Alligators and crocodiles are reptiles.

Reptiles are four-legged animals related to snakes. They are different to amphibians (and so no NOT include frogs and toads) because they lay eggs that hatch as small adults on dry land, whereas amphibians lay eggs in water and have a larva stage (ie. frogs have tadpoles which are quite different from the adults).

The reptiles are divided into four groups. They are the crocodiles (including alligators), turtles, lizards and snakes.

The crocodiles are the largest reptiles. They have powerful jaws with many teeth. Some members of the crocodile group are called alligators. They are very similar to crocodiles but have blunter heads and more teeth (see the book links below).

Turtles are reptiles with shells. Many of the animals in this group live in water. The leathery turtle, for example, lives in the sea, while the terrapin lives in fresh water. Some members of this group live on land and are called tortoises. The shell protects the turtle's body. Many turtles can also draw their head and limbs into their shell when attacked by a predator.

Most lizards are quite small reptiles, but the largest, called the Komodo dragon, may be three metres long.

Snakes are reptiles that do not have any limbs. Some snakes kill their prey by injecting poison into them when they bite. The python and the boa constrictor kill their prey by wrapping their body around it. They hold their prey tightly and stop it breathing. They do not go as far as crushing their prey to death as some people think.