Reptiles and Amphibians

Reptiles

There are 6,800 reptile species on earth. The major reptile groups are:

• Alligators and Crocodiles• Turtles and Tortoises

• Snakes• Lizards

Reptiles are Vertebrates

They have an internal skeleton with a backbone.

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.

Reptiles Have Dry, Scaly Skin

Reptiles 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 with the skin splitting down the lizard’s back. A rapidly growing lizard might shed every two weeks. Legless lizards shed their skins like a snake.

Corn Snake shedding its skin

Leopard Gecko shedding its skin

Green Anole lizard eating its shed skin

Crocodiles 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 Alligator

Alligator Scute Fossils

Turtle Scutes

Reptiles are EctothermicMost 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.

Reptiles 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.

Lizard in egg

Snake

Turtle

Reptiles Lay Eggs

Reptile 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.

  

Is it an Alligator or a Crocodile?American Crocodile•13 to 16 feet long•800 to 1,100 pounds (males)•60 to 66 teeth•Long, slender V-shaped snouts•Lower teeth are visible when the mouth is closed•Dull grayish-green or olive-green color•Life span: 60 to 70 years•Live in brackish and saltwater wetlands•Mothers assist babies in hatching. Young are ready to be on their own right away.

American Alligator•8 to 13 feet long•800 to 1,000 pounds (males)•70 to 80 teeth•Broad, U-shaped snouts•Bottom teeth are not visible when the mouth is closed•Brown, gray, or nearly black•Life span: 30 to 35 years•Live mostly in fresh water swamps•Mothers assist babies in hatching. Young stay with mother for a few months.

There are over 4,675 lizards species in six families:

Iguanas

Chameleons Monitors

Skinks

Geckos

Gila Monsters

Lizards

Lizards 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.

Lizards

Snakes• There 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 for

themselves from the time they are born.

• All snakes are carnivores (meat eaters).

• Their hundreds of tiny vertebrae and ribs

allow them to be very flexible.

•

Northern Water Snake

Turtles•spend most of their lives in water.•have low domed shells.•have webbing between their toes for swimming.•can be carnivores (meat), herbivores (plants), or omnivores (both.)•do not have teeth, but they have as

sharp beak.

Tortoises•are turtles that live on hot dry land, and go 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.

Amphibians

There are about 4,000 species of amphibians.

The major amphibian groups are:

1. Frogs and Toads

2. Salamanders

3. Caecilians (she-SILL-yens)

(a legless, salamander-type animal)

Amphibians are Vertebrates

They have an internal skeleton and a backbone.

Bull Frog Skeleton Toad Skeleton

Amphibians are Ectothermic

Couch’s Spadefoot ToadTiger Salamander

Green Frog

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.

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.

Amphibians Have Special Skin

Tiger Salamander Bull Frog

Amphibians 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!

Amphibians Lay Their Eggs in WaterAmphibian eggs don’t have shells. Instead they are protected by a clear,

jellylike substance and must be kept it water or in wet conditions.

Amphibians Go Through MetamorphosisYoung 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.

Metamorphosis of a Frog

The younger tadpoles still have

their gills. The older tadpoles have lost their gills and are

breathing with lungs.

Adult frogs with spawn (jellylike eggs) Embryos beginning to split in two Tadpoles still in spawn

The back legs are just starting to develop.

The back legs have grown a little.

The back legs are developed.

The front legs are now present.

This froglet is now

8 weeks old. It still has its tail, but it

looks almost like an adult.

Salamander Metamorphosis

Salamanders in eggs.

Salamander with gills. Their heads are not as large as a frog tadpole.

This adult salamander is now able to live on the

land. Salamanders like to stay under moist leaves and

rocks.

Salamander with gills.

The front legs develop first.

•Frogs 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.

Frogs and Toads