1. 28-4: Echinoderms

2. Endoskeleton Structural support located inside the body of an animal.

3. Water Vascular System System of internal tubes in echinoderms that carries out essential functional such as feeding, respiration, circulation, and movement.

4. Madreporite Sievelike structure through which the water vascular that extracts wastes from echinoderm opens to the outside.

5. Tube Foot Suction-cuplike structure attached to radial canals of echinoderms; used to walk and open shells.