Class-Bivalvia

__Class Bivalvia Home of the Twin Doors__ Bivalves are marine animals with a shell with opposite plates called valves connected by a hinge. Bivalves are generally bilaterally symmetrical.

__Some Bivalves to Consider:__ Bay Scallops

__The Bay Scallops (Argopecten irradians)__: Bay scallops are marine bivalves with brightly colored, fan-shaped shells. The term "scallop" comes from the french word "escalope", meaning "shell".

 Bay scallops are quite coastal, growing around the inner Florida region of the U.S.

__LIFE STYLE__: __Locomotion__ Scallops are the only migratory bivalves (meaning all the other bivalves-clams, oysters, mussels, etc- are sedentary). Scallops move by using their adductor muscle, located inside the shell; by "swallowing" water inside their shell, then ejecting it out of hinges at the backside, scallops move in short bursts. (This method is also used as a defense mechanism to get away from predators.) media type="custom" key="5618819" width="293" height="293" __Feeding__ Bay scallops obtain nutrients through filter feeding: they take in water through their gills and "strain" the phytoplankton, zooplankton, algae, and other aquatic nutrients into their stomach. Strangely enough, some of those plankton can include scallop larvae. The food is then digested and passed out through the anus.

__Reproduction__ One of the bay scallops' most interesting characteristics come from their reproductive cycle. Scallops in general are dioecious, but some are hermaphrodites. But the bay scallop is unique in that it is a protandrous hermaphrodite; during its younger years, the scallop produces male gametes, while during its older years, it produces female gametes. (The male spermatozoa are white, and the female roes are red.) After fertilization, the egg sinks to the sea floor and hatches into larva, and drift out in the sea as it matures.

__Fun Facts__ You can tell how old a bay oyster is by counting its annuli-the concentric rings around its shell- much like you would count a tree's rings. The scallop shell is a symbol of fertility, as expressed by sculptures of the Roman goddess Venus; she is usually portrayed with the background of a shell. The scallop was part of British Prime Minister Winston Churchill's coat of arms.