Phylum Echinodermata

∞ generated and posted on 2016.11.05 ∞

Starfish, sea urchins, sea cucumbers, brittle stars, sand dollars, etc.

Echinoderms possess five-sided radial symmetry – think five arms of a starfish – but have bilaterally symmetrical larvae. They include both sessile (not moving) and motile representatives. Echinoderms possess a calcified endoskeleton, what is known as a water vascular system, and the perhaps familiar tube feet such as one sees in starfish.

Remarkably, the transition from bilateral symmetry to radial symmetry involves the decline and then loss of right side of the animal!