These amazing dragonflies. dragonfly insect

Modern insects cannot boast of large sizes, and the word “insect” itself and its derivatives are synonyms for something small and defenseless. But this was not always the case, because in past geological eras our planet was inhabited by such huge insects that it is even difficult to imagine them.

Meganeuras are the largest insects that have ever lived on our planet. Outwardly, they were very similar to modern dragonflies with a wingspan of up to 65-100 centimeters. Giant insects from the genus Meganeura reached their peak about 300 million years ago during the Carboniferous period, although they appeared on the planet at the beginning of the Paleozoic. The Carboniferous is generally characterized by the presence of a large number of large insects that flourished in a warm and humid climate. In that distant era, amphibians and large insects reigned on Earth, and primitive reptiles, the ancestors of giant dinosaurs, had just emerged as a separate class of animals.

The first fossil remains of Meganeura were found in France in 1880. According to paleontologists, meganeuras, both adults and their larvae, were predators and fed on other smaller insects. But why did giant dragonflies and millipedes flourish in the Carboniferous period, and in subsequent eras their extinction and the appearance of related species, but more modest in size, were noted?

Scientists were able to find out that the body size of insects that breathe using tracheas is related to the level of oxygen in the atmosphere. During the Carboniferous period, conditions arose on the planet that resulted in the formation of a large number of coal deposits formed from plant remains. These huge volumes of biomass were derived from decomposition processes that, accordingly, did not require oxygen in the atmospheric air. As a result of lower oxidation costs, the atmosphere experienced higher oxygen levels than in previous periods.

This feature, according to a number of experts, could be the reason that the Carboniferous was inhabited by very large insects that used tracheas for breathing, including meganeuras. Then another period with a high oxygen content was observed on Earth; by that time, birds had already appeared in the air, which did not allow flying insects to develop to such gigantic sizes.

Despite the fact that modern insects have greatly decreased in size, and the largest of them can easily fit in the palm of your hand, representatives of this class can still be called the most prosperous on the planet. Today, science knows more than 1 million species of insects, but, according to experts, there are much more of them - from 2 to 6 million, and entomologists are simply not able to describe and study them all.

A predatory grin of jaws, eyes like two saucers and legs studded with spines - before us is a reconstruction of a giant coal dragonfly . Its wingspan reached 32 cm, but this is far from the limit. The order Protodonata, to which this species belongs, included creatures twice as large.

The reasons for the gigantism of these insects are still being debated: some scientists explain it by the increased oxygen content in the atmosphere, others by the lack of threat from flying insectivorous vertebrates (the first such vertebrates, pterosaurs, appeared only in the Triassic). In any case, giant dragonflies have long been one of the most famous extinct animals, second in popularity only to dinosaurs.

In terms of their maximum size, dragonflies Protodonata (an alternative name for the order is Meganisoptera) held a leading position for the first 50 million years of the evolution of winged insects, from the mid-Carboniferous period to the mid-Permian. These giants are classified as a separate order because their wings do not have a number of features that are found in all modern dragonflies (order Odonata). In particular, protodragonflies (from now on I will call them that) lack a pterostigma - an opaque area at the apex of the wing; They also do not have a node - a very thickened short vein in the middle of the wing. In modern dragonflies, the node plays the role of a hinge, allowing the wing to twist along the longitudinal axis. This helps dragonflies make sharp turns and maneuver. The absence of a node, apparently, doomed the protodragonflies to life in open spaces - and with such dimensions you can’t really fly in dense thickets. The longitudinal veins of protodamselflies were close to the leading edge of the wing, thereby giving it the additional strength necessary to hold such giants in the air.

Limbs dotted with long bristles - when bent, they formed a kind of basket, with the help of which prey was captured on the fly (this is what modern dragonflies do). And the prey of protodragonflies could be, among other things, herbivorous “six-winged” paleodictyoptera, which also reached very significant sizes - 36–37 cm in wingspan and even more. Modern dragonflies are known to avoid grabbing large insects, so the prey of protodamselflies had an incentive to get larger to escape attack. Actually, among other things, the gigantism of Paleozoic insects could be spurred by the evolutionary race between predators and prey: proto-dragonflies, in order not to remain hungry, had no choice but to grow larger after their prey.

