Black-green with orange rims and gills, feeding openly on colonial sea squirts.
A large dorid to about 12 cm, the body black to very dark green, the foot and mantle margins lined in orange to vermilion, the rhinophores and the gill plume the same strong orange. Green ridges and blotches run along the back in a pattern that varies between individuals — hence the other name in circulation, variable neon slug. Congeners such as Nembrotha cristata and N. lineolata differ in carrying green or purple rather than orange on the gills and margins.
Feeds on colonial ascidians — sea squirts — and is usually found on or beside a colony rather than crossing open ground, often several animals on one patch. It takes up defensive compounds from the prey and secretes them in its mucus, which is the usual explanation for how conspicuous it is prepared to be. Mating pairs and white spiral egg ribbons are common on the same colony. Recorded from about 3 to 30 m. Large, slow and brightly coloured, so it is one of the easiest nudibranchs to photograph well.
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.
