Pacific Wing Oyster Shell, Pteria sterna
Pacific Wing Oyster Shell, Pteria sterna. Shell collected from the El Tule tidal pools, Km 17, Baja California Sur, January 2017. Size: 9.0 cm (3.5 inch) x 5.0 cm (2.0 inches).
Phylogeny: The Pacific Wing Oyster, Pteria sterna (Gould, 1851), is a bivalve mollusk that is a member of the Pearl Oyster Shells of the Pteridae Family. The genus Pteria is one of thirteen genera in this family, and there are forty-two species in this genus. This species is also known as the Rainbow-lipped Pearl Oyster. In Mexico they are called Concha Nacar, Concha Perla, Callo de Arbol del Pacifico and Ostra Perlera Nacarada.
Description: Pacific Wing Oyster shells are of thin construction, and have a variable outline. Some specimens have a “P” shaped outline, with the main body of the shell being somewhat rounded, and the hinge and elongated posterior dorsal wing forming the stem of the “P”. Other specimens have a much shorter posterior wing, having more of an oblique oval outline. The shell varies in depth, and is only somewhat inflated. The exterior of the shell is scaly, with the scales becoming short spines as they approach the margin. The exterior of the shell is brown to purple-brown in color. The interior is nacreous and sometimes blistered, with a dark marginal band. Pacific Wing Oyster shells reach a maximum of 15.2 cm (5.9 inches) in length and 9.8 cm (3.9 inches) in height.
Habitat and Distribution: Pacific Wing Oysters are found attached to rocks, gorgonians, and other hard surfaces, by means of byssus. They are generally found in turbid water and are often associated with mangroves. They live from the intertidal zone to depths up to 24 m (80 feet). They are a subtropical to tropical Eastern Pacific species. In Mexican waters they are found along the entire west coast, including the Gulf of California. Pacific Wing Oysters are farmed extensively by the cultured pearl industry.
Ecology and Behavior: Pacific Wing Oysters are suspension feeders that feed primarily on planktonic algae and suspended organic matter. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization. They are known to host endo parasitic tapeworms and other marine worms. There is no mention in the available literature of them engaging in any types of commensal or symbiotic relationships. Pacific Wing Oysters produce valuable pearls and have been harvested for hundreds of years, by both indigenous peoples and Europeans. Over harvesting prompted the Mexican government to outlaw commercial harvesting in the 1940’s. Since then, farming of this species has taken over and populations have recovered. From a conservation perspective they have not been formally evaluated however they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.
Synonyms: Avicula fimbriata, Avicula eximia, Aviclula labella, Aviclua peruvian, Aviclula sterna, Aviclua viresi, Pteria beliana, and Pteria rositae.