Eastern Oyster
Crassostrea virginica (Gmelin, 1791)
Range: Western Atlantic coastline, from Canada to northern South America
Habitat: Brackish and salty waters, up to 10 meters deep
Diet: Plankton
Social Grouping: Large Beds
Reproduction: Spawning influenced by warmer water temperatures. Free-floating, fertilized eggs (each female can produce up to 150 million, of which only a tiny number survive) hatch and, after about 3 weeks, settle on the bottom. Most young oysters ("spat") are male, but some may change to females as they age - and sometimes back to male
Lifespan: 20 Years
Conservation Status: Vulnerable (not listed)
- Can grow up to 20 centimeters shell length, usually about half that length
- Hard, calcium-carbonate, bivalve, cup-shaped shell formed to protect soft tissue. Juveniles have an argon-based shell, transitioning to calcium when they settle on the seabed and are more exposed to predators. Inside of shell is white or off-white
- Filter feeder, sucking in water, filtering out edible material, and spitting out water. A single oyster can filter nearly 200 liters of water in a 24-hour period, helping to purify water
- Oysters gather in large beds, which form structural habitats for other species in a manner similar to coral reefs
- Capable of forming small pearls around particles in the shell, but typically small and economically insignificant
- Traditionally have been very important as a food source, first for Native Americans, later for colonists. New harvesting techniques and better storage/transportation greatly increased pressure on populations, leading to severe overharvesting and decline (down to 1% of historical population levels).
- In addition to fishing, oyster beds were dredged and destroyed, making it harder to spat to settle and grow. Shells were used for mortar, for road construction, or as fertilizer
- Commercially farmed for aquaculture, reintroduction efforts; also introduced to Hawaii
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