Earthworm. Earthworm breath. Respiratory system of insects - locusts General characteristics of the species

In the world of fauna is the earthworm. He can rightfully be called an earthworker, because it is thanks to him that the soil on which we walk is fully saturated with oxygen and other minerals. Passing through various parts of the earth up and down, this worm makes them loose, which then allows you to plant them there. cultivated plants as well as gardening.

General characteristics of the species

The earthworm belongs to the kingdom Animals, to the sub-kingdom Multicellular. Its type is characterized as ringed, and the class is called Small-bristle. The organization of annelids is very high compared to other types. They have a secondary body cavity, which has its own own systems digestive, circulatory and nervous. They are separated by a dense layer of mesoderm cells, which serve as a kind of airbags for the animal. Also, thanks to them, each individual segment of the worm's body can autonomously exist and progress in development. The habitats of these earthly orderlies are moist soil, salty or fresh waters.

The external structure of the earthworm

The body of the worm is round. The length of representatives of this species can be up to 30 centimeters, which can include from 100 to 180 segments. The front part of the body of the worm has a slight thickening, in which the so-called genitals are concentrated. Local cells are activated during the breeding season and perform the function of laying eggs. The lateral outer parts of the body of the worm are equipped with short setae, completely invisible to the human eye. They allow the animal to move in space and touch the ground. It is also worth noting that the tummy earthworm always painted in a lighter tone than its back, which has a maroon, almost brown color.

What is it like from the inside

From all other relatives, the structure of the earthworm is distinguished by the presence of real tissues that form its body. The outer part is covered with ectoderm, which is rich in mucous cells containing iron. This layer is followed by muscles, which fall into two categories: annular and longitudinal. The former are located closer to the surface of the body and are more mobile. The latter are used as auxiliary during movement, and also allow the internal organs to work more fully. The muscles of each individual segment of the worm's body can function autonomously. When moving, the earthworm alternately compresses each annular muscle group, as a result of which its body either stretches or becomes shorter. This allows him to break through new tunnels and fully loosen the earth.

Digestive system

The structure of the worm is extremely simple and clear. It originates from the mouth opening. Through it, food enters the pharynx and then passes through the esophagus. In this segment, products are cleaned from acids released by decay products. Then the food passes through the crop and enters the stomach, which contains many small muscles. Here, the products are literally ground and then enter the intestines. The worm has one middle intestine, which passes into the rear opening. Everything in her cavity useful material from food are absorbed into the walls, after which the waste leaves the body through the anus. It is important to know that earthworm excrement is saturated with potassium, phosphorus and nitrogen. They perfectly nourish the earth and saturate it with minerals.

circulatory system

The circulatory system that the earthworm possesses can be divided into three segments: the abdominal vessel, the dorsal vessel, and the annular vessel, which combines the two previous ones. The blood flow in the body is closed, or annular. The annular vessel, which has the shape of a spiral, combines two arteries vital for the worm in each segment. Capillaries also branch off from it, which come close to the outer surface of the body. The walls of the entire annular vessel and its capillaries pulsate and contract, due to which the blood is distilled from the abdominal artery to the dorsal one. It is noteworthy that earthworms like humans have red blood. This is due to the presence of hemoglobin, which is regularly distributed throughout the body.

Breathing and nervous system

The process of breathing in an earthworm is carried out through the skin. Each cell of the outer surface is very sensitive to moisture, which is absorbed and processed. It is for this reason that worms do not live in dry sandy areas, but live where the soil is always filled with water or in the reservoirs themselves. The nervous system of this animal is much more interesting. The main "lump", in which all the neurons are concentrated in large numbers, is located in the anterior segment of the body, however, its analogues, smaller in size, are in each of them. Therefore, each segment of the worm's body can exist autonomously.

reproduction

We note right away that all earthworms are hermaphrodites, and in each organism the testes are located in front of the ovaries. These seals are located in the front of the body, and during the mating period (and they have a cross), the testes of one of the worms pass into the ovaries of the other. During the mating period, the worm secretes mucus, which is necessary for the formation of a cocoon, as well as a protein substance that the embryo will feed on. As a result of these processes, a mucous membrane is formed in which the embryos develop. After they leave her rear end forward and crawl into the ground to continue their race.

