Respiratory system of insects. What do insects breathe? Respiratory organs of insects What is the peculiarity of the respiratory system of insects

During respiratory movements, they move away from each other and approach each other, and in Hymenoptera they also make telescopic movements, that is, the rings are pulled into each other during "exhalation" and straighten out during "inhalation". At the same time, the active respiratory movement, which is caused by muscle contraction, is precisely "exhalation" and not "inhalation", in contrast to humans and animals, in which the opposite is true.

The rhythm of respiratory movements can be different and depends on many factors, for example, on temperature: in the filly Melanoplus at 27 degrees, 25.6 respiratory movements per minute are performed, and at 9 degrees there are only 9. Before many, they intensify their breathing, and during it inhalation and exhalation are often paused. A honey bee has 40 respiratory movements at rest and 120 during work.

Some researchers write that, despite the presence of respiratory movements, insects lack the typical inhalation and exhalation. One can agree with this given the peculiarities of a number of taxa. Thus, in the locust, air enters the body through the front pairs and exits through the rear, which makes it different from "normal" breathing. By the way, in the same insect, with an increased carbon dioxide content, the air in can begin to move in the opposite direction: it can be drawn in through the abdominal and out through.

How aquatic insects breathe

Insects living in water, breathing is carried out in two ways. It depends on what kind of structure they have.

Many of the aquatic organisms are closed in which they do not function. It is closed, and there are no "exits" outside. Breathing is carried out using - outgrowths of the body, into which they enter and branch abundantly. Thin tracheoles come so close to the surface that oxygen begins to diffuse through them. This allows some insects living in the water (and caddis flies, stoneflies, mayflies, dragonflies) to exchange gas. During their transition to terrestrial existence (transformation into) they are reduced, and from closed it turns into open.

In other cases, breathing of aquatic insects is carried out by atmospheric air. Such insects have an open one. They draw air through, floating to the surface, and then sinking under the water until they are used up. In this regard, they have two structural features:

Other features are also possible. For example, in a swimming beetle, they are located at the rear end of the body. When she needs to "take a breath", she swims up to the surface, takes a vertical position "upside down" and puts out the part where they are located.

The breathing of adult swimmers is interesting. They have developed, from the lateral sides bending downward and inward, towards the body. As a result, when surfacing to the surface with folded elytra, the beetle captures an air bubble that enters the subelitral space. They also open there. Thus, the swimming beetle renews oxygen reserves. The swimmer of the genus Dyliscus can stay under water for 8 minutes between surfacing, Hyphidrus for about 14 minutes, Hydroporus for up to half an hour. After the first frost under the ice, the beetles also retain their viability. They find air bubbles under water and swim over them so as to "pick up" them under.

In the water lover, air is stored between the hairs located on the abdominal part of the body. They are not wetted, so an air supply is formed between them. When the insect swims under water, its ventral part looks silvery due to the air cushion.

In aquatic insects that breathe atmospheric air, those small reserves of oxygen that they capture from the surface should be consumed very quickly, but this does not happen. Why? The fact is that oxygen diffuses from the water into the air bubbles, and from them carbon dioxide partially leaves the water. Thus, taking air under the water, the insect receives a supply of oxygen, which is replenished by itself for some time. The process is highly temperature dependent. For example, the Plea bug can live in boiled water for 5-6 hours at warm temperatures and 3 days at cold temperatures.

In all these cases, skin respiration takes place. Insects breathe all over the body (first instars

Insects have no lungs. Their main respiratory system is the trachea. Insect tracheas are communicating air ducts that open outward along the sides of the body with spiracular openings. The thinnest branching trachea - tracheola - permeate the entire body, entwining organs and even penetrating into some cells. Thus, oxygen is delivered with air directly to the place of its consumption in the cells of the body, and gas exchange is provided without the participation of the circulatory system.

Many insects living in water (water beetles and bugs, larvae and pupae of mosquitoes, etc.) must from time to time rise to the surface in order to capture air, that is, their breathing is also airy. During the renewal of the air supply in the tracheal system, the larvae of mosquitoes, centipedes and some other insects are "suspended" from below to the surface film of water by means of non-wetted fatty hairs.

And aquatic beetles - water lovers (Hydrophilidae), diving beetles (Dytiscidae) and bugs, for example, smoothies (Notonectidae) - breathe at the surface and carry an additional supply of air with them under the water under the elytra.

In insect larvae living in water, in moist soil and in plant tissues, skin respiration also plays an important role.

The larvae of mayflies, stoneflies, caddis flies and other insects, well adapted to life in water, do not have open spiracles. Oxygen penetrates inside them through the surface of all parts of the body, where the integument is thin enough, especially through the surface of leaf-like outgrowths pierced by a network of blindly ending tracheas. In larvae of mosquitoes-bloodworms (Chironomus) respiration is also cutaneous, with the entire surface of the body.

