How Bioluminescence Works

Evolution and Shared Light

Photo by M. J. McFall-Ngai and E. G. Ruby, University of Hawaii via the NSF

Animals can either house these substances in their own bodies or develop a symbiotic relationship with light-producing bacteria. These bacteria live in a light organ in the host organism's body. The bacteria produce light all the time, so in order to turn their lights on and off, some animals can pull their light organs into their bodies. Others cover them with pieces of skin similar to eyelids. Some organisms also use a fluorescent substance, like green fluorescent protein (GFP), to adjust the color of the light they create. The fluorescent substance absorbs the blue-green light and emits it as a different color.

Photo by J. W. Hastings, Harvard University, through E. G. Ruby, University of Hawaii via the NSF

Because of all these variations in luciferins, luciferases and how animals use them, many researchers believe that the ability to make light simultaneously and independently evolved in multiple forms of life. The fact that there are few bioluminescent animals in freshwater environments supports this theory. Fresh, inland bodies of water haven't existed as long as the world's oceans have, so the animals that live there haven't had as much time to adapt to their surroundings. In addition, the bottoms of most bodies of fresh water aren't dark enough to require additional sources of light.


An adult Euprymna scolopes squid, which houses luminescent bacteria in its light organ.

­ ­Animals have lots of methods for producing and using light, and people have discovered lots of uses for the light animals can create. Researchers can use single-celled luminescent organisms that light up when disturbed to study the way animals move through water. Scientists have also given bioluminescent traits to non-luminescent animals in order to perform research on the progression of diseases like cancer and Alzheimer's. Such research can make bioluminescence as useful to people as it is to other forms of life.

To learn more about marine life, bioluminescence and related topics, follow the links below.

Bioluminescence FAQ

What causes bioluminescence?
Bioluminescence occurs when chemical compounds mix together to produce a glow.
Is bioluminescence harmful to humans?
Bioluminescence is not harmful to humans. It's simply a light that certain marine creatures emit which causes the water to glow.
What causes bioluminescence in the ocean?
Bioluminescence in the ocean is often caused by animals that emit light. The animals' glow can travel a long way, and it can blend in with the light from above. In some parts of the ocean, these animals, not the sun, are the primary source of light.
Why are some fish bioluminescent?
There are a few reasons why fish are bioluminescent. They may use it as a form of communication, a way to locate food, as an act of self-defense, a way to attract prey, or a way to camouflage.
Where can I see bioluminescent waves?
­Most of the world's bioluminescence exists in the ocean, not on land. Bioluminescent life forms live throughout the ocean's depths, but most exist in one particular zone -- the twilight zone. This zone is also known as the disphotic, or poorly lit, zone.

Related Articles

More Great Links


  • Coder, Kim D. "Foxfire: Bioluminescence in the Forest." University of Georgia School of Forest Resources. 1999 (6/25/2007)
  • Davidson College. "Bioluminescence." Animal Physiology. (6/25/1007)
  • Haddock, S.H.D.; McDougall, C.M.; Case, J.F. "The Bioluminescence Web Page", (created 1997; updated 2006; accessed 6/25/2007).
  • Harbor Branch Oceanographic Institution. Bioluminescence. (6/25/2007)
  • The Bioluminescence Web Page
  • Jennings, Paige. "Glow with the Flow." Scripps Institution of Oceanography." (6/25/2007)
  • Mills, C.E. "Bioluminescence and Other Factoids About Aequorea, a hydromedusa." University of Washington.
  • Pieribone, Vincent and David F. Gruber. "A Glow in the Dark: The Revolutionary Science of Biofluorescence." Harvard College. 2005.
  • Scripps Institution of Oceanography. "Bioluminescence Questions and Answers." (6/25/2007)
  • Wampler, John E. "Bioluminescence Studies." University of Georgia. (6/25/2007)
  • Wampler, John E. "Earthworm Bioluminescence." 3/5/1999 (6/25/2007)
  • Widder, Edith A. "Marine Bioluminescence." Harbor Branch Oceanographic Institution. 2001. (6/25/2007)