Snake
. Snake (reptile), legless animal with a long, flexible body covered with overlapping scales. Snakes are reptiles , a diverse group of animals that also includes lizards , turtles , and crocodiles . Snakes are thought to have evolved from lizards and share many characteristics with this group—particularly the so-called legless lizards, which have tiny, almost imperceptible legs. But unlike most lizards, snakes have thin, forked tongues, and they lack external ears. And while most lizards have movable eyelids that periodically close to protect and lubricate the eyes, a snake’s eyes are always open, protected by immobile, transparent scales. Like all reptiles, snakes are cold-blooded, or more correctly, ectothermic—that is, they cannot produce their own body heat. Instead, they rely on the sun to heat their bodies and then regulate their temperature with behavior. Because they do not rely on energy from food to generate body heat, snakes can survive on an extremely meager diet. Some wait