Animals that live in the soil. Soil dwellers

Design and interior 17.07.2019

Design and interior

But there is a world hidden from us, inaccessible to direct observation—a peculiar world of soil animals.

There is eternal darkness, you cannot penetrate there without destroying the natural structure of the soil. And only a few, accidentally noticed signs show that under the surface of the soil, among the roots of plants, there is a rich and diverse world of animals. This is sometimes evidenced by mounds above mole burrows, holes in gopher burrows in the steppe or burrows of sand martins in a cliff above a river, heaps of earth on paths thrown out by earthworms, and they themselves, crawling out after rain, suddenly appearing masses of winged ants literally from under the ground. or fat larvae of May beetles, caught when digging up the earth.

Soil animals find their food either in the soil itself or on its surface. The vital activity of many of them is very useful. Especially useful is the activity of earthworms, which drag a huge amount of plant residues: this contributes to the formation of humus and returns to the soil substances extracted from it by the roots of plants.

Invertebrates in forest soils, especially earthworms, recycle more than half of all leaf litter. During the year, on each hectare, they throw up to 25-30 tons of earth processed by them, turned into good, structural soil, to the surface. If this earth is distributed evenly over the entire surface of a hectare, then a layer of 0.5-0.8 cm will be obtained. Therefore, earthworms are not in vain considered the most important soil formers.

In the soil "work" not only earthworms, but also their closest relatives are smaller whitish annelids (enchytreids, or potworms), as well as some types of microscopic roundworms (nematodes), small mites, various insects, especially their larvae, and, finally, wood lice, centipedes, and even snails.

The purely mechanical work of many animals living in it also affects the soil. They make passages in the soil, mix and loosen it, dig holes. All this increases the number of voids in the soil and facilitates the penetration of air and water into its depths.

Such “work” involves not only relatively small invertebrates, but also many mammals - moles, shrews, marmots, ground squirrels, jerboas, field and forest mice, hamsters, voles, mole rats. The relatively large passages of some of these animals penetrate the soil to a depth of up to 4 m.

The passages of large earthworms go even deeper: in most worms they reach 5-2 m, and in one southern worm even up to 8 m. These passages, especially in denser soils, are constantly used by plant roots that penetrate deep into them.

In some places, for example, in the steppe zone, a large number of passages and holes dig in the soil dung beetles, bears, crickets, tarantula spiders, ants, and in the tropics - termites.

Many soil animals feed on roots, tubers, and bulbs of plants. Those that attack cultivated plants or forest plantations, are considered pests, such as the cockchafer. Its larva lives in the soil for about four years and pupates there. In the first year of life, she feeds mainly on roots. herbaceous plants. But, growing up, the larva begins to feed on the roots of trees, especially young pines, and brings great harm to the forest or forest plantations.

A large number of insects that damage the aerial parts of plants- stems, leaves, flowers, fruits, lays eggs in the soil; here, the larvae hatched from the eggs hide during the drought, hibernate, and pupate. Soil pests include certain types of mites and centipedes, naked slugs, and extremely numerous microscopic roundworms - nematodes. Nematodes penetrate from the soil into the roots of plants and disrupt their normal functioning. Many predators live in the soil. "Peaceful" moles and shrews eat a huge amount of earthworms, snails and insect larvae, they even attack frogs, lizards and mice. They eat almost continuously. For example, a shrew eats an amount of living creatures equal to its own weight per day.

Predators are among almost all groups of invertebrates living in the soil. Large ciliates feed not only on bacteria, but not on simple animals, such as flagellates. The ciliates themselves serve as prey for some roundworms. Predatory mites attack other mites and tiny insects. Thin, long, pale-colored geophile millipedes, living in cracks in the soil, as well as larger dark-colored drupes and centipedes, holding on to their stones, in stumps, in the forest floor, are also predators. They feed on insects and their larvae, worms and other small animals. The predators include spiders and haymakers close to them (“mowing-mowing-leg”). Many of them live on the surface of the soil, in bedding or under objects lying on the ground.

Many predatory insects live in the soil: ground beetles and their larvae, playing a considerable

role in the extermination of insect pests, many ants, especially more large species that consume a large number harmful caterpillars, and finally, the famous ant lions, so named because their larvae prey on ants. The ant lion larva has strong sharp jaws, its length is about cm. The larva digs in dry sandy soil, usually at the edge pine forest, a funnel-shaped hole and burrows into the sand at its bottom, exposing only wide-open jaws. Small insects, most often ants, falling on the edge of the funnel, roll down. The ant lion larva grabs them and sucks them out.

