Lagoon Brittle Star

At low tide, this brittle star does something few others do. It comes out into the open and sweeps its arms across the surface of the water to feed.

Most Ophiocoma brittle stars only feed over the seabed. This species is unusual because it can be seen sweeping its arms across the water's surface instead. That one behaviour is enough to confirm the species.

Long, thin arms spread out from a small, disc-shaped body, about the size of an open human hand. The disc and the plates on the arms range from mottled black to pale brown, in uneven bands.

It lives in the Red Sea and across the tropical Indo-Pacific, including East Africa and Madagascar. It hides in cracks and under boulders on shallow reef flats that lie between the tide lines, and under broken coral, down to about 13 m deep.

How it feeds depends on the tide. It stays hidden at high tide and comes out more as the water drops. When feeding, it holds one arm onto the seabed or a plant to stay in place. Then it sweeps two to four other arms across the water's surface. This traps food in sticky, mucus-covered spines. Tube feet then pass the food to its mouth. At other times, it feeds the usual brittle-star way, filtering small particles from the water.

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  Alexander's Spiny Brittle Star

  Ophiocomella alexandri

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  Commensal Brittle Star

  Ophiothela mirabilis

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  Common brittle star

  Ophiothrix fragilis