GENERAL HISTOLOGY

Detailed explanation-1: -Echinoderms and chordates are two closely-related groups of animals. They show bilateral symmetry at any stage of their life cycle. Therefore, they belong to the clade Bilataria. Also, both are deuterostomes whose blastopore develops into the anus.

Detailed explanation-2: -Nevertheless, DNA evidence indicates that echinoderms and chordates are closely related, with both phyla belonging to the Deuterostomia clade of bilaterian animals.

Detailed explanation-3: -Significance of Echinoderm larvae : In general all the larvae show that they might have come from same ancestor which is coelomate, bilaterally symmetrical and free swimming. 2. These larvae also show resemblance with Toronaria of Balanoglossus. Thus the study of Echinoderm larva has a phylogenetic significance.

Detailed explanation-4: -Usually, chordates are bilaterally symmetric while echinoderms are pentaradially symmetric. Both animal groups have internal skeletons, but the one in chordates is complete and very sophisticated, whereas the echinoderms have calcified plates. Nervous system is highly developed in the chordates than in echinoderms.