Exploring the world of reptiles And AMphiBiAns

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2 Exploring the world of REPTILEs AND AMPHIBIANS

3 Copyright 2009 The Brown Reference Group plc All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval systems, without permission in writing from the publisher. For information contact: Chelsea House An imprint of Infobase Publishing 132 West 31st Street New York, NY Library of Congress Cataloging-in-Publication Data Green, Jen. Exploring the world of reptiles and amphibians / authors, Jen Green, Richard Spilsbury, Barbara Taylor. p. cm. Includes index. ISBN (hardover) ISBN (e-book) 1. Reptiles Encyclopedias, Juvenile. 2. Amphibians Encyclopedias, Juvenile. I. Green, Jen. II. Spilsbury, Richard, III. Taylor, Barbara, IV. Title. Project Editor: Sarah Eason Designer: Paul Myerscough Picture Researcher: Maria Joannou Indexer: Angela Anstey-Holroyd Cartographer: Darren Awuah Design Manager: David Poole Managing Editor: Miranda Smith Editorial Director: Lindsey Lowe Consultant Editor John P. Friel, Ph.D. Curator of Fishes, Amphibians and Reptiles Cornell University Museum of Vertebrates Ithaca, New York Authors Jen Green; Richard Spilsbury; Barbara Taylor QL644.2.G dc22 Chelsea House books are available at special discounts when purchased in bulk quantities for businesses, associations, institutions, or sales promotions. Please call our Special Sales Department in New York at (212) or (800) You can find Chelsea House on the World Wide Web at Printed and bound in China For The Brown Reference Group plc

4 Contents Introducing reptiles and amphibians 8 Reptile and amphibian family tree 10 Adder 12 African sand snakes 16 Alligator snapping turtle 18 Alligators 22 American alligator 24 American bullfrog 28 Anaconda 30 Armadillo lizard 34 Asian horned frog 36 Australian toadlets 38 Australian water-holding frog 42 Axolotl 44 Blind snakes 46 Blue-tongued skink 48 Boas 52 Bush squeaker 56 Bushveld rain frog 58 Caecilians 60 Caiman lizard 64 Caimans 66 Cane toad 68 Cape skink 72 Chameleons 74 Clawed toads 80 Cobras 82 Common frog 86

5 Common toad 88 Congo eels 90 Copperhead 92 Coral snakes 94 Crocodiles 98 Darwin s frog 102 Dragon lizards 104 Eastern box turtle 108 Eastern newt 1 0 Edible frog 1 2 Eyed lizard 1 4 File snakes 1 6 Fire salamander 1 8 Fire-bellied toads 122 Flying frogs 124 Flying lizards 126 Frogs and toads 128 Galápagos giant tortoise 134 Garden lizard 138 Garter snakes 140 Geckos 144 Gharial 148 Ghost frogs 150 Giant galliwasps 152 Giant plated lizard 154 Giant salamanders 156 Glass frogs 162 Glass lizards 164 Golden-tailed gecko 166

6 Grass snake 168 Great South American river turtle 172 Green iguana 174 Green toad 176 Green tree python 178 Green turtle 182 Harlequin toads 184 Hellbender 186 Horned lizards 188 House snakes 192 Iguanas 194 Indian cobra 198 Jungle racer 200 Komodo dragon 202 Kuhl s flying gecko 206 Leaf frogs 208 Leatherback turtle 212 Leopard gecko 214 Leopard tortoise 216 Lizards 218 Loggerhead turtle 224 Malaysian tree toad 226 Mambas 228 Mantellas 230 Marine iguana 232 Matamata 236 Mexican burrowing frog 238 Midwife toads 240 Milksnake 242

7 Monitor lizards 246 Monkey-tailed skink 250 Mudpuppy 254 Namaqua chameleon 256 Natterjack toad 258 Newts 260 Night lizards 264 Olm 266 Painted turtle 268 Panther chameleon 270 Pipe snakes 272 Plumed basilisk 276 Poison dart frogs 278 Puff adder 284 Pythons 286 Rain frog 290 Ratsnakes 294 Rattlesnakes 296 Red salamander 302 Reticulated python 304 Rough-skinned newt 306 Salamanders 308 Saltwater crocodile 314 Sand lizards 316 Sandfish 318 Sea snakes and sea kraits 320 Sharp-ribbed newt 326 Sidewinder 328 Sirens 330

