Why fireflies glow at night - what kind of “light bulbs” they have and how they work will now be explained in detail. Glowing fireflies, familiar to everyone since childhood, or scientifically fireflies, are so named because this family of beetles has special light-producing organs located in the abdominal region of the beetle.
Why fireflies glow at night - scientific explanation
The unique ability to reproduce light in flight is inherent in the firefly itself. Light is formed as a result of the work of luminescent organs, which consist of photogenic cells, sort of light emitters, equipped with plexuses of tracheas and bundles of nerves, present in large numbers in the body.
The tracheas in the body serve as “oxygen pipelines”, through which oxygen is supplied to the luminescent organs, without which the oxidative processes occurring in the cells are impossible.
Under the luminescent organs there are several layers of cells, the contents of which consist of uric acid crystals, which are peculiar reflectors of light in the body of the firefly beetle.
In representatives of different species of firefly beetles, these organs are located differently.
This may be one large luminous organ located in the area of the so-called abdominal sternites - this is the scientific name of a part of the body of a beetle, denoting a part of the transparent cuticle located in the abdominal cavity, which is characteristic of firefly species living in Europe, Africa, America, Asia and the Far East. But tropical representatives of beetles have many light organs located in the abdominal cavity, but on the back.
Why do fireflies glow at night and how is the glow of fireflies formed? And it is formed in the form chemical reaction, the main components of which are chemical compounds luciferin, which is heat-resistant, and the enzyme luciferase, a protein rich in sulfhydryl groups. Oxygen entering through the trachea enters into an oxidation reaction with luciferin, and the luciferase enzyme increases its speed, being a natural catalyst for the reaction.
To the question of why nature awarded such an unusual function to an ordinary beetle, one can answer: with the help of glow, the firefly communicates with other individuals.
In the course of evolution, fireflies have developed a unique system of communication using light signals: it fully represents “procreation” signals between male and female, danger warning signals, as well as signals signaling territorial affiliation and related signals expressing aggression.
The glow emitted by firefly beetles is of a natural, strictly defined color, and no temperature increase occurs during the glow process. In some species of beetles, the color of the glow differs depending on their gender.
The ability of some firefly species to dose emitted light, as well as the ability to emit intermittent light, has been well studied. Some tropical species fireflies, forming a swarm, emit an intermittent glow when the moment of flash and attenuation occurs simultaneously. In terms of efficiency, the luminescent organs of fireflies are unusually productive.
Why do fireflies glow at night like small light bulbs? Let's compare them with electrical appliances. The energy produced by an incandescent light bulb is converted into visible light at a rate of only five percent, while that of a firefly ranges from 87 to 98 percent.
Fireflies flickering at night video
A firefly is an insect that belongs to the order Coleoptera (or beetles), suborder heterophagous, family fireflies (lampyridae) (lat. Lampyridae).
Fireflies get their name because their eggs, larvae and adults are capable of glowing. The oldest written mention of fireflies is in a Japanese poetry collection from the late 8th century.
Firefly - description and photo. What does a firefly look like?
Fireflies are small insects ranging in size from 4 mm to 3 cm. Most of them have a flattened oblong body covered with hairs and a structure characteristic of all beetles, in which they stand out:
- 4 wings, the upper two of which have turned into elytra, having punctures and sometimes traces of ribs;
- movable head, decorated with large faceted eyes, completely or partially covered by the pronotum;
- filiform, comb or saw-shaped antennae, consisting of 11 segments;
- the oral apparatus is of a gnawing type (it is more often observed in larvae and females; in adult males it is reduced).
The males of many species, which resemble ordinary beetles, are very different from the females, which more closely resemble larvae or small worms with legs. Such representatives have a dark brown body on 3 pairs of short limbs, simple large eyes and no wings or elytra at all. Accordingly, they cannot fly. Their antennae are small, consisting of three segments, and their hard-to-see head is hidden behind the neck shield. The less developed the female, the more intensely she glows.
Fireflies are not brightly colored: representatives of brown color are more common, but their covers can also contain black and brown tones. These insects have relatively soft and flexible, moderately sclerotized body coverings. Unlike other beetles, the elytra of fireflies are very light, so the insects were previously classified as soft beetles (lat. Cantharidae), but then separated into a separate family.
