There are about seven thousand species of reptiles, belonging to the four main groups: turtles and tortoises; snakes; lizards and worm-lizards; crocodiles, alligators, caimans, and gavials, and tuataras. Reptiles live in all continents of the world except Antarctica. Unfortunately, many of them are losing their homes, and unless we take action to save them, the oldest living animals in the world may soon become extinct.