The bog or mud turtles grow no larger than 4 inches long. The sea-roving turtles are more than 6.5 feet in length and weigh more than 1,100 pounds. The alligator snappers of the southeastern United States reach weights of more than 110 pounds. They are among the largest freshwater turtles.
Turtles carry a protective shell.
The upper arched part is called the carapace. The flat bottom part is called the plastron. The shell is made of horny plates or a rough leathery skin that functions like a skeleton. Turtles have a horny beak, but they do not have teeth. Their powerful jaws and claws are used for defense.