People with poor knowledge of biology usually do not understand the structure of invertebrates. Do they have blood and do they have a brain? Do insects breathe? The vast majority of living organisms need oxygen for life. It oxidizes incoming substances - divides them into structures of simpler structure. Plants also use oxygen in the process of breathing. Only anaerobic microorganisms and some multicellular animals do not need this element. However, they breathe, they only use other organic or inorganic substances for oxidation.

World of small creatures

Insects are small organisms that do not exceed a few centimeters in size. Their structure does not allow an increase in volume and weight in modern conditions. The same cannot be said for the ancient arthropods that lived in the days of the dinosaurs and even earlier. In those days, the atmosphere was completely different: a different density of air, the composition of gases. And the planet Earth itself weighed less. In the distant past, dragonflies reached sizes of more than half a meter.

What do insects breathe? And what prevented them from evolving to the size of, for example, a cat in modern conditions? Scientists believe that this is a kind of respiratory system.

A bit of taxonomy

Insects belong to the subtype Tracheata. The type of arthropods also includes the subtypes of gill-breathing (crustaceans) and chelicerans (spiders, scorpions, ticks, etc.).

What do insects breathe?

The very name of the subtype speaks of the way of breathing. However, chelicerae breathe in the same way. Insects have acquired a complex system of trachea in the course of evolution. Tracheas are inner tubes that carry air to the cells of the body. The tracheal system is not simple, because the trachea branch into a huge number of thin tubes. Each of them fits a small group of cells. The tracheal network in insects is similar to the system of blood vessels and capillaries in vertebrates.

Insect spirits

Air enters the trachea through the spiracles - special openings on the body of insects. Spiracles - stigmas - are located in pairs, usually on the sides of the body. The regulation of air intake is provided by special locking devices.

Three symmetrical large branches of the trachea usually depart from each spiracle:

1. Dorsal. Provides oxygen to the dorsal hemolymph vessel and dorsal muscles.
2. Visceral. Serves the digestive system and genitals.
3. Ventral. Serves the abdominal muscles and nerve cord.

Insect tracheola

The endings of the trachea branch into very thin capillary tubes - tracheoles. Their diameter is less than 1 micrometer. Tracheoli branch out in the intercellular space, entwine the cells. They are a functional part of the tracheal system that diffuses oxygen into the cells of the body.

Additional education

What do most insects breathe? The respiratory organs are the trachea. However, some arthropods also have air sacs. This structure resembles the lungs, or rather the air sacs of birds for increasing the volume of air in the body. Swollen areas are found in fast-flying insects (bees, flies). They lie along the tracheal trunks. As a result of the contraction of the muscles of the body during flight, the air sacs contract and expand, increasing the flow of air in and out.

What organ do insects living in water breathe?

For example, a silver spider living in central Russia spends most of its life under water. He carries a supply of air bubbles with him. So he didn't have to change anything in the respiratory system. Spiders have a tracheal system similar to insects.

The swimming beetle is a common inhabitant of ponds in central Russia. He also breathes with trachea. It periodically rises to the surface of the water, exposes the tip of the abdomen. Air enters under the elytra and remains there. The water beetle carries the oxygen reserve with it.

The rest of the aquatic beetles do the same. The twig hunts on the surface of the pond, however, diving in case of danger, it also captures air with it. It looks like a shiny shell at the end of the abdomen.

Many water bugs also trap air in a bubble from the surface. Like Gladysh, for example. He carries with him an air bubble attached to the end of his abdomen. Such a device helps him to swim even better.

Some water bugs (water scorpion, ranatra) have a special tube at the end of the abdomen. It consists of two grooved halves. The bug moves its abdomen - makes breathing movements. Through the tube, air enters the spiracles.

Respiratory organs of larvae

Adult insects breathe through the trachea. The larvae have more varied respiratory organs. What insect larvae breathe through trachea? Land representatives have a tracheal system. For example, butterfly caterpillars have 9 pairs of stigmas on their sides. The first pair on the chest, the rest on the abdominal segments. Sometimes the second pair of spiracles is closed.

Most aquatic insects and their larvae also have a tracheal system. However, a huge number of representatives have formations similar to gills. These are outgrowths located in the places of spiracles. Oxygen enters the body through the thin layers of the tracheal outgrowths. This is how the larvae of mayflies, stoneflies, caddis flies breathe. The larvae of dragonflies with different wings also have tracheal gills, but they are located in the intestine, that is, inside the body.

Bloodworms have filamentous gills, but they absorb large amounts of oxygen throughout the entire surface of the body. The bloodworm always has a supply of oxygen. For this reason, he can live in polluted water bodies.

The larvae of the pinnacle mosquito (the family thick-lumped mosquitoes) breathe oxygen dissolved in water, absorbing it throughout the body surface.

Respiratory organs of pupae

What do insects at the pupal stage breathe? It is believed that the third stage of insect development is immobile. However, even butterfly pupae can wiggle their belly. And the ladybug chrysalis nods its head, probably scaring off enemies. Insects of this stage breathe through the trachea.

Among the pupae of aquatic insects, there are very mobile individuals. These are, for example, blood-sucking mosquitoes. Their pupae regularly rise to the surface of the water to suck in air through special tubes at the end of the abdomen.

