Eastern Oyster

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Project Description

Eastern Oyster

Crassostrea virginica

Range/Geographical Distribution: Maine to the Gulf of Mexico.  Introduced to the Hawaiian Islands.

Habitat: Intertidal and subtidal zones in brackish water estuaries and sounds.

Description: A variably-shaped bivalve that is gray/tan in color with unequal valves (shells).  The inside of each shell is white with a purple muscle scar.

Size: Can reach ten inches in length.

Food: Filter feeder; eats plankton.

Breeding: Sexual reproduction, spawns from late June to November. Females can produce up to 114 million eggs in a year. Larvae go through several planktonic stages before searching the substrate for a suitable place to setter. Larvae usually cement themselves to live or dead oyster or clam shells and then metamorphosize into a tiny oyster, called spat.

Predators: Crabs and mollusks.

Conservation Status: Not evaluated by the IUCN list.

Interesting Facts: Oyster beds provide habitat for other organisms and serve as a water filter by removing particulates along with the plankton that they consume.  Oysters can live for 20 years but current populations are thought to be about 1% of the historic population.  Massive harvesting, disease, and polluted waters have contributed to the decline in numbers.

On the Coast: Oyster beds are visible in most Georgia estuaries during low tides.  These gray mounds are found along the edges of the marsh and are covered with water during high tide.  Oyster shells commonly wash up on the beaches as well.

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