Necatoriasis is a helminthic invasion, characteristic of countries with a warm climate. It affects the digestive tract, lungs and circulatory system, causing severe complications in the absence of competent and timely treatment. How does the disease manifest itself, by what methods is it recognized, and is it possible to protect yourself from necatoriasis?

Description of the disease

Today, necatoriasis is common, mainly in Africa, South America and some Asian countries. Helminths for the next period of development need a warm wet soil, so in temperate climate they don't live. And the risk of contracting necatoriasis in Russia is minimal (only in exceptional cases: for example, during a blood transfusion).

Pathogen

Infection with necatoriasis most often occurs through contaminated soil. If a person walks barefoot on it, the larvae can attach to the skin flakes, and then penetrate through the microcracks and reach the circulatory system. You can also become infected by eating unwashed fruits and vegetables.

Symptoms

Symptoms of necatorosis can be divided into groups, depending on which stage life cycle helminth passes. But general state weakness almost always persists.

If a child (under 6 years of age) has contracted necatoriasis, there is a risk of reducing it mental development due to anemia. The kid will become lethargic and irritable, lose interest in learning and games. It is urgent to show the child to the doctor so as not to start the process.

Curious! Necatoriasis has another characteristic symptom inherent in dark-skinned people. Their skin may become pigmented, i.e. lighten up in places.

Diagnostics

Additional research methods (X-ray, fluorography, MRI) are used to diagnose not so much necatorosis as complications that have developed as a result of a long course of invasion.

Treatment

Treatment of necatorosis, as well as other helminthic invasions, is based on the principle of deworming. Those. it is necessary to drive the worms out of the body. This can be done with the help of anthelmintic drugs. To destroy nematodes, use:

• Vermox;
• Naftamon;
• Decaris.

All of these drugs are highly toxic. On the one hand, this is good, because the treatment will last only a few days, and all helminths will die. But on the other hand, it will bring a lot side effects, including vomiting, diarrhea, nervousness and other similar manifestations of necatorosis itself.

Auxiliary treatment is necessary to restore the body. The patient is prescribed Hemofer, Ferronal or other medicines to replenish the level of iron in the blood. Antihistamines are necessary for those who suffer from allergic manifestations of necatoriasis. In some cases, you have to resort to hormone therapy. It is possible to say that necatoriasis has been completely cured only after three “clean” analyzes taken within a month.

Prevention

AT tropical countries prevention is intensified: one should not walk barefoot on the ground and drink water from dubious sources. Better to buy bottled. In order not to become infected with necatoriasis in Russia, you do not need to walk near Wastewater, because the sewage waste may contain the feces of an infected person who has recently arrived from a southern country.

earthworms, they are earthworms , this is far from one species, but a whole suborder of the class Small-bristle worms, belonging to the type Annelids. The earthworm is characterized by most of the structural features of its type and class.

Earthworms are ubiquitous. More than a dozen live in our area. similar friend on another species (European earthworms), whose body length is 10-20 cm, the number of segments is 100-180. At the same time, the Australian earthworm can reach a length of 3 meters.

During the day, earthworms crawl in the soil. At night and after rain they can come to the surface. With the onset of cold weather, they go underground, to a depth of 2 m. The back of the body is slightly flattened. When crawling out of the soil, the worm holds on to the edge of the mink with its hind end.

The body of an earthworm, as a representative of annelids, is divided into segments by annular constrictions. As in all oligochaetes, the parapodia are reduced, only tufts of setae have been preserved from them, which allow the worm to cling, rest against the ground and facilitate pushing the body forward. In other words, the bristles provide adhesion to the substrate.

The surface of the body is moist, covered with mucus, which facilitates movement in the soil, and also facilitates the penetration of oxygen into the body.

The epithelium secretes a layer of transparent cuticle, it also contains many mucous cells. Under the epithelium are circular and longitudinal muscles. The body of an earthworm can contract and lengthen. The circular muscles make the body of the worm thin and long, the longitudinal muscles shorten and thicken. The longitudinal layer of muscles is more powerful. Alternate contraction of these muscles provides locomotion. Each segment can change its shape separately.

The coelomic sacs of neighboring segments communicate with each other, thus, the liquid in them is mixed.

