All living beings inhabiting our planet live in certain conditions that correspond to the level of development, features of organization and vital activity of organisms. Who populates the land-air environment? Features of the environment, which is the most populated, and much more will be discussed in our article.

What is habitat

The habitat of organisms is everything that surrounds them. And these are not only natural objects, but also what is created by man.

The totality of all habitats constitutes the biosphere. This is where life is possible. But man, through his activities, has transformed it so much that scientists identify another formation. It is called the noosphere. This is the shell of the planet created by human activity.

Main groups of environmental factors

All environmental conditions that affect organisms to one degree or another are called environmental factors. They are quite diverse. But according to the nature of their impact, they are divided into several groups.

• The first unites all of them. They are called abiotic. These are the amount of sunlight, air temperature, humidity and radiation levels, wind direction and the nature of the relief. For inhabitants of the aquatic environment, this is salinity and the type of currents.
• Biotic factors combine all types of influence of living organisms and their relationships with each other. They can be mutually beneficial, neutral predatory, etc.
• Human activities that change the environment are a group of anthropogenic factors.

Habitats of living organisms

The peculiarities of the ground-air habitat are that it is the most diverse and complex. There is a natural explanation for this fact.

Features of the ground-air environment of life

The complexity of the structure and conditions of this environment is explained by the fact that it is located at the junction of several geographical envelopes- hydro-, litho- and atmosphere. Therefore, the organisms living in it are influenced by the factors of each of them. Their structural features allow them to withstand sudden changes in temperature, chemical and humidity changes.

Abiotic factors of the ground-air environment

Features of the ground-air habitat include several factors. Firstly, this is a low air density. The low density of air masses allows its inhabitants to easily move on the ground or fly.

The next feature is that the air is in constant motion. This “flow” ensures the automatic movement of many inhabitants and their waste products. These are plant seeds, fungal and bacterial spores, small insects and arachnids. At the same time, the atmospheric pressure in this environment is characterized by a low indicator, which is normally 760 mmHg. A change in this value leads to disruption of the physiological processes of local inhabitants. Thus, when pressure drops with altitude, the ability of oxygen to dissolve in the blood plasma decreases. As a result, it becomes smaller, breathing becomes more frequent, which leads to excessive loss of moisture.

Organisms of the ground-air environment

One of the hallmarks of all living things is the ability to adapt. The peculiarities of animals of the land-air environment, as well as other organisms, are that all of them, in the process of evolution, acquired adaptations to sharp changes in temperature, climate and changing seasons.

For example, many plants have modifications to their roots and shoots to survive drought and cold weather. Leek and tulip bulbs, carrot and beet roots, and aloe leaves store water and necessary substances. Spores of bacteria and plants, cells of microscopic animals endure difficult conditions in the state of cysts. At the same time, they are covered with a dense shell, and all metabolic processes are reduced to a minimum. When the unfavorable period ends, the cells divide and move on to active existence.

Many animals of the land-air environment have formed a complex system of thermoregulation and heat exchange with the environment, thanks to which their body temperature remains constant regardless of the time of year.

Action of the anthropogenic factor

It is the ground-air environment that is most changed by human activity. Features of the environment, which were initially natural, remained so, perhaps, only in the Arctic deserts. Low temperatures making this natural area uninhabitable. Therefore, the characteristics of organisms in the ground-air environment also lie in the fact that they experience a greater influence of the anthropogenic factor compared to the inhabitants of other ecological niches.

Man transforms natural landscapes and topography, changes the gas composition of the atmosphere, the chemical basis of soils, and affects the cleanliness of water bodies. Not all living organisms have time to adapt to intensely changing conditions caused by the action of the anthropogenic factor. Unfortunately, Negative influence person on the state of the ground-air environment in this moment prevails over all attempts to preserve life.

Global terrestrial-air habitats

How has the land-air environment suffered at the hands of man? Features of the environment, its main physical indicators in the majority natural areas, suitable for life, changed. This led to the emergence of global environmental problems in the world. Activity industrial enterprises caused a change in the gas composition of the atmosphere. As a result, a higher concentration of carbon dioxide is created in the air than normal, and sulfur and nitrogen oxides and freons accumulate. The result is global warming, Greenhouse effect, destruction of the earth's ozone layer, smog over large cities.

As a result of irrational environmental management, the total area forests, which are the “lungs” of our planet, providing all living things with oxygen. Over time they are exhausted mineral resources and soil fertility decreases.

So, the most diverse is the ground-air environment. Features of the environment lie in its location at the junction of several natural geographical shells. Its main characteristics are low density, pressure and mobility of air masses, constancy of the gas composition of the atmosphere, variability thermal regime, shift climatic conditions and seasons. Special meaning for normal life activity in the ground-air environment they have indicators of humidity and air temperature.

