Examples of soil organisms. Soil is a living organism

T.V. Lukarevskaya

When we enter the forest on a summer day, we immediately notice fluttering butterflies, singing birds, jumping frogs, we rejoice at a running hedgehog, a meeting with a hare. One gets the impression that it is these well-marked animals that form the basis of our fauna. In fact, the animals that are easy to see in the forest are only an insignificant part of it.

Soil animals form the basis of the population of our forests, meadows, and fields. The soil, at first glance so lifeless and unsightly, turns out to be literally crammed with life upon closer examination. If you look closely, unusual pictures will open.

Some of the inhabitants of the soil are easy to see. This - earthworms, centipedes, insect larvae, small mites, wingless insects. Others can be seen with a microscope. In the thinnest films of water that envelop soil particles, rotifers, flagellates scurry about, amoebas crawl, roundworms writhe. How many real workers are here, indistinguishable to the naked eye, but doing, nevertheless, a titanic work! All these inconspicuous beings keep our common Home- Earth. Moreover, they also warn of the danger that threatens this house when people behave unwisely in relation to nature.

In the soil of central Russia, per 1 m2, you can find up to 1 thousand species of soil inhabitants that differ greatly in number: up to 1 million ticks and springtails, hundreds of centipedes, insect larvae, earthworms, about 50 million roundworms, while the number of protozoa is even difficult to estimate .

This whole world, living according to its own laws, ensures the processing of dead plant residues, the cleaning of soils from them, and the maintenance of a water-resistant structure. Soil animals constantly plow the soil, moving up particles from the lower layers.

In all terrestrial ecosystems, the vast majority of invertebrates (both in terms of the number of species and the number of individuals) are soil dwellers or are closely associated with the soil at a certain period of their life cycle. Boucle (1923) calculated that the number of insect species associated with the soil is 95–98%.

In terms of the ability to adapt to living conditions, there are no equal nematodes among animals. In this respect, they can only be compared with bacteria and the simplest unicellular organisms. Such universal adaptability is largely due to the development of a dense outer cuticle in nematodes, which increases their vitality. In addition, the shape of the body and the nature of the movements of nematodes turned out to be suitable for life in various environments.

Nematodes take part in the mechanical destruction of plant tissues: they “burrow” into dead tissues and, with the help of secreted enzymes, destroy cell walls, opening up pathways for bacteria and fungi to penetrate.

In our country, yield losses of vegetables, cereals and industrial crops due to damage by roundworms sometimes reach 70%.

Nematode

The formation of tumors - galls - on the roots of the host plant is caused by another pest - the southern root-knot nematode (Meloidogyne incognita). It brings the greatest harm to vegetable growing in the southern regions, where it is found in open field. In the north, it occurs only in greenhouses, mainly damaging cucumbers and tomatoes. The main harm is caused by females, while males, having completed development, go into the soil and do not feed.

Soil nematodes are notorious: they are seen primarily as pests of cultivated plants. Nematodes destroy the roots of potatoes, onions, rice, cotton, sugar cane, sugar beet, ornamental and other plants. Zoologists are developing measures to combat them in the fields and in greenhouses. A great contribution to the study of this group of animals was made by the famous evolutionary biologist A.A. Paramonov.

Nematodes have long attracted the attention of evolutionists. They are not only extremely versatile, but also amazingly resistant to physical and chemical influences. Wherever they begin to study these worms, new species unknown to science are found everywhere. In this regard, nematodes seriously claim the second - after insects - place in the animal world: experts believe that there are at least 500 thousand species of them, but there is reason to believe that the true number of nematode species is much higher.

I immediately remembered how I help my grandmother in hunting for a mole. :) How he tortured us then, and only by putting the hose into his hole, we managed to get rid of the intruder. In general, despite the benefits of this animal for the soil, it turned out to be not so useful for our crop.

Soil dwellers

This world is practically hidden from us, but this does not mean that life is impossible there. On the contrary, there exists a peculiar world inhabited by a mass of animals. The essential difference lies in the soil itself as a habitat, which is significantly different from air or water. Some are easy enough to see, and some are barely visible through a microscope! So, the soil is inhabited by the following living beings:

• invertebrates;
• microorganisms;
• mushrooms;
• insects;
• vertebrate animals.

The role of animals in soil fertility

With regard to the contribution to soil formation, and hence the increase in fertility, the following types of living organisms can be conditionally distinguished based on the function:

• processing - take part in decomposition, while synthesizing new compounds;
• mixing - this group distributes the processed substance throughout the layer;
• loosening - moving in the thickness, they contribute to the access of air and water.

