Description: War Thunder is a next generation military MMO game dedicated to...
If you look at a dragonfly, it evokes associations with something light, carefree, fluttering. Many people think that the dragonfly is a "jumping bird", as in I. Krylov's fable, but this is fundamentally wrong. The dragonfly is a hard worker. From early morning until sunset, she flutters, over the reservoirs, getting her livelihood in the form of midges, mosquitoes and flies.
It's interesting, but the dragonfly can be called a "orderly", because it catches insects that annoy both people and animals. Some large representatives can be found far from the water: in the meadow, near houses, in gardens. Medieval chroniclers loved to describe the flight of a dragonfly.
dragonfly vision
Separately, it is necessary to note the vision of dragonflies. Theirs is just great! Still - would be, huge compound eyes, allow the dragonfly to view everything around at 360 degrees and in different directions - in front and behind. This is very helpful for dragonflies in hunting. The colors of the dragonfly are not immediately distinguished by the eyes. The upper sections are black and white, the lower sections are colored.
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Who lives in the stream and the river?
What does a dragonfly eat?
Dragonfly is a real predator. She grabs her prey with powerful jaws, helping with her front paws, and quickly eats it right on the fly. If the caught prey is too large, the dragonfly sits on the grass to eat the caught insect. Dragonflies have an amazing appetite. For a whole day of hunting, a dragonfly can catch and eat about 650 insects. She gobbles up her prey in about 15 seconds. In general, watching the flight and hunting of dragonflies is an amazing and fascinating sight. The Dragonfly is an amazing virtuoso when it comes to flying and gliding in open space. Probably, after watching dragonflies, people created a helicopter.
Lifestyle
The dragonfly spends its entire life in the air. There she dine and creates a family there. The place where the future offspring will grow is chosen by the male. He also guards the female while she lays her eggs. These "flyers" place their eggs on aquatic plants. When a larva emerges from an egg, it lives in a river or lake for about 3 years. During this long time, she molts several times, shedding her shell.
So, today we have Saturday, July 8, 2017 and we traditionally offer you answers to the quiz in the "Question - Answer" format. The questions we meet are both the most simple and quite complex. The quiz is very interesting and quite popular, but we just help you test your knowledge and make sure that you have chosen the correct answer out of the four proposed. And we have another question in the quiz - How many eyes does a dragonfly have?
Correct answer is A- 2
The dragonfly has two big eyes...
With no hearing and limited sense of smell, the dragonfly's most important asset is its eyes. Dragonflies are believed to have the most complex eye structure of all insects, which gives them an incredible advantage when hunting. Adults, with a nearly 360-degree field of vision and an extremely mobile head, see in almost all directions except "straight back".
The eyes of these insects consist of 30,000 hexagonal facets that receive information from different areas of space, as a result, the vision of the world is made up of many local images like a mosaic. For various reasons, the vision of dragonflies has become more developed than that of humans. Humans have three opsins (light-sensitive retinal proteins), each of which absorbs a specific color of the spectrum, such as red, green, or blue.
Dragonflies have up to 5 opsins, allowing them to see ultraviolet light in addition to a wide range of colors. Their eyes are also able to pick up the polarization of light and clearly distinguish rapidly changing images. Dragonflies can detect fast flashes of light up to 80 times per second (twice as fast as the human eye can see), which helps them recognize the pattern on their rapidly fluttering wings. The largest of the many dark spots on the eyes of a dragonfly is where dense groups of facets form a fovea that ensures minimal blurring of the image during flight at high speeds. A larger spot indicates improved vision in that direction. In diurnal hunting dragonflies, they are located in the upper part of the eyes and contain facets that are most sensitive to blue and ultraviolet light. In view of this feature, the sky seems brighter than the ground, an optical effect that allows the dragonfly to easily find prey against a bright background and attack it from below.
how many eyes does a dragonfly have?
The dragonfly has two big eyes...With no hearing and limited sense of smell, the dragonfly's most important asset is its eyes. Dragonflies are believed to have the most complex eye structure of all insects, which gives them an incredible advantage when hunting. Adults, with a field of view of almost 360 degrees and an extremely mobile head, see in almost all directions except "straight back".
The eyes of these insects consist of 30,000 hexagonal facets that receive information from different areas of space, as a result, the vision of the world is made up of many local images like a mosaic. For various reasons, the vision of dragonflies has become more developed than that of humans. Humans have three opsins (light-sensitive retinal proteins), each of which absorbs a specific color of the spectrum, such as red, green, or blue.
