The bivalve pump

Abstract

A filter feeding bivalve, represented by the mussel Mytilus edulis , is modelled as a pump, consisting of the bands of lateral cilia along the gill filaments, and a system of afferent and efferent canals. The relation between pump pressure Delta H sub(p) and pumping rate V was approached through studies of the relations between system resistances and V. The most important resistances distinguished were the frictional resistance in the canal system Delta H,) the exit loss Delta H sub(ex), and the back pressure Delta H sub(12), imposed on the pump as a means to study the performance characteristics of the gill system. Removal of the laterofrontal cirri from the flow path by treatment with serotonin did not measurably affect the frictional resistance, but the cirri presumably constituted a flow-rate-independent resistance Delta H sub(lf), arising from their beating against the flow. The interfilament canals and the exhalant siphon presumably constitute the major resistances, in an optimally pumping "standard" 35 mm mussel, thus constituting head losses of about 0.4 mm and 0.5 mm H sub(2)O, respectively. The operating point at zero back pressure was estimated at about 1.4 mm H sub(2)O