour. There is no prominent beakshaped rostrum and the dorsal fin is very small, although it is slightly larger in males than females. The pectoral fins are also quite small when compared to their body size. This species is approximately 3 to 10 feet/1 to 3 m in length. Reproductive behaviour is not greatly studied but it is believed gestation is around eleven months, with sexual maturity reached at around seven years. They are extremely social and will live within tight pods of around 100 to 1000 individuals. This species can quite often be observed porpoising out of the water in large groups. They are often observed socialising with pilot whales and other dolphin species. Genus Lagenorhynchus This genus includes six species: ●● Lagenorhynchus acutus

(Atlantic white-sided dolphin)

●● Lagenorhynchus albirostris

(White beaked dolphin)

●● Lagenorhynchus australis

(Peales dolphin)

●● Lagenorhynchus cruciger

(Hourglass dolphin)

●● Lagenorhynchus obliquidens

(Pacific white-sided dolphin)

●● Lagenorhynchus obscurus

(Dusky dolphin)

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Lagenorhynchus is widely distributed genus, with two species found in the North Atlantic Ocean. Lagenorhynchus acutus and Lagenorhynchus albirostris are both found in the cooler waters of this ocean. Lagenorhynchus acutus in particular prefers the cooler temperate and subarctic waters and can be found ranging around the British coast to Norwegian waters and as far south as Massachusetts. Lagenorhynchus albirostris can be found ranging the Barents Sea, Portugal and Massachusetts. Lagenorhynchus australis is distributed through the South Atlantic Ocean in temperate waters of South America and Falkland Islands. They are quite often observed swimming in shallow waters and sand bars. Lagenorhynchus cruciger is a pelagic species which thrives in the cooler waters of the Southern Ocean, near the Antarctica convergence. Lagenorhynchus obscurus is distributed across the southern hemisphere in cool to temperate coastal waters of South Africa, South America, New Zealand and South Australia. Lagenorhynchus obliquidens can be found distributed across the temperate regions of the North Pacific Ocean ranging from the east to the west. Lagenorhynchus acutus and L.albirostris both have robust bodies with a thickened tail region. Lagenorhynchus acutus is approximately 8 to 10 feet/2.5 to 3 m in length with females being smaller than males. They have a high dorsal fin which is curved, long pectoral fins, and hook-shaped flukes. Lagenorhynchus acutus has a black dorsal region, with greyyellowish flanks and a white ventral region. Dark markings encircle the eye. Lagenorhynchus albirostris has page 27

a short, thick beak-like rostrum which is white to light in colour and may be mottled grey. Their dorsal region is dark in colour with light grey flanks and a white ventral area. Lagenorhynchus albirostris has a large, rounded dorsal fin which curves at the tip. They have long pointed pectorals. Lagenorhynchus australis and L.obliquidens both have a torpedo-shaped body. Lagenorhynchus australis has a dark grey dorsal region with lighter grey on the flanks and white ventral regions. They have a high dorsal fin with long pectoral fins. Lagenorhynchus obliquidens is black to dark grey on the dorsal region with a white ventral area and bicoloured fins. Lagenorhynchus cruciger is a small robust dolphin which is black and white in colour with varying patterns. Generally, the dorsal area and sides are black with white patterns. The have a small dorsal fin. Lagenorhynchus obscurus has no definite beak and has a blunt dorsal fin. The dorsal area is blueish to black in colour, with said colour extending toward the tail. The ventral region is white, and the flanks are dark. There is not a great deal of reproductive data on this genus, but it is believed their gestation period is approximately ten to twelve months. Lagenorhynchus acutus calves are born around June to July. Lagenorhynchus albirostris are born from June to September. Lagenorhynchus obliquidens pods consist of one dominant male who mates with recipient females. There will be a number of females within this pod and less dominant males. Lagenorhynchus obscurus males compete with each other for females and will usually mate in the spring for births in June or July.

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All species within this genus are highly sociable with L.acutus, L.albirostris and L.obliquidens observed in large groups of up to 1000 individuals, although they are also observed in smaller pods. Lagenorhynchus obliquidens have been observed assisting members of their group who are ill or injured. Lagenorhynchus cruciger form smaller social groups of one to one hundred individuals, and L.australis form smaller groups of one to thirteen members. Lagenorhynchus acutus can be seen swimming through the waves and are prone to becoming stranded or beached in groups. This species does travel, however there is no clear migration, so travel may be to reach food sources. Lagenorhynchus albirostris is an acrobatic species which can be observed flipping, and jumping out of the water, and are attracted to smaller boats. This species migrates south of its habitat in autumn and winter and will migrate north again in spring and summer months. Lagenorhynchus australis also like to jump and flip out of the water and will swim alongside boats on their side. This species has been seen swimming with other dolphin species and whale species. Lagenorhynchus cruciger will move south of its habitat for summer months and north for winter months and can be seen travelling alongside a variety of whale species. Lagenorhynchus obscurus can live in pods of six to twenty individuals, with an increase when they are feeding. At night they will rest in their smaller groups in-shore, and in daytime they will feed in larger groups in the open seas. This species is believed to be altruistic assisting other species and humans. All species feed on schools of small fish page 28

within their geographical location. They will also feed on shrimp, crustaceans, and octopodes. Lagenorhynchus acutus will feed separately for efficiency, while most other species will work as a group encircling their prey of fish then dive in one by one. Lagenorhynchus obscurus will feed on the ocean floor and the surface. Genus Orcaella This genus contains two species: ●● Orcaella brevirostris (Irrawaddy

dolphin)

●● Orcaella heinsohni (Australian

snubfin dolphin)

Orcaella brevirostris are distributed across Indo-Pacific regions in tropical to subtropical waters. They can be observed along the Indian coastline, Thailand, Cambodia, Singapore and Indonesia. They prefer the brackish waters found at river mouths and in coastal waters. Orcaella heinsohni are native to the Australian coastline and the waters near Indonesia. They also prefer shallow waters near river mouths. Both species within this genus lack a beak-like rostrum, instead having rounded skulls. Orcaella brevirostris in particular has a bulging forehead which extends past the mouth. Orcaella heinsohni has a more rounded-shape to the head. They both have mobile necks and small dorsal fins. Orcaella brevirostris has triangular-shaped pectoral fins and O.heinsohni has curved pectoral fins. Orcaella heinsohni is grey to blue in colour and is easily distinguished from its relative by the white ventral area between the pectoral

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fins and the anal region. Orcaella brevirostris is slate blue to grey in colour and lacks the cardiac sphincter. Not much is known about the reproductive strategies of this genus. Both species are sociable and live in small, tight pods of three to eight individuals. Both raise their heads out of the water and are slower swimmers when compared to other, more streamlined dolphins.

beak and small curved pectoral fins. Lissodelphis peronni has a black dorsal area which extends over the head, and a white ventral region which extends over the beak, the pectoral fins, and then curves up over flanks. Lissodelphis borealis species are mostly black with a ventral stripe which extends over the thoracic region. Colour variations can occur in both species.

Lissodelphis borealis ia a circumpolar species which ia distributed near the sub-Antarctic polar front. They are a pelagic species which prefers deeper waters between the Falkland Islands and the Antarctic convergence. Lissodelphis peronni is distributed in the North Pacific Ocean from Western North America to Eastern Asia. They also prefer deeper, cooler waters but can occasionally be sighted near the coastline.

Reproductive strategies and rates have not been well studied with this genus, although both species are highly sociable. Lissodelphis peronni can occur in groups of 200 to 1000 individuals and have been known to interact with a variety of dolphin species and pilot whales (Globicephala melas). Lissodelphis borealis can be found in smaller groups ranging from 100 to 200 individuals, and although western groups tend to be larger, they can also be observed solitary. Lissodelphis borealis groups may be tight or loose with a mix of small groups and may also form herds with Lagenorhynchus obliquidens (Pacific white-sided dolphin). They also interact with other species of dolphins and a variety of whale species. Both species adapt to different strategies for breathing while swimming. If swimming in a slower motion, they will only expose the blowhole to breathe and not extend the full head out of the water. If they are swimming in a fast motion, they may perform fast but low leaps. Both these species can be observed belly flopping and side slapping. They are both fast swimmers and will follow waves created by boats.

Lissodelphis borealis and L.peronni species lack the dorsal fin; L.borealis is the only dolphin species in the North Pacific Ocean without the dorsal fin. Both species have a streamlined, slender body with a short distinctive

Both species feed on mesopelagic species of fish native to their waters. They will also feed on squid. Lissodelphis borealis will feed on species like lanternfish and L. peronni will feed on big-eye tuna.

Both will thrive on fish species within their geographical range. They will also eat crustaceans, cephalopods and squid. Genus Lissodelphis This genus contains two species: ●● Lissodelphis borealis (Northern right

whale dolphin)

●● Lissodelphis peronni (Southern right

whale dolphin)

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Genus Sotalia This genus contains two species: ●● Sotalia fluviatilis (Grey dolphin or

Tucuxi)

●● Sotalia guianesis (Guiana dolphin)

These two species were once one species split into two subspecies; new research has caused a reclassification, with each recognised as an individual species within this genus. Sotalia fluviatilis is a freshwater species which is distributed within the Amazon Basin and along the Orinoco River. Sotalia guianesis is a marine species which inhabits the western Atlantic coast of South and Central America, and the Caribbean Islands. Populations do overlap and it is only the size which differentiate these two species. Both species are similar to Tursiops truncatus (bottlenose dolphin), except in the fact they are both much smaller. Sotalia guianesis is larger than its freshwater relative, S.fluviatilis. Both species are grey to blue in colour, and along the ventral region they can be white, pink or light grey. They have small triangular shaped dorsal fins, the pectoral fins are broad, and they have a narrow distinctive beak shaped rostrum. Reproduction is not well studied in this genus, though they are believed to be a highly sociable genus. They will both live in relatively small groups with a few individuals, although coastal populations of S. guianesis will form groups of twenty to thirty individuals. Both species are extremely acrobatic, jumping high out of the water and performing page 30

flips and belly flops. Sotalia fluviatilis have been observed mixing with Inia geoffrensis (the Amazon River Dolphin). Both Sotalia species are carnivorous, consuming a variety of fish and other sea creatures. Sotalia fluviatilis feeds in small groups, with group size affected by geography, food supply, and social hierarchy within the pod. While Sotalia fluviatilis feeds on shrimp, S. guianesis also feeds of squid and crab. Sotalia guianesis hunt in cooperative groups, surrounding fish schools, then eating in turns. While some pod members eat, the others keep the school in check, ensuring its entrapment. Both species are known to use echolocation as part of their hunting behaviours; it is suspected that S. fluviatilis may also communicate in this way. Genus Sousa This genus contains two species: ●● Sousa chinensis (Indo-Pacific

humpback dolphin)

●● Sousa teuszii (Atlantic humpback

dolphin)

Sousa chinensis thrives in warm waters along the coastline, estuaries and river mouths of the Indo-Pacific Ocean. The species is split into two geographical subspecies, S. chinensis chinensis which inhabits the coastlines of the Pacific Ocean and S. chinensis plumbea which inhabits the coastlines of the Indian Ocean. Sousa teuszii is distributed along the tropical coastal waters of the Atlantic Ocean, particularly along the coast of West Africa. They prefer the shallow waters near estuaries and river mouths.

