Pyrosome

A pyrosome drifting in open water off Atauro Island, East Timor, photographed in 2005. It looks like one creature but is a hollow tube made of hundreds of tiny animals called zooids, relatives of sea squirts, each pumping water through the colony. Its name means fire body in Greek. Every zooid carries a pair of light organs, and with no nerves linking them, one zooid's flash sets off its neighbors, so waves of light ripple slowly across the whole colony.