It’s night time at a quiet lagoon in Vieques, PuertoRico. The bay is full of marine organisms known as dino flagellates, each the size of a pinprick. When something bumps into adino flagellate, the impact triggers a chemical reaction that endsin a burst of light. No one really knows why dinoflagellates flashon contact, but scientists think it may startle or expose predators,or help remove toxic oxygen from their bodies.