Planet Ocean - Learning Adventures


	People used to think that almost nothing lived in the dark ocean depths. There's little or no light and it's really cold. But now we know that over ninety percent of all marine animals live in the deep sea! Many of these animals are bioluminescent — they produce their own light. Get out your scorecards and let us know which animal shines the brightest in your eyes!

	Flashlight Fish Flashlight fish not only carry their own light, but they can turn it on and off at will. That's because they have a special flap of muscle that can be raised and lowered like a window shade to cover the pockets of glowing bacteria beneath their eyes. Small prey are attracted to this pale green glow. The light also helps flashlight fish see and catch their prey. If spotted by a predator, flashlight fish can quickly "turn off": their lights or use a flash-and-run technique in which they shine their lights and then swim away while their enemy figures out what just happened.

	Comb Jelly Not all bioluminescent ocean animals are fish. This comb jelly is translucent except for its eight "combs." The shiny lights you see in this picture are actually not bioluminescence, but simply the refraction of light that happens when the comb jelly moves its cilia (tiny hair-like structures that help it move). Bioluminescence is almost always blue. This comb jelly probably uses bioluminescence to scare off predators.

	Shrimp This shrimp is actually vomiting bioluminescence onto an attacking fish. This distraction blinds the attacker just long enough for the shrimp to flip over backwards and hightail it out of there!

Pictures: Jeffrey Jeffords (top) | David C. Powell | OAR/National Undersea Research Program
(NURP) | Harbor Branch Oceanographic Institute (HBOI) |