Bioluminescence is the production and emission of light by a living organism as the result of a chemical reaction during which chemical energy is converted to light energy. Most people know that chemical energy can be released as heat that’s how the food we eat gets transformed into body heat. In bioluminescent organisms, that chemical energy can also be released in the form of light.
Bioluminescent organisms can glow in complete darkness. They contain a unique compound called luciferin, according to scientists who study bioluminescence at the University of California at Santa Barbara. When luciferin is exposed to oxygen, a chemical reaction (aided along by an enzyme called luciferase) emits light.
A jellyfish called the crystal jelly aided in a scientific breakthrough in bioluminescence. Crystal jellies are harvested for a protein called green fluorescent protein (GFP). GFP is made up of about 250 different amino acids that will glow green on contact with UV light. Scientists have created “green mice” that glow green when hit by UV light by inserting the GFP gene from the crystal jelly into the mice. The glowing protein is a widely used biological highlighter that helps scientists find and study genes more quickly.
Bioluminescence is more common in the ocean than anywhere else. There are many different examples of bioluminescent marine organisms, most of which are found at deeper, darker depths.
Rivaling its diverse distribution is its impressive array of colors, intensities, and kinetics. Measurements of bioluminescent emission spectra have revealed a rainbow palette of hues that extend over the full visible range. Because most bioluminescence has evolved in the open ocean, most emission spectra are blue, centered on the wavelength that travels farthest through seawater. Green is the next most common color and is more often found in disphotic, aphotic, and shallow coastal species, possibly because increased turbidity from particles in the water scatters blue light and favors the transmission of longer wavelengths. Violet, yellow, orange, and red occur only rarely, and in most of these cases, their functions and chemistries remain obscure.