Our planet is formed by four main shells: atmosphere, hydrosphere, biosphere and lithosphere. All of them are in close interaction with each other, since representatives of the biosphere shell of the Earth - animals, plants, microorganisms - cannot exist without such formative substances as water and oxygen.
Like the lithosphere, the soil cover and other deeply lying layers cannot exist in isolation. Despite the fact that we cannot see it with the naked eye, the soil is very densely populated. What living creatures do not live in it! Like any living organism, they also need water and air.
What animals live in the soil? How do they influence its formation and how do they adapt to such a habitat? We will try to answer these and other questions in this article.
What are the soils?
Soil is only the topmost, very shallow layer that makes up the lithosphere. Its depth goes about 1-1.5 m. Next, a completely different layer begins, in which groundwater flows.
That is, the upper fertile soil layer - this is the very habitat of various organisms and plants of various shapes, sizes and ways of nutrition. The soil, as the habitat of animals, is very rich and diverse.
This structural part of the lithosphere is not the same. The formation of the soil layer depends on many factors, mainly on environmental conditions. Therefore, the types of soils (fertile layer) also differ:
- Podzolic and sod-podzolic.
- Black earth.
- Soddy.
- Swamp.
- Podzolic marsh.
- Malt
- Floodplain.
- Salt flats.
- Gray forest-steppe.
- Solonetsy.
This classification is given only for the area of Russia. In other countries, continents, parts of the world, there are other types of soils (sandy, clay, arcto-tundra, humus, and so on).
Also, all soils are unequal in chemical composition, moisture supply and air saturation. These indicators vary and depend on a number of conditions (for example, animals in the soil affect this, which will be discussed below).
How are soils formed and who helps them in this?
The soil began its origin since the appearance of life on our planet. It was with the formation of living systems that the slow, continuous and self-renewing formation of soil substrates began.
Based on this, it is clear that living organisms play a role in soil formation. Which one? Basically, this role comes down to the processing of organic substances contained in the soil, and its enrichment with mineral elements. Also, this is loosening and improving aeration. Very well about this in 1763, wrote M.V. Lomonosov. It was he who first argued that the soil is formed due to the death of living things.
In addition to the activities carried out by animals in the soil and plants on its surface, rocks are a very important factor in the formation of the fertile layer. It is on their variety that the type of soil will generally depend.
Abiotic factors also play a role:
- shine;
- humidity;
- temperature.
As a result, rocks are processed under the influence of abiotic factors, and microorganisms living in the soil decompose animal and plant remains, turning organic substances into minerals. As a result, a fertile soil layer of a certain type is formed. At the same time, animals living underground (for example, worms, nematodes, moles) provide its aeration, that is, oxygen saturation. This is achieved by loosening and continuous processing of soil particles.
Animals and plants together give the soil organic matter. Microorganisms, protozoa, unicellular fungi and algae process this substance and transfer it to the desired form of mineral elements. Worms, nematodes and other animals again pass soil particles through themselves, thereby forming an organic fertilizer - biohumus.
Hence the conclusion: soils are formed from rocks as a result of a long historical period of time under the influence of abiotic factors and with the help of the animals and plants that live in them.
Invisible Soil World
A huge role not only in the formation of the soil, but also in the life of all other living creatures, is played by the smallest creatures that form a whole invisible soil world. Who belongs to them?
Firstly, unicellular algae and mushrooms. Of the fungi, the departments of chitridiomycetes, deuteromycetes, and some representatives of zygomycetes can be distinguished. Of the algae, phytoedaphones, which are green and blue-green algae, should be noted. The total mass of these creatures per 1 ha of soil cover is approximately 3100 kg.
Secondly, these are numerous microorganisms, bacteria and such animals in the soil as protozoa. The total mass of these living systems per 1 ha of soil is approximately 3100 kg. The main role of unicellular organisms is to process and decompose organic residues of plant and animal origin.
The most common of these organisms include:
- rotifers;
- ticks;
- amoeba;
- millipedes symphiles;
- protura;
- collembolas;
- two-tails;
- blue-green algae;
- green unicellular algae.
What animals live in the soil?
Soil inhabitants include the following invertebrate animals:
- Small crustaceans (crustaceans) - about 40 kg / ha
- Insects and their larvae - 1000 kg / ha
- Nematodes and roundworms - 550 kg / ha
- Snails and slugs - 40 kg / ha
Such animals living in the soil are very important. Their value is determined by the ability to pass soil lumps through themselves and saturate them with organic substances, forming biohumus. Their role also consists in loosening the soil, improving oxygen saturation and creating voids that are filled with air and water, resulting in increased fertility and quality of the upper layer of the earth.
Consider which animals live in the soil. They can be divided into two types:
- permanent residents;
- temporarily living.
Permanent vertebrate mammals, representing the animal kingdom of the soil, include mole rats, mole rats, mole rats and marsupials. Their importance comes down to maintaining food chains, as they are saturated with soil insects, snails, mollusks, slugs, and so on. And the second meaning is digging long and winding passages that allow the soil to be moistened and enriched with oxygen.
Temporary inhabitants, representing the fauna of the soil, use it only for a short refuge, as a rule, as a place for laying and storage of larvae. These animals include:
- jerboas;
- gophers;
- badgers;
- beetles;
- cockroaches;
- other types of rodents.
