The tongue-twister Polyplacophora is Latin for "many plates." The animals in this class are commonly known as chitons (that's a lot easier to say than polyplacophorans!), and they have eight overlapping plates, or valves, on their flat, elongated shell.
About 800 species of chitons have been described. Most of these animals live in the intertidal zone. Chitons may be from 0.3 to 12 inches long.
Under their shell plates, chitons have a mantle, bordered by a girdle. They may also have spines or hairs.
There are male and female chitons, and they reproduce by releasing sperm and eggs into the water. The eggs may be fertilized in the water or the female may retain the eggs, which are then fertilized by sperm that enters along with water as the female respires. Once the eggs are fertilized, they become a free-swimming larvae, and then turn into a juvenile chiton.
Sources:
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Campbell, A. and D. Fautin. 2001. Polyplacophora" (Online), Animal Diversity Web. Accessed August 23, 2010.
- The Polyplacofora (Online). Man and Mollusc. Accessed August 23, 2010.
- Martinez, Andrew J. 2003. Marine Life of the North Atlantic. Aqua Quest Publications, Inc.:New York
- University of California Museum of Paleontology. The Polyplacophora (Online). Accessed August 23, 2010.