8 Skinks 332 Slimy salamander 336 Slow worm 338 Smooth newt 340 Snakes 344 Spadefoot toad 350 Spotted turtle 352 Surinam toad 354 Tegu 356 Terciopelo 358 Thorny devil 362 Tiger salamander 364 Tokay gecko 366 Tomato frog 368 Tortoises 370 Treefrogs 374 Tuatara 378 Turtles 380 Vipers 384 Viviparous lizard 388 Wall lizards 390 Water frogs 394 Whiptails 398 Worm lizards 402 Xenosaurs 406 Glossary 410 Further resources 413 Picture Credits 414

9 INTRODUCing reptiles AND AMPHIBIANS Reptiles are some of the most feared animals on this planet. But only a few species are so deadly that they could kill someone. Most would rather run or slither away. What unites them all is that they are all cold-blooded creatures with scaly skin, which they shed to grow and replace worn-out skin. Reptiles cannot regulate their own body temperature, so they bask in the sunlight to warm up. Most reptiles lay eggs on the land, but a few species keep the eggs inside their bodies and then give birth to live young. With the exception of the crocodilians, most reptiles do not care for their young. Like the reptiles, amphibians are cold-blooded animals. They are the link between animals that live in water and those that live on land. The majority of amphibians start their lives as eggs in the water. The eggs hatch as tiny larvae, which breathe in the water using gills. Through an amazing transformation called metamorphosis, these aquatic larvae become land-dwelling adults that breathe air through their lungs. Most amphibians also have the ability to breathe through their smooth, moist skin. When you read books or surf the Internet to find information about reptiles and amphibians you might come across the word herpetology. Scientists often use this word to describe the study of reptiles and amphibians. Herpetology comes from the Greek word herpeton, meaning creeping animal. Exploring the World of Reptiles and Amphibians From adders to xenosaurs, these six volumes of Exploring Reptiles and Amphibians contain more than one hundred articles that look at the amazing world of reptiles and amphibians. Some of the articles focus on a single species, such as the Indian cobra or Komodo dragon. Others talk about larger groups of reptiles or amphibians, such as lizards, snakes, or turtles. These overview articles are highlighted in bold typeface within the table of contents for each volume. Each volume has a number of useful features, such as a family tree, which shows how reptiles and amphibians fit into the animal kingdom, how they are related to one another, and provides cross references to articles in this set; a glossary of terms used throughout the set; a further resources page, which includes information about good books to read or Web sites to visit; and a volume-specific index. Volume 6 contains a complete set index. Within each article you will find a Fact File box, which summarizes the main features of the reptile or amphibian. It provides information about the breeding habits, coloration, diet, size, and status of a reptile or amphibian. Other items include Did You Know? boxes, which highlight some amazing facts about specific reptiles and amphibians, and box features that take a closer look at one interesting aspect of the creature in question. Throughout the book, large, colorful photographs and illustrations increase the reader s enjoyment and understanding of the world of reptiles and amphibians.

10 Family ties Above each Fact File in every article there is a color bar that highlights in which particular group the reptile or amphibian belongs. There are four main groups of reptiles: crocodilians; snakes and lizards; turtles, terrapins, and tortoises; and tuataras. So there are four color codes for the reptiles. Amphibians are divided into three main groups: frogs and toads; newts and salamanders; and the wormlike caecilians. So there are three color codes for the amphibians. Just look at the color code to figure out in which group the animal belongs. CROCODILIANS SNAKES AND LIZARDS turtles, terrapins, tortoises TUATARAS FROGS AND TOADS NEWTS AND SALAMANDERS CAECILIANS World Conservation Union (IUCN) The World Conservation Union (IUCN) is the largest and most important conservation organization in the world. It aims to protect the natural world by promoting the conservation of animals and plants that are threatened with extinction. A living creature may be placed in one of the following categories in the IUCN Red List of Threatened Species: Extinct there is no reasonable doubt that the last member of the species has died Extinct in the wild the species survives only in captivity, in cultivation, or as a population well outside its past range Critically endangered facing an extremely high risk of extinction in the wild Endangered facing a very high risk of extinction in the wild Vulnerable facing a high risk of extinction in the wild Near threatened likely to qualify for a threatened category in the near future Least concern is not threatened Data deficient there is not enough information available to make an assessment The IUCN status for the reptiles and amphibians in this book is highlighted at the foot of the Fact File panel in every entry. Classifying reptiles and amphibians Scientists like to group reptiles and amphibians into categories in which all the animals share certain body features. This is called classification. Animals that share body features are likely to be closely related because they have similar genes, which are the instructions found inside cells that tell the animal what to do. The family tree overleaf shows the relationships between all the different reptiles and amphibians. All the reptiles belong to the class Reptilia, while all the different amphibians belong to the class Amphibia. Scientists divided each class into several large groups, called orders, which contain more closely related reptiles or amphibians. In turn, each order comprises smaller groups called families. Families contain genus groups, which are collections of species the smallest family unit. Reptiles or amphibians belonging to the same species can breed to produce offspring.

