The basic science behind bioluminescence

‘A little light is going by,
Is going up to see the sky,

A little light with wings.'

Can you guess the light mentioned in the above poem? Yes, it’s about the glowing fireflies in the midst of darkness. Have you ever wondered how can fireflies produce light? This fact of producing light by organisms is known as ‘bioluminescence’.

If you have seen fireflies, then you have witnessed a bioluminescent organism. Well, there are several bioluminescent organisms and a large number of them are marine organisms. Because of these glowing organisms, the seawater in some places looks like fairylands and draws the attention of tourists. These animals include- jellyfish, squid, anglerfish, lanternfish, fungi, etc. Living things produce light to hunt prey, defend against predators, find mates, and execute other vital activities. Now, let us see the basic chemistry behind it.

Bioluminescence is actually 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. The chemical reaction that results in bioluminescence requires two unique chemicals: luciferin and either luciferase or photoprotein. In most cases, the bioluminescent colors occur due to the arrangement of luciferin molecules. So, basically, luciferin is the compound that actually produces light and in the chemical reaction, it acts as the substrate. The interaction of the enzyme luciferase with oxidized pigment luciferin creates a byproduct, called oxyluciferin. This reaction is known as the enzyme-catalyzed chemiluminescence reaction. Most bioluminescent reactions involve luciferin and luciferase.

Some reactions involve a chemical called a photoprotein where photoproteins combine with luciferns and oxygen but need another agent, often an ion of the element calcium. It is interesting that some bioluminescent organisms do not synthesize on their own. Instead, they absorb it through other organisms, either as food or as a symbiotic relationship. For instance, some species of midshipman fish, obtain luciferin through the ‘seed shrimp’ they consume. On the other hand, squids produce light with the help of bacteria as they share a symbiotic relationship. Different luciferases cause the bioluminescence to be expressed differently.

The science behind bioluminescence could be helpful for humankind. Therefore, researchers are studying the chemicals and circumstances involved to understand how people can use the process to make life easier and safer.

Source: https://www.nationalgeographic.org/encyclopedia/bioluminescence

Image source: Departures.com

Anika Nawar Chowdhury

Shahjalal University of Science and Technology, Sylhet