Found in some places in the soil predatory mushroom The mycelium of this fungus, which has a tricky name - didymozoophage, forms special trapping rings. Small soil worms, nematodes, get into them. With the help of special enzymes, the fungus dissolves the rather strong shell of the worm, grows inside its body and eats it clean.

In the process of adapting to the conditions of life in the soil, its inhabitants developed a number of features in the form and structure of the body, in physiological processes, reproduction and development, in the ability to endure adverse conditions and in behavior. Although each species of animal has features that are unique to it, there are common features in the organization of various soil animals that are common to entire groups, since the conditions of life in the soil are basically the same for all its inhabitants.

Earthworms, nematodes, most centipedes, the larvae of many beetles and flies have a highly elongated flexible body that allows them to easily move through winding narrow passages and cracks in the soil. The bristles of earthworms and other annelids, the hairs and claws of arthropods allow them to significantly speed up their movements in the soil and hold firmly in burrows, clinging to the walls of the passages. See how slowly the worm crawls over the surface of the earth and how quickly, in fact, instantly, it hides in its hole. Laying new passages, many soil animals alternately stretch and shorten the body. At the same time, abdominal fluid is periodically pumped into the anterior end of the animal. It swells strongly and pushes the soil particles. Other animals make their way by digging the ground with their front legs, which have become special digging organs.

The color of animals constantly living in the soil is usually pale - grayish, yellowish, whitish. Their eyes, as a rule, are poorly developed or they are not at all, but the organs of smell and touch are very finely developed,

Scientists believe that life originated in the primitive ocean and only much later spread from here to land (see the article “The Origin of Life on Earth”). It is very possible that for some terrestrial animals the soil was a transitional medium from life in water to life on land, since soil is a habitat intermediate in its properties between water and air.

There was a time when only aquatic animals existed on our planet. After many millions of years, when land had already appeared, some of them fell on the berm more often than others. Here, fleeing from drying out, they burrowed into the ground and gradually adapted to permanent life in the primary soil. Millions of years have passed. The descendants of some soil animals, having developed adaptations to protect themselves from drying out, finally got the opportunity to come to the surface of the earth. But they, probably, could not stay here for a long time at first. Yes, willows - they must have walked only at night. Until now, the soil provides shelter not only for “its own”, soil animals that live in it constantly, but also for many that come to it only for a while from a reservoir or from the surface of the earth to lay eggs, pupate, go through a certain stage of development, save yourself from heat or cold.

The soil animal world is very rich. It includes about three hundred species of protozoa, more than a thousand species of round and annelids, tens of thousands of arthropod species, hundreds of mollusks, and a number of vertebrate species.

Among them there are both useful and harmful. But most soil animals are still listed under the heading "indifferent". Perhaps this is the result of our ignorance. Studying them is another task of science.

Soil is a habitat for many organisms. Creatures that live in the soil are called pedobionts. The smallest of them are bacteria, algae, fungi and unicellular organisms that live in soil waters. In one m can live up to 10?? organisms. The soil air is inhabited by invertebrates such as mites, spiders, beetles, springtails and earthworms. They feed on plant remains, mycelium and other organisms. Vertebrate animals live in the soil, one of them is the mole. He is very well adapted to living in completely dark soil, so he is deaf and almost blind.

The heterogeneity of the soil leads to the fact that for organisms of different sizes it acts as a different environment.

For small soil animals, which are united under the name of nanofauna (protozoa, rotifers, tardigrades, nematodes, etc.), the soil is a system of micro-reservoirs.

For air-breathers of slightly larger animals, the soil appears as a system of shallow caves. Such animals are united under the name microfauna. The sizes of representatives of soil microfauna are from tenths to 2-3 mm. This group includes mainly arthropods: numerous groups ticks, primary wingless insects (springtails, proturs, two-tailed insects), small species of winged insects, centipedes symphyla, etc. They do not have special adaptations for digging. They crawl along the walls of soil cavities with the help of limbs or wriggling like a worm. Soil air saturated with water vapor allows you to breathe through the covers. Many species do not have a tracheal system. Such animals are very sensitive to desiccation.

Larger soil animals, with body sizes from 2 to 20 mm, are called representatives of the mesofauna. These are insect larvae, centipedes, enchytreids, earthworms, etc. For them, the soil is a dense medium that provides significant mechanical resistance when moving. These relatively large forms move in the soil either by expanding natural wells by pushing apart soil particles, or by digging new passages.

Soil megafauna or soil macrofauna are large excavations, mostly mammals. A number of species spend their entire lives in the soil (mole rats, mole voles, zokors, Eurasian moles, African golden moles, Australian marsupial moles, etc.). They make whole systems of passages and holes in the soil. Appearance and the anatomical features of these animals reflect their adaptability to a burrowing underground lifestyle.