11 REPTILE AND AMPHIBIAN FAMILY TREE Animals with a backbone (PHYLUM Chordata, SUBPHYLUM Vertebrata) ANIMAL KINGDOM (Animalia) The numbers below refer to volume and page numbers where a particular animal or group of animals is discussed in an article. CROCODILIA (Alligators 1:18; Crocodiles 2:26) CLASS: BIRDS (Aves) REPTILES (Sauropsida) AMPHIBIANS (Amphibia) FISH (Osteichthyes bony fish, Chondrichthyes cartilaginous fish) MAMMALS (Mammalia) ALLIGATORS (American alligator 1:20; Caimans 1:62) REPTILES CROCODILES (Gharial 3:8; Saltwater crocodile 5:38) TUATARAS (6:34) (Lizards 4:10) SAURIA SQUAMATA (Snakes 5:68) SERPENTES WORM LIZARDS (6:58) CHELYDRIDAE (Alligator snapping turtle 1:14) CHELIDAE (Matamata 4:28) TESTUDINES (Turtles 6:36, terrapins, tortoises 6:26) CHELONIIDAE (Green turtle 3:42; Loggerhead turtle 4:16) DERMOCHELYIDAE (Leatherback turtle 3:72) AMPHIBIANS EMYDIDAE (Eastern box turtle 2:36; Painted turtle 4:60) PELOMEDUSIDAE (Great South American river turtle 3:32; Spotted turtle 6:8) TESTUDINIDAE (Galápagos giant tortoise 2:62; Leopard tortoise 4:8) CAECILIANS (1:56) ANURA (Frogs and toads 2:56) Ambystomidae (Axolotl 1:40; Tiger salamander 6:20) Congo eels 2:18 Giant salamanders 3:16 (Hellbender 3:46) CAUDATA (Newts 4:52 and salamanders 5:32) Newts 4:52 Salamandridae (Eastern newt 2:38; Fire salamander 2:46; Rough-skinned newt 5:30; Sharp-ribbed newt 5:50; Smooth newt 5:64) Plethodontidae (Red salamander 5:26; Slimy salamander 5:60) Proteidae (Mudpuppy 4:46; Olm 4:58) 10 6

