Larval Feeding in Echinoderms |
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Authors: | STRATHMANN RICHARD R. |
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Affiliation: | Friday Harbor Laboratories Friday Harbor, Washington 98250 Department of Zoology, University of Washington Seattle, Washington 98195 |
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Abstract: | In all four types of feeding echinoderm larvae, particles areretained upstream from the ciliated band, probably by an inducedlocal reversal of ciliary beat. Comparative studies and theoreticalconsiderations suggest that increasing the length of the bandmay be the only means of increasing the rate at which wateris processed for paniculate food. This would account for thelong looping band and late development of adult structures inechinoderm larvae. Estimates of the minimum food requirementsof early echinplutei and of uptake of amino acids by embryosare calculated. Various means of rejecting particles are describedand observations related to nervous control of feeding and rejectionare discussed. The possible disadvantages of larvae developingfrom smaller but more numerous eggs are discussed. It is arguedthat loss of a feeding larval stage is usually an irreversibleevolutionary change in echinoderms, and some general implicationsof the irreversibility of such a change in life history arementioned. |
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