Nudibranchs are the technicolor punks of the reef. They’re soft sea slugs - no shell - and they come in every wild color combination you can imagine: hot pink with neon yellow tips, electric blue with white spots, deep purple with orange flames. Some are barely a fingernail long.
The colors aren’t just for show. They warn predators that nudibranchs taste awful - and sometimes much worse than that. Many nudibranchs eat stinging cnidarians like jellyfish, hydroids, and anemones. Instead of being hurt by the stingers, they swallow them whole.
Then comes the trick. The stinging cells, called nematocysts, get sorted through the nudibranch’s digestive system and migrate intact up into the tips of the nudibranch’s own skin. There they sit ready to fire - turning the slug into a walking sting bomb, using weapons that originally belonged to something else.