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between S. chinensis species involves males chasing females, performing flips and flipper slaps. Birth is thought to occur in spring and summer for this species after a gestation period of around ten to twelve months.

Indo-Pacific Humpback Dolphin, Sousa chinensis (an example of toothed cetacean – Order Odontoceti)

Both species have an elevated base to their dorsal fins; this is why they are referred to as ‘humpback’ dolphins. The actual dorsal fin is quite small in both species. S. chinensis shows variation in differences geographically; in western species, the dorsal fin appears shorter and curvier with a longer hump, while in eastern species the dorsal fin is only slightly curved. S. teuszii has a bulky melon and rounded pectoral fins. Both species have long distinctive beaks. S. teuszii is mostly grey in colour, and some individuals have a lighter ventral region with speckled areas. S. chinensis dorsal area may be dark grey, grey, brown and pinkish in colour with a white ventral area. Some individuals may be completely white. One significant difference between both species is that S. teuszii has fewer vertebrae than S. chinensis. Although neither species within this genus is well-studied in terms of reproductive behaviours, it is thought that S. teuszii is polygynous with males mating with many females. Courtship page 31

Both species are relatively slow movers and will form small groups. S.chinensis will form groups of around ten to thirty individuals; S.teuszii forms smaller groups of three to seven individuals, although younger generations may form larger groups. S.chinensis will mix with other species such as Tursiops truncatus (the bottlenose dolphin) and Eubalaena australis (the southern right whale). S.chinensis feeds close to the sea floor, in estuaries and near reefs, and will thrive on dwelling fish within these areas. They have been known to follow trawling boats in order to feed on the discarded species. S.teuszii will feed on schools of fish such as sardines and mullet, but will also feed on crustaceans and squid. Genus Stenella This genus contains five species: ●● Stenella attenuaa

(pantropical spotted dolphin)

●● Stenella clymene (Clymene or short-

snouted spinner dolphin)

●● Stenella coeruleoalba

(striped dolphin)

●● Stenella frontalis

(Atlantic spotted dolphin)

●● Stenella longirostris

(spinner dolphin)

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All five species of genus Stenella inhabit warm tropical to subtropical waters within their regions. Stennella coeruleoalba, S. frontalis and S. longirostris can also be found in temperate regions which have warmer waters. Stennella attenuaa is found in the pelagic waters of the Atlantic, Pacific and Indian Oceans, although they can also be seen along the coast. Stenella clymene is distributed across the Atlantic Ocean, from North American waters to West African waters. It is a pelagic species which particularly inhabits deep waters. Stennella coeruleoalba are distributed across the globe in the Pacific, Indian and Atlantic Ocean, and in the Caribbean and Mediterranean Sea, where they inhabit both inshore and offshore waters. Stennella longirostris inhabits pelagic waters of the Indian, Atlantic and Pacific Oceans, although they can be seen in shallow open waters, not coastlines. All Stenella species have distinctive long narrow beaks, except S. clymene, which has a small, short beak. Stennella attenuaa is dark grey on the dorsal area with light mottled spots and is pale on the ventral area with dark mottled spots. They have a distinctive white beak, tall arrow dorsal fin and a large melon. Stennella clymene is dark from the beak down the dorsal area to the fluke, which extends downwards below the dorsal fin. Their ventral area is pale, and flanks are light grey which rises over the orbital area. They also have distinctive black markings encircling the eyes and snout. Stennella coeruleoalba have a narrow, tall dorsal fin with long, narrow pectoral fins. Their dorsal cape is a dark grey, with pale coloured flanks and a white ventral region. Their name comes from the dark stripe which runs from the eye down to the anal region. Stennella frontalis have page 32

large, robust bodies with large pectoral fins, dorsal fin and tail flukes. The species greatly vary in coloration patterns and can be grey over the dorsal area and a light ventral area, with mottled spots of dark and light areas. Stennella longirostris have a dark grey dorsal region, with white ventral area and pearl grey flanks. There is not a great deal known about the reproductive behaviours of the genus, however S. attenuaa is believed to have births which occur in the spring through to autumn. Stennella coeruleoalba have a gestation period of around twelve to thirteen months. Stennella longirostris are polygynandrous and the male will chase the female when he senses she is ready. These matings seem to occur with members of the same group. All species within the genus are acrobatic, highly activem and sociable. Stennella coeruleoalba can be observed performing behaviours such as roto-tailing, where several body spins occur within one jump. All species live in relatively large groups ranging from twenty members up to several thousand members. Stennella attenuaa has offshore populations which tend to be larger than coastal populations. Groups of S. clymene have been observed in clusters with S. longirostris (the spinner dolphin), Delphinus delphis (the short-beaked common dolphin) and Delphinus capensis (the long-beaked common dolphin). Stennella coeruleoalba species can be observed in groups comprised of several hundred members, with some groups numbering over a thousand. It is believed S. coeruleoalba have three types of pods: juvenile pods, non-breeding pods, and breeding pods. Stennella frontalis may mix with clusters

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of S. longirostris. Stennella longirostris are believed to form a dominance hierarchy within their large pods. This species also rests in the shallow waters and spends its activity and feeding times in deeper waters. Stennella attenuaa will feed primarily on small fish, squid, pteropods and isopods. Stennella clymene will feed on small fish and squid near the surface. Stennella coeruleoalba will thrive on a variety of crustaceans, cephalopods and bony species of fish, and in the Atlantic it will prey on cod. Stennella frontalis will surface feed on herring, eels and invertebrates. Stennella longirostris will prey particularly on vertically migrating species, shrimp, fish and squid. Genus Steno This genus contains one species: ●● Steno bredanensis

(rough-toothed dolphin)

Steno bredanensis has a wide geographical distribution and occurs in the tropical to temperate waters of the Atlantic, Indian, and Pacific Oceans. They prefer deep waters in the open ocean but have been observed in shallower waters. The long beak of S.bredanensis is elongated and prominent. They are dark grey along the dorsal side, with light spotted flanks and white across the ventral region. They also have a dark grey cape which arches over the orbital region and extends down the sides. There is not much evidence on the reproductive strategies of this species, but they are believed to live in pods of around ten to thirty individuals. These page 33

pods have been observed mixing with other species such as: Tursiops truncatus (the bottlenose dolphin), Stenella frontalis (the Atlantic spotted dolphin), Stenella longirostris (the spinner dolphin) and Globicephala species (pilot whales). Steno bredanensis are good divers and extremely fast swimmers. They feed on a variety of species such as mahi mahi, saury, silverside, and some squid. Genus Tursiops This genus contains one species: ●● Tursiops aduncus

(Indo-Pacific bottlenose dolphin)

●● Tursiops truncatus

(bottlenose dolphin)

Tursiops aduncus are distributed in the shallower waters of the Indian and Pacific Ocean, hence their common name. Tursiops truncates can be found distributed in all oceans across the globe, except for the polar regions. They prefer the tropical, subtropical and warm temperate waters and can be found near estuaries, bays, and river mouths. Tursiops aduncus is slate blue to grey dorsally, pink to white ventrally, and has dark pectoral fins. An adult typically weighs around 230 kg. Tursiops truncatus is dark grey to light grey in colour with a paler ventral area. An adult typically weighs 300 to 500 kg. The dorsal fin on both these species is tall and slightly curved. The two species are very similar with only a few minute differences: T.aduncus has a smaller body and larger pectoral fins than T.truncatus. Tursiops truncatus has a

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smaller melon and a longer, prominent rostrum than its counterpart. Males of both species will form male groups to round up receptive females ready to mate, although single males

may work alone. Tursiops aduncus males and females may mate with many partners. The gestation period for both species is approximately twelve months; lactation occurs for around eighteen to twenty months.

Bottlenose Dolphin, Tursiops sp. (an example of toothed cetacean – Order Odontoceti)

Tursiops aduncus will form small pods of around four to fifteen individuals. They form a hierarchy that takes the size and strength of each individual into account. Tursiops truncatus may be in pods of three up to one hundred individuals and has a dominance hierarchy. Larger groups of T.truncatus are usually made up of smaller subgroups which are loosely formed. This species has been known to be quite aggressive which probably relates to group hierarchy and male reproductive strategies. Tursiops aduncus species will hunt cooperatively and will prey on bony fish and cephalopods. Tursiops truncatus will thrive on coastal fish and invertebrates and pelagic species.

and the dwarf sperm whale. Some classifications list this family as a subfamily of Physeteridae. Family Ziphiidae includes a variety of species; some scientists list 19 species, while others list over 20 species in the group. Four species belong to the family Ziphiidae, and the rest in the subfamily Hyperoodontidae. These families include beaked and bottlenose whales. Family Platanistidae includes two species of Indian river dolphin. Family Iniidae includes species of the Amazon river dolphin.

WHALES

Family Lipotidae includes the critically endangered species of Chinese river dolphin.

Family Physeteridae includes one species, the Sperm Whale.

Family Pontoporiidae includes the Franciscana dolphins.

Family/Subfamily Kogiidae includes two species, the pygmy sperm whale

Family Monodontidae includes two species, the narwhal and beluga.

