A brittle star whose five arms branch again and again into hundreds of fine, curling tips, forming a mesh that spreads to about 1.5 m (5 ft) across when fully open. Color is cream, tan or pale orange. By day the animal is unrecognisable as the same creature: the whole net contracts into a tight knotted ball wedged into a crevice or clamped around a gorgonian stem, no bigger than a fist and easily mistaken for a sponge.
At dusk it climbs to a raised perch - the top of a sea fan, a coral head, the lip of a wall - and unfolds into the current, holding the net at right angles to the flow. Passing zooplankton sticks to hooked microscopic spines on the arm tips, which then curl inward and pass the catch down to the mouth on the underside. Feeding is best on nights with current running, and the animal collapses its net if lit by a torch, so it is worth looking with the beam held to one side. Depth runs from about 5 to 40 m (16 to 130 ft) on 🌊 Red Sea walls and drop-offs.
- arms branching over and over into a dense basket
- unfolds into a wide net at night, a tight ball by day
- perched on gorgonians or the edge of a wall
