Bivalves: Bivalvia

Physical characteristics: Outside blackish valves with white to green spots are round and flat. The inner valve surfaces can be blue, gray, green, pink, and yellow. The valves measure 6 to 10 inches (150 to 250 millimeters) across. The mantle is orange, while the foot is gray or black.

Geographic range: This species naturally occurs in the Indian Ocean and the western to central Pacific, including the Hawaiian Islands. It is also raised commercially in French Polynesia, Cook Islands, Gilbert Islands, Marshall Islands, Solomon Islands, southern China, northern and western Australia, Seychelles, and the Sudan.

Habitat: Black-lipped pearl oysters live at depths of 3 to 130 feet (1 to 40 meters) attached to hard surfaces in and around coral reefs. This species prefers calm, clear waters often poor in nutrients.

Diet: They eat bits of plant and animal plankton.

This species is the most important source of mother-of-pearl used for carvings and inlays, as well as Tahitian black pearls. (© Fred McConnaughey/Photo Researchers, Inc. Reproduced by permission.)

Behavior and reproduction: Foreign particles or parasites stuck between the valve and the body are encased in hard, shiny layers of calcium carbonate forming a pearl.

Hermaphroditic adults first develop into males, then females. Eggs and sperm released into the water are fertilized there.

Black-lipped pearl oysters and people: This species is the most important source of mother-of-pearl used for carvings and inlays, as well as Tahitian black pearls.

Conservation status: Black-lipped pearl oysters are not considered threatened or endangered. ∎