In addition to the permanent inhabitants of the soil, among large animals, a large ecological group of burrow dwellers (ground squirrels, marmots, jerboas, rabbits, badgers, etc.) can be distinguished. They feed on the surface, but breed, hibernate, rest, and escape danger in the soil. A number of other animals use their burrows, finding in them a favorable microclimate and shelter from enemies. Norniks have structural features characteristic of terrestrial animals, but have a number of adaptations associated with a burrowing lifestyle.

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Posted on http://www.allbest.ru/

Soil dwellers

Any garden, even the smallest, is not only trees, shrubs, creepers, flowers and herbs that we have planted or sown. Whether we like it or not, other tenants will certainly appear in it, settling, as they say, without permission, and guests, very numerous, dropping in for just a few minutes or staying for a long time. In addition, even before the bookmark, it already had its own world, which had developed a long time ago. Crawling, jumping, flying, in a word, living his intense, difficult life, he is extremely rich and diverse. Let's get to know him a little better. And let's start our acquaintance with the inhabitants of the soil.

Soil: breathable and silent.

The soil is not just earth, a mechanical mass, a mixture of small and large particles, mineral and organic, as it is sometimes imagined, no, it is all inhabited, mastered by various organisms that live and develop. Roots of trees, bushes, flowers, herbs penetrate it in all directions and to a considerable depth. Their secretions and residues after decay have a very significant impact not only on the physical and Chemical properties soil aggregates, but also on the biological activity of the soil. They affect it comprehensively: they contribute to the penetration of air into the deeper layers, cause shifts in balance. aqueous solution, contribute to the decomposition of mineral substances, provide the microcosm with organic nutrition.

Much depends on the amount and composition of plant root secretions, since it is they that determine the development of microorganisms in the root zone, as well as the activity of biochemical processes here. The roots themselves serve as food for many inhabitants of the soil - mites and nematodes, fungi that form mycorrhiza grow on them, and bacteria that form nodules develop here.

There are millions of them per gram.

Often on the surface of the soil, especially in shady places, under trees and bushes, it is easy to notice green or even blue-green, like velvet, surfaces or pads. To the touch from below, they are often hard, like crusts, sometimes thin and delicate, like films, otherwise they lie like a felt coating on a wet surface. This phenomenon is called soil bloom. It's called algae. It is clearly visible in the spring, when there is a lot of moisture, the soil is not yet covered with plants, but it is already warm and sunny. Then hundreds of millions of cells of green algae can develop on one square meter, and their biomass in this area reaches 100 grams or more. In summer, they actively grow along the edges of the ridges, between rows, under trees and bushes. They also inhabit tree trunks, cracks and depressions of the bark on them, live on fallen leaves and under them. Their number varies from 5 thousand to 1.5 million in each gram of soil. In soddy-podzolic, for example, their biomass in a layer of 10 centimeters usually ranges from 40 to 300 kilograms per hectare.

Along with other plants, algae form a lot of organic matter, thereby contributing to the accumulation of humus in the soil and increasing its fertility.

carry out photosynthesis and produce oxygen environment and cyanobacteria. Some of them form on the surface of the soil rather large, several centimeters long, dark olive-green mucoid-cartilaginous colonies, consisting of numerous filaments located inside the mucus. Sometimes such colonies almost completely cover the ground. Others form blurry films of a purple hue on it. Most often they can be found in contaminated areas. They have pure green color, do not form any crusts or films, but populate the upper layer of the soil very densely, sometimes giving it a greenish tint.

Countless in the garden and representatives of mushrooms. It is they who are sometimes the cause of many diseases of horticultural crops and often cause considerable damage to the harvest of fruits and berries. The bulk of fungi lives in the soil, where their mycelium (mycelium) often reaches a total length of 1000 meters in one gram. Mushrooms decompose organic matter and synthesize hydrolytic enzymes, which allows them to absorb complex substances such as pectin, cellulose, and even lignin. During the day, they are able to decompose organic substances three to seven times more than they themselves can absorb. And in the soil, their biomass often exceeds the bacterial one.

Marsupials cause such dangerous diseases like powdery mildew and apple or pear scab. On old, dying parts of trees, stumps and roots, tinder fungi and hat mushrooms. Among them, in the garden, champignons are most often found, developing on a manure or humus substrate, as well as honey agarics, grebes and a number of inedible agaric mushrooms.

