Walking Crinoid

• published: 07 Dec 2015
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Often misidentified as a brittle star, yet plant-like in appearance, with long, flexible and highly contorted feathery arms, crinoids are the most ancient class of spiny skinned animals in the Phylum Echinodermata. Dating back to the Paleozoic period, long before sea urchins, sand dollars, sea cucumbers and even the crown of thorns starfish, these echinoderms are the only representatives that have a mouth oriented away from the bottom and are attached to the bottom, at least as a juvenile. As a young animal, their bodies have an attached stalk, a central crown, and 5-200 jointed arms that radiate off the periphery of the crown. The stalk persists in the sea lilies, but in the other group of crinoids, the feather stars, it breaks off, and the animals become stalk-less and lead a mobile life-style. While some reefs may contain hundreds of crinoids, it’s much less common to see one crawling along the bottom. During a recent dive I found a small crinoid slowly crawling along the reef substrate. It used its arms in a coordinated fashion to slowly lift its body and move forward, inch by inch.