Thriving Oceans

Echinoderms have quite a range of body shapes that include those drawn out with arms like starfish, spherical as displayed by sea urchins, and branched/feathered such as sea lilies.  There are approximately 6000 species in the phylum Echinodermata, many of which are protected by spines.  In the crown of thorns starfish, the poisonous spines protect it from predation as it feeds on coral polyps.