How Bioluminescence and Chemiluminescence Work

Glow in the Dark Animals, Plants, Fungi and Microorganisms

Oct 27, 2009 Bridget Coila

Animals, plants, fungi and microorganisms all have members who produce bioluminescence, a natural glow in the dark mechanism that creates light from a chemical reaction.

Bioluminescence, a kind of chemiluminescence, is the biological process of creating light through a chemical reaction. Only living animals can produce bioluminescence and a surprising number of them do.

The Chemical Reaction Behind Bioluminescence

The chemical reaction that produces bioluminescence and chemiluminescence involves two specific chemicals. The first is luciferin, a protein that produces light. There are many different variants of luciferin in different organisms, but they basically operate in the same way. Luciferin works by binding to an oxygen molecule, O2, and this reaction gives off light. Alone, this reaction operates extremely slowly.

The second chemical, luciferase, catalyzes the reaction, making it go fast enough to generate enough light to be visible. In some cases, luciferin and luciferase and oxygen all bind together to make a structure called a photoprotein and another cofactor is needed to set off the bioluminescent reaction. This usually takes the form of an ion, such as calcium (Ca2+). When the calcium ion attaches to the photoprotein, it triggers the whole complex to make light.

In many bioluminescent animals, such as fireflies, ATP powers the chemiluminescent reaction. At the chemical level, the reaction drives an electron temporarily into a higher energy level and when it drops back down it releases a photon of light. Although light is produced, the reaction lets off very little heat.

Uses of Bioluminescence in Nature

The process of how bioluminescence works is fascinating, but many people wonder why it evolved in the first place. There are many reasons posited by scientists for organisms to glow.

One of the most obvious reasons is to attract other creatures. Fireflies use bioluminescence to attract mates and to communicate with one another.

Luminescent mushrooms glow in the dark to draw animals that will disperse the mushrooms' spores and to attract large predators who will protect them by eating any creatures trying to eat the mushrooms. Dinoflagellates, tiny creatures in the ocean, light up in response to movement of water, which attracts large predators to eat whatever is disturbing the water near them.

Anglerfish use bioluminescence to attract prey. Other fluorescent fish, such as the cookiecutter shark, use it as camoflauge to draw attention to a small part of their body and draw large fish in to investigate, which the shark then eats.

Some squid and crustaceans drop chemiluminescent bombs to confuse or scare away predators. A newly discovered species of marine worms off the Oregon coast also do this. They eject glowing green blobs behind them when threatened, according to Steven Haddock, a scientist at Monterey Bay Aquarium Research Institute and Karen J. Osborn of Scripps Institution of Oceanography in research published in the August 21, 2009 issue of the journal Science.

Evolution of Bioluminescence

The many different forms of luciferin and luciferase indicate to scientists that bioluminescence has evolved many times in a variety of organisms. The reaction and its components may have evolved separately as many as 30 different times. Scientists think that some of these evolutionary pathways could have evolved from antioxidant systems.

The highest concentration of bioluminescent organisms occurs in the world's oceans and seas, and this is where the most diversity in luciferin and luciferase also occur.

Despite so many variations on the bioluminescent theme in nature, one thing is certain. Bioluminescent organisms provide a beautiful and fascinating subject for scientists to study and nature lovers to enjoy.

Resources:

J.W. Hastings. 1983. "Biological diversity, chemical mechanisms, and the evolutionary origins of bioluminescent systems." Journal of Molecular Evolution. v. 19: p.309-321.

Dubuisson, M, Marchand, C, Rees, JF., 2004. Firefly luciferin as antioxidant and light emitter: the evolution of insect bioluminescence. Journal of Bioluminescence and Chemiluminescence. Volume 19 Issue 6, Pages 339 - 344

Haddock, S.H.D.; McDougall, C.M.; Case, J.F. "The Bioluminescence Web Page", University of California at Santa Barbara.

The copyright of the article How Bioluminescence and Chemiluminescence Work in Biology is owned by Bridget Coila. Permission to republish How Bioluminescence and Chemiluminescence Work in print or online must be granted by the author in writing.

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