A NEW LOOK Adaptations of organisms to living in the ground-air environmentLiving organisms in ground-air environment surrounded by air. Air has low density and, as a result, low lifting force, insignificant support and low resistance to the movement of organisms. Terrestrial organisms live in conditions of relatively low and constant atmospheric pressure, also due to low air density.

Air has a low heat capacity, so it heats up quickly and cools just as quickly. The speed of this process is inverse relationship on the amount of water vapor it contains.

Light air masses have greater mobility, both horizontally and vertically. This helps maintain a constant gas composition of the air. The oxygen content in air is much higher than in water, so oxygen on land is not a limiting factor.

Light in conditions terrestrial habitat due to the high transparency of the atmosphere, it does not act as a limiting factor, unlike the aquatic environment.

Ground-air environment has different humidity regimes: from complete and constant saturation of the air with water vapor in some areas of the tropics to their almost complete absence in the dry air of deserts. There is also great variability in air humidity throughout the day and seasons.

Moisture on land acts as a limiting factor.

Due to the presence of gravity and the lack of buoyant force, terrestrial land dwellers have well-developed support systems that support their bodies. In plants, these are various mechanical tissues, especially powerfully developed in trees. Animals, during the evolutionary process, have developed both an external (arthropod) and an internal (chordate) skeleton. Some groups of animals have a hydroskeleton (roundworms and annelids). Problems among terrestrial organisms with maintaining their bodies in space and overcoming the forces of gravity have limited their maximum mass and size. The largest land animals are inferior in size and weight to the giants of the aquatic environment (the weight of an elephant reaches 5 tons, and a blue whale - 150 tons).

Low air resistance contributed to the progressive evolution of locomotion systems of terrestrial animals. Thus, mammals acquired the highest speed of movement on land, and birds mastered the air environment, developing the ability to fly.

The high mobility of air in the vertical and horizontal directions is used by some terrestrial organisms at different stages of their development for dispersal with the help of air currents (young spiders, insects, spores, seeds, plant fruits, protist cysts). By analogy with aquatic planktonic organisms, insects have developed similar adaptations as adaptations to passive soaring in the air - small body sizes, various outgrowths that increase the relative surface of the body or some of its parts. Wind-dispersed seeds and fruits have various wing-like and paragaute-like appendages that enhance their gliding ability.

The adaptations of terrestrial organisms to conserve moisture are also diverse. In insects, the body is reliably protected from drying out by a multilayered chitinized cuticle, the outer layer of which contains fats and wax-like substances. Similar water-saving devices are also developed in reptiles. The ability for internal fertilization developed in terrestrial animals made them independent of the presence of an aquatic environment.

The soil is a complex system consisting of solid particles surrounded by air and water.

Depending on the type - clayey, sandy, clayey-sandy etc. - the soil is more or less permeated with cavities filled with a mixture of gases and aqueous solutions. In the soil, compared to the ground layer of air, temperature fluctuations are smoothed out, and at a depth of 1 m, seasonal temperature changes are also imperceptible.

The uppermost soil horizon contains more or less humus, on which plant productivity depends. The middle layer located underneath contains washed out from the top layer and transformed substances. The bottom layer is represented maternal breed.

Water in the soil is present in voids, tiny spaces. The composition of soil air changes sharply with depth: the oxygen content decreases and the carbon dioxide content increases. When the soil is flooded with water or intensive decay of organic residues, oxygen-free zones appear. Thus, the conditions of existence in the soil are different at different horizons.

In the course of evolution, this environment was developed later than the aquatic environment. Its peculiarity is that it is gaseous, therefore it is characterized by low humidity, density and pressure, and high oxygen content.

In the course of evolution, living organisms have developed the necessary anatomical, morphological, physiological, behavioral and other adaptations.

Animals in the ground-air environment move on the soil or through the air (birds, insects), and plants take root in the soil. In this regard, animals developed lungs and trachea, and plants developed a stomatal apparatus, i.e.

organs with which the land inhabitants of the planet absorb oxygen directly from the air. Strong development received skeletal organs that ensure autonomy of movement on land and support the body with all its organs in conditions of low density of the environment, thousands of times less than water.

Ecological factors in the ground-air environment differ from other habitats in the high intensity of light, significant fluctuations in temperature and air humidity, and the correlation of all factors with geographical location, changing seasons of the year and time of day.

Their effects on organisms are inextricably linked with air movement and position relative to the seas and oceans and are very different from the effects in the aquatic environment (Table

Table 5

Habitat conditions for air and water organisms

(according to D.F. Mordukhai-Boltovsky, 1974)

Land animals and plants have developed their own, no less original adaptations to unfavorable environmental factors: the complex structure of the body and its integument, periodicity and rhythm life cycles, thermoregulation mechanisms, etc.