12 AGAMIDAE (Dragon lizards 2:32; Garden lizard 2:66; Flying lizards 2:54; Thorny devil 6:18) ANGUIDAE (Giant galliwasps 3:12; Glass lizards 3:24; Slow worm 5:62) CHAMELEONS 1:70 (Namaqua chameleon 4:48; Panther chamelon 4:62) CORDYLIDAE (Armadillo lizard 1:30) GECKOS 2:72 (Golden-tailed gecko 3:26; Kuhl s flying gecko 3:66; Leopard gecko 3:74; Tokay gecko 6:22) GERRHOSAURIDAE (Giant plated lizard 3:14) IGUANAS 3:54 (Green iguana 3:34; Horned lizards 3:48; Marine iguana 4:24; Plumed basilisk 4:68) LACERTIDAE (Eyed lizard 2:42; Sand lizards 5:40; Viviparous lizard 6:44; Wall lizards 6:46) NIGHT LIZARDS 4:56 SIRENS 5:54 SKINKS 5:56 (Blue-tongued skink 1:44; Cape skink 1:68; Monkey-tailed skink 4:42; Sandfish 5:42) TEIIDAE (Caiman lizard 1:60; Jungle racer 3:60; Tegu 6:12; Whiptails 6:54) VARANIDAE (Komodo dragon 3:62; Monitor lizards 4:38) XENOSAURS 6:62 BLIND SNAKES 1:42 BOAS 1:48 (Anaconda 1:26) COLUBRIDAE (African sand snakes 1:12; Garter snakes 2:68; Grass snake 3:28; House snakes 3:52; Milksnake 4:34; Ratsnakes 5:18) Arthroleptidae (Bush squeaker 1:52) Bombinatoridae (Fire-bellied toads 2:50) Bufonidae (Cane toad 1:64; Common toad 2:16; Green toad 3:36; Harlequin toads 3:44; Malaysian tree toad 4:18; Natterjack toad 4:50) Ghost frogs 3:10 ELAPIDAE (Cobras 2:10; Indian cobra 3:58; Coral snakes 2:22; Mambas 4:20; Sea snakes and sea kraits 5:44) FILE SNAKES 2:44 PIPE SNAKES 4:64 PYTHONS 5:10 (Green tree python 3:38; Reticulated python 5:28) VIPERS 6:40 (Adder 1:8; Copperhead 2:20; Puff adder 5:8; Rattlesnakes 5:20; Sidewinder 5:52; Terciopelo 6:14) Glass frogs 3:22 Mantellas 4:22 MEGOPHRYIDAE (Asian horned frog 1:32) Microhylidae (Bushveld rain frog 1:54; Tomato frog 6:24) Midwife toads 4:32 Myobatrachidae (Australian toadlets 1:34) Pipidae (Clawed toads 2:8; Surinam toad 6:10) Poison dart frogs 4:70 Rain frog 5:14 Rhacophoridae (Flying frogs 2:52) Rhinodermatidae (Darwin s frog 2:30) RHINOPHRYNIDAE (Mexican burrowing frog 4:30) Spadefoot toad 5:74 Tree frogs 6:30 (Australian water-holding frog 1:38; Leaf frogs 3:68) Water frogs 6:50 (American bullfrog 1:24; Common frog 2:14; Edible frog 2:40) 117

13 ADDER The adder is the only venomous snake in Britain and northern Europe. This shy northern viper is one of the world s most successful snakes, found living throughout Europe and Central Asia. It can even survive in the extreme cold of the Arctic. 12

14 Snakes and Lizards Adders can be found living in many habitats, including moors and heaths, mountains, woodland clearings, and even grassy banks beside railway lines. The number of adders in a habitat depends on how much prey is available, but may be as high as 100 adders per acre. An adder habitat is a dry meadow with lots of bushes and open areas for basking (warming up in the sun). Adders usually bask in a coiled position. At first, they are loosely coiled, with their bodies flattened to absorb as much heat as possible through their undersides. The adders coil more tightly as they warm up. Colors and Stripes The adder is easy to recognize from the dark, zigzag markings along its back. These marks break up the outline of its body, making it hard to see in the shadow of bushes. One rare form of the adder has a continuous black line along its back instead of the usual zigzag, or sometimes the line may be broken up into separate blotches. There is also an all-black form of the adder. Black adders are more common in colder, northern parts of the adder s range, particularly on some of the small islands in the Baltic Sea. Fact File ADDER Vipera berus Family: Viperinae (subfamily Viperinae) Order: Squamata Where do they live?: Europe and Central Asia Habitat: From mountains and moorlands to grasslands and forests Size: Head body length in. (61 76 cm); weight lb. ( kg); females are larger than males Coloration: Dark zigzag stripe on lighter gray or brown background Diet: Reptiles, birds, frogs, small mammals, and invertebrates Breeding: 3 18 young, born after gestation period (pregnancy) of 112 days Life span: About 10 years; possibly up to 20 years Status: Abundant in places Food and Feeding Adders usually feed on small vertebrates (animals with backbones), such as young birds, lizards, or mice. The adder has a large head and a rounded snout, with a distinct X or V marking on the top of the head. Adders have vertically slit pupils in each eye. 13

15 ADDER DID YOU KNOW? The name adder comes from the Anglo-Saxon word naedre, which means creeping thing. Hundreds of adders may hibernate together. A baby adder is about the size and shape of an earthworm when it is born, but it can still give a poisonous bite. An adder s bite does not usually kill people since its venom is weaker than that of other vipers. They may ambush or attack prey, keeping very still and then suddenly stretching their head forward to deliver a poisonous bite through hollow fangs. Once they are warm, however, adders often go in search of food, poking their heads into birds nests, burrows, and crevices. Sometimes, adders climb into low bushes in search of birds nests. With large prey, such as mice, shrews, and voles, the adder bites and then releases the animal, which soon dies from the effects of the poison. The adder has to follow the scent trail of the dying animal before it can start to feed. Winter Sleep Adders usually hibernate (go into a deep sleep) through the five coldest months of the year. This sleep can last for up to eight months in the northernmost parts of the adder s range. Males usually emerge from hibernation earlier than females. Both males andâ females shed their dull winter skin after hibernation. The males follow the scent trails left by the females to find a mate. When an adder strikes its prey, it delivers a dose of venom through its hollow fangs. It waits for the venom to take effect before swallowing its prey. This avoids injuries caused by struggling with the prey. 14

