Larval feeding in echinoderms

Abstract

In all four types of feeding echinoderm larvae, particles are retained upstream from the ciliated band, probably by an induced local reversal of ciliary beat. Comparative studies and theoretical considerations suggest that increasing the length of the band may be the only means of increasing the rate at which water is processed for paniculate food. This would account for the long looping band and late development of adult structures in echinoderm larvae. Estimates of the minimum food requirements of early echinplutei and of uptake of amino acids by embryos are calculated. Various means of rejecting particles are described and observations related to nervous control of feeding and rejection are discussed. The possible disadvantages of larvae developing from smaller but more numerous eggs are discussed. It is argued that loss of a feeding larval stage is usually an irreversible evolutionary change in echinoderms, and some general implications of the irreversibility of such a change in life history are mentioned. © 1975 by the American Society of Zoologists.