THE RATE OF WATER PROPULSION BY THE CALIFORNIA MUSSEL

¹ From the Scripps Institution of Oceanography of the University of California, La Jolla, California

A method is described for determining the approximate average rate at which the California mussel, Mytilus californianus, propels water through its gill chambers.

The method consists of analyses at frequent intervals of the amount of calcium remaining in suspension (as CaCO₃) in a given volume of continually stirred water containing the mussels, which remove the suspended material as they pass the water through their chambers.

Mathematical treatment and interpretation of the data obtained, support the conclusions that (1) virtually all of the suspended matter is removed as the water passes over the mucous surfaces of the gills and mantle of the mussel; (2) the mussel propels the water rhythmically through its filtering system at a rate which on an average is constant, varying according to the size and perhaps also according to other physiological attributes of the animals. In medium-sized animals (of 95 to 130 mm. length) the propulsion rate may vary between extreme values of 2.2 and 2.9 liters per hour, and has an average value of approximately 2.6 liters per hour.