An earthworm often swallows the soil, eating its own way. Nutrient particles are absorbed from the soil in the intestines. If the soil is soft, then it drills with its front end. First, the front end is stretched and thinned, pushed between the lumps of soil. After the front end thickens, as a result, the soil moves apart. Next, the worm pulls up the back of the body.

They feed on decaying plant debris. In addition, fallen leaves can be dragged from the surface. By dragging plant residues into the soil, worms contribute to their decomposition and the formation of fertile soil.

The digestive system consists of the mouth, pharynx, esophagus, goiter, muscular stomach, middle and hindgut, anus. Swallowing food is produced by the muscular pharynx. The stomach grinds food, in addition to the muscles of the walls, swallowed grains of sand participate in this. From the side of the back, the wall of the middle intestine forms an invagination that increases the suction surface. The midgut is lined with ciliated epithelium, in which there are many unicellular glands. It breaks down complex organic substances, and simpler substances are absorbed into the blood. In the walls of the midgut of the earthworm there is a dense network of blood vessels. The hindgut is small, ending in the anus.

A feature of earthworms are calcareous glands, whose ducts empty into the esophagus. Substances released by them neutralize the acids contained in the soil.

Breathing is carried out by the entire surface of the skin. In the superficial layers of the body wall there is a dense network of blood vessels. When it rains, earthworms come to the surface due to lack of air in the soil.

The circulatory, nervous, and excretory systems are similar to polychaete. However, in the circulatory system there are so-called "hearts" - annular vessels capable of muscular contraction. Located in 7-13 segments. A number of species have annular vessels only in the anterior part of the body.

In the anterior three segments, there are no metanephridia (organs of excretion of annelids).

The sense organs are poorly developed. In the skin there are sensitive cells - organs of touch. Also in the skin there are cells that perceive the degree of illumination.

Earthworms are hermaphrodites. reproductive system located in several segments of the anterior part of the body. The testicles are in front of the ovaries.

Fertilization is mutual cross. Each of the mating worms transfers spermatozoa to the partner's seminal receptacle.

In the first third of the body of earthworms there is a special belt, its glandular cells secrete mucus, which, when dried, forms a clutch. Unfertilized eggs are laid in it. After mating, spermatozoa enter here from the spermatozoa. Fertilization takes place. After that, the clutch slips off the body of the worm and turns into a cocoon. The eggs develop into small worms.

Capable of regeneration. If a predator tears off part of the worm's body, then the other half completes the missing part. If the worm is divided into two parts, then two individuals will be obtained, which can be considered asexual reproduction. However, the earthworm itself does not reproduce in this way.

And the suborder of earthworms (Haplotaxida). Its body consists of ring-shaped segments, the number of which can reach 320! These animals are widespread in all corners of our planet. They are not found only in Antarctica. Very often, children are interested in how earthworms move. In our article, we will analyze this issue in detail, and at the same time learn about their appearance, lifestyle and method of reproduction.

Lifestyle of earthworms

If in the morning or after rain you walk through the garden, then, as a rule, you can see small piles of soil thrown out by worms on the ground, and you can see them in the puddles. Due to the fact that these individuals crawl out to the surface of the earth after rain, such a name was assigned to them. (the photo above shows this invertebrate animal) also creeps out to the earth's surface at night. As a rule, it prefers humus-rich soil, so it is rarely found in sandstones. Dislikes earthworm and swampy soils. These features are explained physiological characteristics Lumbricidae. The fact is that worms breathe the entire surface of their body, covered with a mucous epidermis. Too little air is dissolved in moisture-saturated soil. As a result, the earthworm suffocates there. By the way, this explains his behavior during the rain. Dry soil is also detrimental to representatives of Haplotaxida: their skin dries up and breathing stops. In humid and warm weather, earthworms (the photo below shows the Lumbricidae in all their "glory") stay close to the surface of the earth. With a decrease in temperature, as well as with the onset of a dry period, they crawl into the deep layers of the soil.

earthworms

Adults reach 30 centimeters in length, although there are individual specimens of larger sizes. The body of the earthworm is slippery, smooth, has a cylindrical shape, consists of segments - piece rings. Such a constitution is explained by the way of life of Lumbricidae: such a structure facilitates the process of movement in the soil. The number of piece rings reaches two hundred. The surface of the body, which could conditionally be called the back, is convex, the ventral surface is flat and lighter. On the body of an earthworm, where its front part ends, there is a thickening, which is called a girdle. It contains special glands that secrete a sticky liquid. During reproduction, an egg cocoon is formed from the girdle, eggs develop in it.

