Naturally produced light-emitting chemicals offer undersea advantages to (clockwise from top left) a pelagic worm, squid, krill, scaleless black dragonfish, and deepwater jellyfish. Though research on bioluminescence recently garnered a Nobel Prize, the phenomenon is still poorly understood, according to a new paper reviewing recent discoveries about bioluminescence's benefits, its evolution, and the surprising diversity of ways plants and animals generate glowing substances. Eighty percent of all creatures known to produce their own light live in the ocean, according to the report, published today in the journal Science. "There are no hiding places in the open ocean, so a lot...