Unfortunately, large protodamselflies are most often preserved only in the form of fragments of wings; details of their body structure can be studied very rarely. For example, in the same Commentrie coal basin (France), where it comes from , a dragonfly twice as large was found, Meganeura monyi(wingspan - up to 70 cm). But only an incomplete imprint of four wings, as well as several wing fragments, survived from it.

The same applies to proto-dragonfly Meganeuropsis permiana, which is considered the largest flying insect in the history of the Earth. It was found in the town of Elmo (USA) in Early Permian deposits. The length of the largest surviving fragment of its wing is only 14 cm. However, the author of the find, paleoentomologist Frank Carpenter, calculated in 1939 that the wingspan of the dragonfly could reach 710 mm, and since then this figure has been included in all textbooks and anthologies. And in 1947, Carpenter was lucky enough to find in Elmo an almost complete forewing of another giant proto-damselfly, called Meganeuropsis americana. The length of the preserved part of the wing is 26 cm, and the length of the whole wing is estimated at 30 cm. This is the largest wing of a fossil insect that has come down to us in the form of a single imprint. For comparison, the wingspan of the largest modern dragonfly Megaloprepus caerulatus is only 19 cm (see picture of the day The largest dragonfly).

The order Protodonata included not only giants, but also medium-sized species, no larger than modern dragonflies. Actually, it was precisely these forms that this group was represented in the upper half of the Permian, when it was crushed and its diversity fell. By the beginning of the Mesozoic, proto-dragonflies completely disappeared. But, of course, the public’s attention is focused specifically on the giant proto-dragonflies. Back in 1958, one of them appeared in the black-and-white American horror film “Monster on the Campus” to cause the death of one of the heroes. And not so long ago, in the English mining town of Bolsover, a monument was erected to giant dragonflies. The fact is that a proto-dragonfly was found in one of the mines near Bolsover in the late 1970s Tupus diluculum, which reached almost 50 cm in wingspan. However, only a 23-centimeter fragment of one wing survived from it.

Then let's find someone else - a giant.

Giant Dragonfly, Southeast Petaltel (lat. Petalura gigantea) is one of the largest dragonflies. It lives exclusively in Australia: along the east coast of New South Wales.

So, in general, you probably can’t tell from the photograph that she is a giant. Or will those who constantly encounter dragonflies say this?

Females are much larger than males:

Giant dragonflies are of great value to collectors from all over the world, which leads to an annual decline in the population of these unusual insects. In 1998, this species of dragonfly was declared endangered and listed in the Red Book.

Here's what's interesting:

320 million years ago there were no fishermen, no birds, no pterodactyls. While four-legged amphibians and reptiles were still timidly huddling around water bodies, dragonflies - the first of the living world - made their way into the air. They did not fly very skillfully, but they were of a respectable size.

If the largest of modern dragonflies - Megaloprepus caerulenta from South America - has a wingspan of 19 cm, then in the ancient dragonfly Meganeura it reached, according to some sources, 75 cm, according to others - a little less than a meter. This largest known insect was already a dangerous and voracious predator with virtually no competitors. Meganeura's prey was not much inferior to it in size - herbivorous and slow-moving dictyonevrids reached the size of a pigeon and after some time were exterminated by dragonflies as a species.

Why did dragonflies (and other insects) shred so much in the future? It's worth starting with the fact that 300 million years ago the oxygen content in the air was not 21%, as it is now, but 35%. Lushly growing mosses, horsetails and ferns actively saturated the atmosphere with oxygen, and there was no one to consume it. Even the fungi and bacteria responsible for decomposition did not form, so oxygen was not consumed for oxidation processes. As a result, the dead plants did not rot, but turned to stone, subsequently forming deposits of the well-known coal (which is why this entire period will be called Carboniferous).

