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''Pinctada'' is a genus of saltwater clams, marine bivalve molluscs in the family Pteriidae, the pearl oysters. These oysters 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 Unionidae and Margaritiferidae. ''Pinctada maxima'' pearl oysters are the only oyster species that produces South Sea pearls. Currently they are cultured primarily in Australia and Tahiti. A pearl oyster can be seen on the reverse side of the 1,000 Peso bill of the Philippines. ==Species of commercial value== All species within the genus produce pearls. Attempts have been made to harvest pearls commercially from many ''Pinctada'' species. However, the only species that are currently of significant commercial interest are: * Gulf pearl oyster, ''Pinctada radiata''; Persian Gulf, Red Sea, Mediterranean Sea and throughout the Indo-Pacific as far as Japan and Australia. * Black-lip oyster, ''Pinctada margaritifera''; Persian Gulf and southwestern part of Indian Ocean; Fiji; Tahiti; Myanmar; Baja California; Gulf of Mexico * Gold-lip oyster, ''Pinctada maxima''; Australia; Fiji; Tahiti; * White-lip oyster, ''Pinctada maxima''; Australia; Fiji; Tahiti; Myanmar; * ''Pinctada mazatlanica''; Mexico; Panama; * Akoya pearl oyster, ''Pinctada fucata'' (also called ''P. imbricata''), Red Sea; Sri Lanka; Persian Gulf; Indian Ocean; Western Pacific Ocean; Australia; China; Venezuela; * Shark Bay pearl oyster ''Pinctada albina''; Australia The various 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. Research carried out by biologist Aldemaro Romero Jr. allowed him to discover that the first animal population depleted by Europeans in the American continent was a pearl oyster species (''Pinctada imbricata'') off the coast of Venezuela. He analyzed historical records and used information about the biology of these and other species to explain its rapid disappearance. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pinctada」の詳細全文を読む スポンサード リンク
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