Why do fireflies glow?
Most members of the firefly family are known for their ability to emit a phosphorescent glow, which is especially noticeable in the dark. In some species, only males can glow, in others, only females, in others, both (for example, Italian fireflies). Males emit bright light in flight. Females are inactive and usually glow brightly on the soil surface. There are also fireflies that do not have this ability at all, while in many species the light comes even from the larvae and eggs.
By the way, few sushi animals even exhibit the phenomenon of bioluminescence (chemical glow). The larvae of fungus gnats, springtails (collembolas), fire flies, jumping spiders and representatives of beetles, for example, such as fire-bearing click beetles (pyrophorus) from the West Indies, are known to be capable of this. But if we count marine inhabitants, then there are at least 800 species of luminous animals on Earth.
The organs that allow fireflies to emit rays are photogenic cells (lanterns), abundantly intertwined with nerves and tracheas (air tubes). Externally, lanterns look like yellowish spots on the underside of the abdomen, covered transparent film(cuticle). They can be located on the last segments of the abdomen or evenly distributed throughout the body of the insect. Beneath these cells lie others filled with uric acid crystals and capable of reflecting light. Together, these cells work only if there is nerve impulse from the insect's brain. Oxygen enters the photogenic cell through the trachea and, with the help of the enzyme luciferase, which accelerates the reaction, oxidizes the compound of luciferin (light-emitting biological pigment) and ATP (adenosine triphosphoric acid). Thanks to this, the firefly glows, emitting light blue, yellow, red or Green colour.
Males and females of the same species most often emit rays of similar colors, but there are exceptions. The color of the glow depends on temperature and acidity (pH) environment, as well as on the structure of luciferase.
The beetles themselves regulate the glow; they can strengthen or weaken it, make it intermittent or continuous. Each species has its own unique phosphorus radiation system. Depending on the purpose, the glow of fireflies can be pulsating, flashing, stable, fading, bright or dim. The female of each species reacts only to the male’s signals with a certain frequency and intensity of light, that is, his mode. With a special rhythm of light emission, beetles not only attract partners, but also scare away predators and protect the boundaries of their territories. There are:
- search and calling signals in males;
- signals of consent, refusal and post-copulatory signals in females;
- signals of aggression, protest and even light mimicry.
Interestingly, fireflies spend about 98% of their energy emitting light, while an ordinary electric light bulb (incandescent lamp) converts only 4% of the energy into light, the rest of the energy is dissipated as heat.
Diurnal fireflies often do not need the ability to emit light, which is why they lack it. But those daytime representatives who live in caves or dark corners of the forest also turn on their “flashlights”. The eggs of all types of fireflies also emit light at first, but it soon fades away. During the day, the light of a firefly can be seen if you cover the insect with two palms or move it to a dark place.
By the way, fireflies also give signals using the direction of flight. For example, representatives of one species fly in a straight line, representatives of another species fly in a broken line.
Types of firefly light signals
V. F. Buck divided all light signals of fireflies into 4 types:
- Continuous glow
This is how adult beetles belonging to the genus Phengodes glow, as well as the eggs of all fireflies without exception. Neither external temperature nor lighting affects the brightness of the rays of this uncontrollable type of glow.
- Intermittent glow
Depending on factors external environment And internal state insect, it can be weak or strong light. It may completely fade away for a while. This is how most larvae shine.
- Ripple
This type of luminescence, in which periods of light and absence of light are repeated at regular intervals, is characteristic of the tropical genera Luciola and Pteroptix.
- Flashes
There is no time dependence between the intervals of flashes and their absence with this type of glow. This type of signal is typical for most fireflies, especially in temperate latitudes. In a given climate, the ability of insects to emit light is highly dependent on environmental factors.
HA. Lloyd also identified a fifth type of glow:
- Flicker
This type of light signal is a series of short flashes (frequency from 5 to 30 Hz), appearing immediately one after another. It is found in all subfamilies, and its presence does not depend on the location and habitat.
Firefly communication systems
Lampyrids have 2 types of communication systems.
- In the first system, an individual of one sex (usually a female) emits specific calling signals and attracts a representative of the opposite sex, for whom the presence of their own light organs is not mandatory. This type of communication is typical for fireflies of the genera Phengodes, Lampyris, Arachnocampa, Diplocadon, Dioptoma (Cantheroidae).
