Pearl oysters are saltwater clams, marine bivalve molluscs of the genus Pinctada in the family Pteriidae. They have a strong inner shell layer composed of nacre, also known as "mother of pearl".
Pearl oysters are not closely related to either the edible oysters of family Ostreidae, or the freshwater pearl mussels of the families Unionidaeand Margaritiferidae.
Pinctada maxima pearl oysters are the only oyster that produces South Sea pearls. Currently cultured primarily in Australia and Tahiti.
All species within the genus share the phycological properties that can lead to them making large pearls of commercial value. Attempts have been made to harvest pearls commercially from many Pinctada species. However, the only species that are currently of significant commercial interest are:
Pearl oysters waiting to be opened
Opening and extracting pearls from farmed pearl oysters
The species of Pinctada produce different maximum sizes and colors of pearls, depending on the size of the species and the natural color of the nacre inside the shell. Black South Sea pearls, or Tahitian pearls come from the black-lip oyster; white and golden South Sea pearls from the white-lip and golden-lip oysters; and Akoya cultured pearls from Pinctada fucata martensii, the Akoya pearl oyster.
Pearls are also obtained in commercial quantities from some species of the closely-related winged oyster genus Pteria.
Pearls are also produced from freshwater mussel species unrelated to pearl oysters. These freshwater species include Hyriopsis cumingii,Hyriopsis schlegelii, and a hybrid of the two species.
At danger from the large demand for pearls, the typical lifespan of a pearl oyster is usually around 3 years to 14 years. Pinctada maxima are seeded at about 2 years of age and take 2 years to fully develop a pearl. They can be reseeded up to 3 or 4 times. Akoya pearls are harvested after about 9 to 16 months
Also see: pearl diving.
Species list