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The dragonfly is an arthropod insect with six legs, belonging to the subclass of winged insects, the order of dragonflies. The order of dragonflies currently includes more than 6,650 species of these insects. Dragonflies are fairly large predatory insects that have a movable head, large eyes, a long and slender abdomen and four transparent wings. They are found all over the world, with the exception of cold Antarctica.
Origin of the species
Dragonflies are an ancient group of arthropods. The first dragonflies lived on the planet back in the Carboniferous period during the Paleozoic era. The origin is related to the giant dragonfly-like insects Meganeura. Those, in turn, were large arthropods with a wingspan of up to 0.66 meters. They are considered the largest arthropods of that time. Subsequently, it was they who became the descendants of Kennedyina, Ditaxineurina, living already in the Triassic period of the Mesozoic. These arthropods were also distinguished by their large size, with a span of up to 90 mm. When the animals rested, the wings were hidden under the abdomen.
Meganeura
In those days, insects had a well-developed trapping basket. They used it to grab victims. The next descendants of Meganeura living in the Jurassic period are Lestomorpha, Libellulomorpha, the larvae of which are capable of developing in water. Their aircraft has changed significantly, becoming more advanced. The descendants of meganeurinids gradually settled throughout the planet.
At this time, the descendants of the superfamily Calopterygoidea changed dramatically. Their wings became narrower and evened out in size. The Cretaceous era carried away many suborders of insects, and in the Cenozoic era modern suborders of dragonflies can be seen. In the Neocene, dragonflies ceased to differ from modern ones.
Variopterans and Anisozygoptera
The second suborder is heteroptera. They have a powerful body, and the base of the hind wings is widened.
The eyes often touch. The flight speed of heteroptera is high. At rest, the wings of these dragonflies are spread apart. The larvae of dragonflies live in mud and breathe using rectal gills. It is worth mentioning some species of dragonflies belonging to heteroptera. This is an ordinary grandfather, a large rocker, a bronze headstock, and a blood dragonfly.
Representatives of the third suborder (Anisozygoptera) combine the characteristics of the first two, although in appearance they are closer to heteroptera.
Dragonflies (Odonata)
These dragonflies do not live in Russia.
Description, appearance and features
These insects are easy to distinguish from other arthropods with the naked eye. At the same time, the color of animals can vary dramatically. The most expressive parts of the insect's body are:
- Large head with expressive eyes.
- The body is brightly colored, sometimes shiny.
- Chest part.
- Transparent wings of various shades.
Dragonfly: appearance
Depending on the species, animals come in different sizes. The smallest dragonflies are considered to be up to 1.5 cm long. The largest representatives grow up to 10 cm. The large head can rotate 180 degrees. Large eyes consist of thousands of ommatidia, whose number can vary from 10,000 to 27.5 thousand.
It has been proven that the lower ommathia reproduce only colors, while the upper ones determine the shapes of objects. This feature allows dragonflies to perfectly navigate in flight and catch prey. On the crown of dragonflies there is a small swelling on which three additional eyes are located. Dragonflies also have awl-shaped antennae, they are short and consist of approximately four to seven segments.
Dragonfly eyes
Interesting fact : dragonfly eyes have a complex structure.
They consist of 30 thousand ommatii, capable of instantly orienting themselves in space. Powerful jaw apparatus formed by unpaired lips. In this case, the lower lip consists of three blades covering powerful jaws. The upper lip, in the form of a small plate stretched across, covers the upper jaw. The insect is able to catch and chew food during flight due to the difference in size of the upper and lower lips.
Interesting fact : dragonflies hunt other insects and avoid collisions thanks to a viewing angle of almost 360 degrees.
The thoracic part has three sections: anterior, middle, posterior, with a pair of limbs on each. The last two sections also contain the wings of the animal. The anterior section is separated from the middle, which together with the posterior section are fused together, forming a synthorax, which is perceived as a chest.
Structure of a dragonfly
The chest is flattened on the sides, and the dorsum is slightly pushed back. The middle part of the chest is higher than the back, so the wings are intertwined behind the legs. The front part of the backrest is divided into three sections. There is a dent on the middle one. The segments on which the wings grow are hypertrophied pleurites.
Interesting fact : dragonflies are resilient. Red tramps are record holders for migration. They cover enormous distances during flights - more than 6.5 thousand km.
The wings of dragonflies are practically colorless and consist of a pair of layers of chitin formed by a venation system. The veins are superimposed on each other in such a way that they appear to be a single network. The system is complex and dense, each order of dragonflies has a unique network of veins on their wings.
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Dragonfly wings
The abdomen of dragonflies is round and elongated. Some species have a flat abdomen. In all species, the abdomen is the largest part of the body. The abdomen is divided into 10 segments. On the sides of the abdomen you can see pleural membranes, which allow the insect to bend.
On each segment, in addition to the last two, there are sigmas. At the tip of the abdomen are anal appendages, the number of which varies between females and males. Females have two, and males have three to four. The genitalia of females are located at the end of the abdomen, while in males the organ of compilation is located on the second abdominal segment. The opening for the release of sperm in males is located on the tenth abdominal segment. Insects have strong and well-formed limbs, consisting of the femur, pelvis, tibia and leg parts with paws. Each leg has spines.
Arrows
Arrows are not as spectacular as beauties, but just as graceful dragonflies. The photo of the graceful arrow, posted below, confirms this fact.
Shooters lead the same lifestyle as beauties, except that they choose more modest prey.
