They have a simple nervous system consisting of nerve rings, a rudimentary circulatory system, and no brain, and movement is achieved using a rounded muscular sac called an ampulla.
Extant classes of this phylum of animals include Crinoidea and Stelleroidea. They have a simple nervous system consisting of nerve rings, a rudimentary circulatory system, and no brain, and movement is achieved using a rounded muscular sac called an ampulla. Unique in their posession of a water vascular system and tube feet, their spiny skin gives them their name, and many of them have pentaradial symmetry. FTP, name this phylum which includes sea cucumbers, sea urchins, and starfish.
Extant classes of this phylum of animals include Crinoidea and Stelleroidea.
Echinodermata or Echinoderms