Malleus malleus   (Linnaeus,  1758) (Oyster)
Organism information awaits expert curation
Class: Bivalvia

Size: Maximum shell height 25 cm, commonly to 18 cm.

Color: Purplish black color, both on inner and outer surfaces.

The shell is large, very thick, massive, elongated somewhat irregularly twisted. The hinge margin is greatly produced both anteriorly and posteriorly into long narrow lobes and the elongated body of the valves extends at right angles to this straight hinge margin, giving the appearance of a hammer, so characteristic of the members of this genus. The valves are rather tortuous and bear an irregularly undulating margin, the depressions in one valve closely interlocking with corresponding elevations in the other. There is a sort of web like expanded intervening part connecting the lobes of the hinge with the main, central, narrow part of the valves.

The shell is made up of several superimposed layers of calcareous laminae and these give the margins of the shell a coarsely plaited appearance. The outer surface is very rough, uneven and irregular, but the inner surface is comparatively smooth and even slightly glossy. The adductor impression is very large, oval and blackish. The shell is more or less uniform.

Synonym (s)
Malleus vulgaris Lamarck, 1799
Himantopoda vulgaris Schumacher, 1817
Malleus vulgaris Lamarck, 1801
Ostrea malleus Linnaeus, 1758

Common Name (s)
• Common Hammer Oyster
Economic Importance and Threats
Importance:  Commercial
(The shell is used to make lime and for shellcraft.)

Habitat:  Coastal


• Tamil Nadu, Parangipettai Coast (Lat: 11.48) (Long: 79.77) INDIA
• Tamil Nadu, Dhanushkodi INDIA
• Tamil Nadu, Mandapam INDIA
• Tamil Nadu, Gulf of Mannar (Lat: 78.13) (Long: 8.58) INDIA (Record: 01/1994-12/1995)
• Tamil Nadu, Gulf of Mannar (Lat: 79.5) (Long: 9.33) INDIA (Record: 01/1994-12/1995)
• Andaman and Nicobar Islands, Nicobar INDIA
• Andaman and Nicobar Islands, Camorta INDIA
• Andaman and Nicobar Islands, Nancowry Island (Lat: 7.98) (Long: 93.53) INDIA

Literature Source(s)
  • Tikadar, BK; Daniel, A and Subbarao, NV (1986) Sea shore animals of Andaman and Nicobar Islands The Director, ZSI, Kolkatta 188 Available at - ZSI, Pune
  • Subba Rao, NV and Dey, A (2000) Catalogue of marine molluscs of Andaman and Nicobar Islands Occasional paper no 187 Records of the Zoological Survey of India ZSI 1-323 Available at - NCL, Pune
  • Shanmugam, A; Rajagopal, S and Nazeer, RA Common bivalves of Parangipettai coast Available at - NIO, Goa
  • Nagabhushanam, AK and Krishnan, S (1993) Observations on the distribution of some of the marine organism inhabiting the inter-tidal zone along the western continental shelf of the Bay of Bengal, with particular reference to the Tamil Nadu coastal strip Records of the Zoological Survey of India 93(3-4) 449-490 Available at - ZSI, Pune
  • Poutiers, JM (1998) Bivalves FAO species identification guide for fishery purposes. The living marine resources of the western central Pacific. Volume 1: Seaweeds, corals, bivalves and gastropods FAO, Rome 1 686 pp Available at -
  • Samuel, VD; Chacko, D and Edward, JKP (2005) Preliminary study on the molluscan diversity of “the lost world’’– Dhanushkodi, east coast of India Proceedings of the National Seminar on Reef Ecosystem Remediation SDMRI Special Research Publication No.9 54-58 Available at -
  • Sundaram, KS; Sarvesan, R; Mohamed, KH and Shanbhogue, SL (1969) Catalogue of molluscs, prawns, stomatopods and marine algae in the reference collections of the central marine fisheries research institute Bulletin Of Central Marine Fisheries Research Institute CMFRI, Cochin 9 1-52 Available at -
  • Hameed, PS and Somasundaram, SSN (1998) A survey of bivalve molluscs in Gulf of Mannar, India Indian Journal of Fisheries Indian journal of Fisheries for the Indian Council of Agricultural Research, Kochi, India 45(2) 177-181 Available at -
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -

Page last updated on:2012-07-20

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