Rigid, warty and toxic enough to kill fish in a bucket with it.
A firm, almost rubbery dorid to about 11 cm, blue-grey with three or four black longitudinal lines and a series of raised tubercles along the ridges, each tipped in yellow. The rhinophores are yellow-orange. Unusually for a nudibranch there is no gill plume on the back — the phyllidiids breathe through folds under the mantle margin — which is a quick way to place any animal of this shape in the family. The several other Phyllidia on the same ground are separated on the arrangement of the ridges and the colour of the tubercle tips.
Feeds on sponges and takes its chemistry from them, secreting compounds toxic enough that a specimen confined in a small volume of water will kill fish placed with it. Nothing eats it, and it is correspondingly unhurried and easy to approach — often out in the open in daylight where most nudibranchs are not. Recorded from the shallows to about 30 m and among the most frequently seen nudibranchs on any muck site, which is worth knowing when a guide points at one on a first dive.
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.
