The slimy grey slugs we’re used to seeing after a rain shower are anything but colorful, and for some of us they’re barely even tolerable. But in the sea it’s an entirely different story: sea slugs are unusually shaped, brightly colored, and even sort of cute.
Nudibranchs are the underwater cousins of the ugly, cement-slithering slugs we see on dry land. They come in all kinds of bizarre shapes, with one of the only predictable characteristics being the feelers protruding from their heads. Their coloration is similarly unpredictable; they often sport neon colors and wild patterns, often looking more like candy or children’s toys than animals.
Not all sea slugs are nudibranchs, and because of their huge variations in colors and shapes it can be difficult for divers to identify what type they’re looking at. There are many online forums and photo galleries that help divers, underwater photographers and nudibranch lovers share their photographs with one another.
There are around a thousand species of nudibranchs, and most of them live in warm, shallow waters. Their bright colors probably serve to warn off fish and other sea creatures that might take a bite out of them. If anything does manage to scoop up one of these soft-bodied deep-sea clowns, they’ll get a mouthful of poison, or at least foul-tasting flesh. Their coloration is a first line of defense, and their terrible taste helps keep them out of the bellies of bigger animals that might make a meal of them.