The pupa of the cirrus mosquito is similar to the pupa of the common mosquito. But it does not rise to the water surface until the adult emerges. The respiratory organ is the integument of the body.

What do insects that do not have trachea breathe? The respiratory organs of some primordial wingless insects and larvae inhabiting tissues are the skin. They are thin enough to allow gases to pass. Carbon dioxide is also released through the cuticle, which is partially observed in insects with trachea.

Insects often move their abdomen - make breathing movements. Respiratory rate increases during flight. The respiratory muscles contract and relax, for example, in a bee at rest about 40 times per minute. Several times more often during the flight.

In more primitive insects, the spiracles do not close. However, they are protected by hairs from debris. In more complex arthropods, stigmas are able to open and close to regulate air intake. In addition, part of the spiracles can serve for inhalation, and another part for exhalation.

Interestingly, insect stigmas come in different shapes and colors. They can be round, oval, triangular. Their color is sometimes different from that of the surrounding cuticle.

Thus, nature created the tracheal system even before the appearance of the lungs. This system is well organized. The spiracles system provides a constant flow of air. Oxygen is carried to all cells of the body.

The structure of the tracheal system. Respiration of insects is carried out through the system of trachea, which are distributed throughout the body, less often through the surface of the skin. Tracheas are represented by hollow tubes lined with chitin in the form of spiral thickenings that prevent the trachea from collapsing during movement and bending of the body. Tracheas branch into tiny capillaries - tracheoles with a diameter of less than 1 micron, delivering oxygen from the air directly to the tissues and cells of the body.

Breath. The flow of air into the tracheal system occurs most often actively, with the help of respiratory movements. In this case, these or those spiracles open or close, performing an inhalation or exhalation. The rhythm of respiratory movements depends on the type of insect, its condition and external conditions. Thus, a honey bee at rest makes about 40 respiratory movements per minute, and in motion - up to 120; in some locusts, an increase in their number from 6 to 26 or more occurs when the ambient temperature rises from 0 ° C to 27 ° C and above.

In many insect species, air is inhaled through the chest and exhaled through the abdominal spiracles. The rhythm of the spiracles is associated with the respiratory movements of the abdomen; with an increase and decrease in air pressure caused by these movements, some spiracles open outward, others - into the insect's body. However, under the influence of large doses of carbon dioxide, various poisons, and sometimes for no apparent reason, air circulation can change, that is, it begins to flow through the abdominal spiracles and out through the chest. In addition, with an increase in carbon dioxide content and a lack of oxygen in the environment, the spiracles remain open for a longer time, and therefore fumigation of the premises against pests will be more effective.

Breathing is an oxidative process that involves the consumption of oxygen and the release of carbon dioxide. The oxidation process takes place with the participation of oxidative enzymes - oxidases and is accompanied by the gradual breakdown of the molecules of consumable compounds - carbohydrates, fats, proteins - and the release of energy. The cleavage of these compounds ultimately ends with the formation of carbon dioxide and water, and for proteins also the appearance of decay products bound into compounds that are safer for the body, such as urea and its salts.

Thus, breathing is accompanied by gas exchange. The gas exchange process is characterized by the respiratory coefficient (RK), which is the ratio of the emitted carbon dioxide to the total amount of absorbed oxygen. This indicator can be used to judge which substances are used at the moment as a source of energy. With the oxidation of carbohydrates, DC \u003d 1, with the use of less oxidized compounds of fats, DC decreases to 0.7, and proteins - to 0.77-0.82. For example, during starvation of cockroaches, DK decreases to 0.65-0.85, which corresponds to the predominant expenditure of previously stored fats.

Other forms of breathing. Respiration of aquatic insects occurs both due to atmospheric air and due to the use of air dissolved in water. So, swimming beetles, living in water, breathe due to atmospheric air stored under the elytra at the end of the abdomen, and from time to time rise to the surface to renew its reserves. Beetles from the genus of iris extract atmospheric air from the air vessels of aquatic plants.

When using air dissolved in water, insects breathe through their gills. The gills are represented by external branched or lamellar formations located in the place of the missing spiracles. They are developed in the larvae of mayflies, dragonflies, caddis flies, and some Diptera. In the larvae of dragonflies of different wings, rectal gills, that is, they are internal organs and are located in the rectum.

Body temperature. Insects are animals with variable body temperature. It depends on the intensity of the processes of heat generation and its return. The sources of heat generation in insects are, on the one hand, metabolic processes in the body, accompanied by the release of thermal energy, and the radiant energy of the sun or the air heated by it, on the other.

According to I. D. Strelnikov, the body temperature of insects at rest and not exposed to the sun is approximately equal to the ambient temperature. Due to the fact that the temperature optimum for many species fluctuates around 20 ... 35 ° C, insects can, within certain limits, regulate body temperature by changing muscle activity (movement, flight) or moving to warmer or cooler areas, sometimes for account of changing posture. Evaporation of water from the surface of the skin and ventilation of the trachea, especially with the help of air sacs, may have a known role in the regulation of body temperature.