It is impossible not to name unicellular fungi - different types yeast. They develop well in soil environment at a low temperature close to zero, and almost stop development at 20 degrees Celsius. Many yeast fungi occur on leaves, inside them, in the nectar of flowers, in the apiary of trees, on fruits and berries.

Has its representatives in the garden and such a special group lower plants like lichens. Their body is made up of two different organisms- fungus and algae. Lichen fungi are not found in a free-living state. They grow slowly, especially cortical ones - they grow from 1 to 8 millimeters per year. Most often they can be seen on the bark of trees, especially old ones, or directly on the soil, where they form crusts, bushes. Resistant against direct and bright sunlight and drying out, are able to absorb water directly from the atmosphere, even at low humidity. Lichens secrete complex organic acids, the so-called lichen acids, which have antibiotic properties. Studies have shown that lichens provide a habitat for a variety of yeasts and other fungi, spores and bacteria.

Bacteria are involved in almost all biochemical processes occurring in the soil. They make up the bulk of the microbiological population of the soil - their number reaches hundreds of millions and even billions in one gram - and largely determine its biological activity.

Inhabitants of the dark halls.

Numerous soil animals have a very significant influence on the composition of the soil, its structure and fertility in general. Their number in middle lane it is greatest in the uppermost part of the soil horizon, and at a depth of half a meter or more it decreases sharply. In the steppe and forest-steppe zones, on chernozems, they penetrate twice and three times deeper. If there is a sufficient amount of water in the soil pores, unicellular animals actively develop here - flagellates, ciliates, sarcodes. Their number is large - up to several hundred thousand in one gram of soil, and the biological mass reaches 40 grams per square meter.

Life in the soil, which has the thinnest capillaries, has led to the fact that the simplest animals here are 5-10 times smaller in size than similar creatures living in rivers, lakes, ponds. In some of them, the cells have become flat, the usual outgrowths and spines are absent. Among the rhizopods there are naked and testate amoebae, they do not have a constant body shape, but seem to shimmer - from place to place, flowing around their victims - the plant cells that they feed on - and thus include them in their protoplasm. Infusoria - typical inhabitants of water bodies - are much smaller in the soil than flagellates and amoebas, but scientists still found representatives of 43 genera!

But worms play a particularly important role in the life of the soil, in enriching it with organic matter necessary for plants. They are divided into two groups - lower and higher. The former include rotifers and nematodes - the simplest of multicellular living beings.

Rotifers have circular rows of cilia on the front of their body, thanks to which they rotate and move. Usually they live in ponds, lakes, rivers, but they are also found in the soil - they swim in water capillaries and films. They feed on bacteria and unicellular algae.

From higher worms a significant role in the life of the soil is played by enchitreids, which measure from 3 to 45 millimeters in length, and a thickness of 0.2-0.8 millimeters. The smallest move in the soil along its natural pores and channels, others make their way, eating through it. Biomass enchitreid on good garden plots often reaches 5 grams per square meter. Most of them are in the upper soil layer, since their main food is dying roots. Sometimes they gnaw out their parts damaged by nematodes. They are also abundant where there is moist humus. In this they differ from earthworms, of which there are also about 200 species.

Snails. Lives in the garden and another group of animals - snails. Although they, like other mollusks, for the most part are typical inhabitants of water bodies, the so-called lung snails have also adapted to a terrestrial lifestyle. Due to the presence of a shell, they relatively easily tolerate adverse conditions - cold, drought, heat, and slugs that do not have a shell hide under mulch, leaf litter or climb deeper into the soil in heat and cold. Among lung snails there are herbivores and predators, some cause significant damage to plants, such as grape snails.

Slugs feed on freshly fallen leaves, grass, dying tissues, but can also damage living plants. The so-called field slug damages the seedlings of vegetable, horticultural, field and forest crops. Some feed on algae, lichens, mushrooms, that is, they act as orderlies and are harmless to the garden.

There are still many tiny creatures in the soil that influence the life of fruit and berry crops. Some of them are visible to the naked eye and are called tardigrades, or bear cubs. Their body is short, in a kind of shell (cuticle). four couples short legs like muscular tubercles with claws. In the mouth, a stylet is a kind of knife with which they pierce plant tissues and suck out the contents of living cells. In the soil with leaf litter, there are many springtails and shell mites, wood lice, centipedes, and insect larvae. Woodlice, like earthworms, make small passages in the soil, improve its porosity, aeration, and process primary plant material into humus. Millipedes are terrestrial animals but lead a secretive life, hiding in soil burrows, under mulch or leaves. Among them there are very small ones, 1.5-2 millimeters, and quite large ones - 10-15 centimeters, for example, geophiles. The body of centipedes consists of many segments, each of which has two limbs. These include very frequent kivsyaki in the garden.

