An aeolid with cerata carrying the stinging cells of the hydroids it feeds on, transferred intact and used in its own defence.
Up to about 5 cm and commonly 1 to 3. An elongate aeolid tapering behind, with a translucent grey body. There is an orange to red or yellow line running along the middle from the front edge to just behind the rhinophores, often with a broken white line behind it. The rhinophores are ringed, with up to about eighteen rings. The cerata sit in clusters in two rows along the back, banded white or blue, often with bright red or orange tips just below the point. The oral tentacles are longer than the rhinophores. It sheds its cerata readily when handled.
A closely related Caribbean species is separated by its prey and its size: that one is larger and lives on and eats the upside-down jellyfish. This one lives on hydroids.
It is a hydroid predator and the practical way to find it is to find the hydroid: it sits on the colony it is eating. It has also been recorded on bryozoans. It lives from the low intertidal to about 26 m.
The name needs a note. “Bushy-backed nudibranch” is the standard English name of a cold-water North Atlantic and North Pacific animal in a different family. This species is normally called the fringeback nudibranch, and this site now uses that name.
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.
