EVERYDAY SCIENCE

Detailed explanation-1: -echinoderm, any of a variety of invertebrate marine animals belonging to the phylum Echinodermata, characterized by a hard, spiny covering or skin.

Detailed explanation-2: -Echinoderms are named for their “spiny skin.” However, the spines aren’t on their skin. They are part of the endoskeleton. The endoskeleton consists of calcium carbonate plates and spines, covered by a thin layer of skin. Adult echinoderms have radial symmetry.

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. The water vascular system is a complex series of canals running through an echinoderm’s body (Fig. 3.84).

Detailed explanation-4: -Echinoderm means spiny skin so the last characteristic they all share is…. spiny skin. The spines are very obvious in some echinoderms. The sea urchins, for example, have obvious spines covering their body.