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Family Phocoenidae includes the six species of porpoise. Genus Feresa This genus contains one species: ●● Feresa attenuata

(pygmy killer whale)

Genus Orcinus This genus contains one species: ●● Orcinus orca (killer whale)

Genus Globicephala This genus contains two species: ●● Globicephala macrorhynchus

(short-finned pilot whale)

●● Globicephala melas

(long-finned pilot whale)

known as hoofed mammals, include many familiar land animals such as camels and goats. Scientists think the marine ungulates share a common ancestor with land ungulates, an ancestor which dates back to around 60 million years ago. Some scientists refer to marine ungulates as “near-ungulates”, since they share many characteristics with land ungulates, but clearly do not have legs or hooves. Some sirenians show, however, small hoofnails along the flippers. Like most land ungulates, sirenians are herbivorous, and have a remarkably developed digestive tract for processing plant-life. Characteristics of the order include: ●● Being aquatic ●● Two front limbs formed into flippers,

no hind limbs

Genus Peponcephala

●● Hairs only on the muzzle

This genus contains one species:

●● Upper lip enlarged and adapted to

●● Peponcephala electra

(melon-headed whale)

Genus Pseudorca This genus contains one species: ●● Pseudorca crassidens

(false killer whale)

THE ORDER SIRENIA This includes: Manatees and Dugongs Order Sirenia is entirely comprised of marine ungulates. Ungulates, also page 35

grasping food plants

●● Nostrils on the top of the snout ●● Bones are very dense and mostly

lack bone marrow; an adaptation to maintaining buoyancy.

●● Vestigial pelvis ●● From Tropical waters

Families in this order include: Family Dugongidae There is only one living species

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of Dugongidae, Dugong dugon. The only other known species, Hydrodamalis gigas, or Steller’s sea cow, went extinct in the 18th century. This means that Dugong dugon is usually referred to as just “dugong”. Dugongs have a wide distribution. They dwell around coastlines and are found around east Africa and in the Red Sea. Dugongs are also seen around the Australian and Asian coasts. Although they were once common around

the Phillipine coasts, most dugongs in that area are now only found in designatedseabeds. Dugongs can weigh up to 400 kg each; females are usually larger than males. Length ranges from 2.5 to 3.5 m. They are grazers, skimming the sea floor to graze on different marine plants. Dugongs have been known to “stash” food for later, using the upper lip to uproot plants then make piles near the shore.

Dugong, Dugong dugon (an example of the Order Sirenia)

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Tail flukes have deep notches, like a fork. The upper lip is large and split, though not deeply so. In water, they can use their pectoral fins like “feet”, marking the sea floor with distinctive patterns as they move. Dugongs move in groups of 3 to 6 individuals, and have a reasonably long-life span, of up to 50 years. Reproduction is slow, and the gestation period is around 12 months. Reproduction occurs in intervals; females have been known to breed as little as three years after a calf, going up to 7 years after the previous calving. Dugongs are listed as vulnerable on the IUCN Red List. Family Trichechidae Trichechidae are the manatee family. There are three living species of manatee: ●● Trichechus manatus (West Indian

manatee)

●● Trichechus seneglaensis (West

African manatee)

●● Trichechus inunguis (Amazon

manatee, a river species)

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Manatees are also known as sea cows due to their slow, peaceful movements and herbivorous diet. They are social animals, usually found in coastal areas such as estuaries, rivers, and bays. Their diet is mostly plants and algae. Like dugongs, manatees have a strong upper lip for grasping and feeding. Flippers are short in the front and longer in the back. Flippers are also used during feeding. Weight ranges from 400 to 450 kg; Trichecus seneglaensis is smaller than its counterparts. Females are larger. They are up to 3 m/10 feet in length. Manatees have been recorded as reaching up to 1600 kg. Reproductive period is 2 to 5 years, with a long gestation period. Trichechus manatus gestates for 11 months, while T. seneglaensis and T. inunguis gestate for 12 months. Lifespan is up to 60 years. All species of manatees are listed as vulnerable on the IUCN Red List.

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CHAPTER 3 MARINE CARNIVORES Marine carnivores are classified onto 5 main families, which include “pinnipeds”, otters and polar bears.

PINNIPEDS The term “pinniped” is Latin for “wing” or “fin” foot. This refers to the flippers found on pinnipeds. This group includes walruses, eared seals and earless seals. Pinnipeds have a sleek, barrel-shaped body adapted to an aquatic lifestyle.

Walrus Family Odobenidae This family contains only a single living species, Odobenus rosmarus. Walruses are distributed throughout the Arctic Ocean and the northern parts of the Pacific Ocean. Males are very large, up to 3.6 m, with a weight of up to 2 tonnes. Females are smaller, weighing less than half that of males. The body is bulky and heavy. Like true seals, they lack external ears. Like eared seals, they can turn their hind flippers forward and use them for walking and running while on land. Walruses have large paddle-like forelimbs that reach about 25% of the length of the body. The skin is wrinkled and very thick, with underlying blubber of up to 15 cm in thickness.

leopard seal, are voracious predators and will feed on penguins and other seals. Seals are divided into two families: ●● Phocidae - true seals (e.g.

leopard seals);

●● Otariidae - fur seals and sea lions.

Family Phocidae (True Seals) True seals vary greatly in size. The smallest species are the Baikal Seal (Pusa sibirica) at around 35 kg, and the ringed seal (Phoca (pusa) hispida) with a weight of around 90 kg. The largest true seal is the Elephant Seal (Mirounga leonina), which weighs up to 5 tonnes. As with most fast swimmers, the bodies are streamlined. External ears are absent. Forelimbs are relatively short, less than 25% of the length of the body.

True Seals and Fur Seals Families: Phocidae and Otariidae Seals are carnivores and they exist on a varied diet of pilchards, anchovies, mackerel, squid and the occasional lobster. Some species, such as the page 38

Harbour Seal (Phoca vitulina) – True seal (Family Phocidae)

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Claws are well-developed. The large hind flippers cannot turn forward and are not used for movement. Seals are unable to walk or run on land. Instead, they flex and slide on their belly, and move relatively quickly. Adults usually have stiff and short fur; some species have almost naked skin. Some have spotted or banded colour patterns. Most young are covered with dense and soft fur with a thick layer of blubber beneath the skin for insulation in freezing conditions. The weight of the blubber may be around 25% of the entire weight of the animal in some species. Seals mostly feed on fish and molluscs (squid, octopus, and shellfish). Ironically named, the Crabeater Seal (Lobodoncar cinofagus) mainly feeds on krill, and is the only plankton-eating member of the entire order. The largest of the Antarctic species, the leopard seal (Hydrurga

leptonyx) feeds on penguins and smaller seals. Most species are monogamous or associate in small groups. Elephant seals are gregarious and polygamous. Some species are migratory. All seals are expert divers, although their abilities vary from species to species. The Weddell seal (Leptonychotes weddelli) is recorded to reach depths of 600m and to stay submerged for 43 minutes and 20 seconds. Some of the better-known seal species include: ●● Lobodon carcinophagus (Crabeater

Seals)

●● Hydrurga leptonyx (Leopard Seals) ●● Ommatophoca rossii (Ross Seals) ●● Leptonychotes weddellii (Weddell

Seals)

Californian Sea Lion (Zalophus californianus) – Eared seal (Family Otariidae)

Family Otariidae (Eared Seals) Unlike other pinnipeds, Otariidae have external ear flaps, although small and page 39

cartilaginous. Like walruses, Otariidae can turn the hind flippers forward and use them for walking or running on land. Members of this family swim mostly using

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forelimbs. Sea lions have a coat of short, coarse fur. Fur seals have very thick underfur and are hunted as fur animals. ●● Neophoca cinerea

(Australian sea lion)

●● Arctocephalus pusillus

(Australian fur seal)

●● Arctocephalus forsteri

(New Zealand fur seal)

Afro-Australian fur seal (Arctocephalus pusillus)

South American Sea Lion (Otaria byronia) - Eared seal (Family Otariidae)

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MARINE AND SEA OTTERS Family Mustelidae This is the largest family within the Order Carnivora. It includes about 20 recent genera with around 55 species naturally distributed in all continents except Australia, Antarctica, and most oceanic islands (including New Zealand and New Guinea). Many species of river otters inhabit both inland rivers and coastal saline waters. These river otters have front and rear limbs of roughly equal size, and are better adapted to land than sea otters. Sea otters have larger rear limbs, making them better adapted to venturing further out to sea. Sea otters spend most of their time in water swimming on their backs. They can eat and sleep while floating on their backs.

They are small or medium-sized carnivores. The largest species of mustelids are the sea otter Enhydra lutris (more than 1 metre and a weight of up to 41 kg). Male mustelids are usually larger than females (about 25% difference). The fur can be uniformly brown or grey, spotted or striped. They have an excellent sense of smell, good eyesight and hearing. Some species tend to Aquatic mustelids include both the sea otter and the marine otter. Sea Otter Enhydra lutris This otter is found in the northern and eastern North Pacific Ocean. The adults can weigh between 14 and 45 kg. Its thick coat is the otter’s main source of insulation. It is believed to be the densest fur in the animal kingdom. Sea otters dive to the sea floor to forage for prey such as molluscs, crustaceans, sea urchins and some fish. It is renowned for using tools such as rocks to pry open mollusc shells. Marine Otter Lontra feline

Asian Small Clawed Otter (Amblonyx cinereus) – semi aquatic mammal inhabits both coastal and inland waters.

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This species of otter is found in the littoral zones of South America. It differs from the sea otter as it spends much of its time out of the water. It is also relatively smaller than its northern counterpart, with weights ranging from 3 to 5.8 kg. The fur is coarser and stiff than sea otter hair. The marine otter feeds on invertebrates including crustaceans and molluscs as well as some fish species. This species is listed as endangered on the IUCN Red list.

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POLAR BEAR Family Ursidae Ursus maritimus Polar bears are considered the largest land carnivore in the world. However, they do spend much of their time in the seas surrounding the Arctic Circle. They are considered marine animals as

they live on the packed ice of the Arctic Ocean. To exist in such a cold climate, polar bears have a thick fur coat consisting of underfur and guard hairs as well as up to 10 cm of blubber for insulation. They have excellent olfactory senses. They can detect the presence of preferred prey such as ringed and bearded seals from up to 1.6 km away. They are very good swimmers, using their body fat for buoyancy.