When organic residues enter the soil, chlorophyll-free organisms are the first to “work”, which modify substances, making them available for absorption by plants. By the way, the soil has the highest concentration of microorganisms in the world: only 1 gram of forest soil contains over 15 million unicellular organisms. Insects make a lot of moves, thereby significantly increasing ventilation, a number physical properties and water supply. In addition, they process a significant part of plant waste.

As for invertebrates, earthworms, which contribute to the speedy biological cycle, should be highlighted here. Vertebrates are mainly represented by rodents. Thus, not only animals cannot exist outside the soil, but its formation without them is actually impossible, because by destroying and transforming organic substances they not only increase the thickness of the layer, but also increase its fertility.

The heterogeneity of the soil leads to the fact that for organisms of different sizes it acts as different environment. For microorganisms, the huge total surface of soil particles is of particular importance, since the vast majority of the microbial population is adsorbed on them. The complexity of the soil environment creates a wide variety of conditions for a variety of functional groups: aerobes and anaerobes, consumers of organic and mineral compounds. The distribution of microorganisms in the soil is characterized by small foci, since even over a few millimeters different ecological zones can be replaced.

For small soil animals (Fig. 52, 53), which are combined under the name microfauna (protozoa, rotifers, tardigrades, nematodes, etc.), the soil is a system of micro-reservoirs. Essentially, they are aquatic organisms. They live in soil pores filled with gravitational or capillary water, and part of life can, like microorganisms, be in an adsorbed state on the surface of particles in thin layers of film moisture. Many of these species live in ordinary water bodies. However, soil forms are much smaller than freshwater ones and, in addition, they are distinguished by their ability to stay in an encysted state for a long time, waiting out unfavorable periods. While freshwater amoebas are 50-100 microns in size, soil ones are only 10-15. Representatives of flagellates are especially small, often only 2-5 microns. Soil ciliates also have dwarf sizes and, moreover, can greatly change the shape of the body.

Rice. 52. Testate amoeba feeding on bacteria on decaying forest floor leaves

Rice. 53. Soil microfauna (according to W. Dunger, 1974):

1-4 - flagella; 5-8 - naked amoeba; 9‑10 - testate amoeba; 11-13 - ciliates; 14-16 - roundworms; 17-18 - rotifers; 19-20 - tardigrades

For air-breathers of slightly larger animals, the soil appears as a system of shallow caves. Such animals are grouped under the name mesofauna (Fig. 54). The sizes of representatives of the soil mesofauna range from tenths to 2-3 mm. This group includes mainly arthropods: numerous groups of ticks, primary wingless insects (springtails, proturs, two-tailed insects), small species 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. The main means of salvation from fluctuations in air humidity for them is movement inland. But the possibility of migration deep into the soil cavities is limited by the rapid decrease in the diameter of the pores, so only the smallest species can move through the soil wells. More major representatives mesofauna have some adaptations that allow them to endure a temporary decrease in soil air humidity: protective scales on the body, partial impermeability of the integument, a solid thick-walled shell with an epicuticle in combination with a primitive tracheal system that provides breathing.

Rice. 54. Soil mesofauna (no W. Danger, 1974):

1 - false scorion; 2 - Gama new flare; 3-4 shell mites; 5 - centipede pauroioda; 6 - chironomid mosquito larva; 7 - a beetle from the family. Ptiliidae; 8-9 springtails

Representatives of the mesofauna experience periods of flooding of the soil with water in air bubbles. The air is retained around the body of animals due to their non-wetting integuments, which are also equipped with hairs, scales, etc. The air bubble serves as a kind of "physical gill" for a small animal. Breathing is carried out due to oxygen diffusing into the air layer from the surrounding water.

Representatives of micro- and mesofauna are able to tolerate winter freezing of the soil, since most species cannot go down from layers exposed to negative temperatures.

Larger soil animals, with body sizes from 2 to 20 mm, are called representatives macro fauna (Fig. 55). 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. Both modes of movement leave an imprint on external structure animals.

