Scientific Name: Crassostrea virginica
The eastern oyster feeds on plankton and algae. It has numerous
predators, including birds such as the American oystercatcher, ocean
dwellers such as sea anemones, sea stars, sea nettles, some parasites,
and humans. About seven weeks after hatching, the eastern oyster
reaches sexual maturity. Spawning season is from late spring to early
fall during warm weather. Females may release more than 100 million
eggs during a season. Only about one percent of the fertilized eggs
reach the next stage of maturity.
Within hours of mixing with sperm, the fertilized eggs develop a shell and begin to move on their own. Oyster larvae, each about the size of a grain of pepper, use tiny, probing feet to find a suitable place to attach. Once settled, the foot excretes a cement-like glue. The oyster glues itself in place and spends the rest of its life there. Its lifespan varies, depending on freshwater inflow and predation.
The valve or shell length of the eastern oyster reaches up to 8 inches (20 cm). It's two shells (called "valves," hence the name bivalve) attach together at one end by a natural hinge and by a single large muscle. The pale white to gray shell is rough with ridges or bumps.
Oysters are protandric-in the first year, they spawn as males, but as they grow larger and develop more energy reserves, they spawn as females. Oysters are also filter-feeders. They feed by using their gills to filter tiny food particles out of the water. Oysters have been found attached to bricks, boats, cans, tires, bottles, crabs, and turtles, but they prefer to attach to other oysters. When a large number of oysters join together, it's called an "oyster reef".