Polar Bear (Ursus maritimus) - Family Ursidae

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CHAPTER 4 MARINE REPTILES Sea turtles are the most obvious group of marine reptiles, though there are also many different types of snakes, some crocodiles, and one type of lizard that inhabit marine environments. The earliest marine reptiles occurred during the Paleozoic era almost 300 million years ago. Many of these species became extinct at the end of the cretaceous period.

between oceans. They have paddle-like flippers, a modified ribcage (shell) and have lungs to breath like other reptiles. While land turtles can tuck their heads back into their shells, sea turtles cannot.

SEA TURTLES

Sea turtles live their life virtually submerged in water, only leaving the oceans to lay eggs. They have large lungs which enable them to exchange oxygen quickly and avoid trapping gases when diving deeply. They breathe air, but if needed can use anaerobic respiration for extended periods of time. Generally, life histories are relatively similar across species.

Sea turtles have evolved to live in the oceans over 100 million years, predating dinosaurs. They occupy all oceans aside from the polar regions. Sea turtles are known to migrate long distances between feeding and nesting sites. They have even been recorded to travel

A sea turtle with green algae attached to its carapace

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Most sea turtles are long-lived. They are known to have a lifespan of up to 80 years. It can take decades for sea turtles to reach sexual maturity. Sea turtles live in the water for their entire lives, except during the breeding season. All sea turtles lay eggs. Breeding females will lay eggs on a beach in a hole dug with her hind flippers. The eggs are soft-shelled and can number up to 200 depending on the species. The sex of hatchlings is influenced by the temperature of the sand. Lighter sands are generally higher in temperature, which results in a higher incidence of females hatching. Eggs generally hatch at 7-12 weeks. Sea turtles do not exhibit any signs of parental care for the young. Sea turtles can be carnivorous, omnivorous, or herbivorous. Green sea turtles are the only herbivorous adult turtle, feeding on sea grasses and algae. Most carnivorous species feed on crabs, shrimp, molluscs, and jellyfish. As this food source is high in salt, sea turtles possess a unique salt excretory gland. This gland can be positioned in different places depending on the species, such as in the corner of the eye or the nostril. Most sea turtles can hold their breath for around 5 hours underwater. All sea turtles are threatened. The main threats to sea turtles are pollution and habitat modification (especially sea grass beds, nesting beaches, mangroves and corals). They are also affected by fishery bycatch (accidental catching) and plastics affecting their food access.

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Taxonomy (Classification) The extant species of sea turtles fall into two distinct families: ●● Dermochelyidae ●● Cheloniidae

The major differences in the families are: ●● the structure of the carapace ●● reproduction ●● skeletal structure ●● distribution

Family Dermochelyidae Leatherback Turtles Dermochelyids, or the leatherback turtles, are the largest sea turtles. Dermochelys coriacea, the leatherback sea turtle, is the only extant species in this group. It is also the largest sea turtle, growing up to 244 cm long, with a weight of up to 916 kg. Dermochelys coriacea has a leatherlike carapace, made up of osteoderms, or small bony deposits. These bony deposits are set into skin with a leathery texture. The carapace has seven clear ridges across the surface. There is no visible shell. The body is tear-shaped, with large front flippers, which give the turtle significant power in the water. Flippers have been known to grow up to 2.7 m long. The underbelly is pale; the dorsal area is shaded, running dark grey to black. Size

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rangages up to 1.75 m over the carapace and up to 2.2 m in body length. Adults can wight up to 700 kg. Size can vary according to geographic distribution. Dermochelys coriacea has some fatty tissue to help combat colder temperatures. This species can maintain a high body temperature independently, which is highly unusual for reptiles. These turtles are highly active, which appears to affect heat retention. They also use counter-current heat exchange to keep flippers and extremities warm. These adaptations mean that dermocehlyids have a wider distribution toward the poles. Fat deposits can be up 70 mm thick. These turtles have been sighted in Newfoundland, Nova Scotia, and Labrador in the North Atlantic, and Argentina and South Africa in the South Atlantic. They can also be found in Britain and Norway. These turtles can dive to remarkable depth, going as deep as 1,280 m into the sea. Dives are usually 3 to 8 minutes, though longer dives have been recorded (up to 70 minutes). Dermochelys coriacea is the fastest moving reptile in the world; it has been recorded as reaching a speed of almost 36 kph in the water.

to tropical waters to mate. Gestation is 55-70 days. The females will return to the nesting site to lay eggs; usually around 100 eggs to a nest. Leatherback turtles lay between 5 and 7 nests per year, alternating nesting grounds. Males do not leave the water or contribute to nesting. Temperature affects the sex of the young. Warmer environments (such as those found in lighter sand) result in female young, while cooler environments result in male young. A temperature of 29.5 C has an equal chance of producing male or female young. ●● Female: > 29.5ºC ●● Male < 28.75ºC

Leatherback turtles are listed as critically endangered on the IUCN Red List. Family Cheloniidae There are six known, extant species in this group. These are: ●● Caretta caretta (loggerhead sea

turtle)

●● Lepidochelys kempii (Kemp’s Ridley

sea turtle)

Dermochelyids are carnivorous. Their major food source is jellyfish and other inverterbrates, such as salps, small crustaceans, sea urchins, and cephalopods. They will also eat fish. Feeding grounds are usually found in temperate waters.

●● Lepidochelys olivacea (Olive Ridley

Male turtles will mate with multiple females – usually as many as possible. Adult males and females will return to the same mating areas, migrating

●● Natator depressus (flatback sea

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sea turtle)

●● Chelonia mydas (green sea turtle) ●● Eretmochelys imbricata (Hawksbill

sea turtle) turtle)

Common characteristics include a

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wide, flat shell with some rounding and paddle-like flippers. These species are most commonly found in tropical waters. Unlike the leatherbacks, cheloniids have a bony carapace and a plastron (bottom shell). Size ranges from .7 m to 2.13 m across the carapace. Lepidochelys kempii (Kemp’s Ridley sea turtle) is the smallest species in this group. Cheloniids lay eggs 2-3 times each nesting season. Adults usually return to their hatching beach to breed. During nesting events, the female swims ashore at night, then digs a nest with her rear limbs. Nests are dug above the

Green sea turtle (Chelonia mydas)

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reach of high tide. The female centres her tail into the nest, then lays the eggs; she later covers the eggs over with sand. A female turtle may lay over a hundred eggs in the nesting period. The incubation period is 50 to 60 days. Egg development requires a certain temperature to proceed normally. Once hatched, young head toward the ocean; artiifical light sources can cause confusion. Hatchlings are very vulnerable to predators. Young are pelagic. Sexual maturity varies, with some species reaching maturity at 3 years, and others at 20 years.

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Loggerhead sea turtle Genus Caretta Caretta caretta Caretta caretta has a wide distribution, with populations discovered in temperate and tropical oceans. Its range includes Newfoundland to Argentina, southern Africa to the Arabian Gulf to western Australia in the Indian Ocean; from Alaska to Chile and Australia to Japan in the Pacific Ocean; and in the Mediterranean Sea. This species draws its common name from the out-sized head-to-body ratio. The carapace is wide, flat, and generally heart shaped. Many specimens show extensive barnacle colonies and algal growth along the carapace. It is made up of large scutes (plates) and is usually a reddish brown colour; flesh is pale, with reddish brown spotting. The plastron, or bottom shell, is pale, ranging from cream to yellow. Young turtles exhibit two rows of ridges along the plastron; these fade as the turtle matures. Males have darker skin and a wider carapace, and a long claw on the forelimbs. Females are usually larger. Size varies according to geographic distribution; Mediterranean specimens are usually smaller than their Atlantic counterparts. Length ranges from .8 m to 1 m long, and weight from 77 through to 545 kg, with an average weight of 135 kg. There is some discussion of taxonomic change in this species; some scientists have suggested the species be divided into the subspecies C. caretta gigas and C. caretta caretta due to certain morphological differences in the carapace. page 47

Diet includes a variety of fish, molluscs, worms, crustaceans, and general invertebrates. Caretta caretta’s head size and jaw strength mean it can easily feed on crustaceans such as horseshoe crabs. Although the diet is largely carnivorous, this species is also known to eat algae and some plant-life. Mating occurs in early summer, with females laying eggs on tropical beach grounds. Nests are dug 2 to 5 times over the season, with approximately 12 days in between. Nests are dug with the rear limbs only and contain an average of 120 eggs. Incubation is 45-80 days, with eggs buried at higher temperatures developing faster and hatching earlier. There is a 2-4-year break in the breeding period of females. Sex determination is temperature dependent. Lower temperatures usually result in male young, while higher temperatures usually result in female young. Caretta caretta are listed as endangered on the IUCN Red List. Kemp’s Ridley Sea Turtle Lepidochelys kempii The smallest sea turtles in the world, Lepidochelys kempii are also the most endangered. With a greenish-grey carapace and a white to pale yellow underbelly, they are found in the North Atlantic Ocean running from the Gulf of Mexico to far north, with sightings as far as Nova Scotia. Shell length is around .61 m, with weight ranging up to 45 kg. The average lifespan in the wild is around 50 years; sexual maturity is reached at 10 to 12 years of age, with females nesting

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every 1 to 3 years. Lepidochelys kempii take part in arribadas, or nesting processions, with females invading large sections of beach like tiny warships. They drag themselves over the sand until settling into an appropriate nest, where they will lay a clutch of eggs. Young hatch at night and are vulnerable to predators. A caruncle (temporary tooth) is used to break out of the shell. Lepidochelys kempii live in shallow waters, feeding on crabs, other crustaceans, jellyfish, and molluscs. This species is also known to eat seagrass and seaweed, though it is not the preferred diet. Lepidochelys kempii is critically endangered. In the past, eggs have been over-harvested, and the adult population affected by fishing practices. With the species is now protected, the significant damage to their population, combined with the vulnerability of young, has left the species in a precarious position. They are listed as critically endangered on the IUCN Red List. Olive Ridley Sea Turtle Lepidochelys olivacea With its greenish skin and carapace, Lepidochelys olivacea draws both its common name and scientific name from the colour “olive”. While features are similar to Lepidochelys kempii, but Lepidochelys olivacea prefers warmer climes, and is found in the southern Atlantic, Pacific, and Indian oceans. Lepidochelys olivacea is of similar size to Lepidochelys kempii, with a shell page 48

length of around .61 m and weight up to 45 kg. It is also sometimes described as the world’s smallest sea turtle. There is, however, a strong morphological difference in the head and shell; Lepidochelys olivacea is smaller in both. Males have longer tails when compared to females. Diet is comprised of molluscs, jellyfish, and small crustaceans such as shrimp. Like Lepidochelys kempii, these turtles march up the shore in an arribada, or nesting procession, each year. Females usually return to their hatching beach to nest. Egg clutches are approximately 100 eggs; the season runs from June through December, with some females nesting two or three times a year. Many of these turtles’ nest along the beach at Rancho Nuevo in Mexico. Lepidochelys olivacea is under threat – adults are preyed upon by sharks, and eggs are stolen by humans. Females who have come ashore for their arribada may be hunted for meat. These turtles may also be harmed by fishing practices. They are listed as critically endangered on the IUCN Red List. Green Sea Turtle Chelonia mydas Chelonia mydas, or the green sea turtle, is found throughout tropical and subtropical waters. They prefer temperatures of around 20 C, though some individuals have moved into more temperate waters. With a weight range of 70 to 180 kg and a length of 80 to 120 cm, these are some of the largest

