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.
Reptiles and Amphibians
Reptiles are Vertebrates
They have an internal skeleton with a backbone.
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
lizard eating its
shedding its 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
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.
Lizard in egg
Reptiles Lay Eggs
Is it an Alligator or a Crocodile?
There are over 4,675 lizards species in six families:
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.
Northern Water Snake
There are about 4,000 species of amphibians.
The major amphibian groups are:
1. Frogs and Toads
3. Caecilians (she-SILL-yens)
(a legless, salamander-type animal)
Amphibians are Vertebrates
They have an internal skeleton and a backbone.
Bull Frog Skeleton
Amphibians 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 Toad
Amphibians 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.
Amphibians Shed their Skin
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.
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.
Metamorphosis of a Frog
Embryos beginning to split in two
Adult frogs with spawn (jellylike eggs)
Tadpoles still in spawn
The younger tadpoles still have their gills. The older tadpoles have lost their gills and are breathing with lungs.
The back legs have grown a little.
The back legs are just starting to develop.
The back legs are developed.
This froglet is now
8 weeks old. It still has its tail, but it looks almost like an adult.
The front legs are now present.
Salamanders 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.
Frogs and Toads