16 Snakes and Lizards Life Cycle The courtship display of the adder consists of the male-crawling along the female s back, rubbing her with his chin. Sometimes, the male has to fight off a rival male before he can mate with the female. Females may also mate with more than one male. Pregnant females spend a lot of time basking, since the warmth of the sun helps the young snakes to develop inside the mother s body. The duller color of the female helps to protect her from predators, such as birds of prey, while she basks. The female gives birth in late summer. Newborn adders do not feed in the first year of their birth. They can survive on the goodness of the yolk sac stored inside their stomachs. The young adders take about three to four years to mature into adults but only-about 10 percent of them will survive long enough to raise young of their-own. Out in the cold The adder lives farther north in the world than any other species of snake. Adders can survive in cold places partly because of their small size and dark color, which allow them to warm up more quickly in the sun than larger, lightercolored snakes. Female adders also keep their eggs inside their bodies until they hatch. This makes it easier for the females to keep their eggs warm while they develop. They give birth to live snakes, which are more likely to survive in cold places than a clutch of eggs. Adder Wrestling Match Male adders fight each other to stand a better chance of mating with a female. During this show of strength, the two males twist the front part of their bodies around each other and rear up in the air. Each male tries to force his rival down to the ground, rather like a wrestling match. The winner is usually the largest adder, which then chases away his rival. The dark body of the adder helps it absorb as much heat from the sun as possible. 15

17 AFRICAN SAND SNAKES African sand snakes are alert, fast-moving snakes that hunt during the heat of-the day. They can often be seen speeding across roads and tracks in front of vehicles. These common snakes have a strong venom, but they rarely bite people. 16

18 Snakes and Lizards With their narrow heads, long tails, and long, slim bodies, African sand snakes move swiftly through their grassland and dry scrubland habitat in search of their prey. These snakes can change direction rapidly and maintain high speeds over long distances. Larger sand snakes can sustain speeds of 6 miles per hour. African sand snakes often raise their heads off the ground to get a better view of their surroundings and can move along in this position as well. African sand snakes hunt mainly lizards. They use their large eyes to track their prey by sight, then chase it down, grip the lizard firmly in their jaws, and kill it with a lethal dose of venom. Some African sand snakes are good climbers and scale bushes to take young birds from their nests. Larger species can overcome prey as large as mice and shrews. Tails and Scales African sand snakes are one of the few kinds of snakes that can break off their tail to escape from predators such as birds, small mammals and African file snakes, which eat other snakes. Unlike lizards, however, African sand snakes cannot grow a new tail to replace the one they have lost. Another unusual behavior is the way the African sand snakes polish their scales by covering them with an oily substance from their nostrils. This may help to seal their scales and protect the snakes from drying out in the scorching heat. Fact File AFRICAN SAND SNAKES Family: Colubridae; subfamily Psammophinae (23 species) Order: Squamata Where do they live?: Africa, Middle East, and Pakistan Habitat: Tropical grassland, mountain grassland, and dry scrub Size: Head body length 31 in. to 5.9 ft. (80 cm to 1.8 m) Coloration: Gray, brown, or olive, often with light or dark stripes; some species have intricate markings on head and neck Diet: Lizards, birds, frogs, and small mammals Breeding: Female lays up to 30 eggs, which hatch after days Life span: Not known Status: Varies, most species locally common Sand snakes use their slender bodies to move with great speed. They use their large eyes to track lizards and other prey across the African scrub. 17

19 ALLIGATOR SNAPPING TURTLE The alligator snapping turtle is the heaviest freshwater turtle. It is named for its powerful snapping jaws and the bumpy ridges on its shell, which look like the big, tough scales on the back of an alligator back. 18