Insect larvae. The soil of the garden is also densely populated by various representatives of a countless family of insects. Many always, and others only at a certain stage, live in the soil, for example, the larvae of the ground beetle, the click beetle, the beetle, the May beetle, and the dung beetle. Some larvae behave like earthworms, others damage healthy plant roots and cause significant damage to them, especially when mass reproduction. So, for pupation in the soil, more than a hundred caterpillars of the meadow moth leave on each square meter. Wireworms have a noticeable effect on the state of some garden and garden crops - long, yellowish, hard-to-touch larvae of click beetles, legless weevil larvae. The larvae of some butterflies and sawfly beetles also live in the soil. photosynthesis cyanobacteria soil

Medvedka. Well adapted to permanent life in the soil, especially in the structural, highly humus, chernozem, and such an insect as the bear. It is able to quickly make fairly wide, long passages at the very surface of the soil and cause considerable damage to crops, especially in areas with loose, humus and fairly moist soil. She and her larvae feed on the roots and stems of plants: they eat out tubers, corms, root crops and seeds. Strawberries, strawberries, vegetable crops suffer the most from them.

Adult insects and their larvae overwinter in the soil. They wake up in the spring as soon as it warms up. Places inhabited by a bear are easy to detect by winding rolls of loose earth and holes that go to the surface of the soil, as well as damaged plants. Usually in May, bears make in the ground at a depth of up to 15 centimeters a cave-nest the size of egg and lay 300-350 eggs in them, from which larvae (nymphs) soon appear, living in the soil for more than a year. And the entire period of development of the bear from an egg to an adult insect lasts about two years. They destroy the bear with the help of poisoned baits or mechanically. The activity of such widespread insects as ants is great, but since their role in the garden is very diverse, we will talk about them separately, as well as about earthworms, frogs, birds, bees, and here we will briefly touch only on the main ones after earthworms - rodents and moles.

Hosted on Allbest.ru

...

Similar Documents

Sanitary-indicative microorganisms for the soil. requirements for tap water. The microflora of the oral cavity of an adult. Sanitary and hygienic condition of the air. Microorganisms of the perineum. Chemical factors acting on bacteria.

test, added 03/17/2017

The history of the discovery of photosynthesis - the conversion of carbon dioxide and water into carbohydrates and oxygen under the influence of the energy of sunlight. Description of the ability of chlorophyll to absorb and transform solar energy. Light and dark phases of photosynthesis.

presentation, added 03/18/2012

Characterization of soil as a source of transmission of pathogens of infectious diseases. Study of the quantitative and species composition of soil microorganisms. Sanitary assessment of soil by microbiological indicators. Pollution and self-purification of soils.

presentation, added 03/16/2015

Characterization of ants as social insects. Characteristics of red forest ants. An anthill as a very complex architectural structure. The value of ants in nature and human life. Order Hymenoptera - soil formers and forest nurses.

presentation, added 05/23/2010

Analysis of the possibility of using tardigrades as bioindicators of the degree of environmental disturbance, in particular, air pollution. Conditions for the existence of tardigrades. Influence of the degree of environmental disturbance on the communities of tardigrade epiphytic mosses and lichens in Moscow.

thesis, added 01/27/2018

Sampling procedure and research methods. Determination of the viability of eggs or larvae of various helminths by appearance: human roundworm, whipworm, hookhead, intestinal acne. Evaluation and interpretation of the obtained results.

test, added 04/06/2019

The history of the discovery of photosynthesis. The formation of substances in the leaves of plants, the release of oxygen and the absorption of carbon dioxide in the light and in the presence of water. The role of chloroplasts in the formation of organic substances. The importance of photosynthesis in nature and human life.

presentation, added 10/23/2010

The essence of the process of photosynthesis is the process of converting carbon dioxide and water into carbohydrates and oxygen under the influence of sunlight energy. The green pigment is chlorophyll, and the plant organs containing it are chloroplasts. Light and dark phases of photosynthesis.

presentation, added 03/30/2011

History of development and study of soil bioindication. The structure of the animal population of the soil and factors of its diversity. Place of invertebrates in soil formation. Influence of technogenic pollution and other external factors on soil invertebrates.

abstract, added 11/14/2010

The number and ecological groups of roundworms (nematodes), which, after protozoa, are the richest group of soil animals in terms of abundance and species diversity. Successions, spatial distribution. Soil biological role.

