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Flashlight Fish — printable fact sheet
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Flashlight Fish
Anomalops katoptron
Flashlight fishes carry a light organ in a pocket directly beneath each eye, and the light is not theirs. The organ is a bacterial farm, packed with luminous symbiotic bacteria that glow continuously and cannot be switched off — so the fish, unable to turn the lamp off, has evol…
Did you know?
- Flashlight fish can shut off their bioluminescent light instantly by rotating a special organ or covering it with dark skin, making them almost invisible in the dark ocean.
- The light organ has evolved this bacterial partnership independently in several fish lineages, and the flashlight fish's bacteria are so committed to the arrangement that they have lost genes needed to live free and cannot survive outside their host. The fish blink at rates that vary with what they are doing — faster when startled, slower and more regular when feeding. Because the bacteria glow constantly, the organ must be shuttered whenever the fish wants to be invisible, which means "off" is an active behaviour and "on" is the default. The light is bright enough to read by at close range, and Indonesian and Pacific fishermen have historically used the organs of dead flashlight fish as bait lures.
What I learned
Draw the flashlight fish
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