Dragonflies have up to 5 opsins, allowing them to see ultraviolet light in addition to a wide range of colors. Their eyes are also able to pick up the polarization of light and clearly distinguish rapidly changing images. Dragonflies can detect fast flashes of light up to 80 times per second (twice as fast as the human eye can see), which helps them recognize the pattern on their rapidly fluttering wings. The largest of the many dark spots on the eyes of a dragonfly is where dense groups of facets form a dimple that ensures minimal image blur during flight at high speeds. A larger spot indicates improved vision in that direction. In diurnal hunting dragonflies, they are located in the upper part of the eyes and contain facets that are most sensitive to blue and ultraviolet light. In view of this feature, the sky seems brighter than the ground, an optical effect that allows the dragonfly to easily find prey against a bright background and attack it from below.
QUOTES from some articles:
“... When examining a dragonfly, huge eyes occupying most of the head attract attention. The eye consists of 28 thousand facets (ommatidia), each of which is served by 6 light-sensitive cells. The dragonfly is able to spot a mosquito at a distance of up to 10 meters. Eating mosquitoes, horseflies and other bloodsuckers, dragonflies are of great benefit ... "
“…- Insects have the so-called faceted vision,” explains Ms. Chubarova. - The eye is made up of thousands of tiny facets, and the information from all the facets comes together to form a big picture. For example, The dragonfly eye is made up of 28,000 eyes.…»
“... in many ways, dragonflies are even more perfect than humans. At least their adaptation mechanism, which allowed them to exist for such a long time and practically in the same appearance in the changing biosphere. Or the structure of the dragonfly's eye, which provides it with a spherical view - it simultaneously sees what is happening in front, behind, from below, above, from any side. By the way, in those days, this ability of theirs was described in scientific article one scientist from Tomsk University in the journal "Physiology". And after that he had a long conversation in the KGB, because he described with a one-to-one accuracy the principle of operation and even the formulas of the equipment then in service in the air defense, in the anti-missile forces. Thank God it worked out…”
Dragonflies are familiar representatives of the fauna temperate latitudes. it large detachment amphibious insects whose adults live on the ground, and the larvae in aquatic environment. Thanks to their open lifestyle, they are well known to man. The common dragonfly has a slender body, red or yellow-brown color. Her offspring grows in stagnant water with a lot of vegetation. Despite its modest size, the insect is of great benefit, destroying mosquitoes, flies and various agricultural pests.
Dragonfly groups
Scientists have found and described more than 6 thousand species of dragonflies. They are divided into two large groups:
- Different-winged dragonflies - the suborder includes about 3 thousand species, among which the common dragonfly. Feature- placement during rest of the wings perpendicular to the axis of the body. The anterior pair of wings is larger than the posterior one. This group includes the fastest predators, the record speed is up to 100 km / h. Nymphs live in stagnant water.
- Dragonflies are a group of insects with the same size fore and hind wings. Their flight is smooth and measured. At rest, the wings are roof-like folded over the abdomen. The larvae live in stagnant and flowing water bodies.
The common dragonfly belongs to the family of true dragonflies. Its representatives are small in size (3-5 cm). They are found everywhere except Antarctica.
Description Sympetrum vulgatum
Insect classification:
- Order - dragonflies (Odonata).
- Family - real dragonflies (Libellulidae).
- Genus - compressed belly (Sympetrum).
- Species - common dragonfly (Sympetrum vulgatum).
The structure and color of the body
Dragonflies of the genus Sympetrum or shrimp belly are typical representatives of the Russian fauna. Their body length is 38-40 mm, of which up to 28 mm falls on the abdomen. The head is large, well-defined, mobile. In adults, it is wider than the thorax and is movably connected to the prothorax. The eyes are large, complex, consisting of 20-30 thousand individual facets. Top part the organ is responsible for recognizing the contour of objects, and the lower one distinguishes colors. Antennae are presented in the form of short thin setae. There are three simple eyes on the crown of the head. Across the brown head, between the crown and forehead, there is a black stripe. The mouth apparatus is of a gnawing type, strong mandibles are equipped with sharp denticles.
On the chest of the insect are limbs and two pairs of wings. The back of the prothorax has a vertical protrusion. A fringe of long hairs grows on it. Black stripes run along the thoracic sutures. The back of the dragonfly is pushed obliquely back, so the wings are behind the limbs. In males of the common flattened belly, the chest is red with three black stripes, the color of the females is yellow-brown, three stripes are also present.
