Small hermits by the dozen on open sand, most of them in worn nassarius shells.
Small hermit crabs, most of them under 2 cm including the shell, with the left claw clearly larger than the right, long slender eyestalks and claws and legs clothed in fine setae that hold a film of silt. Colour is grey, brown or olive with pale banding on the legs, and it matches the sediment closely. The shells they occupy are usually small worn gastropods, most often the nassarius shells that are the commonest empty shell on a muck bottom.
Identification below the genus is not practical from a photograph. Species are separated on the ornament of the large claw and the proportions of the eyestalks, and several look alike on the same stretch of sand. What is easy is the genus: the combination of the enlarged left claw, the hairy legs and the small size distinguishes them from the large Dardanus hermits that use big shells and from Calcinus, which is smoother and brighter and prefers rubble.
They are the most numerous large-enough-to-see animal on much muck ground and are usually passed over. They scavenge, gathering on anything dead within minutes, and a discarded fish head on the sand will collect thirty of them. Shell competition is constant, and animals that have outgrown their shell carry the abdomen partly exposed. Recorded from the shallows to beyond 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.