Many species of deep ocean fish have special adaptations to living in extremely high pressure, low light conditions. Viper fish (Mesopelagic - found at 80-1600 meters - about a mile down) are some of the most wicked looking fish dredged up from the depths. Some of them are black as night all over with light organs (called photophores) in strategic places on their bodies, including one on a long dorsal fin that serves as a lure for the fish it preys upon. Some viperfish (and many other deep ocean fish species) don't have any pigment (color) at all - they're "see through". They also have enlarged eyes, presumably for gathering as much light as possible where there is little or no light at all. The light organs create lights by using a chemical process called bioluminescence.

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