If you're a marine predator -- you probably aren't, but who knows? -- you might want to pass on that tasty-looking dinoflagellate. Some species are bioluminescent, meaning that they glow in the dark. When some predators eat these luminous lunches, their skin is thin enough to reveal the glowing dinoflagellate inside. This in turn makes the predator visible to even bigger deep-sea monsters. Yikes!