All about turtle shells
Turtles are reptiles whose protection comes from a shell. The shell of a turtle or tortoise is composed of an upper dome-shaped piece called the carapace and a lower plate called the plastron. These two are joined together by bony bridges. In most species, except for the soft-shelled turtles, the carapace is composed of bony plates overlaid by hard dermal plates. The most obvious function of the Turtle shell is to provide the animal with a protective fortress. Some species, box turtles in particular, have a hinged shell which allows even greater protection. Shells of turtles and tortoises grow larger as the anima matures. Although the shell provides excellent protection from many predators, it can also make the turtle vulnerable to health problems if it is not given good care in captivity.