Relevant Synonyms Ostrea forskali "Chemnitz" [Moazzo, 1939] Ostrea forskali Gmelin, 1791 [Tillier and Bavay, 1905] Misidentification Crassostrea gigas [El-Faham, 1997] ? Saccostrea commercialis [Çevik et al., 2001]  photo: P. Pravlis / Coll. A.E. Kideys

SHORT DESCRIPTION Shell solid, inequivalve, inequilateral. Shape oyster-like, very variable, depending on the substratum and biotope with outline irregular, almost circular to oval. Sculpture smooth or with strong radial ribs or even with spines. Lower valve (lv) larger and sometimes prominently convex, having a large area with no sculpture at the umbo (area of attachment); its margin with plications. Upper valve (rv) almost flat with plicated margin to fit the plications of the lower valve. Hinge without teeth, Ligament internal. Muscle scar close to the pallial line, very prominent, kidney shaped. Interior shell margin of rv with prominent denticles which fit into the corresponding pits in the lv margin. color : externally purple-brown; internally white with a purple-black zone in the periphery. Denticles white. Muscle scar often darker color. common size : 40-60 mm in height in the Mediterranean (up to 130 mm in the Pacific). DISTINGUISHING CHARACTERISTICS Saccostrea differs from Crassostrea in having the margin crenulated and from Ostrea by crenulation present all along the shell's periphery (in Ostrea only in the anterior margin near the hinge). Because of shell plasticity, the taxonomy of Saccostrea has been problematic. Oliver (1922) thinks that Saccostrea is a monospecific genus and reports S. cucculata in the Red Sea. However molecular biology studies (mitochondrial DNA 16S sequence) of Saccostrea populations in Australia recognize at least three different species (Lam and Morton, 2001). BIOLOGY / ECOLOGY Epifaunal, suspension feeder. Spawning period from June to mid-October. Optimum temperature for reproduction 20-30°C. Can tolerate a wide range of temperatures, between 5 and nearly 40°C. Gametogenesis is concominant with higher salinity values (33.37-34.65‰ ) and full maturation is attained when the salinity is maximum (35‰). habitat : high intertidal on rocky shores, cemented to rocks. In the Mediterranean, attached to rocks in harbours. At depths 1-15 m covered with macroalgae.

1st Mediterranean record Southern Turkey, 2000 [1999]. DISTRIBUTION Worldwide: throughout the Indo-Pacific including the Red Sea, recorded in the Suez Canal (Moazzo, 1939). Mediterranean: recorded first in 1999 from Turkey at Erdemli (Kideys, identification confirmed by S. Gofas) and Yumurtalik, Tasuçu as Saccostrea commercialis (Çevik et al., 2001); successively from Egypt (El-Faham, identification confirmed by A. Zenetos). ESTABLISHMENT SUCCESS Locally common. Established populations have been observed in southeastern Turkey, although locals believe it is mistaken for Dendrostrea frons. speculated reasons for success : - MODE OF INTRODUCTION Unknown; transportation via shipping appears likely due to life mode (fouling organism) and occurrence in Yumurtalik (ships transporting petroleum from the Iraq-Yumurtalik pipeline). IMPORTANCE TO HUMANS Edible, its cultivation is very popular in many parts of the world (Thailand, Australia).

KEY REFERENCES Çevik C., Öztürk B. and Buzzuro G., 2001. The presence of Crassostrea virginica (Gmelin, 1791) and Saccostrea commercialis (Iredale and Roughley, 1933) in the Eastern Mediterranean Sea. La Conchiglia, 298: 25-28. Davenport J. and Wong T.M., 1992. Effects of temperature and aerial exposure on three tropical oyster species, Crassostrea belcheri, Crassostrea iradelei and Saccostrea cucullata. Journal of thermal Biology, 17(3): 135-139. Roustaian P., 1994. Preliminary notes on reproductive biology of the edible oyster Saccostrea cucullata at Kohin, on the northeastern coast of the Persian Gulf. Journal of aquaculture in the tropics, Calcutta, 9(4): 329-334.   Sukumar P. and Joseph M.M., 1988. Annual reproductive cycle of the rock oyster Saccostrea cucullata (von Born). Pp. 207-210. In: Proceedings of the 1st Indian Fisheries Forum, Mangalore, Karnataka, 4-8 Dec. 1987. FEEDBACK / COMMENTS TO AUTHORS

Last update : December 2003 ©ciesm 2002