Meeting Abstract
In molluscan and annelid larvae that feed with opposed ciliary bands, a preoral prototrochal band of long cilia creates a current for both swimming and feeding. A postoral metatrochal band of shorter cilia beats toward the prototroch and aids capture of food particles. The larvae regulate particle capture while swimming in water with non-nutritious particles or with satiating concentrations of food. Larvae of a gastropod reduced but did not stop capture of algal cells while swimming with the velum extended. In observations thus far, arrests of the metatrochs were less obvious in mollusc larvae than in annelid larvae (Polygordiidae, Serpulidae, Capitellidae). The molluscs’ metatrochs arrested while cilia were in several positions of the beat cycle, whereas metatrochs of the annelids arrested with cilia aligned. Continued observations are testing the hypothesis that metatrochal behavior is similar within molluscs and annelids but different in the two phyla. If the opposed band feeding mechanism originated separately but only once in each phylum, then consistent differences between phyla in metatrochal behavior would be expected. If the opposed band mechanism arose several times within each phylum, consistent differences would not be expected.
