A flat, fast crab of shallow rubble, often within reach of an urchin.
A crab with a very flat, nearly circular carapace to about 3 cm across, dark green to almost black with fine pale lines running over the shell and pale spots at the leg joints. The legs are long, flattened and edged with short spines, and the eyes sit close together at the front. The whole animal is built to hold onto rock in moving water, and it runs sideways faster than anything else on the same ground.
Found on shallow rubble, boulders and rock, frequently alongside long-spined urchins, where it uses the spines as cover rather than living on the urchin itself. It is active by day, which is unusual among the crabs of a muck site, and it retreats into a crack rather than burying. Recorded from the surf line down to about 15 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.