All around us: on the ground, in the grass, on the trees, in the air - life is in full swing everywhere. Even a resident of a big city who has never delved into the forest often sees around him birds, dragonflies, butterflies, flies, spiders and many other animals. Well known to all and the inhabitants of the reservoirs. Everyone, at least occasionally, had to see schools of fish near the shore, water beetles or snails.
But there is a world hidden from us, inaccessible to direct observation, a peculiar world of soil animals.
There is eternal darkness, you cannot penetrate there without destroying the natural structure of the soil. And only a few, accidentally noticed signs show that under the surface of the soil among the roots of plants there is a rich and diverse world of animals. This is sometimes evidenced by mounds above mole burrows, holes in gopher burrows in the steppe or burrows of sand martins in a cliff above a river, heaps of earth on a path thrown out by earthworms, and they themselves, crawling out after rain, as well as masses suddenly appearing literally from under the ground. winged ants or fat larvae of May beetles that come across when digging up the earth.
Soil is usually called the surface layer earth's crust on land, formed during the weathering of the parent rock under the influence of water, wind, temperature fluctuations and the activities of plants, animals and humans. The most important property of the soil, which distinguishes it from the barren parent rock, is fertility, that is, the ability to produce a crop of plants.

As a habitat for animals, soil is very different from water and air. Try to wave your hand in the air - you will not notice almost any resistance. Do the same in water - you will feel a significant resistance of the environment. And if you lower your hand into the hole and cover it with earth, then it will be difficult to pull it back out. It is clear that animals can move relatively quickly in the soil only in natural voids, cracks, or previously dug passages. If there is nothing of this on the way, then the animal can advance only by breaking through the passage and raking the earth back or by swallowing the earth and passing it through the intestines. The speed of movement in this case, of course, will be insignificant.
Every animal needs to breathe in order to live. Conditions for respiration in soil are different than in water or air. Soil is composed of solid particles, water and air. Solid particles in the form of small lumps occupy a little more than half of its volume; the rest is accounted for by gaps - pores that can be filled with air (in dry soil) or water (in soil saturated with moisture). As a rule, water covers all soil particles with a thin film; the rest of the space between them is occupied by air saturated with water vapor.
Due to this structure of the soil, numerous animals live in it and breathe through the skin. If they are taken out of the ground, they quickly die from drying out. Moreover, hundreds of species of real freshwater animals inhabiting rivers, ponds and swamps live in the soil. True, these are all microscopic creatures - lower worms and unicellular protozoa. They move, float in a film of water covering soil particles. If the soil dries out, these animals secrete protective shell and how they fall asleep.

Soil air receives oxygen from the atmosphere: its amount in the soil is 1-2% less than in atmospheric air. Oxygen is consumed in the soil by animals, microorganisms, and plant roots. They all emit carbon dioxide. In the soil air it is 10-15 times more than in the atmosphere. Free gas exchange of soil and atmospheric air occurs only if the pores between solid particles are not completely filled with water. After heavy rains or in the spring, after the snow melts, the soil is saturated with water. There is not enough air in the soil, and under the threat of death, many animals leave it. This explains the appearance earthworms on the surface after heavy rains.
Among soil animals there are both predators and those that feed on parts of living plants, mainly roots. There are also consumers of decaying plant and animal remains in the soil - perhaps bacteria also play a significant role in their nutrition.
Soil animals find their food either in the soil itself or on its surface.
The vital activity of many of them is very useful. The activity of earthworms is especially useful. They drag a huge amount of plant debris into their burrows, which contributes to the formation of humus and returns to the soil substances extracted from it by plant roots.
In forest soils, invertebrates, especially earthworms, recycle more than half of all leaf litter. For a year, on each hectare, they throw up to 25-30 tons of earth processed by them, turned into a good, structural soil, to the surface. If you distribute this land evenly over the entire surface of a hectare, you get a layer of 0.5-0.8 cm. Therefore, earthworms are not in vain considered the most important soil formers. Not only earthworms “work” in the soil, but also their closest relatives - smaller whitish annelids (enchytreids, or potworms), as well as some types of microscopic roundworms (nematodes), small mites, various insects, especially their larvae, and finally woodlice, centipedes and even snails.

