Pearl Oyster (Pinctada margaritifera) - ROM2004_861_1

Pearl oyster, Pinctada margaritifera

Pearl Oyster (Pinctada margaritifera)

Date: pre- 1986 AD
length=15.5; height=15.0 cm
    • Attributes
    • Objects
    • Taxonomy
    • KingdomAnimalia
    • PhylumMollusca
    • ClassBivalvia
    • OrderPterioida
    • FamilyPteriidae
    • GenusPinctada
    • SpecificEpithetmargaritifera
Object number: ROMIZ M12448
Not on view
DescriptionThis bivalve is famous for the pearls it produces and is a valuable source of mother-of-pearl—the iridescent internal layer of a mollusc shell that is used to make decorative objects. This species is now cultured or grown for pearls in French Polynesia and in many other areas of the tropical Pacific. Historically, in the Red Sea region it provided pearl divers with large black pearls for Indian and Persian monarchs. Ordinarily though, pearls produced by Pinctada margaritifera are gray with green, blue or rose overtones and hardly ever pure black. A pearl is formed naturally when an organic irritant such as a parasite or food particle becomes lodged between the fleshy mantle of the oyster and its shell. The mantle is a fold of the body wall that lines the shell and secretes the substance that forms the shell. Concentric layers of lustrous pearly shell are deposited around the foreign particle forming the pearl. Contrary to popular belief, pearls are rarely the result of the intrusion of a grain of sand into an oyster\'s shell. Cultured pearls are made by inserting small beads of glass or shell inside pearl oysters. Marketable pearls are formed around such beads in about three years. The Pearl Oyster may grow to the size of a dinner plate and weigh four or five pounds. This species lives in Indo-Pacific waters in beds (an underwater or intertidal area in which a particular organism is established in large numbers) at depths of 5 to 30 metres and is attached to the bottom with special anchoring lines called byssal threads.
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