While I was grad student at UCLA, I twice had the opportunity to TA a field course in Mo’orea, a small island next to Tahiti in French Polynesia. These are some photos I snapped on a night dive last time I was there, in the spring 2012. Enjoy!
Arms races between predators and their prey have been common in the evolution of life. Gazelles run a little faster to help them escape cheetahs, then of course the cheetahs speed up to keep catching their meals. Bivalves (clams, scallops, etc.) and snails have evolved some tough and elaborate shells to protect themselves, and in response the crabs, octopuses, and fishes that eat them have developed incredibly strong claws, drills, or teeth to crush, open, or bore into the shells. And of course toxins can be synthesized to ward off all sorts of enemies looking to take a bite out of you (the slow loris is by no means the only animal to do this, but it may be the cutest).
But what if you’re just slow and squishy? In the case of nudibranch sea slugs, some of them make up for this vulnerability by eating cnidarians (jellyfishes, coral, sea anemones), stealing their stinging cells, and planting them in their own tissues, ready to fire at an unsuspecting predator. The process is called kleptocnidae, and even though it was discovered almost 100 years ago, it’s been the subject of very little study since then.
A while back, I wrote about kleptoplasty. It’s the process whereby sacoglossan sea slugs steal chloroplasts from their algal prey and use them for photosynthesis, essentially turning themselves into solar-powered animals. However, see a recent study calling into question the extent to which the slugs use photosynthesis for survival.
Regardless of exactly how important solar power may or may not be for the survival of sacoglossans, nudibranchs have arguably taken the art of stealing from their prey to a different level. Nudibranchia is the best known group of sea slugs, largely because their patterns are so colorful that they often look more like cartoon characters or art projects than real animals. But we all know beauty doesn’t necessarily make you nice, and nudibranchs could be considered masters of deception in that regard. In contrast to the herbivorous (i.e. vegan) sacoglossans, nudibranchs are voracious predators, devouring sponges, corals, bryozoans, or other sea slugs – some will even cannibalize members of their own species!