NEET BIOLOGY

Detailed explanation-1: -Echinoderms are marine invertebrates. They include sea stars, sand dollars, and feather stars. Echinoderms have a spiny endoskeleton. They have radial symmetry as adults but bilateral symmetry as larvae.

Detailed explanation-2: -The echinoderms have a radially arranged, pentamerous body structure that is very different from the bilateral body structure of the related deuterostome phyla, the hemichordates and the chordates. Yet, all three phyla evolved from a common bilaterally symmetric ancestor (Eernisse & Peterson 2004; Smith et al. 2004).

Detailed explanation-3: -Radial symmetry is found in the cnidarians (including jellyfish, sea anemones, and coral) and echinoderms (such as sea urchins, brittle stars, and sea stars).

Detailed explanation-4: -For example, pies, snowflakes, and starfish are radially symmetric because they have many different lines of symmetry (dividing them into matching halves) and the lines cross one another at the center.

Detailed explanation-5: -Echinodermata means “spiny-skinned, ” and this phylum includes such spiny animals as sea stars and sea urchins. The skin covers an internal skeleton. Like cnidarians (e.g., jellyfish and corals), the bodies of echinoderms are organized around a central point; they exhibit radial symmetry.