Syllid fireworms are a part of the Syllidae family, which is a type of polychaete worm. Usually these small worms, not getting much bigger than 13 cm, live on the ocean floor. But when the worms mate, they move from their home on the sea bottom to the surface of the water and swim around in small circles. The females use bioluminescence to attract the males during this ritual that occurs around the time of the new moon.
Another family of Polychaete worms, the bearded or marine fireworm, can be found on corals and soft bottoms of shallow reefs in the Tropics of the Atlantic Ocean. They have hollow bristles that, when broken off, release a venom that can cause burning and irritation (a different kind of fire than the bioluminescent species!). The worms feed on corals, anemones and crustaceans.