Why do fireflies glow? Understanding the reasons in one article
Fireflies are named for their ability to emit a fluorescent light from their tails. Adults use species-specific flash signals to locate and attract the opposite sex, thereby completing the mission of courtship, mating and reproduction. A small number of adult fireflies use flash signals to hunt prey, and another function is as a warning signal. Now let us take a look together at why fireflies glow!
Why do fireflies glow?
Fireflies have specialized light-producing cells, and in these light-producing cells there are two types of chemicals: one is called luciferin, and the other is called luciferase. Under the catalysis of luciferase, luciferin can consume ATP and react with oxygen, producing excited-state oxyluciferin during the reaction. When oxyluciferin returns from the excited state to the ground state, it releases photons. Almost all of the energy released in the reaction is released in the form of light, with only a very small portion released as heat. The reaction efficiency is 95%, which is why fireflies do not overheat and burn themselves. So far, humans have not been able to create such an efficient light source.
In what season do fireflies appear?
Fireflies usually appear in summer by riversides, pond edges and farmland, and their range of activity does not leave clean water sources. Depending on the species, the time of activity of adults also differs. There are both diurnal and nocturnal species active during the day and at night. For nocturnal species, the times they appear range from 18:00 to 3:00-4:00 in the early morning. Generally speaking, most species begin activity after sunset, and most stop activity at 20:00-21:00 in the evening.
Composition of firefly flash signals
1. Light organs: The shape and size of the light organs are usually the basis for species recognition among fireflies. The morphology of light organs varies greatly among different fireflies. The light organs of male fireflies generally have 2 segments, while those of female fireflies have 1-3 segments, a relatively large difference. For example, in aquatic fireflies, the male light organ has 2 segments, with the first light organ on the 5th abdominal segment and the second light organ on the 6th abdominal segment, while the female has only 1 light organ segment, located on the 5th abdominal segment.
2. Spectral composition: The color of the light emitted by fireflies is determined by the structure of luciferin in their bodies and the way luciferin interacts with luciferase. It is species-specific, and different species of fireflies have different spectra. Most fireflies emit yellow-green fluorescence. At night, the information contained in yellow-green light is easily received by fireflies of the same species. In signal transmission, yellow-green light can minimize loss and thereby improve the efficiency of signal reception, that is, the signal-to-noise ratio.
3. Movement of light: Among non-bioluminescent animals, whether vertebrates or invertebrates, posture is the most important and most direct visual signal in behavioral contact. Male fireflies usually fly in the air and emit species-specific flashes for courtship, and their light trajectories are species-specific. Females do not identify species and sex based on a single flash pulse from a male, but rather recognize the sequence of flash signals and the flash trajectory emitted by the male while flying.
4. Signal pattern: The flash pattern of fireflies contains many sub-parameters, such as the male-specific flash pattern, the male-specific flash interval, the female response time and the female flash time. The flash signals of different fireflies differ greatly, and the same species of firefly has different flash signals for different behaviors. Research has found that only when a simulated response flash is emitted 2 seconds after the male firefly's flash can the male firefly be attracted.