More info: Tortoises are found on all continents except for Antarctica and Australia. With nearly 50 species spread across more than 15 genera, tortoises vary widely in terms of size, color, and other characteristics.

Turtles and tortoises are believed to have first appeared around 220 million years ago.

Tortoises are cold-blooded, animals with high-domed shells, or carapaces. The only species with a flat shell is the pancake tortoise. Their shells consist of 59 to 61 bones that are covered by plates called scutes. Tortoise shells are made up mostly of keratin, and tortoises are able to sense pain through their shells just as people can sense pain through their fingernails.