Oysters are cultivated along the Atlantic coasts of Europe and the Americas; along the Pacific coasts of the Americas, Japan, Australia, China, and Korea, and along the eastern coast of Africa. In the United States, most cultivated oysters are raised in the Middle Atlantic, Chesapeake Bay, Gulf Coast, and North Pacific fisheries.

Oystermen provide oysters with places to set, enough room to develop, and a good food supply. They transfer some oysters to special beds where they can fatten in the last few months before they are harvested. Oysters are harvested from the beds with dredges or tongs.

The harvested oysters are brought to a processing plant where they are washed. If they are to be sold for eating raw on the half shell, they are shucked (removed from the shell) by inserting a knife between the two halves and prying them open and placed back in one side of the shell, and then chilled, packed in ice, and sent to market. Shucked oysters are also sold, without the half shell, canned or frozen. Large commercial processing plants have automatic shucking machines.

Cooked oysters are steamed (which automatically opens the shell) and the meats are canned and sterilized. Oysters are also dried and powdered for use in soups.

Most of the oyster shells removed during processing are returned to the beds to provide places on which the larvae may set. Crushed oyster shells are fed to chickens. The shells are also burned and slaked to make lime for fertilizer.

A beautiful pearl actually starts out as a grain of sand or dirt. Water carries the grain into an oyster’s mantle, where it settles. The rough grain can really disturb the oyster’s soft body. So the oyster uses its mantle to produce a soft substance that covers the grain. Over time, the substance hardens. Eventually, the covering over the grain grows in size and becomes a smooth pearl.

Not all oysters make perfect pearls. Chances are that any pearls you’ve seen were made by pearl oysters. True oysters, the kind people eat, sometimes make pearls, too. But their pearls look more like hard gray peas.

True oysters belong to the three genera of the oyster family, Ostreidae. Most deep-sea oysters belong to the genus Pycnodonta. The American Atlantic coast oyster is Crassostrea virginica; the Portuguese oyster, C. angulata; and the Japanese oyster, C. gigas. The European flat oyster is Ostrea edulis; the American Pacific coast oyster, O. lurida.