Rides on a sea cucumber, and moves round to the underside when it is looked at.
A small swimming crab to about 2.5 cm with a smooth rounded carapace, patterned in bold irregular blotches of dark chocolate on cream — or, in many individuals, cream on dark. The pattern varies enough between animals that no two are quite alike, and it is close enough to that of the tube-anemone-dwelling Lissocarcinus laevis for the two to be told apart mainly by which host they are on.
An obligate associate of holothurians, living on the body wall of large sea cucumbers, most often Pearsonothuria, Bohadschia and Thelenota, and occasionally inside the host around the cloaca. It feeds on mucus and on particles the cucumber collects. Pairs are common. Recorded from about 3 to 30 m. The behaviour to expect is simple and consistent: as a diver’s light lands on it, the crab walks round the cucumber onto the underside, so a photograph is taken by approaching low and lighting from the side, or by rolling nothing and waiting for it to come back round on its own.
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.
