A hermit crab that never carries a shell, living in a worm hole in living coral.
A small hermit crab, the visible part rarely more than a centimetre, that lives head-out in an abandoned worm tube or barnacle borehole in a living coral head and does not carry a shell at all. What shows is the front of the animal: two stalked eyes, a pair of long antennae carried erect and fringed on both sides with fine setae, and the claws held close to the opening. Colour varies, with banded orange, brown and white antennae common, and the setal fringe often paler than the shaft.
The feathered antennae are the feeding apparatus. They are held out into the current in a V, combed through by the mouthparts at intervals, and the animal takes suspended particles rather than grazing. This is why it can afford to be sessile, and why it is found on the current-facing side of a coral head more often than in the lee.
Withdrawal is instantaneous and is triggered by shadow, so the animal is normally seen for a second and then not at all, and the shape of the hole is the only thing left. Waiting a minute at a distance is the method that works; approaching with a light already on the head does not. Recorded from about 2 to 25 m on massive corals, most often Porites.
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.