THE CILIARY CURRENTS ASSOCIATED WITH FEEDING, DIGESTION, AND SEDIMENT REMOVAL IN ADULA (BOTULA) FALCATA GOULD 1851

¹ Pacific Marine Station, Dillon Beach, California

The mode of sediment removal by A. falcata, and its relationship to the ciliary currents of feeding and digestion was determined. Where possible, morphological and functional comparisons were made with other rock-boring bivalves.

1. A. falcata moves sediment material from the walls of its burrow into its mantle cavity by means of the ciliated surfaces of its unusually extensible foot and the mantle folds. After entering the bivalve's mantle cavity, sediment particles are treated as potential food material by the ciliary sorting mechanisms associated with feeding and digestion. Most sediment matter is rejected from the burrow as pseudofaeces via extrusion through the inhalant siphon opening. However, small amounts of sediment particles find their way past rejectory mechanisms of the gills and labial palps, and pass into the stomach. Following sorting and subsequent rejection by the stomach, this material is incorporated into faecal pellets which are later swept from the area of the burrow by the strong currents of the exhalant siphon.

2. It is suggested that particle discrimination, during sorting by A. falcata, is dictated by the weight, size, and mucus-bound state of the material being sorted.