ABSTRACT

Most echinoderms possess larvae with a more or less long pelagic life, although all classes have incubating species which generally inhabit the polar seas. Since then, most authors have reared echinoderm larvae with nanoplankton from sea water. The stomach contents of many different planktotrophic larvae collected in the sea have been described. Nervous structures have been described in echinoderm larvae. Lecithotrophic larvae, pelagic or demersal, often have a different morphology to those of the classic planktotrophic larvae. The planktotrophic larva of the echinoderms is a suspension-feeder which feeds on small diatoms, phytoplankton, small flagellates and detritus. It develops easily in a laboratory if given a food complement at the end of the endotrophic phase. The digestive tract consists of an epithelium supported by a fine basal membrane. The environmental role of planktotrophic larvae of echinoderms in the transfer of substances formed by the phytoplankton can be especially important.