And it is not surprising, because the body length of the graceful arrow is only 3.5 cm, while the wingspan is 4.5 cm. The male has an elongated blue chest with a longitudinal black stripe and a black abdomen, as if intercepted by thin blue rings. The wings are narrow and transparent. Some females have a similar coloration, others are rather inexpressively colored and have neither stripes nor rings.
Arrows fly slowly and rarely leave their homes. Their larvae live and hunt in the stems and roots of aquatic plants. Distinguishing one species from another within this family is not an easy task. But it is impossible to confuse them with another family of arrows.
How to distinguish between male and female dragonflies?
Male and female dragonfly
Insects are characterized by sexual dimorphism. These are external differences between males and females, which are clearly noticeable especially in dragonflies. Dimorphism is important for dragonfly reproductive behavior. Surprisingly, the color of insects changes throughout life , the final establishment of color is noted at sexual maturity.
There are different types of sexual dimorphism in dragonflies. Some species are distinguished by large females and small males, while for others the opposite is true. Insect families also show certain trends in dimorphism. The beauties are distinguished by large males, and the shooters are distinguished by large females. The color of individuals is considered an important sign of sexual dimorphism. The pattern on the wings is also a sign of gender.
Sometimes insects exhibit polymorphism, that is, the presence of certain forms of one species that differ in color. In such cases, color is not associated with dimorphism.
Grandfathers
Among the features of these dragonflies are the variegated coloration, widely spaced eyes and the presence of a notch at the base of the hind wings in males.
Grandfathers are capable of long flights and prefer flowing reservoirs with clean water, where females lay eggs directly in flight.
Common dedka, tailed dedka and horned dedka are the most common species of dragonflies in Central Russia. These names sound funny (as well as “metal grandmother” or “bronze grandmother”), but you need to keep in mind that grandfathers are also called rivermen, and grandmothers – patrolmen.
The Common Dedka is a black and yellow dragonfly with transparent wings. The coloring is vaguely reminiscent of wasp.
Dedok larvae are voracious, strong and can burrow into soft mud. And adult grandfathers, oddly enough, are short-lived. They live no longer than a month.
Habitat – where does the dragonfly live?
Dragonflies are distributed throughout the world. The only place where dragonflies cannot be found is Antarctica. Most species are found in the Indo-Malayan region. There are approximately 1,664 species of animals found there. There are 1,640 species common in the neotropics, 889 in the Afrotropics, and 870 species in Australia and the region. Temperate areas are home to fewer species. This is because insects prefer warm, moist conditions.
Eggs are laid in water reservoirs and rivers. Depending on the variety, they are particularly sensitive to the choice of breeding site. Dragonflies Pseudostigmatinae prefer small water reservoirs, while other species can only breed in rivers or large lakes. The larvae are constantly in the water and can stay there for up to two years. Individuals that have learned to fly gradually fly away from their place of birth over long distances, migrating.
Selection of reservoirs and migration
When choosing a place for their offspring, dragonflies tend to show incredible plasticity. It can be said that almost all bodies of water, from rivers, lakes and streams to ditches, flooded hollows and depressions in the soil, are a completely acceptable habitat for larvae.
However, some species are more specialized and adapted only to certain conditions. There are nymphs that require high oxygen levels and require running water. Many tropical larvae, on the contrary, are adapted only to small bodies of standing water. A rather curious feature is the fact that in the cleanest lake on earth - Baikal, dragonflies are completely absent.
Moving over long distances is inherent in many insects. Dragonflies are no exception, capable of migrating over distances of several thousand kilometers , flying across entire oceans and mountain ranges. This phenomenon is adaptive in nature; insects fly away from an unfavorable environment in search of a more suitable home.
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Migration is usually carried out by scattered insects, but sometimes there are cases when dragonflies gather in huge flocks. For example, in the early 90s of the last century, a gigantic migration was recorded, numbering about 5 billion individuals, the total mass of which amounted to thousands of tons.
Habitat
Dragonfly habitat
Insects prefer warm zones, and spread in those areas where negative temperatures are not maintained for more than three months a year. The lifestyle of animals is amphibiotic, that is, the offspring are raised in water, and adults live in the ground-air environment.
Dragonflies are fast and easy to maneuver. The air is considered their home. Having occupied certain territories, dragonflies will defend them from enemies to the last, even from their relatives.
Flying yoke
Although the large rocker dragonfly is not the largest in the world, it is not called large for nothing. Its length reaches 73 mm. It is not difficult to meet such a large dragonfly - from May to September it flies around its hunting grounds. And the rocker has a lot of them, because they live throughout Europe, in Transcaucasia, right up to Lake Baikal, in Siberia and Central Asia. Truly an omnipresent rocker!
The body shape of this insect really resembles a rocker
How long do dragonflies live?
Insects live for several months. Moreover, the entire development of dragonflies takes more than one year. The larvae that hatch under water live there from several months to four years. They evolve, hunt and hide from enemies. Gradually, dragonflies molt and grow, learning to fly. Adults leave water bodies and begin migration.
Dragonflies are special insects. They do not require pupae or cocoons to develop into adults. After emerging, the adult dragonfly dries out from the water for some time and begins its flight. A few hours after growing up, dragonflies begin hunting winged insects, gradually adapting to new conditions. At this stage of development, the insect is greatly influenced by the surrounding temperature and climate. In warm conditions without precipitation, dragonflies live up to six months, but in cold conditions they survive for several weeks.
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