Turtles, tortoises, and terrapins are all members of the super order of Chelonia and as such are classified as chelonians. Most people refer to the reptiles in this order as turtles, though there are differences between them. Chelonians are characterized by the shell extending from their ribs, called a carapace. The carapace is comprised of bone or cartilage. Like other reptiles, turtles are cold-blooded, meaning they draw their warmth from their surroundings. Although some turtles are water-dwelling animals, they breathe air and lay their eggs on land. Aquatic turtles...