Tortoises are reptiles related to turtles and terrapins. They are some of the most ancient reptiles alive. Tortoises are shielded from predators by a shell. Tortoises can be as small as a few centimetres to two metres. They tend to be most active around dawn and dusk, and otherwise keep out of the sunshine and are normally hard to find.

Most species of tortoises lay small clutches of eggs. Eggs take about half a year to hatch. Tortoises lay their eggs at night in a shallow scrape, and then cover them with soil or sand. Tortoises hatch fully formed using an egg tooth to break out of the shell. The young of commonly eat worms or insect larvae for additional protein, although they may be come plant-eating only when they are fully grown.

The number of concentric rings on the shell can give a clue to how old the animal is, However, tortoises that have regular food and water will grow steadily and evenly and have no growth rings. Only those in places where food and water become scarce will have rings, as they grow when water and food are available, and stop growing when they are not.

Some tortoises live in places where there is a cycle of drought every few years, and they have adapted to it. They have very large bladders that can hold water for very long periods of time.