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sea turtles in the world. Average weight is around 150 kg. Outer colouring varies, ranging from olive through to brownish and reddishbrown along the carapace. The underbelly is pale, white or cream. Fat is usually greenish, a result of the diet. This is the green quality referred to in the name. Darker shelled specimens have been referred to as “black turtles” in the Eastern Pacific. Chelonia mydas has only one pair of prefrontal scutes, which will change colour as the turtle matures. The skull is round and smooth, with a short snout and strong beak. The jaws are serrated – as an herbivore, this is necessary for tearing at plant life. Males have longer tails and smaller carapaces; females display a cloacal opening between the anus and tail tip. Population appears to be generally increasing on a global scale, though

Turtle nesting in Heron Island (Dec 2011)

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this species shows significant decline in Indonesia. There appear to be no nesting turtles in some areas of Indonesia, including Bali. Coastal development affects nesting behaviours due to habitat loss; it may also reduce seagrass and algae available in turtle feeding grounds. Many are harmed as bycatch due to fishing practices; populations are also harmed by hunting. Eggs and meat are eaten, though there is still trade in turtle parts, with this species also used for traditional medicines in some places. Females nest ashore then return to the ocean. After hatching, young head for the water, and generally remain at sea until maturity. When sexual maturity is reached, they will return to their hatching beach to mate. These turtles use current systems during migration. They are listed as vulnerable on the IUCN Red List.

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Hawksbill sea turtle Eretmochelys imbricata With their narrow and pointed beak and distinctive shell patterns, Eretmochelys imbricate is easy to spot. These turtles are scattered throughout the world, found in tropical, subtropical, and temperate waters, though nesting generally occurs in the tropics. They are often found around coral reefs, where they feed on sponges, sea anemones, and jellyfish. Compared to other marine turtles, scientists know very little about E. imbricate. The body is flattish, with a carapace that shows slight shifts in colouring according to water temperature. It has an elongated head with a distinctive beak that has a sharp, cutting edge called a tomium. The carapace can grow up to 1 m in length, with the average individual weighing around 80 kg. Forelimbs have 2 claws on each flipper, and these turtles have a distinctive alternating gait, which leaves clearly identifiable marks along nesting beaches. Diet varies according to location; many adults feed around coral reefs. The high intake of some marine species can make flesh toxic. Sea sponges are their primary food source, making up to up to 95 % of the diet in some populations. Eretmochelys imbricata is bioluminescent – indeed, it is the only known bioflourescent reptile – and it is hypothesized that this may be due to a high intake of biofluorescent organisms. There are three major subpopulations: the Atlantic subpopulation, Eastern Pacific subpopulation, and the IndoPacific subpopulation. page 50

Mating is biannual and occurs along lagoons and nesting beaches. The season varies according to location. Females dig nests on the beach and lay clutches of eggs before returning to the water. Maturity is reached at around 20 years of age, though lifespan is currently unknown. Five locations are “super” nesting sites hosting over 1000 females each year. These are found in Mexico, the Seychelles, Indonesia, and Australia (home to two such sites). Hawksbills shells are in high demand for their distinctive patterning. This means there is a high amount of illegal hunting and trade. Like other sea turtles, this species is also vulnerable to bycatch. They are listed as critically endangered on the IUCN Red List. Flatback sea turtle Natator depressus Natator depressus has no known nesting beaches outside of Australia, though its feeding ranges extends out to Papua New Guinea and Indonesia. It is considered native to Australia and has the smallest range of all the sea turtles. Natator depressus dwells in the northern waters of Australia, staying close to the shore, or around the edges of bays. They have not been sighted around coral reefs. Weight is usually around 70 kg, and females are generally larger than males. Males have longer tales. The head is rounded, and generally an olive green colour. The carapace is also green, though the underbelly is pale, white or yellowish. The shell usually turns up around the edges, making N. depressus

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easy to identify. The carapace is generally thin; it is hypothesized that this affects range, with the threat of potentially damaging the carapace keeping these turtles away from coral reefs. Length is usually between .76 and .96 m. Diet generally consists of molluscs, jellyfish, and other marine crustaceans and invertebrates. Natator depressus is mostly carnivorous. Mating – and nesting – take place in the summer, in November and December. Females dig nesting holes and lay clutches of around 50 eggs, a relatively small number compared to other marine turtles. This may be due to the size of the young. Gestation is usually around 42 days. Sexual maturity can be reached as early as 7 and as late as 50 years of age. Young are quite large, with hatchling displaying a shell length of around 6 cm. This means N. depressus young have a higher chance of survival than young of other species. They are also strong swimmers, though most juveniles remain near the shore. Flatback young generally go to sea for a year, sometimes known as the “lost year”. There is currently no data on where these turtles go during this time. Lifespan is up to 100 years in the wild. This turtle is sometimes considered a tourist draw and is generally not hunted for human consumption. Their tendency to remain near the shore means they are not as affected by bycatch, and the size and strength of hatchlings increase the likelihood of survival. They are listed as vulnerable on the IUCN Red List. page 51

EXTINCT MARINE TURTLES Modern sea turtles are part of the order Testudines. The two living families of marine turtles Cheloniids and Dermochelyids have their origins in the late Jurassic and early Cretaceous, most likely diverging in the early Cretaceous. Four extinct genera have been recorded, so far. Cosmochelyds were present in Nigeria during the Eocene; Eosphargis during the early Eocene of Europe; Psephophorus in Eocene-Pliocene of Europe, North Africa and North America; and Pseudosphargis in late Oligocene of Germany. Current research suggests that the first true turtle ancestor hailed from South Africa, around 260 million years ago. It was likely a small, lizard-looking reptile called Eunotosaurus africanus. Eunotosaurus africanus possessed a proto carapace-like structure formed from the curvature of its ribs and skin. Around 220 million years ago Odontochelys semiestacea, appeared. This create evolved around the Chinese coastline. And with it came the plastron, the bottom shell of today’s turtles. Next comes Proganochelys, or the beast turtle. Appearing in the area between modern Thailand and Germany, this reptile had a plastron, but also developed upper armour and neck spikes. It appears that these protective structures developed in response to the evolution of dinosaurs. Proganochelys lived on land. Like modern turtles, it had a bony carapace and beaked mouth. Around 110 million years ago, the first semi-aquatic turtles appeared, mostly around the US. Over time, these animals

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developed into distinct freshwater and marine species. The armour further developed and refined from here. In terms of direct relatives to modern day sea turtles, the oldest ancestor appears to be from the Early Cretaceous (145 million years ago), Desmatochelys padillai, with modern sea turtles radiating around 110 million years ago. There are two distinct families of marine turtles. The Dermochelyidae, or leatherback turtles, descend from the Archelon. Archelon was a giant sea turtle, up to 4 m long, with a flipper span of almost 5 m – about the size of a compact car. Archelon gave rise to a number of descendants, which spread throughout the ocean. These included Alienochelys and Ocepechelon. When marine mammals came along, however – a group which included very large competitors such as whales – Archelon’s descendants lost their hold over the ocean and faded away. Modern day leatherbacks – Dermochelys coriacea – are the sole remaining member of this group. The Cheloniidae – or hard-backed turtles – come from other “stem-turtles”, or early turtle ancestors. This group developed a strong shell and streamlined body. The most likely ancestor of modern Cheloniidae turtles appears to be Ctenochelys acris, which dates back around 80 million years. This species, however, was still a blend of sea turtle characteristics and freshwater turtle characteristics. True sea water turtles appeared about 40 million years later. Turtles survived a mass climate event around 34 million years ago. It is after this that the specialisations we see in modern sea turtles began to appear, most likely page 52

due to climate and environment changes that affected feeding.

CROCODILES Crocodiles, alligators, caimans, and gharials (also known as gavials) are members of the Order Crocodilia. Crocodilians resemble enormous lizards, but they are very distinctive animals. Crocodilians are the only group of modern reptiles with a four-chambered heart like birds and mammals. Crocodiles are the oldest of the reptiles and the most successful. They range in size from the dwarf caimans which grows to 1.4 m, to the saltwater crocodile (Crocodylus propsus) which can be longer than 7m and weigh over a tonne. All are well-adapted to amphibious life. They possess a secondary palate, valves in the nostrils and throat, and a powerful tail for aquatic locomotion. The average life span is up to 70 years of age. Crocodilians eat a wide variety of prey, though research shows that they also routinely ingest stones. Early hypotheses suggested stone ingestion was intended as “roughage” to help with digestions, as seen in some bird species. Research from early 2019, however, suggests that crocodilians ingest stones to act in a similar manner to a diver’s weight belt; eating stones helps the animals remain underwater longer while their lungs still contain a reasonable amount of air. The researchers observed American alligators (Alligator mississippiensis) when underwater. Individuals who swallowed small rocks (~2.5% of overall bodyweight) stayed underwater

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significantly longer and showed an increase in diving time.

