Fireflies: A Prime Example of Bioluminescence

For whatever reason, when I hear “biochemistry”, one of the first things that comes to mind is bioluminescence: the production of light via chemical reactions in organisms. When I hear “bioluminescence”, I immediately think of fireflies, and I am sure a lot of others think of them too. Fireflies (which are actually beetles) are famous for their unique ability to make their abdomens glow, though not many are aware of how this kind of light creation is possible, for both fireflies and other bioluminescent organisms. Fortunately, the resources and methods required for bioluminescence are shared among forms of life, and fireflies demonstrate them extremely well.

The key requirement for an organism to achieve bioluminescence is luciferin, a molecular compound of carbon, hydrogen, nitrogen, oxygen, and sulfur. While the types of luciferin used in bioluminescence can differ, that which is used in firefly abdomens is unchanging, with its chemical formula being C11H8N2O3S2. When luciferin is exposed to oxygen, the other component in bioluminescence, which is to be inhaled by the firefly and make its way down to the abdomen, where the luciferin is stored, it oxidizes. With the help of ATP, a standard energy carrier that fuels cellular processes, Luciferin’s respective enzyme, luciferase, takes this oxidized luciferin as its substrate, and produces oxyluciferin, which has the chemical formula of C10H6N2O2S2. However, this chemical reaction also creates light, which is what bioluminescence revolves around in the first place. It should be mentioned that the reaction creates byproducts of CO2 and AMP. Luciferin-luciferase reactions can be summarized with this formula:

(Alternatively, certain bioluminescent organisms use “photoproteins” to trigger their luciferin reactions, instead of luciferase enzymes.)

The unique part of this reaction for fireflies is that they aim to control its frequency. Since their body produces luciferin automatically, they can simply choose when to inhale oxygen to trigger the reaction in their abdomen, creating a short glow. The fireflies’ control over their own bioluminescence (which a range of other bioluminescent organisms still possess) allows them to partake in their signature mating rituals, choosing what flashes or signals to make to others.

Sources:

https://news.ncsu.edu/2019/07/how-fireflies-glow-and-what-signals-theyre-sending/

https://earthsky.org/earth/fireflies-light-up-why-how/#:~:text=The%20light%20of%20a%20firefly,off%20the%20firefly's%20familiar%20glow.

https://education.nationalgeographic.org/resource/bioluminescence