Some are brilliant yellow, while others are painted with an outrageous pattern of stripes and dots that clash with the equally garish tufts on the animal's back. Most are less than two inches long and can sit comfortably on the tip of your finger. And since form does indeed follow function, nudibranches also demonstrate some of biology's most ingenious adaptations. For starters, they're hermaphrodites, meaning that they can mate with and mutually fertilize any adult of their species that they happen upon. As peculiar as that might be, it's not that unusual in the sub-sea realm.
Many nudibranches feed on anemones and hydroids.
Normally the stinging cells of these animals protect them from being eaten. However, not only is the foraging nudibranch undeterred by such defenses, but after eating its prey it manages to separate the stinging cells from the rest of its dinner and store them undischarged in the tips of the projections that line its back. The nudibranch uses the defense of its prey for its own defense. Others steal and incorporate pigments from their food, a sponge perhaps, and change colour so as to be completely camouflaged as they slowly munch away on their prey. The common Caribbean lettuce sea slug is a thief of a different sort.