Why are there no giant dragonflies on Earth now? Why do the descendants of six-legged giants now not exceed the size of a chicken egg (which is reached by the well-known Goliath bronze beetles, South American stag beetles and Far Eastern longhorned beetles)? To answer this question, you should think about what prevents insects from growing unlimitedly in all directions.

Contrary to popular belief, this is not a hard shell of chitin at all: all insects that have it grow immediately after molting, when the old “corset” has already been shed, and the new clothes are still soft and stretchable. The limitation that prevents them from constantly increasing in size is the respiratory system of these amazing creatures. Let me remind you that the “blood” of insects - hemolymph - is devoid of respiratory pigments (like our bright red hemoglobin) and does not participate at all in the transfer of oxygen.

Therefore, their breathing is carried out using tracheas - branching tubes that open on the sides of the back of the abdomen and directly connect the cells of the internal organs with the air environment. Moreover, the tracheal network in insects is so dense and branched that it literally covers every cell of the body.

However, until now, scientists were not entirely clear why not all representatives of the Carboniferous insect fauna were giants. Coal cockroaches, for example, were not much larger in size than their modern descendants. To solve this mystery, a group of American scientists from the University of Arizona (Temple, USA), led by John Van den Broeks, conducted one interesting experiment. They decided to grow dragonflies and cockroaches in conditions of hyperoxia, that is, high oxygen levels, and see what prevents the latter from becoming giants in such conditions.

During the experiment, dragonflies in an atmosphere containing 35% oxygen developed in the same way as their carbon ancestors - they grew quickly and at the same time increased in size (the wingspan of these “oxygen giants” reached 50 cm, which is only 20 cm less that of Meganeura). But the cockroaches demonstrated a completely different “behavior” - they grew slowly, much more slowly than under normal conditions, and never turned into giants.

It turns out that the very fact of a large amount of oxygen in the atmosphere did not at all force all insects to become “six-legged titans.” Only those who needed it became them - mostly active predators. Those who ate the remains of animal corpses and parts of plants preferred to increase the amount of storage tissue - if you are not very active, then an extra supply of body weight will not hurt. Or, perhaps, the cockroaches were simply afraid to increase greatly in size - what if Meganeura noticed, and then... In general, nothing good will clearly happen.

Like any Golden Age, the era of giant insects has ended. This happened about 290 million years ago, when the amount of oxygen on Earth began to decline. By that time, “factories for processing wood” from microorganisms and fungi had already appeared on land, so there was no longer any excess O2 - everything that plants created went into their own processing, as well as into the respiration of all land creatures (which in the end carbon has become many times more).

Since then, insects have never grown to the size of “six-legged titans.” Perhaps this is for the best - it’s unlikely that any of us would like a mosquito the size of a kitten flying into the window. Or a fly of the same length.

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Dragonfly is one of the most ancient insects inhabiting our planet. Their distant relatives, who lived more than three hundred million years ago (long before the appearance of the first dinosaurs), had very impressive dimensions, exceeding the size of many modern ones.

The wingspan of these prehistoric giant insects reached one meter, it is not for nothing that the name “Dragonfly” is still preserved in English, which literally means “flying dragon”.

In Latin insect dragonfly called “Libella” - small scales. This name is due to the fact that the insect’s wings resemble scales during flight.

This insect is very popular among the people, which is confirmed by its repeated mention in literature (the famous fable “ dragonfly and ant") and in the modern music industry (the song " white dragonfly Love", which has been at the top of various charts for a long time).

Golden dragonfly, in turn, is considered a powerful amulet that brings good luck.

Features and habitat of the dragonfly

Description of dragonfly It’s worth starting with the eyes of this insect, which at first glance seem disproportionate and too large relative to the overall size of the body.

However, dragonflies have so-called faceted vision, which is due to the presence of several tens of thousands of small eyes, each of which works independently and is separated from the others by special pigment cells.

The structure of the dragonfly's eyes allows it to see even what is happening behind

Thanks to this strange eye structure, the dragonfly's vision is much better than many other insects and allows it to see everything that is happening behind, on the sides and in front and track prey at a distance of up to ten meters.