- In the second type of system, individuals of the same sex (usually flying males) emit calling signals, to which flightless females give sex- and species-specific responses. This method of communication is characteristic of many species from the subfamilies Lampyrinae (genus Photinus) and Photurinae, living in North and South America.
This division is not absolute, since there are species with an intermediate type of communication and with a more advanced interactive luminescence system (in the European species Luciola italica and Luciola mingrelica).
Synchronized flashing of fireflies
In the tropics, many species of beetles from the family Lampyridae seem to shine together. They simultaneously light their “lanterns” and extinguish them at the same time. Scientists call this phenomenon the synchronous flashing of fireflies. The process of synchronous flashing of fireflies has not yet been fully studied, and there are several versions regarding how insects manage to shine at the same time. According to one of them, within a group of beetles of the same species there is a leader, and he serves as the conductor of this “chorus”. And since all representatives know the frequency (break time and glow time), they manage to do this very amicably. Mostly male lampyrids flash synchronously. Moreover, all researchers are inclined to believe that the synchronization of firefly signals is associated with the sexual behavior of insects. By increasing population density, their ability to find a mating partner increases. Scientists also noticed that the synchrony of insect light can be disrupted by hanging a lamp next to them. But with the cessation of its work, the process is restored.
The first mention of this phenomenon dates back to 1680 - this is a description made by E. Kaempfer after a trip to Bangkok. Subsequently, many statements were made about the observation of this phenomenon in Texas (USA), Japan, Thailand, Malaysia and the mountainous regions of New Guinea. Especially many of these types of fireflies live in Malaysia: this phenomenon occurs there local residents called "kelip-kelip". In the United States, in Elcomont National Park (Great Smoky Mountains), visitors watch the synchronous glow of representatives of the species Photinus carolinus.
Where do fireflies live?
Fireflies are fairly common, heat-loving insects that live in all parts of the world:
- in North and South America;
- in Africa;
- in Australia and New Zealand;
- in Europe (including the UK);
- in Asia (Malaysia, China, India, Japan, Indonesia and the Philippines).
Most fireflies are found in the Northern Hemisphere. Many of them live in warm countries, that is, in tropical and subtropical regions of our planet. Some varieties are found in temperate latitudes. Russia is home to 20 species of fireflies, which can be found throughout the entire territory except the north: in the Far East, in the European part and in Siberia. They can be found in deciduous forests, swamps, near rivers and lakes, and in clearings.
Fireflies do not like to live in groups; they are loners, but they often form temporary clusters. Most fireflies are nocturnal animals, but there are also those that are active during daylight hours. During the day, insects rest on the grass, hide under bark, stones or in mud, and at night those that are able to fly do so smoothly and quickly. In cold weather they can often be seen on the surface of the ground.
What do fireflies eat?
Both larvae and adults are often predators, although there are fireflies that feed on the nectar and pollen of flowers, as well as decaying plants. Carnivorous bugs prey on other insects, cutworm caterpillars, mollusks, millipedes, earthworms, and even their fellow insects. Some females living in the tropics (for example, from the genus Photuris), after mating, imitate the rhythm of the glow of the males of another species in order to eat them and obtain nutrients for the development of their offspring.
Females in adulthood feed more often than males. Many males do not eat at all and die after several matings, although there is other evidence that all adults eat food.
The firefly larva has a retractable tassel on the last abdominal segment. It is needed in order to clean off the mucus remaining on its small head after eating slugs. All firefly larvae are active predators. They mainly eat shellfish and often live in their hard shells.
Reproduction of fireflies
Like all Coleoptera, fireflies develop with complete metamorphosis. The life cycle of these insects consists of 4 stages:
- Egg (3-4 weeks),
- Larva, or nymph (from 3 months to 1.5 years),
- Pupa (1-2 weeks),
- Imago, or adult (3-4 months).
Females and males mate on the ground or on low plants for 1-3 hours, after which the female lays up to 100 eggs in depressions in the soil, in debris, on the undersurface of leaves or in moss. The eggs of common fireflies look like pearly yellow pebbles washed with water. Their shell is thin, and the “head” side of the eggs contains the embryo, which is visible through the transparent film.
