Reptiles are animals that have dry, scaly skin and breathe by using lungs. There are thousands of kinds of reptiles. They include alligators, crocodiles, lizards, snakes, turtles, and the tuatara. Most reptiles are harmless to humans.
Reptiles are cold-blooded. That means that their body temperature changes with the temperature around them. To stay alive, reptiles need to avoid very hot or very cold temperatures. Although most of them live in the tropics, reptiles live on every continent except Antarctica.
Scientists divide reptiles into four main groups. They are lizards and snakes, turtles, crocodilians, and the tuatara.
Lizards and snakes make up the largest group of reptiles. Most lizards have four legs and long tails. Most also have ear openings and movable eyelids. Snakes have tails of different lengths. However, they have no legs, eyelids, or ear openings.
Turtles are the only reptiles with shells. Turtles can pull their heads, legs, and tails into their shells for protection.
Crocodilians include alligators, caymans, crocodiles, and gavials. All of them live in or near water. They have long snouts, strong jaws, and webbed back feet. They use their long, powerful tails to swim.
The tuatara is found only on several islands off the coast of New Zealand. The tuatara looks like a lizard, but it is more closely related to dinosaurs. Dinosaurs died out about 65 million years ago.
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