One of a series for younger readers which helps them to recognize and define the huge variety of life on earth, this book questions the definition of a reptile. It describes the characteristics reptiles have in common with each other and what makes them different from other types of animals. It explains that reptiles can be divided into four main groups. First there are the turtles and tortoises of which there are more than 200 different types. Their bodies are protected inside a shell and they have four legs. The next group, snakes and lizards, have long bodies and skin covered in small, overlapping scales. They usually have large mouths and tongues that are forked or have a notch in the end. Lizards mostly have four legs, but there are a few that don't have any legs at all. All snakes are legless, although some show signs of tiny legs near their tails. The third group, crocodiles and alligators are very large reptiles. Their bodies have bony plates like armour in the skin along their backs. They have heavy jaws lined with pointed teeth, long powerful tails and short legs.
Finally, there is a reptile called the tuatara which looks like a lizard but is in fact a different type of reptile and is the only living member of a group of reptiles that lived around 200 million years ago. To cover all aspects of these groups of reptiles this book describes their methods of heat control, skin appearance, teeth and jaws, methods of getting around, sight and sound, taste and scent, defenses, feeding and breeding habits, parental care and their safety in the modern world.