Wings
Dragonflies are equipped with two pairs of wings. In heteroptera, the anterior pair exceeds the parameters of the posterior. The wing plate is formed by two chitinous layers and reinforced with veins. Their length is approximately equal to the size of the body. The hind wings are widened at the base. The wingspan of Sympetrum vulgatum is 60 mm, the length of the hind wing is 24-29 mm, the length of the front wing is 33-37 mm. The venation is very dense, in large veins there is a hemolymph, small ones do not have gaps. One of the significant areas is pterostigma, a thickening in the anterior part of the wings. Outwardly, it looks like a dark spot; during flight, it makes the top of the wing heavier, allowing you to increase the stroke amplitude.
Information. The common dragonfly lacks ocher-yellow patches at the base of its wings.
limbs
The legs of the common dragonfly are black, with a yellow stripe on the outside. Three pairs of limbs are designed to hold the insect's body and catch prey. They are not used for walking or running. Legs are made up of 5 main parts:
- basin;
- swivel;
- hip;
- shin;
- paw.
There are several rows of spiny setae on the inner side of the tibia and femur. The coxa is the thickest and shortest part of the limb. On the paw are two sharp forked claws. Long limbs and spikes allow the formation of a "trapping basket" for catching prey in the air.
Abdomen
The abdomen of the common dragonfly is flattened and wide. It consists of 10 complete and one rudimentary segment. Each part is formed by the upper and lower chitinous shield. Due to the movable joint, insects can freely bend the abdomen. The body structure of males and females is different. Male individuals have special appendages on the last segment to hold a partner during mating. Their secondary copulatory organ is located in the lower part of the second segment. The genital opening of the female is between the eighth and ninth segments. The females have an ovipositor. In males, the abdomen is red with a black lateral stripe, in females it is brown with a black stripe.
Larvae
Dragonfly larvae are called nymphs or naiads. By appearance and structure they are strikingly different from adults. Nymphs of the common dragonfly have a massive body 17-19 mm long. Breathing is carried out through the internal organs - rectal gills. The larvae draw water into the rectum, where gas exchange takes place. The body color is dark gray, greenish or red-brown. The nymphs are covered with a motley pattern.
Interesting fact. In order to make a sharp dash for prey or hide from the enemy, the larvae throw out a stream of water from the anus.
The unique structure has oral apparatus larvae. It consists of an upper lip, paired mandibles, and a modified lower lip. This organ has been transformed into a mask. The movable joint allows you to throw it forward and cling to prey sharp teeth. When at rest, the mask is folded under the head. The rudiments of wings are located on the dorsal part. On each part of the chest is a pair of limbs. Larvae of the family Libellulidae burrow into the mud. The way of life affected the structure of their legs. The limbs are shortened, wide, with many hairs and spines. Nymphs feed on small invertebrates, insect larvae, fish eggs, cannibalism is not excluded.
reproduction
Sexual dimorphism of insects is manifested in coloration. It affects the reproductive behavior of dragonflies. Males are characterized by attachment to the place and territorial competition. They do not allow rivals to their sites. Only females ready for fertilization are allowed. Dragonflies have a complex mating process: the male holds the female with his anal appendage behind the head, the female partner bends the abdomen forward, leaning it against the spermatophore on the 2nd segment of the partner's abdomen. It turns out a closed figure, which is held for several minutes.
In the process of laying, the male common dragonfly accompanies his partner. He flies around her and protects from re-mating. Territorial behavior leads to the fact that some males that have not received good sites will not be able to participate in procreation.
Offspring
Dragonflies are insects with incomplete metamorphosis. Them life cycle is divided into three phases:
- egg;
- larva (nymph);
- imago.
The female common dragonfly lays her eggs in coastal mud, wet soil, or water. Through the winter, larvae appear from the masonry, remarkable for appearance and biological features. They play a significant role among the inhabitants of the reservoir. Nymphs live in stagnant or weakly flowing water. They prefer to lead a secretive life, hiding among aquatic plants or burrowing in silt. The common dragonfly larva has a short and wide body. The shape of the mask is helmet-shaped.
Small predators feed only on live prey. They spend a lot of time in ambush, waiting for the approach of insect larvae or daphnia. Food is consumed in large quantities, especially young nymphs have a great appetite. During the day they eat invertebrates, the mass of which exceeds their own. Before growing up, offspring require from 7 to 11 molts. Their number depends on the environmental conditions and food supply. The final molt takes place on dry land. To do this, the nymph is selected on a hard surface - a stone, a snag or a stem. The skin of the larva dries out and cracks. A formed dragonfly is selected from it. Imago needs time to spread and harden the wings. The final color characteristic of the species is acquired in a few days.
