Spiny Oysters of the Spondylidae Family
Three Spiny Oysters of the Spondylidae Family can be found in this website:
Phylogeny: Spiny Oyster Shells of the Spondylidae Family are bivalve mollusks in the order Pectinida. The superfamily Pectinoidea is one of four superfamilies within this order. The superfamily Pectinoidea consists of four families. The Pectinidae Family is a simple family with only one subfamily (Spondylinae) and one genus (Spondylus). The genus Spondylus contains around seventy-five species. Shells in this family are also commonly known as Thorny Oysters or Spondylids.
Description: Spiny Oyster Shells have attractive circular shells, topped by a straight hinge. The hinge is prolonged on both sides by small auricles (“ears”). The valves are inequivalve (not equal in size and shape), with the right valve being more convex. The left valve has strong, irregular, axial ribs, which may be scaly or spiny. They are closely related to scallops. Like scallops they have a row of eyes along their mantle that allow the detection of light and dark. These oysters have less noticeable auricles than scallops and a ball and socket type hinge instead of the interlocking teeth found in other bivalves. Shells in this family may be drably or brightly colored. Spiny Oyster Shells are small to large in size. The largest species in the family is 20 cm (7.9 inches) in length.
Habitat and Distribution: Spiny Oyster Shells are usually found cemented, by the right valve, to hard surfaces such as rock, coral, other shells, and pilings. A few species are free living. They live in the intertidal zone and to depths exceeding 840 m (2,755 feet). Deeper water species tend to have more delicate spines because they are less exposed to turbulence. These shells are found worldwide in tropical and subtropical seas. Eighty percent of the species in the family are found in the Indo-Pacific. Six species of the Spondylidae Family are found in Mexican waters.
Natural History: Spiny Oyster Shells are suspension feeders, filtering plankton and fine detritus from the water. They are prey for fish, crabs, lobsters, mantis shrimps, gastropods, octopuses, and sea stars. Most Spiny Oyster Shells are gonochoric, but a few species are hermaphrodites. They reproduce sexually, through broadcast spawning, with external fertilization. Their rough exteriors often host sponges and other epibionts. They have been used as burial goods, fertility symbols, jewelry, religious symbols, and as trade items for thousands of years. Spiny Oyster Shells are a common component of archaeological excavations in South and Central America, Mexico, and the American Southwest. Occasionally these shells produce pearls. Spiny Oysters are edible and are commercially fished and farmed. They are also harvested for lime production and by shell collectors.