Echinoderms, such as starfish, sea urchins and sea lilies, use small, flexible, tubular projections called "tube feet" for locomotion, feeding, respiration and sensory perception. Crinoids, a subgroup ...

Echinoderms are a phylum of exclusively marine deuterostome invertebrates characterized by pentaradial symmetry in adults, a calcareous endoskeleton composed of ossicles, and a unique water vascular ...