3Alligators and Crocodiles There are 6,800 reptile species on earth.The major reptile groups are:Alligators and CrocodilesTurtles and TortoisesSnakesLizards
4Reptiles are Vertebrates They have an internal skeleton with a backbone.
5Reptiles Have Dry, Scaly Skin Reptiles have tough, dry, scaly skin made of keratin (what fingernails are made of) that protects them from drying out. The large scales of turtles, tortoises, and crocodilians are called scutes.
6Reptiles shed their skin to grow bigger. Snakes shed their skin all in one piece, turning it inside out as they shed. The skin is left in one piece and looks like a tube. An adult snake will shed two to five times a year. A young snake will shed more often as it grows faster.Most lizards shed their skin in pieces. That often begins withthe skin splitting down the lizard’s back. A rapidly growing lizard might shed every two weeks. Legless lizards shed theirskins like a snake.Corn Snake shedding its skinGreen Anolelizard eating itsshed skinLeopard Geckoshedding its skin
7Crocodiles and alligators have large scales (scutes), which are shed individually . A turtle’s skin is shed like a lizard’s. The hard shells of most turtles are not shed. Instead new layers are added to the underside of their shells. The age of the turtle can be determined by the number of rings on its shell’s scutes.Scutes on a live AlligatorAlligatorScute FossilsTurtle Scutes
8Reptiles are Ectothermic Most reptiles are ectothermic - they use their environment to warm and cool their bodies. If they are cold, they must lay in the sun to raise their body temperature. If they get too hot, they must find shade to cool off. Many reptiles are active at night, so they can avoid becoming too hot and having their skin dry out.
9SnakeLizard in eggTurtleReptiles Lay EggsReptiles produce tough, leathery shelled eggs that keep moisture and warmth in and predators out. Most reptiles lay their eggs in a place where they will be kept warm and humid. Some reptiles keep their eggs inside their bodies and then give birth to live young. Most reptiles lay their eggs and then leave them.
10Reptile Babies Look Like Little Adults Reptiles possess most of their adult characteristics at the time of hatching. Unlike most amphibians, they do not undergo a larval stage or experience metamorphosis.
11Is it an Alligator or a Crocodile? American Alligator8 to 13 feet long800 to 1,000 pounds (males)70 to 80 teethBroad, U-shaped snoutsBottom teeth are not visible when the mouth is closedBrown, gray, or nearly blackLife span: 30 to 35 yearsLive mostly in fresh water swampsMothers assist babies in hatching. Young stay with mother for a few months.American Crocodile13 to 16 feet long800 to 1,100 pounds (males)60 to 66 teethLong, slender V-shaped snoutsLower teeth are visible when themouth is closedDull grayish-green or olive-green colorLife span: 60 to 70 yearsLive in brackish and saltwater wetlandsMothers assist babies in hatching. Young areready to be on their own right away.
12Lizards There are over 4,675 lizards species in six families: Geckos IguanasMonitorsChameleonsGila MonstersSkinks
13LizardsLizards have different types of diets. Some eat only plants (herbivores), some eat only insects or small mammals (carnivore), and some eat both plants and animals (omnivores).Some lizards (such as whiptails) lose their tails when they feel threatened. The lost tail distracts the predator so the lizard can get away. The tail grows back later.Some lizards (Gila monsters) store foodin their fat tails.Some lizards (geckoes) have special feet which allow them to hold on to walls, ceilings, etc.
14There are about 2,600 species of snakes. Most snakes are not venomous. All snakes can bite, swim, climb,and drink water.Snakes only strike people in self-defense.Most baby snakes are able to care forthemselves from the time they are born.All snakes are carnivores (meat eaters).Their hundreds of tiny vertebrae and ribsallow them to be very flexible.Northern Water Snake
15Tortoisesare turtles that live on hot dry land, andgo to water only to drink or bathe.mostly have high domed shells.have elephant shaped legs.have round stumpy feet for walking and digging burrows.eat low growing shrubs, grasses,and cacti.do not have teeth, but they do have a sharp beak.Turtlesspend most of their lives in water.have low domed shells.have webbing between theirtoes for swimming.can be carnivores (meat), herbivores (plants), or omnivores (both.)do not have teeth, but they have as sharp beak.
17There are about 4,000 species of amphibians. The major amphibian groups are:1. Frogs and Toads2. Salamanders3. Caecilians (she-SILL-yens)(a legless, salamander-type animal)
18Amphibians are Vertebrates They have an internal skeleton and a backbone.Toad SkeletonBull Frog Skeleton
19Amphibians are Ectothermic Amphibians are ectothermic - they use their environment to warm and cool their bodies. If they are cold, they must lay in the sun to raise their body temperature. If they get too hot, they must find shade to cool off. Many amphibians are active at night, so they can avoid becoming too hot and having their skin dry out.Couch’s Spadefoot ToadGreen FrogTiger Salamander
20Amphibians Have Special Skin Amphibians have thin, permeable skin. This means the skin lets water pass into their bodies easily. Many amphibians don’t need to drink water. Animals that don’t live near the water absorb enough water from the moist soil they live in. Their thin skin also allows them to absorb oxygen. This is helpful for the animal because they have small lungs.Tiger SalamanderBull Frog
21Amphibians Shed their Skin Frogs, toads, and salamanders have thin skins that they shed regularly.They shed their skin in one piece.Once the skin is shed, they eat it!
22Amphibians Lay Their Eggs in Water Amphibian eggs don’t have shells. Instead they are protected by a clear, jellylike substance and must be kept it water or in wet conditions.
23Amphibians Go Through Metamorphosis Young amphibians do not look like they will when they are adults.Amphibian means "double life" in Greek. Most amphibians start life in the water and then, through metamorphosis, develop into adults that live mostly on land.During metamorphosis the animals’ bodies will have many changes.
24Metamorphosis of a Frog Embryos beginning to split in twoAdult frogs with spawn (jellylike eggs)Tadpoles still in spawnThe younger tadpoles still have their gills. The older tadpoles have lost their gills and are breathing with lungs.
25The back legs have grown a little. The back legs are just starting to develop.The back legs are developed.This froglet is now8 weeks old. It still has its tail, but it looks almost like an adult.The front legs are now present.
26Salamander with gills. Their heads are not as large as a frog tadpole. Salamander MetamorphosisSalamanders in eggs.Salamander with gills. Their heads are not as large as a frog tadpole.Salamander with gills.The front legs develop first.This adult salamander is now able to live on the land. Salamanders like to stay under moist leaves and rocks.
27Frogs and ToadsFrogs have ridges along the sides of their backs, narrower bodies and faces and large eardrums.They have moist, smooth skin.Frogs have teeth.They have long, powerful legs. Most frogs have webbed hind feet and pointed toes.They lay their eggs in clusters of single eggs.They live mostly in water.Their tongues are attached in the front of their mouths, so they can reach far to catch prey.They jump long distances to get away from predators.Most have mild poison glands, which don’t protect them much from predators.Toads have plump bodies with large glands on the sides of their faces.They have dry, warty (bumpy) skin.Toads do not have teeth.They have plump, shorter, less powerful legs (for walking).They lay their eggs in long chains. A few toads give birth to live young.They live on land as adults. Toads return to the water to lay eggs.Their tongues are attached at the back of the mouth.Toads have stronger poison glands for protection. In some species, the poison is strong enough to kill dogs and cats.