Differences between gharials, alligators, and crocodiles Although all in the same general group, these animals have obvious distinguishing features. Alligators have a U-shaped snout, and all teeth are hidden when the mouth is closed. Crocodiles, on the other hand, have a V-shaped snout; teeth are visible even when the mouth is closed. Gharials have a distinct, bulbous snout. Alligators do have a salt-excretion gland, but it is non-functional in modern day species. American Crocodile Genus Crocodylus Crocodylus acutus This crocodile is found in the Americas, with a range running from southern Florida to Peru. Populations are found on both the Pacific and Atlantic coasts. The American crocodile primarily lives in coastal areas and some salted environments, such as brackish lakes, marsh, and mangrove swamps. It is saltwater tolerant. A population of American crocodiles has been recorded in the hypersaline lake, Lake Enriquillo, located in the Dominican Republic. The Floridian population is small compared to populations found in Central and South America. They also live in freshwater environments, and are remarkably versatile, with the seeming ability to adapt to human-affected environments, with populations found near a Florida power plant. page 53

Size is moderate, with an average length of 3.5 m, though individuals as long as 7 m have been recorded. Males are generally longer than females. Colouring is brown; adults are olivebrown, while young are light brown. The skin shows some mottling. The head is narrow, and the snout is long. They appear to have fewer scales than other species within this genus. The lower jaw shows 28-32 teeth; the upper jaw has 30-40 teeth. Teeth are interlocking. Two long teeth jutting from the lower jaw are visible when the mouth is closed. Central and South American populations are generally larger than their North American counterparts. American crocodiles are adapted for night vision; they have protective eyelids, and irises which improve sight in the dark. The tail is quite long, and makes them powerful swimmers. Like the rest of this genus, American crocodiles are carnivorous. They are largely indiscriminate eaters, consuming fish, mammals, birds, crustaceans, and even insects. They will also eat turtles and amphibians (e.g. frogs). They will eat carrion, though this is uncommon. Like other crocodiles, they have slow digestive systems, meaning they can survive long periods without feeding. Breeding occurs once per year. The mating season runs from January to February. Males are territorial and compete for females. Males roar and display teeth; females respond to potential mates with roars. Gestation is 2 to 3 months, with females laying 30-60 eggs in nests during breeding season (April through May). Females dig nests above the high tide

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mark on the shore; females usually dig nests before mating season. Nests are covered with detritus and other decaying matter to provide warmth to the eggs. Nests are generally 1.5 m in depth, with a width of up to 2 m. Females do not remain with the nests but return regularly to check on progress. Visits occur more frequently close to hatching time. As hatching nears, the female with lay over the nest and listen for signs of hatching; when these are heard, the females will uncover the next, wait for the young, then usher them to the water. No further parental care is given. Young crocodiles are at risk from predators, with over 75% of the young perishing before the age of 4. Young remain hidden, appearing to forage for insects, until developed enough to fend for themselves out in the open. Sexual maturity occurs at 8-10 years of age. Sex is temperature dependent. Eggs will only hatch at 27.5ºC and above; males are more likely at temperatures of 31 to 33ºC; females are more likely at temperatures lower than 31ºC. Average lifespan is 60-70 years. American crocodiles are nocturnal and live mostly solitary lives. They dig burrows for times when the water level is low; in the dry season, they cover themselves in mud and lie, quietly lethargic, until the season changes. As ectotherms, they regulate body temperature through environment, lying underwater, out in the sun, or burying themselves in the mud as necessary. Research suggests that the preferred body temperature is approximately 25ºC. They are listed as of vulnerable on the IUCN Red List. page 54

Saltwater Crocodile Crocodylus porosus Also known as estuarine crocodiles, these are the largest extant reptiles on earth. Lifespan in captivity is approximately 40 years, and up to 70 years in the wild. It is suspected some specimens live to over 100 years in the wild, though this number remains unverified. Populations are found from southwest India through to eastern Sri Lanka, southeast Asia, the Philippines, Indonesia, and into Australia and the Solomon Islands. Saltwater crocodiles are strong swimmers, with sightings recorded as far out as Fiji. They can remain at sea for several weeks at a time. The snout is broad and short, usually a little less than half the width of the head. Colouring is golden-brown through to grey and black in adults, with some darker mottling over the skin in adults. Juveniles have darker spots and bands over the body; tails are darker, but colour fades as they age. The underbelly is pale. Length ranges from 3 to 5 m; males are longer than females. Saltwater crocodiles can run at a speed of 12-14 kph for short periods; this is generally seen when the crocodile is in danger. Saltwater crocodiles are opportunistic predators. Prey is usually proportional to body size, with larger specimens hunting birds, turtles, and even medium to large mammals (as such, this species is arguably the most likely to attack humans). Smaller specimens will usually live on insects and crustacea. There have been reports of cannibalism in

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some populations, and they will feed on carrion. Saltwater crocodiles rarely fully emerge for feeding; they lurk near the edges of the water, then dart out just far enough to grab the target. Small prey is crushed;

larger prey is dragged underwater, where it is broken into smaller pieces before feeding. The skull and jaw are fixed, which means these animals must “toss” the food about to make it easier to swallow. Leftovers may be stockpiled underwater or near mangroves.

Saltwater Crocodile (Crocodylus porosus) Saltwater crocodiles are nocturnal, but as opportunistic predators, they have been known to hunt during daylight hours. They regulate temperature by alternating sun and water exposure and are active all year. Ideal body temperature ranges up to around 35ºC; when even slightly higher than this, this species moves into shaded areas or submerges. The species appears to have some navigational skill, with reports of saltwater crocodiles finding their way back to original habitats after being moved. Saltwater crocodiles can also engage in unihemispheric sleep, which means they can stay awake with page 55

one half of their brain while the other sleeps. This means they are much more alert to potential threats. Breeding season begins with the wet season. Males compete for females, engaging in head snapping, growling, and fighting. Males may be seriously injured or die in competition over females. Females also begin nesting during the wet season. Females build nests close to water, clearing an area then building a mound of vegetation and dirt. Nests are always built near permanent water bodies. The mound can be as tall as 0.8 m and up to

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2.5 m in length. Nests are several metres apart; the female usually clears a space of around 20 m before construction. Females dig an “egg chamber” into the mound, where they lay around 50 eggs. Eggs are covered with more detritus for incubation. Optimum incubation temperature is 31-32ºC. Sex is temperature dependent; higher temperatures are more likely to produce males, while lower temperatures are more likely to produce females. If incubation temperature drops below 26-28ºC eggs may terminate or produced deformed young; the same is true if incubation temperature rises above 33-34ºC. Sexual maturity is reached at 10-12 years of age. Females guard the nests throughout the incubation period. Eggs hatch at around 90 days. Females carry young in their mouths until they reach water. Unlike American crocodiles, saltwater crocodiles remain with young until they can swim. This increases survival significantly. This is especially significant as saltwater crocodiles were hunted until close to extinction in the 1960s; in 2019, they are listed as of least concern on the IUCN Red List. It is important to note, however, that saltwater crocodiles are considered a vulnerable population in Queensland, Australia.

EXTINCT MARINE CROCODILES AND CROCODILE-LIKE GROUPS There are several now-extinct species of marine crocodile. The fossil record indicates that marine crocodiles entered the oceans during four separate colonisation events in the past. The first appears to have been around 180 million years ago. Like many modern reptiles, ancient marine crocodiles were heavily affected by their environment. Colonisations appear to have occurred around times the earth experienced global warming events, with extinctions coming during global freezing events. Like modern crocodiles, extinct species varied in size, weight and diet. Teleosaurids This group of extinct reptiles was similar to today’s gharial species, with long jaws. They lived in shallow waters and were spread throughout the world. Metriorhynchids This was a very specialised group of crocodyliforms, and one which may not have been affected by global warming events. They appear to date to the late Jurassic period. Pholidosaurids This group appears to have emerged during the middle Jurassic period, and become extinct in the late Cretaceous period. Dyrosaurids

Saltwater crocodile eggs nest

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Dyrosaurid fossils have been found the world over, and the fossil record shows

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over 12 species. They appear to have had both freshwater and marine species. Size and head shape vary widely. This group, though now extinct, is significant because they survived a mass extinction event, the Cretaceous-Paleogene event, during which around 75% of life on earth was extinguished.

MARINE LIZARDS There is only one known species of marine lizard, Amblyrhynchus cristatus, or the marine iguana. There are, however, fossil records suggesting a number of extinct marine lizards, particularly in the group Mosasauridae. Mosasaurs are sometimes referred to as extinct monitor lizards.

MODERN MARINE IGUANAS FAMILY: IGUANIDAE The marine iguana is a close relative of several land species found in the Galapagos Islands, and around the scattering of volcanic islands nearby. There are 11 known subspecies at the time of this writing, though it is important to note that classification may change as new data is discovered through research projects and genome mapping. The subspecies have been divided according to similarities in phenotype and genotype. These differences are generally seen in reasonably clear geographic distributions around the Galapagos Islands.

Species

Geographical Distribution within the Galapagos Islands

Amblyrhynchus cristatus cristatus

Isabela, Tortuga, Fernandina and their satellite islets

Amblyrhynchus cristatus wikelskii subsp. nov.

Santiago, Rabida and satellite islates

Amblyrhynchus cristatus hassi

Santa Cruz and its satellite islets

Amblyrhynchus cristatus mertensi

Southern part of Isla San Cristobal (Loberia), islets off the southern coast of the island

Amblyrhynchus cristatus trillmichi subsp. nov.

Santa Fe and satellite islets

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Species

Geographical Distribution within the Galapagos Islands

Amblyrhynchus cristatus godzilla subsp. nov.

Northern part of Isla San Cristobal (Punta Pitt) and satellite islets off northern coast of San Cristobal

Amblyrhynchus cristatus jeffreysi subsp. nov.

Wolf, Darwin< Roca Redonda and satellite islets

Amblyrhynchus cristatus hayampi subsp. nov.

