Echinoderms are slow animals radically different from us, but they are an evolutionary success. All echinoderms have five-part symmetry. We see the inner workings of sea stars, from their tube feet to their skeleton on this animation....

The five-part symmetry of echinoderms is demonstrated, as the five-armed starfish is morphed into an urchin that is then morphed into a sea cucumber. [1:42]