How do earthworms move?

Representatives of Haplotaxida crawl. First, they stretch the front end of their body and cling to bumps with special bristles, which are located on the ventral side of the rings. earth's surface. After this, muscle contraction occurs, and the back is pulled forward. The movement of the worm in the ground is characterized by the fact that it makes passages in the soil. At the same time, with the pointed end of the body, he pushes the earth apart, and then squeezes between its particles. It is also interesting how earthworms move in denser layers. In the process of movement, they swallow the earth and pass it through the intestines. The worms usually swallow the soil at a considerable depth, and throw it out through the anus already at the top, near their own mink. It can often be observed in the summer on the surface of the earth in the form of lumps and elongated "laces".

Earthworm and its biology

Worms have well-developed muscles, thanks to which such a method of movement became possible. Their muscles are located under the epidermis, in fact, together with the skin, they form a kind of skin-muscle bag. Musculature is located in two layers. Directly under the epidermis are circular muscles, and below them is a second, thicker longitudinal layer (consists of contractile long fibers). When the longitudinal muscles are compressed, the body of the earthworm becomes thicker and shorter. With a contraction of the circular muscles, on the contrary, it is long and thin. Alternate contraction of both layers of muscles, carried out under the influence of the nervous system branching in the muscle tissue, determines the movement of Lumbricidae.

The movement of worms is greatly facilitated by the presence of small bristles on the lower part of the body. They can be felt if you run a wet finger along the abdomen of the worm from the back to the front end. Thanks to these bristles, earthworms not only move in the soil, but also “grab” the ground when they are pulled out. They also help to rise and fall along the already made earthen passages. At this point, we will finish dealing with the question of how earthworms move, and move on to at least interesting facts about the life of the Lumbricidae.

Circulatory system

It consists of two longitudinal vessels - the abdominal and dorsal, as well as the branches connecting them. Due to muscle contraction of the walls, blood moves throughout the body. The blood of earthworms is scarlet. With its help, a connection is established between the internal organs, and metabolism is also carried out. As the blood circulates, it carries nutrients from digestive organs, as well as oxygen from the skin. At the same time, it is excreted from the tissues carbon dioxide. In addition, the blood removes unnecessary and harmful compounds into the excretory organs.

Earthworm nutrition

The basis of nutrition of representatives of Haplotaxida is half-decayed remains of plants. As a rule, at night, earthworms drag leaves, stems, etc. into their holes. In addition, they can pass humus-rich soil through their intestines.

Irritation of earthworms

Special earthworms do not have. They perceive external stimuli due to nervous system. Worms have a highly developed sense of touch. Nerve cells, responsible for this, are located over the entire surface of the skin. The sensitivity of earthworms is so great that the slightest fluctuations in the soil make them hide in burrows or in deeper layers of the earth as quickly as possible. However, the significance of sensitive nerve endings is not limited to the function of touch. Scientists have found that with the help of these cells, earthworms are able to sense the rays of light. So, if a lantern beam is directed at a worm at night, then it high speed hide in a safe place.

The response of animals to any irritation, carried out thanks to the nervous system, is called a reflex. It is customary to distinguish between different kinds of reflexes. Thus, the contraction of the body of an earthworm from touching it, as well as its movement in sudden illumination, is protective function. This is the defensive reflex. Experiments of scientists have shown that earthworms can smell. They use their sense of smell to find food.

reproduction

Earthworms reproduce sexually, although protostomes are generally hermaphrodites. Each representative of Haplotaxida has male organs, which are called testes (they develop spermatozoa), as well as female organs called ovaries (they produce eggs). The earthworm lays its eggs in a slimy cocoon. It is formed from a substance that is released through the girdle. Further, the cocoon in the form of a clutch slides off the body and is pulled together at the ends. It remains in the ground until the young worms come out of it. The cocoon serves to protect the eggs from moisture and other adverse effects.

What are worms for?