Marchena and satellite islets

Amblyrhynchus cristatus nanus

Genovesa and satellite islets

Amblyrhynchus cristatus venustissimus

Espanola, Gardner, Floreana, Champion, and satellite islets

Amblyrhynchus cristatus sielmanni

Pinta and satellite islets

This species is found on the Galápagos Islands in the Pacific Ocean. These iguanas are unique amongst lizards as they have adapted to live and forage in the sea. Researchers hypothesize that a land iguana species in South America adapted to marine life after becoming “lost at sea”. It is speculated that this event occurred around 4.5 million years ago. They can dive to a depth of around 10 m. Males generally grow to 1.3 m in length and can weigh up to 1.5 kg. Like other reptiles, they are ectothermic, so they spend much of their time basking in the sun. The skin is dark in colour (grey to black), which means that they can absorb heat quickly and efficiently (other, variable colouration also appears, differing across subspecies). page 58

The scales are generally pyramid like along the dorsal side. Teeth are small and sharp, adapted for scraping algae off rock and rocky surfaces. Claws are long and sharp. Generally, marine iguanas have more blunted snouts than their land counterparts. The tail shows some lateral compression; this enables better movement in the water. Younger specimens show a lighter colour in the dorsal stripe. In the wild, marine iguanas can live to between 5 and 12 years of age. The head usually shows a white “crust” made up of salt, the result of a special salt-filtering gland in the nose. This salt is often sneezed out but can easily

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catch on and around the head. This gland is a unique adaptation in the marine iguana. With a diet primarily comprised of marine algae – much of which is consumed underwater – this lizard takes in large amounts of sodium during feeding. High amounts of salt (sodium) can lead to dehydration, even when surrounded by water; allowing the lizards to filter out the salt while keeping fluid intake intact, this special nasal gland is an essential part of the species’ survival. Marine iguanas are herbivores, feeding mainly on marine algae, along with some seaweed. Prior to feeding, marine iguanas must raise their body temperature to above 36°C/96.8°F. Feeding occurs largely underwater, in bouts of a few minutes at a time (though marine iguanas can spend up to 30 minutes under water at a time when not feeding). Marine iguanas breed annually, with the breeding season lasting around 3 months, from January through March. The females dig egg chambers of 0.3 to 0.8 m in depth, and lay eggs in groups of 1 to 4. Some larger, more aggressive females may steal almostfinished egg chambers from smaller females. Colouring can change during this season, with some subspecies showing red or turquoise in males ready to fight; fighting involves wrestling and head locking. In some cases, females may also show red colouration. Young emerge 3 to 4 months after egg laying. Sexual maturity is reached at around 2 years of age. As ectotherms, marine iguanas must spend time in the sun to raise body temperature. This is especially page 59

important in the marine iguana, which can only feed successfully when the body temperature is above 36ºC. Dark colouring helps with increasing temperature quickly and effectively. Marine iguanas are generally a solitary species, though they will huddle together at night to conserve warmth. Juveniles are especially vulnerable; population changes are seen during El Nino events, as increased water temperature reduces availability of marine algae and seaweed, the iguanas’ primary diet. There is no concrete data on the marine iguana population. They are vulnerable to predators, including: ●● Galapagos hawk ●● Striated Heron ●● Great blue heron ●● Short-eared owl

They are also at risk from feral species, including cats and dogs, and from rats. The eggs and young are especially vulnerable. They are considered a protected species by the Ecuadorian government. They are listed as vulnerable on the IUCN Red List.

EXTINCT MARINE LIZARDS The Mosasauridae were squamate reptiles (i.e. lizards and snakes) that radiated during the Late Cretaceous period (95-66 million years ago). Mosasaurs bore a similar shape to modern day lizards, such as

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the Komodo dragon. The bodies were longer than their modernday counterparts, however, with a more streamlined shape to improve swimming. Most of the swimming power came from the tail, which moved in a shark-like manner to propel them quickly and efficiently through the water. Jaws were hinged in two places, and the skull was most likely flexible, similar to the skulls found in modern day snakes. This flexibility meant mosasaurs could eat prey whole, or close to whole. The diet appears to have consisted of ammonites (common during the Cretaceous). They also ate several varieties of fish; larger mosasaurs also ate other marine reptiles. Recent research suggests this group observed prey before quick strikes, rather than chasing it around the ocean. Research further suggests that smaller mosasaurs may have made forays into freshwater environments when hunting. Larger mosasaurs were most likely apex predators, as a result of their size, speed, and strength. Another type of squamate reptile, the dolichosaurs, may also have been marine lizards. A fossil of Primitivus manduriensis was discovered in Italy in June 2018. Some intact soft tissue was recovered, allowing researchers to better examine the paddle-like limbs, scales, and more. This particular lizard appears to have lived around 70 to 75 million years ago and to have been abundant in shallow waters, its paddlelike limbs allowing it to move easily on both land and sea. The body is more elongated along the neck than modern day lizards.

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MARINE SNAKES There are over 70 species of sea snakes, where nearly 50% of them recorded in Australian waters. As they are cold-blooded most are found in coastal tropical waters of the Pacific and Indian Oceans, with high abundance and diversity off the coast of northern Australia and Indonesia. They are generally 1 metre long, however some have been recorded at more than 3 metres. With the invasion of the aquatic habitats by some terrestrial snake taxa, morphological adaptations evolved to overcome the selective pressure of such a high viscosity medium as water compared to the air – water is approximately 50 times more viscous than air. Consequently, all sea snakes have developed a paddle tail and eel-like body shape that is laterally compressed to adapt to an aquatic lifestyle. The ventral scales found on most other snakes is absent as are the muscular links. This means almost all sea snakes are unable to move on land, as the underbelly is exposed. (Sea kraits, the Laticauda spp., are a notable exception.) Just like whales and dolphins, sea snakes have adapted to the aquatic realm by developing physical traits more like fish than to their terrestrial counterparts. The way snakes move is based on propulsive force, resulting in forward progression movement due to the contraction mechanisms that push their bodies against the water. Marine snakes are all adapted to feed, breed and breathe in an aquatic environment. Sea snakes breathe

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through nostrils valves that close when underwater. Some species can stay below water for up to 80 minutes before coming up for air. They can dive to a depth of 100 metres or more. The lungs can extend the entire length of the body. This can assist with buoyancy, storing air when diving. Most true sea snakes can also respire through the skin. Sea snakes are carnivorous. Most feed on fish, but they can also feed on fish eggs and eels. Like sea turtles, sea snakes have a salt excretory gland under their tongue that help them to regulate the amount of salt in their bodies (osmoregulation). Most of these snakes are extremely venomous; venom is used to paralyze prey. Sea snake venom is the most potent venom known in the animal kingdom, however there has never been a recorded human death from a sea snake bite. Sea snakes have no natural predators in the ocean, which means they sometimes exhibit significant curiosity around humans. Most sea snakes are viviparous. Litter size can vary from 1 to 30 young; however, most sea snakes produce fewer than 10 offspring at any one time. The young are born in the water where they live their entire life. The young can be quite large, some being half the size of the mother. It is important to note the difference in “true” sea snakes, or elapids and other sea snakes. True sea snakes live entirely in the marine environment, in the water (with the exception of sea kraits). Other snakes commonly referred to as sea snakes may be able to move around on land and live in a variety of salty, brackish, and freshwater environments. page 61

True sea snakes, which cannot hunt on land, appear to have developed unique sensory abilities to help them locate prey. This is important because water affects the ability to perceive sound, visual information, and tactile information clearly. It is hypothesized that these snakes are able to detect changes in pressure, and even the electromagnetic field, though there is no data available as yet. One species of sea snake, Aipysurus laevis, has been found to have photoreceptors in its tail. Family Acrochordidae

File Snakes There are three dominant species in this family, all in the genus Acrochordus: Acrochordus arafurae (Arafura filesnake) Acrochordus granulatus (Little filesnake) Acrochordus javanicus (Javan file snake) File snakes have rough-looking skin due to a multitude of small scales and spiky protrusions that look like warts. The skin is baggy and fits loosely around the body. The bite is harmless to humans; these snakes have no poison. There is only one genus in this family. Also known as wart snakes, elephant trunk snakes and dog-faced snakes, acrochordidads are found throughout the tropical areas of Asia, including the western coast of India, Southeast Asia, the Phillipines, Indonesia, and into New Guinea. They are also found in northern Australia. Acrochordus granulatus is

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also found in marine environments and estuaries, while A. javanicus is found in freshwater and marine environments. Acrochordus arafurae appears to only inhabit freshwater. It is important to note that all snakes in this group move between land and water. Length ranges from 0.5 m in A. granulatus through to 2.7 m in A. javanicus. Small differences are seen between males and females. Head size is generally larger in females, accompanied by a thicker body and shorter tail. Diet is primarily fish; they will eat fish that has died from other causes. This group is susceptible to dehydration, which means they generally require access to freshwater. They taste waterbodies, such as lakes and ponds, to ensure they are freshwater. Some file snakes have been known to taken in up to 50% of their mass in freshwater when experiencing significant dehydration. This family is viviparous, meaning young are nourished through a placenta and yolk sac. Young are born live, into litters, in the water. Litters are between four and forty young, and reproduction occurs roughly every two years; for A. arafurae, reproduction may occur less often. This is due to changes in climate (e.g. drought) affecting suitability for mating and young bearing. This group spends most of its time in the water, but may move between bodies of water, or during times of strong tidal oscillation. They hunt at night and hide during the day. Hiding spots include mud, tucked in between roots, or small holes around the water. Specially adapted bristles in their spiky protrusions detect movement page 62

and changes in water, allowing them to easily locate prey even when it cannot be seen. Once prey is located, acrochordidads strike, then coil around prey to keep it still while eating. Prey is not choked prior to consumption. Family Colubridae This family consists of several subfamilies, including: ●● Dipsadidae ●● Grayiinae

Colubridae has over 200 genera spread out over its subfamilies and is the biggest known family to date. Fossil records show it dates back as far as the Oligocene, approximately 33.9 million to 23 million years ago. Colubridae are found all over the world, though there are no colubrids in Antarctica. Colubrids are generally aquatic or arboreal. The majority of snakes in this group are not harmful to humans. Reproduction can be both oviparous and viviparous. It is important to note that there are ongoing changes in this family, with subfamilies changing as more molecular data emerges. A noted member of this family is the genus Boiga. These snakes are found in aquatic areas, and around semi-aquatic environments such as saltmarshes and mangroves. Their distribution covers Asia, India, and Australia. Boiga spp. are mildly venomous. The venom gland is in the rear of the mouth. Diet is generally fish and frogs, though they may also eat crustaceans. Reproduction is viviparous.

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Subfamily Dipsadidae

Genus Hydrops

This is a very large subfamily of Colubridae, with over 90 genera and 700 species. Also known as the dipsadinae, this group is found throughout the Americas and West Indies.

