Bioluminescence is the production of light within a living organism as the result of a chemical reaction. Bioluminescence is the production of a cold light. This means that less than 20% of the light produced will generate any type of thermal radiation or heat.
The majority of organisms that are able to bioluminescence are found in the ocean. Land has a very limited diversity of organism that can bioluminescence and there are no known freshwater species that can produce bioluminescent light. Freshwater and terrestrial habitats have not been around long enough in order for bioluminescence to have evolved into a very useable form of communication. The marine environment contains a wide diversity of organisms, such as fish, bacteria, jellyfish, and dinoflagellates that have been found to be able to produce light through bioluminescence.
The Science of Bioluminescence
In order for bioluminescence to occur the chemical luciferin and either luciferase or photoprotein are required. Luciferin is the substrate in the chemical reaction that will be acted upon by the luciferase or photoprotein enzyme. When luciferin interacts with luciferase it will create a byproduct called oxyluciferin. This interaction is what will produce the familiar bluish-green color of bioluminescence. Some marine organisms produce luciferin while others acquire it from their food sources. Some marine mammals, such as squid, don’t produce the bioluminescence themselves. Instead they house bioluminescent bacteria within their light organs and use the bacteria to produce their light.
Dinoflagellates are single-celled organisms that are commonly referred to as plankton. Their size can range from 30 um to 1 mm and they can be found in all the world’s oceans. Most dinoflagellates are short lived organisms and in order to maintain their population levels they most often reproduce thru asexual reproduction. One individual can divide and become two individuals in a short amount of time thus sustaining their populations. Dinoflagellates are a significant component of the plankton load in every marine ecosystem on earth.
Bioluminescence has evolved to serve a variety of needs for different organisms. Some species use it to hunt their prey, defend against predators, attract mates, or other activities that will increase their chances of survival. Dinoflagellates evolved bioluminescence as a defensive adaptation. When a fish or other animal swims through the mass of dinoflagellates at night the dinoflagellates will bioluminescence in an effort to distract the predators. The flash of color will draw the attention of other predators, hopefully distracting the initial predator, giving the dinoflagellates a chance to attempt escape. The disturbance of a boat motor will produce the same effect as that of a predator swimming through the water.
Bioluminescence at Anderson Lagoon
Anderson Lagoon is a warm-water lagoon, located in southern Belize, near the village of Hopkins. The lagoon is home to billions upon billions of bioluminescent dinoflagellates that run the luciferin-luciferase reaction causing regions of the lagoon to be illuminated at night. The tides bring dinoflagellates into the lagoon and the narrow opening of the mouth of the lagoon prevents them from returning to the sea. The concentration of dinoflagellates is what makes the lagoon so spectacular. A similar phenomenon can be experienced if a snorkeler or diver stirs up the sand on the bottom of the ocean at night. As the dinoflagellates are stirred up from the sand bed they will bioluminescence, giving the appearance of stars sparkling within the water.
Bioluminescence is being studied by biologists and engineers alike. They are interested in understanding how humans can use bioluminescence to enhance our lives. Scientists can monitor the activity of different genes by enhancing an organism with a bioluminescent gene and then studying its expression within the organism. Experimental bioluminescent trees are being tested in order to determine whether or not they can be used to help light city streets and highways, reducing the dependence on traditional sources of electricity.
For More Information
- Bioluminescence: National Geographic
- Dinoflagellates and Bioluminescence: Scripps Institute of Oceanography
Dave Cox is a Professor of Biology, author, and President of Howler Publications. He has been leading study abroad trips to Belize, for students and community members, to study tropical ecology, marine biology and Mayan culture since 2007. If you would like to join Professor Cox on a lionfish hunt in Belize contact him at firstname.lastname@example.org for more details.
- Bioluminescence in the ocean: Jed from San Diego, California Republic – Bioluminescence 2, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=7326007
- Dinoflagellates: By Maria Antónia Sampayo, Instituto de Oceanografia, Faculdade Ciências da Universidade de Lisboa – http://planktonnet.awi.de (provided under a Creative Commons Attribution 3.0 License), CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=4611081
- Anderson Lagoon: image courtesy of VivaBelize.com and used by permission