After 3-4 weeks, the eggs hatch into terrestrial or aquatic larvae, which are voracious predators. The body of the larvae is dark, slightly flattened, with long running legs. U aquatic species lateral abdominal gills are developed. The small elongated or square head of nymphs with three-segmented antennae is strongly retracted into the prothorax. There is 1 light eye on each side of the head. The strongly sclerotized mandibles (mandibles) of the larvae are shaped like a sickle, inside of which there is a sucking canal. Unlike adult insects, nymphs do not have an upper lip.
The larvae settle on the soil surface - under stones, in the forest floor, in mollusk shells. Nymphs of some firefly species pupate in the same fall, but mostly they survive the winter and only turn into pupae in the spring.
The larvae pupate in the soil or by hanging themselves on the bark of a tree, as they do. After 1-2 weeks, beetles crawl out of the pupae.
The general life cycle of fireflies lasts 1-2 years.
Types of fireflies, photos and names.
In total, entomologists count about 2,000 species of fireflies. Let's talk about the most famous of them.
- Common firefly ( aka large firefly) (lat. Lampyris noctiluca) It has popular names Ivanov worm or Ivanovo worm. The appearance of the insect was associated with the holiday of Ivan Kupala, because it is with the arrival of summer that the mating season begins for fireflies. This is where the popular nickname came from, which was given to a female very similar to a worm.
The large firefly is a beetle with the characteristic features of fireflies. appearance. The size of males reaches 11-15 mm, females - 11-18 mm. The insect has a flat, villous body and all other characteristics of the family and order. The male and female of this species are very different from each other. The female looks like a larva and leads a sedentary, ground-based lifestyle. Both sexes have the ability to bioluminescence. But in the female this is much more pronounced; at dusk she emits a rather bright glow. The male flies well, but glows very faintly, almost imperceptibly to observers. Obviously, it is the female who gives the signal to her partner.
- - a common inhabitant of Japanese rice fields. Lives only in wet mud or directly in water. Hunts at night on mollusks, including intermediate hosts of fluke worms. When hunting, it shines very brightly, emitting a blue light.
- lives on the territory North America. Males of the genus Photinus glow only during takeoff and fly in a zigzag pattern, while females use mimetic illumination to eat males of other species. From representatives of this genus, American scientists isolate the enzyme luciferase to use it in biological practice. The common eastern firefly is the most common in North America.
This is a nocturnal beetle with a dark brown body 11-14 mm long. Thanks to the bright light, it is clearly visible on the soil surface. The females of this species look like worms. Fire photinus larvae live from 1 to 2 years and hide in damp places - near streams, under bark and on the ground. They spend the winter buried in the ground.
Both adult insects and their larvae are predators, eating worms and snails.
- lives only in Canada and the USA. An adult beetle reaches a size of 2 cm. It has a flat black body, red eyes and yellow underwings. On the last segments of its abdomen there are photogenic cells.
The larva of this insect is nicknamed the “glow worm” for its ability to bioluminescence. The worm-like females of this species are also capable of light mimicry, imitating the signals of the firefly species Photinus in order to grab and eat their males.
- Cyphonocerus ruficollis- the most primitive and little-studied species of fireflies. It lives in North America and Eurasia. In Russia, the insect is found in Primorye, where females and males actively glow in August. The beetle is included in the Red Book of Russia.
- Red firefly (pyrocoelia firefly) (lat. Pyrocaelia rufa) is a rare and little-studied species that lives in the Russian Far East. Its length can reach 15 mm. It is called the red firefly because its scutellum and rounded pronotum have an orange tint. The beetle's elytra are dark brown, the antennae are saw-toothed and small.
The larval stage of this insect lasts 2 years. You can find the larva in the grass, under stones or on the forest floor. Adult males fly and glow.
- - a small black beetle with an orange head and saw-shaped antennae (antennae). The females of this species fly and glow, but the males lose the ability to emit light after turning into an adult insect.
Fir fireflies live in the forests of North America.
- - inhabitant of the center of Europe. On the pronotum of the male beetle there are clear clear spots, and the rest of his body is colored light brown. The body length of the insect varies from 10 to 15 mm.
Males glow especially brightly in flight. Females are worm-like and are also capable of emitting bright light. The organs of light production are located in Central European worms not only at the end of the abdomen, but also in the second segment of the chest. The larvae of this species can also glow. They have a black fuzzy body with yellow-pink dots on the sides.