20 Turtles, Terrapins, Tortoises The muddy-brown color of the alligator snapping turtle camouflages (disguises) it against the bottom of deep, dark, slow-moving rivers. This turtle often feeds during the day and eats almost anything, from fruit and nuts to birds, fish, mammals. Alligator snapping turtles can even overcome and eat smaller turtles, such as the common musk turtle and their smaller relatives, the common snapping turtles. The alligator snapping turtle is a poor swimmer, and it is too big and bulky to chase after its prey. Instead, it is an ambush predator, sitting still and waiting for its prey to pass within reach of its powerful, hooked jaws. This turtle also has a clever way of luring prey into its mouth. By pumping blood into its tongue, it creates a thin red strip, which it moves to make it look like a wriggling worm. When prey animals come to eat the worm, the turtle snaps shut its massive jaws. The alligator snapping turtle has a keen sense of smell, which helps it to find the decaying remains of dead animals in the river. It also eats a lot of plant matter, such as acorns and persimmons. It gathers the fruits and nuts as they fall into rivers from trees and bushes overhanging the water. Eggs and Nests Alligator snapping turtles mate in the spring, between February and April. Mating lasts between five and twenty-five minutes and takes place under the water. Fact File ALLIGATOR SNAPPING TURTLE Macroclemys temminckii Family: Cehlydridae Order: Testudines Where do they live?: Central and southeastern North America Tropic of Cancer Habitat: Slow-moving rivers Size: Shell length 26 in. (66 cm); weight 219 lb. (99.5 kg) Coloration: Dark brown Diet: Fruit, nuts, shellfish, fish, birds, other turtles, and small mammals Breeding: Up to 50 eggs in a clutch; eggs hatch after 100 days Life span: years Status: Vulnerable to rare in many places, protected locally The alligator snapping turtle is one of the largest freshwater turtles in the world. It lives in the rivers and streams of the southeastern United States. 19

21 ALLIGATOR SNAPPING TURTLE DID YOU KNOW? Alligator snapping turtles are strong enough to catch prey such as raccoons and wood ducks, dragging them underwater to drown them. One of these turtles was trained to find dead people in the waterways of Indiana. The nest chamber of the alligator snapping turtle may extend more than 12 inches under the ground. When they mate, the male uses his sharp claws to hold onto the female s shell and releases a steady stream of bubbles from his nose. If several males gather near one female, they often behave aggressively toward their rivals to drive them away. When the female is ready to lay her eggs, she drags her heavy body out of the water and digs a nesting chamber with her back feet. She starts by digging a large pit and then lowers her body down into the hole. She then digs a smaller hole at the bottom of the large one and lays the eggs there. The female produces one clutch of eggs each year. The number of eggs depends on the size of the female. Larger females lay larger clutches of up to fifty eggs, while smaller ones lay only about ten eggs. The eggs are hard and round, with smooth shells. Alligator snapping turtles do not look after their nests, which can sometimes be raided by predators such as raccoons. Baby Turtles It takes about 100 days for the eggs to hatch, and most of the young turtles emerge from their eggs in September or October. Higher nest temperatures cause more females to hatch out of the eggs than males. The hatchlings make their way to the water, where they are often caught and eaten by predators such as alligators, adult alligator snapping turtles, or gar fish. Mossbacks Many large alligator snapping turtles look like they have green shells and are nicknamed mossbacks. The green color is due to a dense covering of algae (not moss). The algae grow when the turtles spend a lot of time in shallow water. Sunlight falls on their backs, warming them up and triggering the growth of the algae. To attract prey, such as fish, the turtle pumps blood into its tongue. This makes the tongue look like a worm, which draws in the fish. 20

22 Turtles, Terrapins, Tortoises fearsome flippers Once they have grown into adults, alligator snapping turtles are very dangerous for people to handle. As well as their strong jaws, these large turtles also have extremely powerful flippers, which end in sharp claws. They can even bite chunks out of boats when people try to lift them on board. Despite the dangers, alligator snapping turtles were once heavily hunted to make turtle soup. In some areas, hunting continues to be a problem for these formidable reptiles. Water pollution has forced them to change their diet, and the turtle population has also been reduced as people continue to drain rivers and swamps. 21

