Chiton, a genus of marine mollusk. The boat-shaped shell of the chiton is composed of overlapping symmetrical plates. The chiton clings tightly to rocks and easily resists heavy surf with its powerful foot. Very small species are found on the Atlantic coast. A larger species, 8 to 10 inches (20 to 25 cm) long, occurs in the Gulf of Mexico and on the western coast of the United States.

Which Mollusks Have Eight-Piece Shells?

A univalve has one valve. A bivalve has two. But some mollusks have eight valves. They are called chitons (KY tuhnz). A chiton’s eight valves, or plates, overlap one another. The plates are held together by a piece of tough, leathery flesh called a girdle.

A chiton has a very long and wide foot. With its long foot, a chiton can cling to coastal rocks. In fact, a chiton spends most of its life clinging to these rocks. There it feeds on algae and other tiny organisms in the seawater.If a strong wave or a predator causes the chiton to lose its grip, it will roll itself into a ball for defense—just like an armadillo.

The genus Chiton belongs to the class Polyplacophora.