Purposeful mobility of animals in search of food developed, wind-borne spores, seeds and pollen appeared, as well as plants and animals whose life was entirely connected with the air environment. An exceptionally close functional, resource and mechanical relationship with the soil has been formed.

Many of the adaptations were discussed above, as examples in characterizing abiotic factors environment.

Therefore, there is no point in repeating ourselves now, since we will return to them in practical classes.

Soil as a habitat

Earth is the only planet that has soil (edasphere, pedosphere) - a special, upper shell of land.

This shell was formed in historically foreseeable time - it is the same age as land life on the planet. For the first time, M.V. answered the question about the origin of soil. Lomonosov (“On the Layers of the Earth”): “…soil originated from the decay of animal and plant bodies…through the length of time…”.

And the great Russian scientist you. You. Dokuchaev (1899: 16) was the first to call soil an independent natural body and proved that soil is “... the same independent natural historical body as any plant, any animal, any mineral... it is the result, a function of the total, mutual activity of the climate of a given area, its plant and animal organisms, topography and age of the country..., finally, subsoil, i.e.

ground source rocks. ... All these soil-forming agents are, in essence, completely equivalent quantities and take an equal part in the formation of normal soil...”

And the modern well-known soil scientist N.A.

Kaczynski (“Soil, its properties and life”, 1975) gives the following definition of soil: “Soil must be understood as all surface layers of rocks, processed and changed by the joint influence of climate (light, heat, air, water), plant and animal organisms” .

The main structural elements of soil are: mineral base, organic matter, air and water.

Mineral base (skeleton)(50-60% of all soil) is an inorganic substance formed as a result of the underlying mountain (parent, soil-forming) rock as a result of its weathering.

Skeletal particle sizes range from boulders and stones to tiny grains of sand and mud particles. The physicochemical properties of soils are determined mainly by the composition of soil-forming rocks.

The permeability and porosity of the soil, which ensure the circulation of both water and air, depend on the ratio of clay and sand in the soil and the size of the fragments.

In temperate climates, it is ideal if the soil is composed of equal amounts of clay and sand, i.e. represents loam.

In this case, the soils are not at risk of either waterlogging or drying out. Both are equally destructive for both plants and animals.

organic matter– up to 10% of the soil, is formed from dead biomass (plant mass - litter of leaves, branches and roots, dead trunks, grass rags, organisms of dead animals), crushed and processed into soil humus by microorganisms and certain groups of animals and plants.

Simpler elements formed as a result of the decomposition of organic matter are again absorbed by plants and are involved in the biological cycle.

Air(15-25%) in the soil is contained in cavities - pores, between organic and mineral particles. In the absence (heavy clay soils) or filling of pores with water (during flooding, thawing of permafrost), aeration in the soil worsens and anaerobic conditions develop.

Under such conditions, the physiological processes of organisms that consume oxygen - aerobes - are inhibited, and the decomposition of organic matter is slow. Gradually accumulating, they form peat. Large reserves of peat are typical for swamps, swampy forests, and tundra communities. Peat accumulation is especially pronounced in the northern regions, where coldness and waterlogging of soils are interdependent and complement each other.

Water(25-30%) in the soil is represented by 4 types: gravitational, hygroscopic (bound), capillary and vapor.

Gravitational– mobile water, occupying wide spaces between soil particles, seeps down under its own weight to the level groundwater.

Easily absorbed by plants.

Hygroscopic or related– adsorbs around colloidal particles (clay, quartz) of the soil and is retained in the form of a thin film due to hydrogen bonds. Freed from them when high temperature(102-105°C). It is inaccessible to plants and does not evaporate. In clay soils there is up to 15% of such water, in sandy soils – 5%.

Capillary– held around soil particles by surface tension.

Through narrow pores and channels - capillaries, it rises from the groundwater level or diverges from cavities with gravitational water. Better hold clay soils, evaporates easily.

Plants easily absorb it.

Vaporous– occupies all water-free pores. It evaporates first.

There is a constant exchange of surface soil and groundwater, as a link in the general water cycle in nature, changing speed and direction depending on the season and weather conditions.

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Gas composition of the atmosphere is also an important climatic factor.

Approximately 3 -3.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen in it. The composition of the atmosphere was largely determined by volcanic gases.

It is in a ground environment, on the basis of high efficiency oxidative processes in the body, animal homeothermy arose. Oxygen, due to its constantly high content in the air, is not a factor limiting life in the terrestrial environment. Only in places, under specific conditions, is a temporary deficiency created, for example in accumulations of decomposing plant residues, reserves of grain, flour, etc.

For example, in the absence of wind in the center of large cities, its concentration increases tens of times. There are regular daily changes in the carbon dioxide content in the ground layers, associated with the rhythm of plant photosynthesis, and seasonal changes, caused by changes in the respiration rate of living organisms, mainly the microscopic population of soils. Increased saturation of air with carbon dioxide occurs in areas of volcanic activity, near thermal springs and other underground outlets of this gas.

