There are over 6,800 reptile species including alligators and crocodiles, turtles and tortoises, snakes, and lizards. Reptiles are ectothermic vertebrates with scaly skin and internal skeletons. They lay shelled eggs and undergo little development from hatching to adulthood. Amphibians include over 4,000 species of frogs, salamanders and caecilians. They are also ectothermic vertebrates but have permeable skin and undergo metamorphosis from aquatic young to terrestrial adults. Both groups shed their skin and use environmental heat to regulate their body temperature.

1. Reptiles and Amphibians

2. Reptiles

3. There are 6,800 reptile species on earth.
The major reptile groups are:
• Alligators and Crocodiles
• Turtles and Tortoises
• Snakes
• Lizards

4. Reptiles are Vertebrates
They have an internal skeleton with a backbone.

5. 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

6. 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

7. 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

8. Reptiles 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.

9. 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

10. 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.

11. 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.

12. There are over 4,675 lizards species in six families:
Iguanas
Chameleons
Monitors
Skinks
Geckos
Gila Monsters
Lizards

13. 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 food
in their fat tails.
Some lizards (geckoes) have special feet which allow
them to hold on to walls, ceilings, etc.
Lizards

14. 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

15. 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.

16. Amphibians

17. 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)

18. Amphibians are Vertebrates
They have an internal skeleton and a backbone.
Bull Frog Skeleton Toad Skeleton

19. Amphibians are Ectothermic
Couch’s Spadefoot Toad
Tiger 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.

20. 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

21. 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!

22. Amphibians 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.

23. Amphibians 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.

24. 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

25. 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.

26. 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.

27. •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