Ocean STEMulation: How does bioluminescence work?

Focusing on science, technology, engineering, and math (STEM), as they pertain to the ocean.

This is part 1 out of 2 blogs on bioluminescence. Read part 2 here

Bioluminescence is light produced by a living organism through a chemical reaction.

The bioluminescence reaction involves two main compounds: a luciferin (which produces the light) and a luciferase (which allows the chemical reaction to happen). The luciferase is a catalyst, helping the reaction happen, allowing oxygen to combine with the substrate luciferin. Oxidizing the luciferin creates photons, or light. It also results in oxyluciferin, which is inactive, and sometimes other byproducts like water. To continue the reaction to make more light, usually a fresh luciferin must enter the system.

Corals and feather stars bioluminesce in a lab tank. Photo by NOAA Photo Library, Bioluminescence 2009 Expedition, NOAA/OER via Flickr, Creative Commons License. 

The details of this process can vary and aren’t fully understood in every organism since luciferin and luciferase aren’t specific compounds. Many different chemicals can act as the luciferin or luciferase in this type of reaction. The reaction also often requires ATP (adenosine triphosphate).

Unlike incandescence (the method for creating light in traditional lightbulbs), luminescence doesn’t emit heat, and this makes it much more energy efficient (like LED lights, which create light through electroluminescence).

As waves stir up water containing dinoflagellates, the planktonic organisms emit light. Photo by catalano82 via Flickr, Creative Commons License. 

Usually (but not always), the chemical reaction occurs inside of the organism. On bioluminescent fish, you can often see distinct pockets that emit light either continuously or in bursts. The light organ, or photophore, contains photocytes, cells that specialize in performing the bioluminescent reaction. Sometimes these are contained in symbiotic bacteria that live inside the photophore. It may also have features such as skin that covers it, sort of like an eyelid, in order to “turn off” the light.

With the lights turned off on the submarine, scientists can see animals such as this jelly glow bright in the dark. Photo by NOAA's National Ocean Service via Flickr, Creative Commons License. 

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