<p>A sunflower sea star is draped moplike over a seafloor rock off the British Columbia coast. Though commonly called starfish, sea stars are not fish but echinoderms, more closely related to sea urchins and sand dollars. Only the five-armed species really resemble stars—others may boast as many as 40 appendages.</p>

Sunflower Sea Star

A sunflower sea star is draped moplike over a seafloor rock off the British Columbia coast. Though commonly called starfish, sea stars are not fish but echinoderms, more closely related to sea urchins and sand dollars. Only the five-armed species really resemble stars—others may boast as many as 40 appendages.

Photograph by Paul Nicklen, National Geographic

Sea Stars

These spiny-skinned echinoderms are found worldwide in a colorful menagerie of shapes and sizes.

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