bivalve: Quick Facts

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Facts

Also Known As	Lamellibranchiata • Pelecypoda • Acephala • Bivalvia

Photos

Organizational levels and body diagrams of mollusks

Internal structure of a clam. A ligament hinges the shell's two halves (valves) open, and the beating motion of cilia on the gills causes water to enter through the incurrent siphon. As water moves over the gills, oxygen diffuses into the blood, and food particles become trapped in mucus and are moved to the mouth. A pair of adductor muscles can hold the shell tightly closed. A fold of tissue (mantle) encloses the body's organs and releases the material that forms the shell. A large muscular foot allows the clam to creep and burrow. The circulatory system consists of a heart and blood vessels, and kidneys remove wastes from the blood. Deoxygenated blood and wastes are removed in the water that exits through the excurrent siphon.

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