According to Professor Sara Lewis from Tufts University, Boston (USA), the glowing fireflies seen on summer nights may just be a form of display, similar to the brilliant tails of male peacocks aimed at attracting potential mates.
This research has shown that the display of sexual beauty is not limited to certain species such as birds, mammals, or humans; even insects are not exceptions.
The luminescent substance in fireflies’ tails emits a faint light when it encounters oxygen, which is why it is best seen at night. Male fireflies have wings, while females do not. Therefore, male fireflies glow to attract mates.
For instance, male fireflies that can gather fluorescent light for a longer duration are more likely to successfully find partners and help females produce more offspring.
Fireflies are divided into two groups: flying fireflies and ground-dwelling fireflies. Both groups can emit the same special cold light, which does not emit heat like artificial light. This is because, during the luminescent process, almost all the energy from the organism is converted into light energy rather than being dissipated as heat, as is the case with other artificial light sources.
The light of fireflies is emitted from a few segments at the end of their abdomen. During the day, these segments appear grayish-white, but at night they emit a mystical glow through the translucent skin. Inside the abdominal skin is a series of photogenic cells, with an inner layer of reflective cells that function like mirrors to project the light outward.
Fireflies glow due to a chemical reaction that occurs within their bodies. This type of luminescence is known as bioluminescence.
The photogenic cells contain two types of substances: luciferin and luciferase. When separated, they are just ordinary chemicals with no ability to glow. However, when they are in proximity, the luciferase enzyme catalyzes the oxidation of luciferin (a process that uses oxygen to combust luciferin). This oxidation process produces light energy.
Essentially, this luminescent mechanism also occurs in other organisms, such as jellyfish. Scientists believe that almost all living organisms can emit a very faint light, even humans have this capability. This is the result of biochemical reactions.
How does bioluminescence differ from the luminescence of electric lights?
The most significant difference is that electric lights emit a lot of heat during the luminescent process. The light emitted by fireflies is cold light because the energy dissipated as heat during the firefly luminescence process is minimal. This is crucial for fireflies because if their photogenic cells produced as much heat as electric lights, fireflies would likely not survive after a single glow.
Fireflies can control the initiation and termination of this chemical reaction. They can start or stop glowing by adjusting the amount of oxygen available for the chemical reaction.
According to Science World Report, an article published in the journal Physical Review Letters states that scientists using contrast-enhanced tomography and X-ray microscopy discovered that fireflies redirect oxygen used for other cellular functions, drawing oxygen into the reaction that breaks down luciferin. During this time, the oxygen consumption in the cells decreases, slowing down the energy production process.
The light emitted by fireflies does not emit as much heat as electric lights.
Insects, which do not have lungs, obtain oxygen from the environment through a series of small connected tubes known as tracheoles. To date, it is still not understood how fireflies can flash at the high frequencies we observe while their muscles control oxygen intake at a relatively slow rate.
The most widely accepted explanation currently is that nitric oxide (NO) plays a crucial role in coordinating the light. When the firefly’s light is off, NO is not produced. In this case, the amount of oxygen entering the light-producing cells has been bound to the surface of the mitochondria—a cell organelle responsible for producing energy for the cell—resulting in no oxygen for the luminescent reaction.
The presence of NO in the light-producing cells allows oxygen to participate in the luminescent reaction because NO has bound to the mitochondria instead of oxygen. Since NO decomposes very quickly, when it is no longer produced, oxygen will be captured again by the mitochondria, leaving no oxygen for the luminescent reaction.