Hydrops triangularis

This subfamily includes marine and land snakes. Dipsadids are small venomous snakes, though their venom is usually harmless to humans. Length ranges up to around .8 m. Dipsadids have been found in arboreal environments, terrestrial environments, and the water. The rear jaw contains larger, grooved teeth, which are used to inject venom into prey animals. Diet includes small mammals, birds, and reptiles, and varies according to location. Reproduction is generally oviparous (i.e. through egg-laying). Some genera have specialized feeding habits and adaptations. Several genera of marine dipsadids are listed below. Genus Farancia Farancia abacura (Mud snake) Farancia erythrogrammus (Rainbow snake) Genus Helicops Helicops angulatus (Brown-banded water snake) Helicops infrataeniatus Helicops scalaris

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Genus Leptodeira Leptodeira rubricata (Costa Rican cateyed snake) Genus Pseudoeryx Pseudoeryx relictualis Genus Tretanorhinus Tretanorhinus nigroluteus Tretanorhinus variabilis Subfamily Grayiinae Also referred to an African water snakes, this subfamily has only one genus, Grayia. They are found in the tropical areas around Africa. There is very little data about Grayiinae snakes. They appear to lack venom and are generally thought to be of little risk to humans. Distribution is generally throughout seasonal and permanent bodies of water, such as lakes, swamps, and streams. Diet includes fish and frogs. Limited studies on G. smythii suggest males may have longer tails than females. This group is oviparous, laying eggs across several nesting sites. Nests are generally dug into mast and other surrounding litter. Genus Grayia Grayia smythii (Smith’s African water snake)

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Grayia ornata (Ornate African water snake) Grayia tholloni (Tholloni’s African water snake) 

Cerberus dunsoni Cerberus microlepis Cerberus rynchops

Grayia caesar (Caesar’s water snake)

Cerberus schneiderii

Family Homalopsidae

Genus Djokoiskandarus

Rear-Fanged Snakes

Djokoiskandarus annulata (Banded water snake)

This group, once marked as a subfamily of Colubridae, is also known as the rearfanged snakes. They are also referred to as Indo-Australian water snakes and mud snakes. Snakes in this group may have mild venom. Some genera have special adaptations that likely help in their preferred environment. Bitia spp. have enlarged teeth along the inside of the upper jaw bones (palatine teeth). Dog-faced snakes (Cerberus spp.) are known to move across mudflats when the tide is low, moving in long, s-like motions (sidewinding). Both Fordonia and Gerarda rip up their prey prior to ingestion.

Genus Myrrophis Myrrophis bennettii (Bennett’s mud snake) Genus Fordonia Fordonia leucobalia (White-bellied mangrove snake) Genus Myron Myron karnsi Myron resetari Myron richardsonii

Genus Bitia

Subfamily Hydrophiinae

Bitia hydroides (Keel-bellied water snake)

True Sea Snakes, Elapid Snakes

Genus Cantoria Cantoria violacea (Cantor’s water snake) Genus Cerberus (Dog-faced water snakes) Cerberus australis

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This is a diverse group of snakes with around 16 genera, though classification and discovery are constantly changing. Snakes in this group are adapted for the marine environment. They are also known as venomous elapid snakes, as they are a subfamily of the elapid snakes, or Elapidae. They are distributed along the Indo-Pacific Ocean - extending from the western coast of India though Southeast Asia, including the Philippines

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and Indonesia, to New Guinea, northern Australia, the Bismarck Archipelago and the Solomon Islands. At first glance, members of this family may be mistaken for eels. The tail is paddle-like, and most species have compressed, eel-like bodies. Some species have especially strong venom, and all are poisonous; some are also extremely aggressive. Reports suggest bites are not especially painful. This means it can be hard to identify what has caused the envenomation in some individuals (e.g. sea snake vs jellyfish). The genus Laticauda (sea kraits) is notable as it can still move about on land, albeit in a limited fashion. Other sea snakes in this group are limited to marine environments due to a lack of ventral scales. Laticauda spp. do not have dorsal nostrils, but internasal scales. Sea kraits (Laticauda spp.) have also developed the ability to detect and respond to low pressures that precede tropical storms. Length is generally 1.2 m to around 1.5 m. Hydrophis spiralis has been recorded at 2.7 m. Eyes are usually small, and nostrils dorsal with valves to keep seawater out. Fangs are generally short. Scales generally do not overlap, though there are exceptions. Tails are usually flattened. Adaptations include a special valve to keep water out, while the trachea can be “pulled” upward so that it opens into the roof of the mouth. This means snakes can keep most of the head under the water when surfacing to breathe. Many species can take in oxygen through the skin. Hydrophiinae can also “spit” salt out through the tongue through the use of special glands beneath and around the tongue sheath. Sea snakes shed page 65

regularly – more often than their land counterparts. Sea snakes also require freshwater for drinking. As such, they have physiological and behavioural traits to help them to detect rainfall. When surfaced, snakes’ “taste” the water, flicking the tongue to identify its salt content before drinking. Chemical cues and sensory oral papillae are present to help them to identify water salinity. Some will still drink water if raindrops reach up to 30% of seawater whereas others up to 50% seawater. A few experiments have been conducted with different species of sea snakes where researchers captured the movement of their tongue while drinking water and observed that snakes can tolerate long dehydration periods. Diet includes fish and some eels. They rarely eat invertebrates. Most are benthic foragers, feeding on demersal fish, crabs and fish eggs. Many show preferences for particular types of prey. With the exception of the sea kraits (Laticauda spp.) snakes in this group are all viviparous, meaning they have live births. Litters range from 1 to 30 young; the average is 10 young per birth. Reproduction is generally once every 2 years. Sexual maturity is reached at around 3 years in males, and 4-5 years in females. Mating is generally in winter. The gestation period is long. According to a study conducted by the IUCN, International Union for Conservation of Nature (2009), 67 species of sea snakes (Laticaudinae and Hydrophiinae) and 8 species of Acrochordid snakes were considered to be at risk of extinction (9% of true sea snakes), and 53% were reported as ‘least concern’.

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Sea snake, Sea Krait (Laticauda laticaudata)

Genus Aipysurus

Disteira walli (Wall’s sea snake)

Aipysurus eydouxii (Spine-tailed sea snake)

Genus Enhydrina

Aipysurus laevis (Olive sea snake) Astrotia stokesii (Stoke’s sea snake) As reef-dwellers, snakes in this genus generally have overlapping scales (imbricate scales) to protect against coral. Aipysurus laevis opens nostril valves inwards, which keeps sea water out of the lungs during dives. Genus Disteira Disteira major (olive-headed or greater sea snake) Disteira nigrocincta

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Enhydrina schistosa (Beaked sea snake, hook-nosed sea snake, common sea snake, Valakadyn sea snake) Enhydrina zweifeli (Sepik or Zweifel’s beaked seasnake) Snakes in the genus Enhydrina are generally aggressive. Environment is generally estuarine, though they are also found in lagoons. The “beak” in their name comes from the deep notch between the lower jaws, giving these snakes the appearance of a beak-like snout. This jaw adaptation appears to help the snake eat spiny catfish and puffer fish, as the jaw can open wider than the jaws of other marine snakes.

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Genus Hydrophis Hydrophis belcheri (faint-banded sea snake, Belcher’s sea snake)

Hydrophis mamillaris (Bombay sea snake) Hydrophis melanocephalus (Slender-necked sea snake)

This species is found in the Indian Ocean, the Gulf of Thailand, Vietnam, Indonesia and New Guinea, and Australia. It is yellow or greyish above, yellow-whitish below, dark or black bands. Head dark with olive spots or yellowish marks on the prefrontal area of the head and surrounding the eye.

Hydrophis obscurus (Russell’s sea snake)

Hydrophis bituberculatus (Peters’ sea snake)

Hydrophis spiralis (Yellow sea snake)

Hydrophis brooki

Hydrophis stricticollis (Collared sea snake)

Hydrophis caerulescens (Dwarf sea snake)

Hydrophis ornatus (Ornate reef sea snake) Hydrophis semperi (Garman’s sea snake)

Hydrophis viperinus

Hydrophis cantoris

Genus Kerilia

Hydrophis cyanocinctus (Annulated sea snake, blue-banded sea snake)

Kerilia jerdonii (Jerdon’s sea snake)

Hydrophis fasciatus (Striped sea snake) Hydrophis gracilis (Graceful small-headed sea snake, slender sea snake) Hydrophis inornatus (Plain sea snake) Hydrophis klossi (Kloss’ sea snake) Hydrophis lapemoides (Persian Gulf sea snake)

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Genus Kolpophis Kolpophis annandalei (Bighead sea snake) Genus Lapemis Lapemis curtus (Shaw’s sea snake) Lapemis hardwickii (Hardwicke’s spine-bellied sea snake) Genus Laticauda Laticauda colubrina (Colubrine sea krait, yellow-lipped sea krait)

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Laticauda laticaudata (Blue-lipped sea krait) Genus Pelamis Pelamis platurus (Yellowbelly sea snake, pelagic sea snake) This snake is notable for how it attacks its prey. Large groups of these snakes have been drifting along the water; this is thought to be a hunting strategy. Solitary snakes hunt by floating atop the water, then swimming backwards and lunging at prey. It is possible these snakes sense vibrations, and that this helps their attack strategy.Venom is quite potent. Genus Thalassophis Thalassophis anomalus (Anomalous sea snake)

EXTINCT MARINE SNAKES Lepidosaurs were reptiles closely related to lizards, snakes and tuatara. They lived around 240 million years ago, during the Middle Triassic period. The fossils predate all other lepidosaur records by 12 million years. this group lie the squamates, the largest order of reptiles. Snakes and lizards are included in this group. The fossil records of the squamate family shows the divergence between anguimorphs, iguanians, and advanced snakes dates back to around 200 million years ago, in the Late Triassic/ Early Jurassic. In 2018, researchers found a species of the lepidosaur genus Megachirella in the Italian alps, which lived during the Middle Triassic, around 240 million years ago, is a stem-squamate (squamate ancestor). This means it is page 68

the oldest squamate – around 75 million years older than previous specimens -- and so the oldest ancestor of marine snakes and lizards researchers have. Research into bone structures of modern and fossil snakes, however, suggests that the first snakes were probably burrowers, though they may also have been comfortable in aquatic environments. That said, the long, elongated body of snakes – which is well-suited to eel-like swimming – means some researchers still think snakes evolved in an aquatic environment first. The answer is likely a little of both – studies of snakes and their relatives are limited by availability of modern specimens and fossils alike. In fact, it is quite difficult to track the evolution of squamates due to a gap in the fossil record. This gap – of around 70 million years – lies between the oldest known fossils, and the time they likely originated.

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