Shell The evolutionary success of the turtle is said to be largely attributed its shell. Turtles, unlike other reptiles, have a shell which serves as a natural suit of armor. Sea turtles are the only species of turtles that cannot pull their head, legs and tail into their shell. The shell is made up of three parts. The upper part of the shell that covers the turtle's back is called the carapace, which has two layers. The inner layer of the carapace is actually part of the skeleton and consists of bony plates that are fused to the ribs. The outer layer of the carapace is formed from skin tissue. Among hard-shelled turtles, this layer of skin forms hard, horny shields called scutes. Soft-shelled turtles, like the leatherback sea turtle, do not have scutes. They simply have a tough layer of skin covering their back. The part of the shell covering the underside of the turtle is the plastron. Some turtles have a hinged plastron, which allows these species to close their plastron tightly against the carapace when they retract into their shell. A bony structure called the bridge runs along both sides of the turtle's body, joining the carapace and the plastron. Most land turtles, or tortoises, have a high, domed shell. Marine turtles have much flatter shells offering a streamlined surface, so they can swim easily. Some turtles have very plain black, brown or green shells. Others have more elaborate shells with green, orange, red and/or yellow markings. Head For protection, most turtles have hard scales covering their head. Beak Turtles do not have teeth. Instead, they have a hard, sharp beak which is used to cut and tear their food. Most carnivorous (meat-eating) turtles have powerful jaws, allowing them to capture and crush their prey. Legs and feet The legs and feet vary among turtle species. Tortoises, or land turtles, have short, club-like legs and feet. Most aquatic turtles have longer legs with webbed feet. The legs of a sea turtle are like long paddles and have flippers instead of feet. Hips and shoulders Unlike any other animal on earth, the turtle's hip and shoulder bones are inside its rib cage. This allows turtles (except sea turtles) to pull their legs inside their shell. Tail Turtles have short, pointed tails. Top of this page Copyright 1999 U-Haul International, Inc. All rights reserved.	The Graphic The Giant Archelon Ischyros The Cretaceous Period: Age of Reptiles The Western Interior Seaway Interview with an Expert The Anatomy of a Turtle Turtles Today Related Links   Store Feedback