Adaptations of soil inhabitants
In order to live in such a difficult environment as soil, animals must have a number of special adaptations. Indeed, in terms of physical characteristics, this medium is dense, rigid and low-oxygen. In addition, there is absolutely no light in it, although a moderate amount of water is observed. Naturally, one must be able to adapt to such conditions.
Therefore, animals that live in the soil, over time (during evolutionary processes) acquired the following features:
- extremely small size to fill the tiny spaces between the soil particles and feel comfortable there (bacteria, protozoa, microorganisms, rotifers, crustaceans);
- flexible body and very strong muscles - advantages for movement in the soil (annelids and roundworms);
- the ability to absorb oxygen dissolved in water or breathe the entire surface of the body (bacteria, nematodes);
- a life cycle consisting of a larval stage, during which neither light, nor moisture, nor nutrition is required (insect larvae, various beetles);
- larger animals have devices in the form of powerful digging limbs with strong claws that make it easy to break through long and winding passages underground (moles, shrews, badgers, and so on);
- mammals have a well-developed sense of smell, but there is practically no sight (moles, zocors, mole rats, sea lilies);
- streamlined body, dense, squeezed, with a short rigid, tight-fitting fur.
All these devices create such comfortable conditions that the animals in the soil feel no worse than those that live in a land-air environment, and perhaps even better.
The role of ecological groups of soil inhabitants in nature
The main environmental groups of soil inhabitants are considered to be:
- Geobionts. Representatives of this group are animals for which the soil is a permanent habitat. It goes through their entire life cycle in combination with the basic processes of life. Examples: earthworms, polytails, tailless, double-tailed, beetleless.
- Geophiles. This group includes animals for which the soil is an essential substrate during one of the phases of its life cycle. For example: insect pupae, locusts, many beetles, weevils.
- Geoxenes. An ecological group of animals for which the soil is a temporary shelter, shelter, place of laying and breeding offspring. Examples: many beetles, insects, all burrowing animals.
The totality of all animals in each group is an important link in the overall food chain. In addition, their livelihoods determines the quality of soils, their self-renewability and fertility. Therefore, their role is extremely important, especially in the modern world, in which agriculture forces the soil to become poorer, leached and salted out under the influence of chemical fertilizers, pesticides and herbicides. Animal soils contribute to a more rapid and natural restoration of the fertile layer after severe mechanical and chemical attacks by humans.
The relationship of plants, animals and soils
Not only animal soils are interconnected, forming a common biocenosis with their food chains and ecological niches. In fact, all existing plants, animals and microorganisms are involved in a single circle of life. As well as all of them are associated with all habitats. A simple example illustrates this relationship.
Grasses of meadows and fields are food for land animals. Those, in turn, serve as a food source for predators. The remains of grass and organic matter, which are excreted with the waste products of all animals, fall into the soil. Here, microorganisms and insects, which are detritophages, are taken for action. They decompose all residues and convert them to minerals that are convenient for absorption by plants. Thus, plants get the components they need for growth and development.
In the soil itself, microorganisms and insects, rotifers, beetles, larvae, worms and so on become food for each other, and, therefore, a common part of the entire food network.
Thus, it turns out that animals living in the soil and plants living on its surface have common intersection points and interact with each other, forming a single common harmony and force of nature.
Poor soils and their inhabitants
Poor are called soils that have been repeatedly exposed to human influences. Construction, cultivation of agricultural plants, drainage, reclamation - all this over time leads to depletion of soils. What inhabitants can survive in such conditions? Unfortunately, not many. The most enduring underground inhabitants are bacteria, some protozoa, insects, and their larvae. Mammals, worms, nematodes, locusts, spiders, crustaceans in such soils cannot survive, therefore they die or leave them.
Poor soils, in which the content of organic and mineral substances is low, also belong to the poor. For example, loose sands. This is a special environment in which certain organisms live with their adaptations. Or, for example, saline and strongly acidic soils also contain only specific inhabitants.
Studying animal soil at school
The school course of zoology does not provide for the study of animal soil in a separate lesson. More often than not, this is just an overview in the context of a topic.
However, in elementary school there is such a thing as "The World." Animals in the soil are studied in the framework of the program of this subject in great detail. Information is presented according to the age of the children. Kids are told about the diversity, role in nature and human economic activity that animals play in the soil. Grade 3 is the most suitable age for this. Children are already educated enough to learn some kind of terminology, and at the same time they have a great desire for knowledge, to know everything around them, to study nature and its inhabitants.
The main thing is to make the lessons interesting, non-standard, and also informative, and then the children will absorb knowledge like sponges, including about the inhabitants of the soil environment.
Examples of animals living in the soil
A short list reflecting the main soil inhabitants can be given. Naturally, to make it complete will not work, because there are so many of them! However, we will try to name the main representatives.
Animal Soils - List:
- rotifers, ticks, bacteria, protozoa, crustaceans;
- spiders, locusts, insects, bugs, millipedes, woodlice, slugs, snails;
- earthworms, nematodes and other roundworms;
- moles, mole rats, mole rats, zokors;
- jerboas, ground squirrels, badgers, mice, chipmunks.