To be included in the phylum is based upon these four characteristics: Skeleton Composition, water vascular system, mutable tissue, and radial symmetry. All echinoderms live in salt water, and they cannot live outside of water or in fresh water. Echinoderms also have a vascular system that carries water and which in some echinoderms end in suckered feet enabling the creature to grip and move objects.
Echinoderms have a simple digestive system with a mouth, stomachs, intestine and anus. In many, the mouth is on the underside and the anus on the top surface of the animal.
Echinoderms have a simple digestive system with a mouth, stomachs, intestine and anus. In many, the mouth is on the underside and the anus on the top surface of the animal.