American Oyster | Oceana
Home / American Oyster

Marine Life Encyclopedia

Cephalopods, Crustaceans, & Other Shellfish

American Oyster

Crassostrea virginica

Distribution

Sub-tropical to temperate latitudes of the western Atlantic Ocean

ECOSYSTEM/HABITAT

Soft bottoms

FEEDING HABITS

Filter feeder

TAXONOMY

Class Bivalvia (clams, oysters, and relatives), Family Ostreidae (true oysters)

The American oyster is an iconic species of the Chesapeake Bay and other coastal waters of eastern North America. Historically, this species was so common and made such large reefs that it was a documented navigation hazard in some areas. Unfortunately, a history of overexploitation, pollution, and physical damage has reduced the American oyster population size to as low as one percent of its original abundance in some areas.

American oysters, like all true oysters, live a sessile lifestyle. After a short mobile phase in the plankton, juveniles settle on dead oyster shells or some other hard surface and permanently cement themselves in place. From then on, they build strong, calcium carbonate shells. In this manner, they form very large reefs that provide habitat for several other species of invertebrates and fishes. American oysters are filter feeders that strain plankton and other organic matter from the water above the surface of their reefs. In areas with high oyster densities, they can keep the water nearly free of floating matter. Each American oyster filters approximately 50 gallons of water per day.

American oysters reproduce via broadcast spawning, where several females release their eggs and several males release their sperm into the water column at the same time. This behavior increases the likelihood that eggs will be fertilized and decreases the likelihood that the eggs will be eaten by predators near the reef’s surface. These oysters are extremely productive, and a single female may release as many as 150 million eggs throughout her lifetime. When they hatch, all American oysters are male. Most of them reproduce at least once as male, but as they mature, some individuals change to female. This sex change is a result of the difference in energy required to make sperm and eggs. Small individuals can make sperm, while continuing to grow. Larger individuals that have stopped actively growing can afford to utilize their energy to make the larger eggs. Reproduction is triggered by temperature in this species.

The American oyster has been overfished and depleted for more than 120 years. The Chesapeake Bay population has been exploited particularly hard, and catches peaked as early as the 1880s. By the early 1900s, it was already depleted. Catch now is approximately one percent of what it was at its 1880s peak. The overexploitation of American oysters has changed the Bay significantly. While the oysters formerly filtered the entire contents of the Bay in short periods of time, that is no longer the case. High levels of pollution in the Chesapeake are exacerbated by the fact that its natural scrubber system has been removed. Though it is likely not at risk of full extinction – thanks to its large range and very high reproductive output – the American oyster is severely depleted throughout its range and no longer provides the habitat and filtration services that it once did.

Additional Resources:

NOAA Fisheries

Get Involved

Donate Today

SUPPORT OUR WORK TO PROTECT THE OCEANS BY GIVING TODAY

With the support of more than 1 million activists like you, we have already protected nearly 4 million square miles of ocean.

Donate Now

TAKE ACTION NOW

Support policy change for the oceans

Decision-makers need to hear from ocean lovers like you. Make your voice heard!

Sign Now

VISIT OUR ADOPTION CENTER

SYMBOLICALLY ADOPT AN ANIMAL TODAY

Visit our online store to see all the ocean animals you can symbolically adopt, either for yourself or as a gift for someone else.

Shop Today

DOWNLOAD OCEAN ACTIVITIES

HELP KIDS DISCOVER OUR BLUE PLANET

Our free KELP (Kids Environmental Lesson Plans) empower children to learn about and protect our oceans!

Learn More

FEATURED CAMPAIGN

Save the Oceans, Feed the World

We are restoring the world’s wild fish populations to serve as a sustainable source of protein for people.

Learn More

More CAMPAIGNs

Protect Habitat

Bycatch

Plastics

View All

CONTACT

Oceana International Headquarters
1025 Connecticut Avenue, Suite 200
Washington, DC 20036 USA

General Inquiries
+1(202)-833-3900
info@oceana.org

Donation Inquiries
+1(202)-996-7174
wavemaker@oceana.org

Press Inquiries
+1(202)-833-3900
press@oceana.org

OCEANA'S EFFICIENCY

BECOME A WAVEMAKER

Sign up today to get weekly updates and action alerts from Oceana.

SHOW YOUR SUPPORT WITH A DONATION

We have already protected nearly 4 million square miles of ocean and innumerable sea life - but there is still more to be done.

Donate Now

QUICK LINKS: