Image: Peter Shearer/National Institute of Water and Atmospheric Research
I don't know about you, but I'm utterly fascinated with weird and scary creatures that troll the deep ocean. Dark Roasted Blend has a fantastic post (as usual) filled with images of such creatures.
This one above is the Dragon Fish:
Light is so rare down there that its uniqueness is an allure, for mating, as well as a lure, for eating. Grammatostomias flagellibarba, 'dragon fish' to you and I, uses bioluminescence – biological light – mainly for the latter: EATING. Any deep, deep, deep swimmer that notices and becomes interested in a certain tiny flickering light will end up becoming caught by the dragon fish's monstrously huge and needle-sharp toothed mouth. The light being a glowing lure at the end of a long, thin filament connected to the underside of the fish's jaw.