Biology and functional morphology of the pallial organs of the Antarctic bivalve Mysella charcoti (Lamy, 1906) (Galeommatoidea : Lasaeidae)

摘要

Mysella charcoti is an Antarctic lasaeid bivalve and the most frequently encountered mollusc in Admiralty Bay, King George Island, South Shetlands. The behaviour of the species in aquaria, combined with analyses of the gross and microscopic morphologies and functioning of the organs in the mantle cavity of living and preserved specimens have allowed an understanding of important aspects of its biology. The role of the foot and its ciliature during the processes of dislodgement and burrowing within the sediment are described. The species is a free-living, shallow-burrower, with a predominantly deposit-feeding habit and derives part of its food from the labile settled organic deposits carried into the mantle cavity by the anterior-posterior current of water. Pedal sweep-feeding was not detected. M. charcoti is the first known lasaeid with ctenidia formed of the descending lamellae of the inner demibranchs only, a feature probably related to its highly specialised brooding habit.