Pinctada margaritifera

Pinctada margaritifera (Lannaeus)

Intro: Pinctada margaritifera, commonly known as the Black-Lip Pearl Oyster, is a bivalve common in the Indo-Pacific marine region, specifically within tropical coral reefs. Its name comes from the black coloring along the margins of the shell. Appearance is dark grayish brown or green, though white spots are common across the shell. Adults usually reach between 200mm and 250mm in height (Ceism). A distinctive feature of the species is that the hinge has no teeth. (FAO). Pinctada and Pteria genuses are often confused. In the Pinctada genus, the hinge is long and straight, the long end of the shell forms a right angle to the hinge, and the left valve is slightly deeper than the right. The Pinctada genus differs from the Pteria genus, which has a shell width much longer than its height and the angle of the hinge is prominent and pronounced. The ability of the Pinctada margaritifera to produce pearls makes it a valuable human commodity on the world market. The oysters are harvested from coral reefs and also commonly grown in aquaculture, both primarily taking place in the Indo-Pacific region.

Classification: Animalia Mullusca Bivalvia Pteriomorphia Pterioda Pteriidae Pinctada margaritifera (Temkin).

Range: The Pinctada margaritifera occupies a wide range throughout the Persian Gulf, Red Sea, Sudan, Papua New Guinea, Australia, French Polynesia, Indonesia, Andaman and Nicobar Islands, Southwestern part of the Indian Ocean, Japan and the Pacific Ocean, and various locations on the coast of India.

Habitat: Pinctada margaritifera are suspension feeders able to thrive in low phytoplankton conditions.The oyster attaches itself to barnacles and other hard substrata via a byssus in coral reef areas(Ceism; Yukihara, et al.; Richmond). They thrive at intertidal and subtidal zones, at depths from the low tide to up to 75 meters(FAO). Habitats are usually characterized as oligotrophic and having low turbity. Other species including sponges, hydroids, polychaetes, lamellibranchs, amphipods, decapods, echinoderms, and fishes usually have close relationships with pearl oyster beds (FAO).

Unique element: This species is commonly farmed and harvested for pearls, and there is general consensus that the quality of pearls from Pinctada margaritifera is the highest quality out of all the pearl oysters (Ceism). Pearls form when a small particle enters into the oyster and nacre is released by the oyster to coat the particle or object, eventually creating a small pearl. The particle might be a grain of sand, organic material, or even a parasite. The oyster’s release of the nacre serves as an adaptation of the immune system to isolate the invasive particle and irritation. The Pinctada margaritifera in particular produces gray or black pearls. The benthic ecology of the region is a significant factor in the rate of production and the quality of pearls (FAO). Rocky, gravelly bottoms and low silt concentrations are preferable, and currents are necessary to keep the water clean with fresh phytoplankton and removal of fecal matter. Stronger currents cause faster but lower quality pearl development.

References:

Yukihara, H., et al (1999). “Feeding Adaptations of the Pearl Oysters Pinctada margaritifera and P. maxima to variations in particulates.” Marine Ecological Progress Series. Retrieved 2014-2-19. http://www.int-res.com/articles/meps/182/m182p161.pdf

Ciesm (2002). “Pinctada margaritifera.” Retrieved 2014-2-19. http://www.ciesm.org/atlas/Pinctadamargaritifera.html

Tëmkin, I. (2013). “Pinctada margaritifera (Linnaeus, 1758)”. World Register of Marine Species. Retrieved 2014-2-19. http://www.marinespecies.org/aphia.php?p=taxdetails&id=207899

Fishing and Aquaculture Department (1991). “Pearl Oyster Farming and Pearl Culture.” FAO Corporate Document Respository. Retrieved 2014-2-19 http://www.fao.org/docrep/field/003/ab726e/ab726e02.htm

Richmond, Matthew D. (1997). A Guide to the Seashore of Eastern Africa and the Western Indian Ocean Islands.