Bioluminescence can be used for myriad purposes in different species—this recently discovered species of annelid, Swima bombaviridis, probably uses bioluminescence to escape from predators. It was described by Karen Osborn and friends. The worm carries eight fluid-filled packets near its head that it can release at will. When these packets are released, they bioluminesce a bright green for several seconds. Since the worms live in the deep sea, these flashes are a contrast to the dark environment and may distract predators—instead of getting a bite of worm, they are left with nothing. The mechanism for releasing these bioluminescent bombs is unclear—in addition to the lack of light at the depths the worms live at they are without eyes—but the release is probably related to a tactile sensory system, as they release their bioluminescent organs when touched.
Photo by Casey Dunn. The head is to the left, and the green bioluminescent packets can be seen attached to the body just behind it.