Oyster

Oysters are mollusks which grow for the most part in marine or brackish water. The two main edible groups belong either to the Ostrea or Crassostrea, more recently called Saccostrea. Members of the Ostrea generally live continually immersed in sea water, brood their fertilized eggs for various proportions of the period from fertilization to hatching and are quite flat with roundish shells. They are members of the group bivalvia, but differ to most bivalves by having shells completely comprised of calcite but with internal muscle scars of aragonitic composition.

They do best in water with a not too thick concentration of phytoplankton. Members of the Saccostrea/Crassostrea generally live in the intertidal zone, broadcast sperm and eggs into the sea and can thrive in water which is very rich in phytoplankton. One of the most commonly cultivated oysters of the Crassostrea/Saccostrea is Saccostrea gigas, the Japanese oyster, which is ideally suited for oyster cultivation in seawater ponds.

Oysters can be eaten either raw or cooked, but like all shellfish they have an extremely short shelf-life. They should be fresh when consumed or serious illness can result. Additionally, oysters can host various illness-causing pathogens. Therefore, consumption of raw oysters should be done with caution.

Researchers in Oregon have invented a self-shucking oyster.

Oysters are the source of pearls, both cultivated and natural.