Reptile

Reptile, cold blooded vertebrate with dry, scaly skin. Reptiles can be found in a wide variety of habitats, including the sea and points north of the Arctic Circle, but most live in the tropics. There are no reptiles in Antarctica. There are about 6,000 species of reptiles. They range in size from 2 in (5 cm) to 30 ft (9 m). They breathe through lungs and are cold blooded, meaning that their body temperatures vary with external conditions making it necessary for reptiles to seek conditions favorable to their metabolisms. Most reptiles lay eggs. Certain snakes and lizards retain the eggs in their bodies until the young hatch, and they are born live. The major species of reptiles are lizards and snakes, turtles, crocodilians, and tuatoras. The last are related to the now-extinct dinosaurs and live on islands off the coast of New Zealand. Lizards and snakes account for some 3,000 species, among them certain venomous types. The turtles comprise some 250 species and some are among the longest lived of all animals. Crocodilians include alligators, caymans, crocodiles, and gavials, about 20 species altogether. Most reptiles live by eating other animals and are descendants of the dinosaurs, or giant reptiles.