One of the most romantic moments of summer holidays is watching small flying lights in the evening darkness. And not every adult knows where the glow of fireflies comes from, but for small children it’s just like magic. But everything has been known for a long time, let's reveal the veil of mystery about the glow of these small insects, and why they do it.
Fireflies in a cave
Nature of the glow
In total, there are about two thousand species of fireflies. Each firefly has the ability to glow with phosphorescent light in the dark. The luminescence organ, most often in these beetles, is the photophore. It is located on top at the end of the abdomen.
The photophore consists of only three layers. The mirror layer is located at the bottom and is capable of reflecting light. The top one is a special translucent cuticle. The middle layer contains photogenic cells that produce light. Behind its device, the photophore looks like a regular flashlight.
This type of light emission is called bioluminescence. It appears after the combination of calcium with intracellular oxygen, and the pigment luciferin with the adenosine triphosphate molecule (ATP) in the presence of louciferase enzymes.
Glowing insect abdomen Fireflies emit cold light. In a typical electric lamp more than half of the energy goes into waste heat, and the efficiency is only 5% to 10%, and fireflies convert 87% to 98% of the energy released into light. The glow emitted by these insects belongs to the yellow-green visible part of the spectrum, corresponding to a wavelength of 500-600 nm.
Chemical processes of light formation
Many different species of fireflies can increase or decrease the intensity of the glow, as well as intermittent light, at their discretion. The signal to turn on the light comes from nervous system beetle At the same time, oxygen begins to intensively enter the photophore. Accordingly, turning off the light occurs simply by shutting off the oxygen supply.
The nature of the glow is oxidation Insects do not have lungs, and oxygen is transmitted through special tubes called tracheoles. The supply of oxygen is contained in mitochondria. In order to quickly release the required amount of oxygen, the firefly’s body produces nitric oxide, which, upon entering the mitochondria, begins to displace oxygen from them.
Why do insects need glow?
Bioluminescence can act as a means of intersexual communication for fireflies. In addition to signaling their location, insects also distinguish their partners by a special flickering frequency.
Huge swarms of insects North American and tropical firefly species sometimes perform choral serenades to attract the attention of their mates. They simultaneously plow and die out as a whole flock. A flock of females begins to respond to them with similar light music.
Video lesson on why fireflies glow
These fireflies are wonderful insects. Fabulous, glowing, interesting, it’s just a pity that they are nocturnal inhabitants, you won’t meet them during the day or admire them. How does a firefly glow? And why? For what? So many questions about such a tiny creature.
A little about fireflies: nocturnal insects, they sleep during the day and hunt at night, there are 2000 species in total, they live in all corners of the world, there is no country where they do not know about fireflies. The size of fireflies is from 2 to 4 mm (mm not centimeters!). A single number of species are capable of laying larvae that float in the water.
The most unusual species Fireflies live in Japan, their habitat is rice fields, where they feed on freshwater snails. Consequently, fireflies in Japan bring great benefits to people by clearing rice plantations of pests.
You can talk for a long time about different types fireflies, discuss their way of life at night, find out their favorite treat, but the most interesting thing is to find out where the glow comes from?
The glow in a firefly is caused by a chemical reaction that occurs when oxygen and calcium combine inside the insect. The glowing process itself is called bioluminescence. A large accumulation of calcium is located in the firefly's abdomen, so it is mainly its abdomen that glows, resembling a small flying lantern in the dark. There are species that emit a glow with their entire body, then their glow is muted, not bright.
Scientists compared this feature of insects to a fluorescent lamp, but unlike a lamp, fireflies do not heat up; they emit a cold glow. Think logically - if an insect heats itself, it will immediately burn, so nature took care of protecting the firefly, giving it the ability to glow without heating the body.
The glow does not occur spontaneously or simply when darkness falls; the firefly needs to activate it. To do this, the “light” control element supplies oxygen to those places where calcium accumulations have appeared. To stop the glow, it is enough to stop the oxygen supply. It's simple. Think about it, how often do people catch fireflies, put them in a jar and wait for the firefly to light up? In this case, the insect is almost deprived of air. Few people know that the firefly needs oxygen, not darkness, to glow.
