AP BIOLOGY

Detailed explanation-1: -In Greek, echinos means spines, and derma means skin. Thus, these are spiny skinned organisms.

Detailed explanation-2: -Echinoderm means spiny skin. If we break the word down echino = spiny and derm= skin, so these animals are spiny-skinned. Sea stars and their cousins are part of a group of spiny-skinned animals. Sea Stars: Most sea stars have five arms.

Detailed explanation-3: -In addition to radial symmetry, echinoderms have a water-vascular system. True. True or False? The hard, spiny skin of an echinoderm is called an exoskeleton.

Detailed explanation-4: -Spiny skinned animals are placed in Echinodermata. The spines on the skin in echinoderms are part of the endoskeleton. The endoskeleton is made up of calcium carbonate plates called ossicles that bear spines which project outside.

Detailed explanation-5: -echinoderm, any of a variety of invertebrate marine animals belonging to the phylum Echinodermata, characterized by a hard, spiny covering or skin.