A large green ophiuroid that hunts small fish, and the brittle star that will bite.
The largest brittle star on these sites apart from the basket star: a heavy disc to about six centimetres across and five thick, tapering arms giving an overall span of roughly 45 cm. The colour is a solid olive to dark green, with a pale green or yellow-green spot at each arm joint that runs the length of the arm as a row of dots, and the arms carry short blunt spines rather than the long glassy fringe of Ophiothrix purpurea. The build is the quickest separation from the rest of the ophiuroids — the arms are muscular and hold their shape rather than whipping, and an animal this size and this colour is not confused with anything else once seen.
It is a predator, and that is unusual for the group. Alongside the scavenging and detritus feeding most brittle stars do, this species takes small live fish: it raises the disc off the substrate on arched arms to make a low shelter, which small fish enter, and then drops the disc and closes the arms over them. The behaviour is best documented in aquaria, where the animal is a known consumer of tank fish, but it is consistent with what is seen on a reef at night. By day it packs into rubble and under debris with a few arm tips showing, and it comes out onto open ground after dark. It has functional jaws at the centre of the oral surface and will grip a finger put within reach.
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.