Medvedka

The purely mechanical work of many animals living in it also affects the soil. They make passages, mix and loosen the soil, dig holes. All this increases the number of voids in the soil and facilitates the penetration of air and water into its depth.
Such “work” involves not only relatively small invertebrates, but also many mammals - moles, shrews, marmots, ground squirrels, jerboas, field and forest mice, hamsters, voles, mole rats. Relatively large passages of some of these animals go deep from 1 to 4 m.
The passages of large earthworms go even deeper: in most of them they reach 1.5-2 m, and in one southern worm even 8 m. These passages, especially in denser soils, are constantly used by plant roots penetrating into the depths. In some places, for example in steppe zone, a large number of moves and holes are dug in the soil by dung beetles, bears, crickets, tarantula spiders, ants, and termites in the tropics.
Many soil animals feed on roots, tubers, and bulbs of plants. Those that attack cultivated plants or forest plantations are considered pests, such as the cockchafer. Its larva lives in the soil for about four years and pupates there. In the first year of life, it feeds mainly on the roots of herbaceous plants. But, growing up, the larva begins to feed on the roots of trees, especially young pines, and brings great harm to the forest or forest plantations.

The paws of the mole are well adapted to life in the soil.

Larvae of click beetles, dark beetles, weevils, pollen eaters, caterpillars of some butterflies, such as nibbling scoops, larvae of many flies, cicadas, and, finally, root aphids, such as phylloxera, also feed on the roots of various plants, severely damaging them.
A large number of insects that damage the aerial parts of plants - stems, leaves, flowers, fruits, lay eggs in the soil; here, the larvae hatched from the eggs hide during the drought, hibernate, and pupate. Soil pests include some types of mites and centipedes, naked slugs and extremely numerous microscopic roundworms - nematodes. Nematodes penetrate from the soil into the roots of plants and disrupt their normal life. Many predators live in the soil. "Peaceful" moles and shrews eat a huge amount of earthworms, snails and insect larvae, they even attack frogs, lizards and mice. These animals eat almost continuously. For example, a shrew eats an amount of living creatures equal to its own weight per day!
There are predators among almost all groups of invertebrates living in the soil. Large ciliates feed not only on bacteria, but also on simple animals, such as flagellates. The ciliates themselves serve as prey for some roundworms. Predatory mites attack other mites and tiny insects. Thin, long, pale-colored geophile centipedes, living in cracks in the soil, as well as larger dark-colored drupes and centipedes, keeping under stones, in stumps, are also predators. They feed on insects and their larvae, worms and other small animals. The predators include spiders and haymakers close to them (“mow-mow-leg”). Many of them live on the surface of the soil, in bedding or under objects lying on the ground.

Antlion larva.

But there is a world hidden from us, inaccessible to direct observation - a kind of world of soil animals.

Soil is usually called the surface layer of the earth's crust on land, formed in the process of weathering of the original parent rock under the influence of water, wind, temperature fluctuations and the activities of plants, animals and humans. The most important property of the soil, which distinguishes it from the barren parent rock, is fertility, that is, the ability to produce crops (see Art. "").

Burrowing animals and their passages in the soil: 1 - toad; 2 - cricket; 3- harvest mouse; 4 bears; 5 - shrew; 6 - mole.

Every animal needs to breathe in order to live. Conditions for respiration in soil are different than in water or air. Soil is composed of solid particles, water and air. Solid particles in the form of small lumps occupy a little more than half of its volume; the rest is accounted for by gaps - pores that can be filled with air (in dry soil) or water (in soil saturated with moisture). As a rule, water covers all soil particles with a thin film; the rest of the space between them is occupied by air saturated with water vapor.

Due to this structure of the soil, numerous animals can live in it, breathing through the skin. If they are taken out of the ground, they quickly die from drying out. Moreover, hundreds of species of real freshwater animals live in the soil - the very ones that inhabit rivers, ponds and swamps. True, these are all microscopic creatures - lower worms and unicellular protozoa. They move, float in a film of water covering soil particles.

If the soil dries out, they release a protective shell and cease to be active for a long time.

Among soil animals there are predators and those that feed on parts of living plants, mainly roots. There are also consumers of decomposing plant and animal remains in the soil - perhaps bacteria also play an important role in their nutrition.

Soil animals find their food either in the soil itself or on its surface. The vital activity of many of them is very useful. Especially useful is the activity of earthworms, which drag a huge amount of plant debris into their holes: this contributes to the formation of humus and returns to the soil substances extracted from it by plant roots.

In forest soils, invertebrates, especially earthworms, recycle more than half of all leaf litter. For a year, on each hectare, they throw up to 25-30 tons of earth processed by them, turned into a good, structural soil, to the surface. If you distribute this land evenly over the entire surface of a hectare, you get a layer of 0.5-0.8 cm. Therefore, earthworms are not in vain considered the most important soil formers.

Not only earthworms “work” in the soil, but also their closest relatives - smaller whitish annelids (enchytreids, or potworms), as well as some types of microscopic roundworms (nematodes), small mites, various insects, especially their larvae, and finally woodlice, centipedes and even snails.