23 ALLIGATORS The armor-plated alligators are survivors from a prehistoric age. These fearsome reptiles are members of the crocodile family, along with caimans, crocodiles, and gharials. There are two true alligators alive today the American alligator and the Chinese alligator. How can you tell an alligator and a crocodile apart? It is not always easy, but when an alligator closes its mouth, all its bottom teeth are hidden. One large bottom tooth can still be seen in the closed mouth of a crocodile. Alligators also usually have wider, shorter, and more rounded snouts than crocodiles. This allows alligators to tackle a wider range of prey, including birds and mammals. Crocodiles have narrow, pointed snouts, which are more suited to eating fish. 22

24 In addition to the physical differences, the two crocodilians have some behavioral differences. Alligators can survive in cooler places than crocodiles. During the winter, alligators become sluggish and rest at the bottom of a waterway or burrow into a riverbank. They only emerge when the weather is warm. Alligators can even survive in the water under a layer of ice, as long as they keep a breathing hole open. They-do lose their appetite in the winter, however, and may stop eating if the temperature is too low for them to digest their-food. Chinese Alligator Smaller than the American alligator, the Chinese alligator lives only in the Yangtze River valley of China. It is critically endangered, with a total population of 150 individuals. Chinese alligators are being bred in captivity in China and overseas, with the hope of returning some captive-born alligators to the wild. Fact File Alligators Family: Alligatoridae Order: Crocodilia Where to they live?: American alligator in the southeastern United States; Chinese alligator in the Yangtze River Valley in China Habitat: Rivers, marshland, and swamps Size: American alligator Head body length 13 ft. (4 m); weight 550 lb. (249 kg). Chinese alligator 7 ft. (2.1 m); weight 88 lb. (40 kg) Coloration: Dark green-black; Chinese alligator has lighter patterns Diet: Snails, mussels, clams, fish, turtles, birds, small mammals Breeding: American alligator eggs; Chinese alligator eggs. Hatchlings emerge after 2 months Life span: years Status: American alligator least concern; Chinese alligator critically endangered Alligators and Caimans Alligators are represented by the caimans in both Central and South America. Caimans have the same rounded snouts as true alligators, and their lower teeth are hidden when their mouths are closed. However, caimans are usually much smaller (apart from the black caiman) and have sharper, longer teeth. Most American alligators are pale brown to green. The body of the alligator appears much greener if it lives in water full of algae. 23

25 AMERICAN ALLIGATOR Once on the brink of extinction, American alligators have made a comeback. They are now a key species in their swampy environment. American alligators use their powerful tails to move swiftly through the water, and they can run faster than a person on the land. 24

26 crocodilians American alligators help plants and other animals to thrive by digging gator holes using their tail and snout. These deep pits fill with water and provide temporary reservoirs for a variety of wildlife in the dry season. Plants always grow well around gator holes because of the rich mud that the alligators dig up and deposit around the edges of the holes. Regular paths worn by alligators also create channels through which water can run into marshlands when it rains heavily. Lazy Lifestyle American alligators can move quickly over short distances when they have to. Most of the time they float on the surface of the water, looking more like logs than living reptiles. In this lazy position, the alligators can spot and ambush prey. They can also warm up in the sun without leaving the water. They absorb heat into their blood through bony swellings on their back called osteoderms. The dark color of the American alligator also helps it to absorb heat easily, which is especially useful during the colder winter months. Fact File american alligator Alligator mississippiensis Family: Alligatoridae Order: Crocodilia Where do they live?: Southeastern United States Habitat: Rivers, marshland, and swamps Size: Head body length 13 ft. (4 m); weight 550 lb. (249 kg) Coloration: Dark green-black Diet: Snails, mussels, clams, fish, turtles, birds, small mammals Breeding: Female lays eggs, which hatch after 2 months Life span: years Status: No longer endangered least concern Teeth and Feeding The mouth of an American alligator contains approximately eighty teeth. As the old teeth wear out or break, new ones growing in the jaw underneath push up to replace them. Teeth last for around two years and are replaced throughout the life of the alligator. The gaping mouth of the American alligator reveals rows of sharp teeth. Alligators open their mouth in this way to cool down in the heat. 25

