Turtle Tracks Photo courtesy of Mark Seaver . Natural History of Turtles Turtles are fascinating animals that carry their homes around on their backs. They have a hard shell, called a carapace, that encloses all their internal organs. Tortoises are turtles that retract their heads into their shells by pulling their neck into an S-shaped curve.
Some turtles hide their heads by bending their necks sideways.
Turtles vary in size. Small North American box turtles can be six inches long, while the huge leatherback sea turtles can reach eight feet in length. Turtles do not have teeth. While some turtles are vegetarians, most are omnivorous. Turtles lay their eggs in sand or dirt.