''Pinctada fucata'', the Akoya pearl oyster (), is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the family

Pteriidae Pteriidae, also called the feather oysters, is a family of medium-sized to large saltwater clams. They are pearl oysters, marine bivalve molluscs in the order Pteriida. Some of the species in this family are important economically as the sou ...

, the pearl oysters. Some authorities classify this oyster as ''Pinctada imbricata fucata'' (Gould, 1850). It is native to shallow waters in the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

region and is used in the culture of pearls.

Description

''Pinctada fucata'' has two

valves A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...

connected by a long straight hinge. The length of the shell is slightly greater than its width, and the latter is about 85% of the length of the hinge. The right valve is flatter than the left and there are hinge teeth in both valves. The

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

ear is larger than that in other members of the genus and there is a slit-like notch for the

byssus A byssus () is a bundle of filaments secreted by many species of bivalve mollusc that function to attach the mollusc to a solid surface. Species from several families of clams have a byssus, including pen shells (Pinnidae), true mussels (Mytilid ...

threads to pass through at the junction of the ear and the rest of the shell. The posterior ear is large. The outer surface of the valves is scaly and reddish or golden brown with pale radiating streaks. The inner surface of the valve is lined with a thick layer of golden-yellow

nacre Nacre ( , ), also known as mother of pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer; it is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is f ...

with a metallic sheen.

Distribution

''Pinctada fucata'' is native to the Indo-Pacific region. Its range includes the

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; T ...

, the

Persian Gulf The Persian Gulf ( fa, خلیج فارس, translit=xalij-e fârs, lit=Gulf of Persis, Fars, ), sometimes called the ( ar, اَلْخَلِيْجُ ٱلْعَرَبِيُّ, Al-Khalīj al-ˁArabī), is a Mediterranean sea (oceanography), me ...

, and coastal waters of India, China, Korea, Japan, and the Western Pacific Ocean. It has been introduced in coastal waters of Venezuela

Biology

Like other bivalve mollusks, ''Pinctada fucata'' is a

filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

. Water enters the shell through an opening in the mantle, passes over the gills where food particles are filtered out and gas exchange takes place, and passes out through another opening. These pearl oysters feed on

infusoria Infusoria are minute freshwater life forms including ciliates, euglenoids, protozoa, unicellular algae and small invertebrates. Some authors (e.g., Bütschli) used the term as a synonym for Ciliophora. In modern formal classifications, the term i ...

ns,

foraminifers Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an ...

radiolaria The Radiolaria, also called Radiozoa, are protozoa of diameter 0.1–0.2 mm that produce intricate mineral skeletons, typically with a central capsule dividing the cell (biology), cell into the inner and outer portions of endoplasm and Ecto ...

ns and other small

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

ic organisms. The sexes are separate in ''Pinctada fucata'' and gametes are released into the sea where fertilisation takes place. In India, spawning peaks from June to September and again in November and December, during the

monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal oscil ...

periods. The developing larvae pass through a

veliger A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells. Description The veliger is the characteristic larva of the gastropod, bivalve and scaphopod ...

stage and after about twenty-four days settle on the seabed and become juvenile oysters known as spat.

Pearl culture

Japan and Australia are the largest producers of cultured pearls. The process takes place within the tissues of living oysters, the species ''Pinctada fucata'' and '' Pteria penguin'' being mainly used for this purpose in Japan and ''

Pinctada maxima ''Pinctada maxima'' is a species of pearl oyster, a marine bivalve mollusk in the family Pteriidae, the pearl oysters. There are two different color varieties: the Silver-lipped oyster and the Gold-lipped oyster. These bivalves are the largest ...

'' in Australia. The oyster spat is grown in mesh baskets immersed in the sea for two or three years until large enough to seed. Then a tiny

mother-of-pearl Nacre ( , ), also known as mother of pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer; it is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is f ...

bead is inserted into the shell and layers of nacre become deposited around this. The oysters are kept in wire nets suspended from rafts while both oysters and pearls grow. Readiness for harvest is often determined by x-ray. Not only is the pearl gathered, but the nacre lining the inside of the valves of the shell is used in jewellery and in the manufacture of ornamental objects.

References

{{Taxonbar, from=Q420600 Pteriidae Bivalves described in 1850