27 AMERICAN ALLIGATOR DID YOU KNOW? The American alligator can run at speeds of up to thirty miles per hour over very short distances. The roar of an American alligator can be heard over one mile away. The American alligator s eggs will not survive if they are left underwater for more than twelve-hours. They grow more slowly in older alligators. Without a mouthful of sharp teeth, older alligators may have difficulty holding on to their prey and may even face starvation. American alligators can kill people. Alligators are not usually a major threat, but now that their numbers have increased, they do come into conflict. Attacks usually happen when alligators are caught unawares or threatened. Older alligators are more likely to attack people as they are an easy target. Feeding alligators is dangerous, since they come to associate people with food. Courting Gators Male and female American alligators live on their own for most of the year but come together to mate in the spring. Males fight each other to win their own special area, called a territory, and they bellow loudly to attract females. Males also give off a strong, sweet smell, which is very attractive to female alligators. Females visit the territories of several males between March and May. After she has laid her eggs, the female stays close to the nest for about two months, guarding it from raccoons and other predators. When she hears yipping calls inside the eggs, she digs them out and carries them to water in her mouth. The hatchlings are about 9 inches long and are more brightly colored than the adults. They stay in a group, called a pod, near to their mother until they are about two years old. 26

28 crocodilians During this time, their mother tries to protect them from predators, such as large male alligators, birds, and fish. Back from the Brink In the first half of the twentieth century, up to ten million American alligators were killed for their valuable skins. However, the trade in alligator skins, teeth, and meat is now controlled and alligator numbers have increased due to conservation measures. These include taking some eggs from the nests of wild alligators, hatching them on alligator farms, and then returning some of the young alligators back to the wild. There are now more than 150 farms in various states, including Florida, Louisiana, and Texas. Rearing alligators in captivity has helped to increase understanding of their biology. In turn, this has helped to develop better ways of managing wild alligator populations. Better habitat management has made larger areas available to alligators and the wildlife living alongside them. There are still some concerns, however. One problem is water pollution from factories, which has included poisonous metals, such as Alligators spend most of their time basking in the heat of the sun. mercury. Alligators are at the top of the food chain, so the poisons build up in their bodies as they eat more and more contaminated prey. Since alligators live for such a long time (at least fifty years), the long-term effects are unknown. Dry nest sites Adult American alligators can grow up to 13 feet, but their babies are only 9 inches long when they hatch out. In June or July, a female American alligator chooses a dry nesting site near the water. She piles up plant material to a height of about 6 inches. In the middle of this mound of plants, the female digs a hole and lines it with mud. She lays her eggs in the hole and then seals them up inside the mound. As the plants rot, they give off heat, which warms the eggs and helps them to develop. Higher temperatures encourage more male alligators to develop. 27

29 AMERICAN BULLFROG American bullfrogs are the largest of all the frogs in North America, with a huge appetite to match their size. Males are famous for their loud, bellowing calls, which they use to attract females to their territory in spring. 28

30 Frogs and Toads The American bullfrog spends almost all of its life in or near water, floating just below the surface or basking at the water s edge. These frogs control their body temperature by warming up in the sunlight or cooling down in the shade or in the water. At night, bullfrogs come onto land to forage for food. Bullfrogs are sensitive to danger, however, and will quickly jump into the water if they are disturbed on land. With their heavily webbed back feet, and long, powerful back legs, bullfrogs can swim several feet with just one or two kicks. They can also make huge leaps of 3 to 6 feet to hide among plants on land. In the spring and early summer, male bullfrogs come ashore to call for a mate. The males call the females from the water and mating takes place. The female lays thousands of eggs, which hatch as tadpoles. The tadpoles then gradually change into adults in a process called metamorphosis, which can take up to two years. Food Feast Bullfrogs eat a variety of prey, including insects, lizards, snakes, and small mammals. They even eat frogs, including other bullfrogs. They are attracted to the distress calls of frogs, probably in the hope of finding an easy meal. Usually, bullfrogs sit and wait for their prey to come within striking range of their long, sticky tongue. They lunge towards their prey and may use their short legs to push food into their mouth. Fact File AMERICAN BULLFROG Rana catesbeiana Family: Ranidae Order: Anura Where do they live?: North America; introduced into parts of Europe, Central America, and Asia Habitat: Ponds and lakes Size: Snout toe length in. (9 20 cm); 36 in. (90 cm) stretched out; weight up to 7.25 lb. (3.3 kg) Coloration: Mottled olive, brown, or green above; legs, chin, and throat have dark markings Diet: Large invertebrates (animals without backbones) and small vertebrates, including other frogs Breeding: Female lays around 11,000 eggs (80,000 in a lifetime), which hatch after 4 days Life span: 5 9 years in the wild; up to 16 years in captivity Status: Least concern The American bullfrog is a large aquatic frog. Most are green or brown with darker blotches on the back, with a yellow or white underside. 29