What are the basic morphological features of echinoderms?
Echinoderms, as the name indicates (echino = spiny, derma = skin), are creatures with spines originated from an endoskeleton. Their endoskeleton is made of calcareous plaques that besides spines contain pedicellaria, small pincers used to clean the body and to help the capturing of prey. They also present a hydrovascular system known as the ambulacral system. Adult echinoderms have pentaradial symmetry; the radial symmetry in these animals is secondary, present only in adults.
