The functional morphology of the branchial chambers and associated structures of Ebalia tuberosa (Crustacea : Decapoda : Leucosiidae), with special reference to ventilation of the egg-mass

Abstract

Ebalia tuberosa bury themselves in sediment but do not construct permanent burrows. There are no functional Milne-Edwards' openings, the respiratory currents passing along channels formed by apposition of several interlocking buccal appendages. In adult females, the dome-like abdomen fits over the concave sternum to form a large abdominosternal chamber which completely encloses the egg-mass. The branchial chambers are connected to the abdominosternal chamber by two branchiosternal canals plugged by modified pericardial sacs which act as one-way valves. When the telson is extended, water is sucked into the abdominosternal chamber and then into the branchial chambers, thus ventilating the eggmass. The setation of the respiratory and associated structures serves to lock appendages together, to form screens and gaskets and to groom the buccal appendages. Setal morphology is shown to be correlated with function.