This section will be useful for those who think that earthworms are needed only for fishing. Of course, a fisherman without them has nothing to do without them on the river, but this is not the whole benefit of representatives of Lumbricidae. The role of the earthworm in nature is so great that it is impossible to overestimate it. They contribute to the decomposition of organic matter in the soil. In addition, earthworms enrich the earth with the most valuable fertilizer - humus. They are also a kind of indicator: if the soil contains a lot of worms, then it is fertile.

A complete understanding of the role of Haplotaxida has come to mankind relatively recently. However, even now, many farmers prefer to use chemical fertilizers, despite the fact that they kill all living things. Today, chemicals have found an alternative - vermicompost and biohumus. Essentially, this Magic wand for the earth, because they contain a large number of phosphorus, potassium, nitrogen, that is, precisely those substances that are vital for plants for their full growth.

Conclusion

Earthworms are the most important link in soil formation. Let's look at the process. In autumn, leaves fall from the trees and cover the entire surface of the earth. Immediately after that, they get down to business and decompose the leaves to the compost stage. And then the baton is picked up by worms, which process the foliage to the stage of vermicompost. Thus, the most valuable fertilizers get into the soil.

And the cylindrical shape provides an optimal ratio of volume and surface area involved in obtaining oxygen. Given that they move quite a bit, we can say that such breathing through the skin is quite enough for them.

However, worms have a circulatory system, unlike unicellular organisms and some types of insects, hemoglobin is dissolved in the rain, which spreads throughout the body by contracting large vessels when the worm moves. This distributes oxygen throughout the body, helping to maintain diffusion. Large vessels- this is one vein and one artery, that is how many vessels the worm has (except for the capillaries located under the cuticle).

As such, the earthworm, in principle, does not have skin, like in mammals, there is a very thin cover - the cuticle. Such skin is moistened with epithelial secretion, and due to its minimal thickness allows the worm to breathe. However, such skin is not protected from drying out, because the worms must live in some kind of humid environment in order to protect the skin from drying out. Oxygen is pre-dissolved in the water that covers the body of the worm, and only then is absorbed into the blood through the capillaries. If the worm's skin dries out, it cannot receive environment oxygen is destroyed.

Since the earthworm practically does not come to the surface, such a breathing system is extremely beneficial for him - he can take oxygen directly from the soil for gas exchange. Between the particles of the earth there is enough oxygen to provide them with a worm. When it rains, worms crawl out of the ground to the surface, this is due to the fact that the water sticks together the particles of the earth, and there is no air left between them. To get the oxygen they need, the worms must rise to the surface.

To check the breathing of an earthworm, you can conduct a simple experiment: earth is poured into a jar, several worms are placed on top. Through a short time worms will burrow into the ground, but if you pour water on the ground, they will rise to the surface. Everyone breathes the same way. annelids- with the help of the skin, the entire surface of the body.

An earthworm is a representative of the phylum annelids. Its long, elongated case consists of separate segments - rings, separated by annular constrictions, which is the reason for the name of the species. Thanks to this structure, it can move freely both in dense soil and on the soil surface.

Instruction

The body of the earthworm is elongated by 10-16 cm. It is rounded at cross section, but divided longitudinally by annular constrictions into 100-180 segments. Elastic bristles are located on them, with which the worm clings to the unevenness of the soil during movement.

During the day, the worms are in the soil and make moves in it. They easily drill the soft one with the front end of the body: at first it becomes thin, and the worm pushes it forward between the lumps of earth, then, thickening, the front end pushes the soil apart, and the worm pulls up the back of the body. In dense earth, worms can eat their way through the digestive tract. At night, they come to the surface of the soil and leave behind characteristic earthen heaps.

The skin of an earthworm is moist to the touch, because it is covered with a layer that facilitates the movement of the worm in the soil. The oxygen needed for breathing can also only be absorbed through moist skin. Under it is a skin-muscular sac - ring (transverse) muscles fused with the skin, under which lies a layer of longitudinal muscles. The first make the body of the animal long and thin, the second - thickened or shortened. The coordinated alternating work of these muscles ensures the movement of the worm.

Under the skin-muscle sac, you can see the body cavity filled with fluid. In it are located internal organs animal. Unlike roundworms, in rainflies, the body cavity is not continuous, but jointed, divided by transverse walls.