ABSTRACT
The echinoderms comprise feather stars and sea lilies, sea cucumbers, sea urchins, pencil urchins, heart urchins, sand dollars and sea biscuits, sea stars as well as basket, brittle and snake stars. Studies on reproduction and development of echinoderms have gained much importance in exploration of their genes responsible for extra-ordinary potency for regeneration and agametic cloning. Echinoderms together with primitive deuterostomes constitute a basal group of non-chordate invertebrate deuterostomes and occupy a key position in evolution. The genomes of echinoderms and vertebrates have revealed 70% homologies of sea urchin with human. Echinoderm biologists report Gonad Index values, in view of large quantums of body fluids being maintained in the unique water-vascular system. Egg size is correlated with important reproductive and developmental patterns including fecundity, quality and quantity of maternal investment per egg, Fertilization Success, durations of embryonic and larval development, larval size and modes of development as well as larval habitat and dispersal.
