True Oyster Shells of the Ostreidae Family

Four True Oysters of the Ostereidae Family can be found in this website:

Phylogeny: True Oyster Shells of the Ostreidae Family are bivalve mollusks in the order Ostreida. There are three superfamilies in this order: Ostreoidea, Pinnoidea, and Pterioidea. The superfamily Ostreoidea contains three families: Flemingostreidae, Gryphaeidae, and Ostreidae. The Ostreidae Family is comprised of five subfamilies, sixteen genera, and seventy-five species. Shells in this family are also commonly called Ostreids.

Description: True Oyster Shells have irregularly shaped shells, with both valves differing in size and shape (inequivalve). The left valve is cemented to solid substrate and shapes to match that substrate. The right valve is less convex and smaller than the left. True Oyster Shells are solidly built and range from small to large. The exterior is rough with commarginal foliation or spines. One, or both, valves may have radial folds or ribs. Like scallops, these shells have a single adductor muscle. The muscle attachment scar is semi-circular or crescent-shaped. The hinge lacks teeth. Shells in this family tend to be gray, brown, or whitish, sometimes with purplish or black blotching. The interior is usually white, often with dark staining, and not nacreous. The largest species in this family is 35.5 cm (14 inches) in length.

Habitat and Distribution: True Oyster Shells can be found in brackish water and marine environments. They live cemented to solid surfaces such a rocks, coral, mangroves, concrete, and steel. Most species are found intertidally or in shallow waters, though they can be found as deep as 550 m (1,800 feet). True Oyster Shells are found globally in tropical to temperate seas. Fourteen species from this family are found in Mexican waters.

Natural History: True Oyster Shells are suspension feeders that consume phytoplankton and detritus from the surrounding water. They are considered oligotrophic (being able to survive in low nutrient level environments). Some species filter over 189 liters (50 gallons) of water every day They are preyed upon by carnivorous mollusks, fish, shorebirds, crabs, and sea stars. True Oyster Shells are sequential hermaphrodites and reproduce through broadcast spawning, with external fertilization. True Oyster Shells are reef builders when generation after generation attaches to the shells of their dead ancestors. They edible and are commercially fished and farmed.