The passages of large earthworms go even deeper: in most worms they reach 1.5-2 m, and in one southern worm even up to 8 m. These passages, especially in denser soils, are constantly used by plant roots that penetrate deep into them.

In some places, for example, in the steppe zone, a large number of passages and holes are dug in the soil by dung beetles, bears, crickets, tarantula spiders, ants, and in the tropics - termites.

Many soil animals feed on roots, tubers, and bulbs of plants. Those that attack cultivated plants or forest plantations are considered pests, such as the cockchafer. Its larva lives in the soil for about four years and pupates there. In the first year of life, it feeds mainly on the roots of herbaceous plants. But, growing up, the larva begins to feed on the roots of trees, especially young pines, and brings great harm to the forest or forest plantations.

A large number of insects that damage the aerial parts of plants - stems, leaves, flowers, fruits - lay eggs in the soil; here, the larvae hatched from the eggs hide during the drought, hibernate, and pupate.

Soil pests include some types of mites and centipedes, naked slugs and extremely numerous microscopic roundworms - nematodes. Nematodes penetrate from the soil into the roots of plants and disrupt their normal life.

Many predators live in the soil. "Peaceful" moles and shrews eat a huge amount of earthworms, snails and insect larvae, they even attack frogs, lizards and mice. They eat almost continuously. For example, a shrew eats an amount of living creatures equal to its own weight per day!

Predators are among almost all groups of invertebrates living in the soil. Large ciliates feed not only on bacteria, but also on simple animals, such as flagellates. The ciliates themselves serve as prey for some roundworms. Predatory mites attack other mites and tiny insects. Thin, long, pale-colored geophile centipedes, living in cracks in the soil, as well as larger dark-colored drupes and centipedes, keeping under stones, in stumps, in the forest floor, are also predators. They feed on insects and their larvae, worms and other small animals. The predators include spiders and haymakers close to them (“mow-mow-leg”). Many of them live on the surface of the soil, in bedding or under objects lying on the ground.

Many predatory insects live in the soil: ground beetles and their larvae, which play a significant role in the extermination of pests, many ants, especially larger species, which exterminate a large number of harmful caterpillars, and, finally, the famous ant lions, so named because their larvae prey on ants. The ant lion larva has strong sharp jaws, its length is about 1 cm. The larva digs a funnel-shaped hole in dry sandy soil, usually at the edge of a pine forest, and burrows into the sand at its bottom, exposing only wide-open jaws. Small insects, most often ants, falling on the edge of the funnel, roll down. The ant lion larva grabs them and sucks them out.

In some places, a predatory ... mushroom is found in the soil! The mycelium of this fungus, which has a tricky name - didymozoophage, forms special trapping rings. Small soil worms - nematodes get into them. With the help of special enzymes, the fungus dissolves the rather strong shell of the worm, grows inside its body and eats it clean.

Earthworms, nematodes, most centipedes, the larvae of many beetles and flies have a highly elongated flexible body that allows them to easily move through winding narrow passages and cracks in the soil. The bristles of earthworms and other annelids, the hairs and claws of arthropods allow them to significantly speed up their movements in the soil and hold firmly in burrows, clinging to the walls of the passages. See how slowly the worm crawls over the surface of the earth and how quickly, in fact, instantly, it hides in its hole. Laying new passages, many soil animals alternately stretch and shorten the body. At the same time, abdominal fluid is periodically pumped into the anterior end of the animal. He. strongly swells and pushes soil particles. Other animals make their way by digging the ground with their front legs, which have become special digging organs.

Scientists believe that life originated in the primitive ocean and only much later spread from here to land (see Art. ""). It is very possible that for some terrestrial animals the soil was a transitional medium from life in water to life on land, since the soil is a Habitat intermediate in its properties between water and air.

There was a time when only aquatic animals existed on our planet. After many millions of years, when land had already appeared, some of them hit the shore more often than others. Here, fleeing from drying out, they burrowed into the ground and gradually adapted to permanent life in the primary soil. Millions of years have passed. The descendants of some soil animals, having developed adaptations to protect themselves from drying out, finally got the opportunity to come to the surface of the earth. But they, probably, could not stay here for a long time at first. And they must have come out only at night. Until now, the soil provides shelter not only for “its own”, soil animals that live in it all the time, but also for many that come to it only for a while from water bodies or from the surface of the earth to lay eggs, pupate, go through a certain stage of development. , escape from heat or cold.

The soil animal world is very rich. It includes about three hundred species of protozoa, more than a thousand species of round and annelid worms, tens of thousands of arthropod species, hundreds of molluscs and a number of vertebrate species.