Feeds by sweeping the water with a pair of feathered fans, from inside an anemone.
A flat, smooth crab to about 3 cm across, cream to white and covered in round red to maroon spots. It is not a true crab but a porcelain crab, family Porcellanidae, which is closest to squat lobsters; the fifth pair of legs is reduced and folded away, so it appears to have three pairs rather than four. The claws are broad and flattened and are used for display and defence rather than feeding.
Feeding is done with the third maxillipeds, a pair of appendages carrying long feathered setae that are unfolded and swept through the water in alternating strokes to strain out plankton. A crab in a current will do this continuously and it is one of the more watchable pieces of behaviour on a shallow dive. It lives among the tentacles of the large host anemones — the same ones the anemonefish use — usually as a pair, and retreats under the anemone’s mantle when pressed. Legs shed easily and regrow, which is where “porcelain” comes from. Recorded from the shallows to about 30 m.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
