On the Feeding Mechanism of the Copepods, Calanus Finmarchicus and Diaptomus Gracilis

Abstract

1. Calanus finmarchicus and Diaptomus gracilis both feed automatically when swimming slowly and steadily through the water. 2. A feeding current is produced which is filtered by the stationary maxillae. Food so obtained is passed on to the mandibles by the maxillulary endites and setae on the bases of the maxillipeds. 3. The feeding current is a vortex passing through the mouth parts which results automatically from the swimming activities of the antennae, mandibular palps and maxillules. 4. The feeding vortex is caused to pass through the maxillae by the combined activities of the maxillipeds and the maxillulary exites. The former suck water into the filter chamber between the maxillae while the latter suck it out through the maxillary setae. 5. The views of Storch and Pfisterer on the feeding mechanism of Diaptomus gracilis are criticised. There is no powerful antero-posterior swimming current as described by these authors. The swimming current is in the form of a vortex encircling the body and most marked at the sides in the angle between the body and the antennules.