Rice. 55. Soil macrofauna (no W. Danger, 1974):

1 - earthworm; 2 - woodlice; 3 - labiopod centipede; 4 - bipedal centipede; 5 - ground beetle larva; 6 - click beetle larva; 7 - bear; 8 - grub grub

The ability to move along thin wells, almost without resorting to digging, is inherent only in species that have a body with a small cross section that can bend strongly in winding passages (millipedes - drupes and geophiles). Pushing soil particles apart due to the pressure of the body walls, earthworms, larvae of centipede mosquitoes, etc. move. Having fixed the posterior end, they thin and lengthen the anterior one, penetrating into narrow soil cracks, then fix the anterior part of the body and increase its diameter. At the same time, strong hydraulic pressure of the incompressible intracavitary fluid is created in the expanded area due to the work of the muscles: in worms, the contents of coelomic sacs, and in tipulid, hemolymph. The pressure is transmitted through the walls of the body to the soil, and thus the animal expands the well. At the same time, an open passage remains behind, which threatens to increase evaporation and the pursuit of predators. Many species have developed adaptations to an ecologically more beneficial type of movement in the soil - digging with clogging the passage behind them. Digging is carried out by loosening and raking soil particles. For this, the larvae of various insects use the anterior end of the head, mandibles and forelimbs, expanded and reinforced with a thick layer of chitin, spines and outgrowths. At the posterior end of the body, devices for strong fixation develop - retractable supports, teeth, hooks. To close the passage on the last segments, a number of species have a special depressed platform, framed by chitinous sides or teeth, a kind of wheelbarrow. Similar platforms are also formed on the back of the elytra in bark beetles, which also use them to clog passages with drill flour. Closing the passage behind them, the animals - the inhabitants of the soil are constantly in a closed chamber, saturated with the evaporation of their own body.

Gas exchange of most species of this ecological group is carried out with the help of specialized respiratory organs, but along with this, it is supplemented by gas exchange through the integuments. It is even possible exclusively skin respiration, for example, in earthworms, enchitreid.

Burrowing animals can leave layers where unfavorable conditions arise. In drought and winter, they concentrate in deeper layers, usually a few tens of centimeters from the surface.

Megafauna soils are large excavations, mainly from among mammals. A number of species spend their whole lives in the soil (mole rats, mole voles, zokors, moles of Eurasia, golden moles

Africa, marsupial moles of Australia, etc.). They make whole systems of passages and holes in the soil. The appearance and anatomical features of these animals reflect their adaptability to a burrowing underground lifestyle. They have underdeveloped eyes, a compact, valky body with a short neck, short thick fur, strong digging limbs with strong claws. Mole rats and mole voles loosen the ground with their chisels. Large oligochaetes, especially representatives of the Megascolecidae family living in the tropics and the Southern Hemisphere, should also be included in the soil megafauna. The largest of them, the Australian Megascolides australis, reaches a length of 2.5 and even 3 m.

In addition to the permanent inhabitants of the soil, among large animals, one can distinguish a large environmental group burrow dwellers (ground squirrels, marmots, jerboas, rabbits, badgers, etc.). 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. For example, badgers have long claws and strong muscles on the forelimbs, a narrow head, and small auricles. Compared to non-burrowing hares, rabbits have noticeably shortened ears and hind legs, a stronger skull, stronger bones and muscles of the forearms, etc.

For a number of ecological features, the soil is an intermediate medium between water and land. WITH aquatic environment the soil is brought closer by its temperature regime, the reduced oxygen content in the soil air, its saturation with water vapor and the presence of water in other forms, the presence of salts and organic matter in soil solutions, the ability to move in three dimensions.

The soil is brought closer to the air environment by the presence of soil air, the threat of desiccation in the upper horizons, rather sharp changes temperature regime surface layers.

The intermediate ecological properties of the soil as a habitat for animals suggest that the soil played a special role in the evolution of the animal world. For many groups, in particular arthropods, the soil served as a medium through which the originally aquatic inhabitants could switch to a terrestrial way of life and conquer the land. This path of evolution of arthropods was proved by the works of M. S. Gilyarov (1912-1985).

Who lives in the soil? In this article you will learn what animals live in the soil.

What animals live in the soil?

All animals need 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 the volume of the soil; the rest of the volume is accounted for by the pore spaces, which can be filled with air (in dry soil) or water (in soil saturated with moisture).

Animals that live in the soil:

Earthworm

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

Medvedka

Not only earthworms live in the soil, but also their closest relatives are small whitish annelids(enchitreid, 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.