Since the insect does not have lungs, it is difficult to supply air to the body - through the tracheoles, which are equipped with a powerful system of muscular structure. The muscles practically control the glow of the firefly.
Muscle work is slow, but the firefly lights up quickly - scientists have recently solved this mystery. the main role in the glow - nitric oxide, which is produced at the command of the brain. The insect collects oxygen during the day, holding it in the mitochondria, and if necessary, the brain gives a command, nitrogen is released and an instant glow is provided. The role of muscles remains only in physical support of the entire system.
The firefly lights up at night for a reason too - a life-threatening situation must arise, the body produces steroids that make the firefly unpalatable, and the light serves as a signal for the enemy - a signal to retreat.
Fireflies - a luminous miracle of nature
The flying, flickering lights of fireflies are a real mystical attraction in the summer. But how much do we know about what fireflies are? Here are some facts about them.
1. What are fireflies?
Fireflies are nocturnal insects - they lead active image life at night. They are members of the winged beetle family Lampyridae (which means "to shine" in Greek). The name "firefly" is a little misleading because of the more than 2,000 species of fireflies, only a few of these species have the ability to light up.
2. Besides fireflies, there are other types of glowing species.
Fireflies are probably one of the most popular types, because of its ability to glow. Most bioluminescent creatures live in the ocean—people have little contact with them. Their light is created through a chemical reaction in which oxygen combines with calcium, adenosine triphosphate (ATP) and luciferin using the enzyme luciferase. Fireflies use their bioluminescence probably to ward off predators.
3. Not all fireflies have "fire"
Fireflies, most of their species, simply do not burn. Non-bioluminescent fireflies, which do not produce light, are generally not nocturnal bugs—they are most active during the day.
4. Scientists discovered luciferases thanks to fireflies
The only way to obtain the chemical luciferase is to extract it from fireflies. Eventually, scientists figured out how to create synthetic luciferases. But some people still collect enzyme from "flying lanterns." Luciferase is used in scientific research for security testing food products and certain forensic procedures.
5. Fireflies are energy efficient
Firefly lights are the most efficient energy sources in the world. One hundred percent of the energy they create is emitted through light. By comparison, an incandescent light bulb emits only 10 percent of its energy as light, while fluorescent light bulbs emit 90 percent of its energy as light.
6. Their light show is mating acts.
Most flying male fireflies are looking for a mate. Each species has a specific light pattern that they use to communicate with each other. After the female sees the male and responds to his affection, she responds to him with the same light pattern. Usually females sit on plants, waiting for a male.
7. Some species have the ability to synchronize their blinking
Scientists aren't sure why fireflies do this, but some theories suggest that fireflies do it to become more visible. If a group of fireflies blink in a single pattern, they are likely doing so to attract the attention of females. The only firefly species in America that blinks synchronously is Photinus carolinus. They live in national park USA Great Smokies, where the park service organizes an evening light show for visitors.
8. Not all fireflies shine the same way.
Each species has its own specific color of light. Some produce a blue or green glow, while others glow orange or yellow.
9. They taste disgusting
Unlike cicadas, fireflies cannot be cooked into grilled bugs. If you try to eat firefly, it will taste bitter. The bugs can even be toxic. When fireflies are attacked, they shed drops of blood. Blood contains chemical substances, which create a bitter taste and poison. Most animals know this and avoid chewing fireflies.
10. Fireflies sometimes practice cannibalism
When fireflies are still in their larval stage, they are ready to feast on snails. Usually, when they mature, they become vegetarians - they move away from meat. Scientists believe that adult fireflies live off nectar and pollen, or do not eat at all. But others, fireflies such as Photuris, may enjoy eating their own species. Photuris females often eat males of other genera. They attract unsuspecting beetles by mimicking their light patterns.
11. Their numbers are decreasing
There are several reasons why firefly populations are declining, including climate change and habitat destruction. When a firefly's habitat is disturbed due to road or other construction, they do not migrate to a new location, but simply disappear.
12. Enjoy the firefly light show while you can.
Researchers know little about fireflies and have no clear answer as to why they are disappearing. Enjoy the light show while this insect still exists in nature. Perhaps the generations of people who will come after us will not be given such an opportunity to see these beetles with their amazing mystical glow.