 | These animals have a five-part body plan with a radial symmetry. Composed of endoskeleton, the external spines are only extensions of these endoskeletons. They have specialized tube feet to suck in water for mobility and to feed on other animals. They lack a head and a centralized nervous system. They do not have an excretory or respiratory systme. They use seawater as circulatory fluid in their circulatory system. |