Mole

Its front paws are well adapted for digging.

shrews

These are small animals that look like mice, but with a muzzle elongated in the form of a proboscis. The body length is 3-4 cm. The head of shrews is quite large, with an elongated facial region. The nose is transformed into a mobile proboscis. The eyes are very small. The fur is short, thick, velvety. The tail is very short to very long, sometimes even longer than the body.

mole rats

The body length is 20-35 cm, the tail is very short, the eyes are undeveloped, hidden under the skin: only traces of eyelid growth in a continuous fold are visible from the outside. Slepak's lifestyle is underground: he digs branched systems of underground galleries, which serve as his habitat. It feeds on bulbs and plant roots. Blind people are distributed mainly in the forest-steppe and steppe.

mouse rodents arrange paths, burrows, whole tunnels in the soil, where they not only live, but also go to the "toilet". In these places, the soil is enriched with nitrogen. In addition, mice contribute to the rapid grinding of the litter, mixing of soil and plant residues.

Also, many predatory insects live in the soil. This beetles and their larvae, which play a large role in the extermination of pests, many ants that exterminate a large number of harmful caterpillars, and, finally, the famous antlions, 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. Adult antlions outwardly resemble dragonflies, their body length reaches 5 cm, and the wingspan is 12 cm.

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 develops 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 plantation.

We hope that the information in the article “What animals live in the soil?” became useful to you, was useful and interesting.

Long arthropods often come across in the ground, which move on many legs. In most cases, they are harmless to plants.

Centipedes scare everyone with their formidable appearance. However, they rarely eat plants, and even then mainly indoors. Basically, they hunt their relatives - insects.

Thin - evil

If, digging the beds, you see a long larva swarming in the soil, similar to a worm, but with a rigid body, you should know that this is one of the dangerous pests.

Wireworm (larva of the click beetle). Yellow (brown or dark brown) creatures up to 15-17 mm long, living in the soil to a depth of 10-12 cm. Wireworms got their name due to the fact that their bodies are extremely hard and rigid.

Wireworm. Photo: Nina Belyavskaya

The larvae feed on plant roots, seeds, seedlings, shoots and can cause great damage.

Prevention. In small areas - watering with a solution of potassium permanganate (2-5 g per 10 liters of water). Sowing seeds not lower than the recommended depth with the simultaneous application of mineral fertilizers. Keeping the soil free of weeds. Loosening to a depth of 10-12 cm. Timely cleaning of mowed grass. Early autumn digging of the soil (until mid-September).

biological protection. Bookmark in the spring before sowing pieces raw potatoes, carrots or beets into the soil to a depth of 5-15 cm (with a mark of their location). After 3-4 days, the destruction of baits with larvae.

Chemical protection: see table. Against adult click beetles, shading traps made from freshly weed weeds treated with any of the approved contact insecticides help.

False wireworm (dark beetle larva). In appearance, this is the brother of the wireworm: only the first pair of legs is noticeably larger than the next, and the head is convex from above.

False wire. Photo: Nina Belyavskaya

Prevention and protection measures. Application to the soil before planting preparations Vallar and Terradox, Contador maxi. Use of shading poison baits.

Thick - different

In the soil there are fleshy, light-colored insect larvae folded into half rings. They can be both harmful and relatively harmless, and you can identify the pest ... by the legs!

Dangerous

Adult beetle larvae are rather large (depending on the species, from 1.5 to 7.5 cm in length), fatty, curved with the letter “C”, yellowish-white with translucent intestines. Try to remember a good identifying feature of beetle larvae: the back pair of their legs is the longest.

The larva of the grub. Photo: Nina Belyavskaya

Prevention. Destruction of weeds. Part of the grub larvae die when the soil is rolled in the spring.

Fight without harm. Collection and destruction of larvae during tillage. Daily shaking may beetles on shields or gauze panels and their subsequent destruction.

Harmful, but rare

Often the larvae of the bronzes are mistaken for the larvae of the grubs, which is not surprising, because they are the closest relatives. True, in the larvae of bronzes, all pairs of legs are of the same length. Bronze beetles can be harmful in rare cases - sometimes these beautiful bronze beetles eat the flowers of plants, and their larvae cause bald spots on the lawn.

Harmless

Larvae of saw beetles and dung beetles. Photo: Nina Belyavskaya

When digging the site, you can find greenish-brown or off-white larvae with a clearly visible head and a body curved in the shape of the letter "C", very similar to the larvae of the beetles, but with long front legs (in the beetles, on the contrary, the longest are the hind legs ). These are the larvae of saw beetles and dung beetles. They do not harm plants!

Chemistry against pests

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