GENERAL HISTOLOGY

Detailed explanation-1: -Echinoderms have a spiny endoskeleton. They have radial symmetry as adults but bilateral symmetry as larvae. Echinoderms have a unique water vascular system with tube feet. This allows slow but powerful movement.

Detailed explanation-2: -Echinoderms possess a unique internal skeleton (or endoskeleton) composed of thousands to millions of calcium carbonate components known as ossicles. Similar to a complicated 3-D puzzle, these pieces are infused with tissue and covered by an epidermis, or skin like covering.

Detailed explanation-3: -Although they may appear very different, echinoderms all have two major defining characteristics that set them apart from all other animals: a water vascular system and five-sided radial symmetry.

Detailed explanation-4: -The bodies of echinoderms are made of tiny, hard calcium-based plates. The plates are often spiny and always covered by a thin skin. Because the echinoderm skeleton is on the inside, it is called an endoskeleton. Echinoderms seem little more than a skeleton of tiny plates and water.

Detailed explanation-5: -All echinoderms also exhibit radial symmetry in their body plans-specifically pentaradial symmetry, or fivefold symmetry, which is unique among animals. Only cnidarians, like jellyfish and hydra, have anything close to this kind of arrangement.