Have you ever seen glowing waves? How about angler fish? What about fireflies? What do all of these have in common? They are all bioluminescent! Bioluminescence is when organisms perform chemical reactions to produce light. Note that this is different from fluorescence, which occurs when light is simply re-emitted back at a different wavelength. These organisms actually do the work!
So why exactly would you need to be able to light up? Well, as they say, absence makes the heart grow fonder, so this evolved in the absence of light! Bioluminescence evolved in the deep sea, so most bioluminescent organisms live in the ocean. Bioluminescent organisms utilize molecules called luciferins and enzymes called luciferases. Luciferases add oxygen to luciferins to generate oxyluciferins, emitting light in the process. Certain bioluminescent organisms can even control their bioluminescence, and choose how bright they want to glow and what color.
Bioluminescence has many uses in different organisms: feeding, communicating, attracting mates, camouflage, and protection. Some organisms use bioluminescence to hide from their predators. Sharks tend to hunt from below so that they can see the shadows of their prey above. However, some prey have developed a strategy called counterillumination, in which they light up themselves to counter the effect of the shadows and escape getting eaten. How cool is that?
Other organisms use bioluminescence to find mates or perform other vital activities. Even our favorite, sweet little bacteria use bioluminescence to count each other! In small populations of bioluminescent bacteria, they do not light up because there is not enough luciferase to go around. But when in larger populations, there is enough, and the larger the population size, the more they glow!
Humans use bioluminescence in many different ways. For example, we use it to track certain cells in the body, particularly cancer cells and tumor growths/spread. We also use bioluminescence to track immunodeficiency viruses* in animals, to get a better understanding of how the viruses work. Bioluminescence is also used to track blood clots, and also has other medical uses. Though it is important to note that while we use external sources of bioluminescence, we ourselves are slightly bioluminescent, so be proud of yourself!
*sound familiar? HIV is the human immunodeficiency virus
Post By: Roshni P. M. and Hannah W.
Photo credits: 贝莉儿 DANIST, Unsplash, https://unsplash.com/photos/bviex5lwf3s
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