Sits in a small anemone with its abdomen curled up over its back, waving.
A shrimp of about 1.5 cm, olive to chocolate brown with white saddles edged in a fine blue line, and a tail fan patterned in the same colours. It is named for its posture rather than anything else: the abdomen is held curled up and forward over the back, and the animal rocks it continuously in a motion that carries a long way for something this small. Nothing else of this size and habit occurs on the same hosts, so the posture is the identification.
Lives on small anemones, corallimorphs and occasionally on hard coral, usually in groups of three to a dozen on one host, and is unaffected by the anemone’s stinging cells. Females carry visible green eggs under the abdomen. Recorded from the shallows to about 25 m wherever a suitable host grows, including on isolated anemones out on rubble. The photographic problem is depth of field against constant motion — the animal never stops rocking — and the usual answer is to frame the whole host and wait for the shrimp to come round to the front of it.
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.