The dragonfly's body consists directly of the head, chest and long belly, which ends in a pair of special forceps.

The length of the insect ranges from 3 to 14 centimeters. Coloration is quite varied and can vary from white, yellow and orange to red, blue and green.

The wings have many transverse and longitudinal veins, which serve as reinforcements.

Insect dragonfly - animal, which is one of the record holders for the speed of movement: although its average flight speed is usually from 5 to 10 km/h, some varieties are capable of reaching speeds of up to one hundred km/h when flying over long distances.

So, despite the image of an idly staggering jumping dragonflies, created in one famous fable, this insect is very mobile and leads an active lifestyle.

Dragonflies have three pairs of legs, which are covered with a layer of protective bristles. During flight, the limbs of the insect are folded into a “basket” in order to quickly grab prey if it is detected. The wings have dark spots that serve as vibration protection.

It is worth noting that the first jet aircraft took off due to the fact that entomologists shared with designers and engineers this structural feature of the wings of dragonflies, who used this element in the structure of aircraft, which would still crumble as soon as they left the surface of the earth, if would not be dragonflies.

The habitat of dragonflies is very extensive and extends from the territory of modern Europe and Asia to the African continent, Australia and America.

Dragonflies live mainly among meadows, fields and on the edges of forests. A prerequisite must be the presence of a body of water nearby.

Character and lifestyle of the dragonfly

Dragonflies lead a solitary lifestyle, preferring to hunt on their own. Thanks to its specific wing structure, a dragonfly can either hover in the air, making an instant stop, or fly over vast distances, covering several hundred kilometers without rest.

During landing, the dragonfly does not fold its wings, like many other insects, but always leaves them in a straightened state.

The main peak of activity occurs during daylight hours, during which dragonflies fly in search of prey.

During hot hours, they can be observed in huge numbers along the banks of reservoirs and above forest edges.

The flight of the dragonfly is characterized by noiselessness, thanks to which the dragonfly can unnoticed approach its prey.

They can make intricate turns in the air, do somersaults and even fly backwards. Thanks to this ability, dragonflies can easily escape from predators pursuing them.

Types of dragonflies

Today there are about 5,000 in the world dragonfly species. The main varieties are divided into three orders:

• Homoptera, which include beauties, arrows and lute. They are incredibly light in weight.
• Heteropterans, which include such varieties as orthetrum, libellula, sympetrum and rockers. This species has a pair of hind wings with an expanded base, which serves as the name for this suborder.
• Anisozygoptera is a rare suborder, which is distributed exclusively in countries such as Nepal, Tibet and Japan. They combine the characteristics of both of the above suborders.

Beauty girl - lives mainly in the southern regions and regions with a subtropical climate.

The male and female dragonfly, beauty girl, differ from each other in color

Females of this species are able to descend directly into water to a depth of one meter to lay eggs, forming an air bubble around themselves.

They are found exclusively within clean water bodies, being a kind of indicator of their purity.

Fatima is a rare species, listed as red. Inhabits areas of mountain rivers and streams along the sandy coast.

Dragonfly Fatima

Common Dedka is a species inhabiting the territory of modern Europe. It is also found in the Urals and around the Caspian Sea.

Dedka ordinary

The antlion is dragonfly-like insects, although its flight is rather slow, and its behavior is generally sluggish and leisurely.

The photo shows an antlion insect, which is often confused with a dragonfly

Dragonfly nutrition

What does a dragonfly eat? Since she is a predator, then dragonfly feeds on insects. It grabs small insects with the help of serrated jaws in flight, and large ones with the help of tenacious legs.

In order to hunt large prey, a dragonfly has to descend to the surface of the earth and wait for prey while sitting on a blade of grass or a twig.

If a dragonfly notices its prey directly in flight, it will masterfully repeat the flight path of its prey, after which it will approach it as close as possible and make a sharp leap in order to grab it with its paws.

The structure of the dragonfly's jaws allows it to easily absorb even large prey.

The dragonfly eats its prey unusually quickly, since it is a very voracious insect.