Lifestyle
Dragonflies are diurnal predators, they are active in warm sunny weather. Night time and inclement weather are experienced in shelter. In the morning, adults gain energy by basking in the sun. They sit on the bark of trees, branches, grass stalks. In the heat, they direct the tip of the abdomen upward, reducing the area of solar exposure. Imagoes have excellent eyesight. They notice prey at a great distance and successfully attack.
Insects do not have food preferences, they prey on any objects of suitable size. Multi-winged predators easily maneuver and dive, can make high-speed flights and move a considerable distance from their birthplace. The mass flight of the common dragonfly is observed in July-September. Departure of adults after molting occurs gradually, so some individuals are found even in October.
Despite the reputation of a ruthless predator, the dragonfly itself often becomes prey. Birds, reptiles, and mammals prey on it. Insects that land on the water are attacked by fish. Cannibalism flourishes among representatives of the Odonata order, large individuals catch and eat smaller ones. For larvae, swimming beetles and water bugs are dangerous. How long does a common dragonfly live? This species spends several months at the age of adults. The larva develops for about 1 year.
Habitat
The common dragonfly belongs to the transpalearctic species. Insects live in large numbers in Europe, Central Asia, Siberia, Far East and northern Africa. They settle near lakes, swamps, reclamation canals. Prefer ponds, abundantly overgrown with vegetation.
Significance for a person
Dragonflies and humans rarely have conflicts. Representatives of the Odonata family are of great benefit. They control the number of blood-sucking insects - mosquitoes, gadflies, mosquitoes. Imago destroy pests on land, and nymphs in water. Dragonflies are absolutely safe for humans. They have stings, do not tolerate disease. Many species are sensitive to water conditions. They die when water is polluted.
Human economic activities often threaten populations certain types dragonflies. Representatives of Sympetrum vulgatum are safe for now. Being at the reservoir, with sufficient patience and caution, you can wait for close contact with the dragonfly. The insect will land on your hand.
Scientists identify about 5 thousand species of dragonflies. Dragonflies are the largest representatives of flying insects.
Dragonflies are of two types: heteroptera and homoptera. Equipteran dragonflies are smaller in size, moreover, they do not fly as well as heteroptera dragonflies.
The appearance of a dragonfly
The dragonfly has a long abdomen with a pair of forceps, a chest and a head. The body length of dragonflies, depending on the species, varies between 3-12 centimeters. The color is also diverse: white, red, green, orange, yellow. The wings are transparent and thin, they have a large number of longitudinal veins that strengthen their fragile structure. In addition, there is a dark spot on the wing, this is not just a decoration, it serves to ensure that the insect in flight is not affected by vibration.
All dragonflies have 3 pairs of bristle-covered legs. They have a gnawing type of mouth apparatus, while the lower lip acts as a harpoon, it flies forward and grabs the victim. Dragonflies have huge eyes that help them find prey: they are able to see the victim at a distance of about 10 meters. The eyes are complex, have a faceted structure.
Dragonfly lifestyle
Dragonflies are very agile, they fly at tremendous speeds, for example, some species are able to fly at a speed of 100 kilometers per hour. But most often they fly at a speed of 5 kilometers per hour. At the same time, they can cover hundreds of kilometers without stopping. Dragonflies can hover in the air, stopping instantly.
Dragonflies are the fastest of insects. When a dragonfly lands on the ground or other surface, it does not fold its wings; its wings are always in a straightened state.
All dragonflies are predatory insects, they feed on flies, mosquitoes, moths and other small insects. Dragonflies pursue their victims with great speed. During the flight, the dragonfly folds its legs in a basket, so that it is convenient to grab prey on the fly.
Dragonflies lead a solitary lifestyle. Their enemies are a variety of birds, as well as spiders.
Where do dragonflies live
According to the way of life, dragonflies are loners. Dragonflies are found in Europe, Asia, Africa, Australia and America. They settle on the edges, meadows and fields. They need a body of water to live.
Dragonfly breeding
During the breeding season, males perform a courtship dance, with the help of which they gain the attention of the female and drive away other applicants from her. After mating, the female lays about 200 eggs. She is laying in fresh water or on various plants and wood.
The development of dragonflies includes 3 stages: egg, larva and adult. The larvae move very little, they develop in fresh water. Larvae of some species of dragonflies can develop for 5 years. The larvae have huge eyes. These predators are very voracious, they even eat their relatives. The larva sits for hours in a shelter, as soon as the victim approaches, the predator attacks with lightning speed. They feed on fry and aquatic insects.
