Reproductive bionomics of the wedge clam Mesodesma glabratum (Lamarck) along the south-east coast of India

Abstract

The intertidal zone, being a precarious marine habitat, is characterised by heavy wave action, and the po~.ible erosion and accretion caused by climatic changes of land and sea. Therefore, the organisms living therein, have contrieved special adaptive features. The intertidal zone of the sandy beach can be classified into three zones. They are: (a) the supralittoral fringe <otherwise known as eulittoral fringe), <b) midlittoral zone <eulittoral zone) and (c) infralittoral fringe <sublittoral fringe) (Pichon, 1967). The organisms living in the supralittoral fringe are subjected to prolonged aerial expowure, and therefore specialised to survive, feed and reproduce under aerial conditions. The organi§ms that inhabit the midlittoral zone are e xperiencing about 50% of aquat ic and aerial conditions, whereas those inhabiting the infralittoral fringe ar@ truely aquatic, but well adapted to resi.t short period~ of exposure to aerial conditions. The organisms of the supralittoral fringe are e xpofied to aquatic conditions only for a brief p.riod during the spring tide. Con vergely, the organisms of th. infralittoral fringe are e xposed to aerial conditions only for a short duration of few hours in each fortnight (Newell, 1979).