In one day, she needs to consume an amount of food that significantly exceeds her own weight, so her daily diet is several dozen, and other insects.

Reproduction and lifespan of dragonflies

Pairing dragonfly insects happens on the fly. It is certainly preceded by a mating dance, performed by the male to attract the female to himself.

After mating has occurred, the female lays up to two hundred eggs in one clutch. Subsequently, from the egg arises dragonfly larva, the development of which takes a very long time, up to five years.

The photo shows a dragonfly larva

The larvae are already predators and even prey on tadpoles, although they themselves often become prey for some species of fish, so that out of hundreds of larvae, only a few individuals survive.

The lifespan of a dragonfly reaches seven years, taking into account all stages from the larva to the adult, which can live about one month in the wild.

Homes do not actually breed such insects, so you can limit yourself to observing them in their natural habitat and viewing photo of dragonfly on the Internet.

Continuing the theme of prehistoric giants, today we will tell you about mega-insects that lived millions of years ago.

Dragonflies Meganeura

Giant fossil dragonflies Meganeura (lat. Meganeura) inhabited the planet from the beginning of the Paleozoic era to the beginning of the Permian period, they became extinct approximately 250 million years ago. Outwardly, they were similar to modern dragonflies, only their head and eyes were smaller, and their belly was more fleshy. Two representatives of this species: Meganeura monyi And Meganeuropsis permiana considered the largest flying insects of all time, their wingspan reached 65 cm and 1 meter respectively.

Meganeura dragonflies were predators, hunting mainly other large insects - dictyonevrids, the size of which is comparable to modern pigeons. Interestingly, Meganeura larvae, unlike their modern descendants, did not lead an aquatic lifestyle; they developed on land and were also predators.

Dictyoneuridae

Dictyoneuridae is an ancient insect that lived on Earth 230 million years ago. The closest living relatives are mayflies. The giant's wingspan exceeded 43 cm. Impressive size! Mayflies and dictyonevrids are the only insects of their kind; they molt not only in the larval stage, but also in the adult stage.

Dictyoneurids are also interesting for their unusual oral apparatus, more similar to the beak of birds, which, apparently, was intended for piercing various cones and scooping out seeds.

Mazotair is huge

Class paleodictyoptera- existed 320 million years ago. These insects reached enormous sizes. One of the representatives of paleodictyoptera - Mazotair is huge- was simply gigantic in size. Mazotair's wingspan reached 55 cm. Paleodictyoptera were also very unique, because. had three pairs of wings. Prehistoric insects fed on nectar and plant juice.

Prehistoric flea Pseudopulex Jurassicus

Even fleas had prehistoric giant relatives. Fossils of a prehistoric insect have been studied in central Mongolia - Pseudopulex jurassicus. It existed 165 million years ago in the Jurassic period. Ancient fleas fed on dinosaurs and pterosaurs. In appearance, it resembled a modern flea, but the body was flattened and covered with stiff bristles. Dimensions were from 1.7 to 2.3 cm, the length of the piercing-sucking proboscis reached 5 mm! In addition, the insect had long, tenacious claws and a strong sucking apparatus.

Arthropleura

Arthropleura- a genus of the largest arthropods in the entire history of the planet. Sizes varied greatly depending on the species - from 30 cm to 2.6 meters. Arthropleura lived approximately 340 - 280 million years ago.

Despite their size and good mobility, which, by the way, was provided by 30 pairs of legs, arthropleura were vegetarians, feeding mainly on ferns and other spore-bearing plants.

Huge insects disappeared 150 million years ago. Scientists have put forward several hypotheses about the reason for their extinction. Some believe that oxygen was the cause of gigantism in the prehistoric world. The concentration of oxygen in the atmosphere in those days was high, and this affected the growth of all living organisms. Over time, oxygen levels dropped, causing the mega-insects to become extinct or shrink in size.

The second opinion has to do with birds. Perhaps the insects lost in the fight against the birds for dominance in the sky. After all, it was then that stronger and faster birds began to appear.

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