Steals working chloroplasts from the algae it eats and keeps them alive in its own tissue.
A sacoglossan to about 5 cm — a sap-sucking slug rather than a nudibranch, though it is filed with them by everyone who dives. The body is green to olive, sometimes almost black, and the two large lateral flaps that fold up over the back are edged in a band of white, then a band of orange, then a fine black line. The head carries two rolled rhinophores. Nothing else in the shallows here has that triple-banded margin.
It feeds by piercing the cells of green algae, chiefly Bryopsis, and sucking out the contents — and it retains the chloroplasts, keeping them functional inside its own digestive tissue for days to weeks and drawing some nutrition from their continued photosynthesis. That is the mechanism behind the “solar-powered” slugs, and it is worth being precise about what it does and does not mean: the animal still has to eat, and the chloroplasts are not passed to its offspring. Found in the top few metres wherever the food algae grows, including on rubbish and rope.
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.
