Oyster is the common name for a number of different groups of bivalve mollusks. Oysters are soft-bodied animals that have two hard, protective shells. They spend their entire lives underwater. The shape of the oyster's shells varies, depending mostly upon how crowded they are in the oyster bed.

There is an interesting phenomena that the oysters change their sex during their lives. Their sex starts as males and usually ending as females.

There are all kinds of oysters. Some can breed pearls. Thus, pearls are sometimes found in oysters. When a grain of sand gets stuck between the oyster's mantle and shell, the oyster will secrets nacre. This shiny substance coats the grain of sand, and over the years, forms a lustrous pearl.

However, it takes a long time for the oysters to form these pretty pearls naturally. That's the reason why so many people want to culture the pearls.

There has been a long history of oysters farming. Oysters have been cultured for more than a century. The oysters are cultivated to the size of "spat," or they may be allowed to mature further to form "seed" oysters. In either case they are then set out to mature. They may be distributed over existing oyster beds and left to mature naturally, to be collected using the methods for fishing wild oysters. Or they may be put in racks or bags and held above the bottom. The oysters are harvested by lifting the bags or rack to the surface and removing mature oysters. In these ways, people can breed a large quantity of brilliant pearls.

The pearl oysters are eaten not often, however, some other oysters are usually highly prized as food. These oysters are usually considered as delicious food to some people. They can be eaten half shelled, raw, smoked, boiled, baked, fried, roasted, stewed, canned, pickled, steamed, broiled or used in a variety of drinks. Have you ever tried before?

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