An Oyster’s World: Inside and Out
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Oyster photo by Diane Supple; background photo by Sue Corcoran
By Ally Valadares
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hen you think of the Lowcountry, what
comes to mind? My mind always drifts to
pluff mud, sweetgrass baskets, shrimp and
grits, historic plantations, and beautiful
marsh sunsets. And oysters. Lots and lots of oysters.
The eastern oyster, Crassostrea virginica, is a saltwater,
bivalve mollusk with a hard calcium-carbonaceous shell.
Oysters grow in beds, which, similar to coral reefs, act as
“ecosystem engineers,” providing essential habitat for a variety
of species. As our oysters are intertidal—meaning they live
in the space between high and low tide—they develop with
irregular, elongated shells. But oysters don’t begin life as the
delicious, hard-to-crack-open, shelled mollusks that we all
think of. It takes a bit of time to reach that stage. Oysters,
believe it or not, start out as eggs.
Female oysters produce about 75 to 150 million eggs, but
only one in one thousand survive. The fertilized eggs are
released into the water column. After hatching from their
eggs, eastern oysters begin life as free swimmers. About
six hours post-hatch, the oysters have become planktonic,
trochophore larvae, and possess a small shell and cilia. Within
the next twenty-four hours, the larvae have developed into
a fully-shelled veliger larvae. These larvae have a hinged
side and velum and use their cilia to capture food and swim