Low air density determines its low lifting force and insignificant support.

Inhabitants of the air environment must have their own support system that supports the body: plants - with various mechanical tissues, animals - with a solid or, much less often, hydrostatic skeleton.

Wind

storms

Pressure

Low air density causes relatively low pressure on land. Normally it is 760 mmHg. As altitude increases, pressure decreases. At an altitude of 5800 m it is only half normal. Low pressure may limit the distribution of species in the mountains. For most vertebrates, the upper limit of life is about 6000 m. A decrease in pressure entails a decrease in oxygen supply and dehydration of animals due to an increase in respiration rate.

The limits of advancement into the mountains are approximately the same higher plants. Somewhat more hardy are arthropods (springtails, mites, spiders), which can be found on glaciers above the vegetation line.

In general, all terrestrial organisms are much more stenobatic than aquatic ones.

Ground-air habitat

In the course of evolution, this environment was developed later than the aquatic environment. Ecological factors in the ground-air environment differ from other habitats in the high intensity of light, significant fluctuations in temperature and air humidity, the correlation of all factors with geographic location, changing seasons and time of day.

The environment is gaseous, therefore it is characterized by low humidity, density and pressure, and high oxygen content.

Characteristics of abiotic environmental factors: light, temperature, humidity - see previous lecture.

Gas composition of the atmosphere is also an important climatic factor. Approximately 3 -3.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen in it. The composition of the atmosphere was largely determined by volcanic gases.

Currently, the atmosphere consists mainly of nitrogen, oxygen and relatively smaller amounts of argon and carbon dioxide.

All other gases present in the atmosphere are contained only in trace quantities. Of particular importance for biota is the relative content of oxygen and carbon dioxide.

It was in a terrestrial environment, on the basis of the high efficiency of oxidative processes in the body, that animal homeothermy arose. Oxygen, due to its constantly high content in the air, is not a factor limiting life in the terrestrial environment.

Only in places, under specific conditions, is a temporary deficiency created, for example in accumulations of decomposing plant residues, reserves of grain, flour, etc.

The carbon dioxide content can vary in certain areas of the surface layer of air within quite significant limits. For example, in the absence of wind in the center of large cities, its concentration increases tens of times. There are regular daily changes in the carbon dioxide content in the ground layers, associated with the rhythm of plant photosynthesis, and seasonal changes, caused by changes in the respiration rate of living organisms, mainly the microscopic population of soils.

Increased saturation of air with carbon dioxide occurs in areas of volcanic activity, near thermal springs and other underground outlets of this gas. Low carbon dioxide content inhibits the process of photosynthesis.

In conditions closed ground you can increase the rate of photosynthesis by increasing the concentration of carbon dioxide; this is used in the practice of greenhouse and greenhouse farming.

Air nitrogen is an inert gas for most inhabitants of the terrestrial environment, but a number of microorganisms (nodule bacteria, Azotobacter, clostridia, blue-green algae, etc.) have the ability to bind it and involve it in the biological cycle.

Local pollutants entering the air can also significantly affect living organisms.

This especially applies to toxic gaseous substances - methane, sulfur oxide (IV), carbon monoxide (II), nitrogen oxide (IV), hydrogen sulfide, chlorine compounds, as well as particles of dust, soot, etc., polluting the air in industrial areas. The main modern source of chemical and physical pollution of the atmosphere is anthropogenic: the work of various industrial enterprises and transport, soil erosion, etc.

n. Sulfur oxide (SO2), for example, is toxic to plants even in concentrations from one fifty-thousandth to one millionth of the volume of air. Some plant species are especially sensitive to S02 and serve as a sensitive indicator of its accumulation in the air (for example , lichens.

Low air density determines its low lifting force and insignificant support. Inhabitants of the air environment must have their own support system that supports the body: plants - with various mechanical tissues, animals - with a solid or, much less often, hydrostatic skeleton.

In addition, all inhabitants of the air are closely connected with the surface of the earth, which serves them for attachment and support. Life in a suspended state in the air is impossible. True, many microorganisms and animals, spores, seeds and pollen of plants are regularly present in the air and are carried by air currents (anemochory), many animals are capable of active flight, but in all these species the main function of their life cycle is reproduction - carried out on the surface of the earth.

For most of them, staying in the air is associated only with settling or searching for prey.

Wind has a limiting effect on the activity and even distribution of organisms. The wind can even change appearance plants, especially in those habitats, for example in alpine zones, where other factors have a limiting effect. In open mountain habitats, wind limits plant growth and causes plants to bend on the windward side.

In addition, wind increases evapotranspiration in low humidity conditions. Great importance have storms, although their effect is purely local. Hurricanes, and even ordinary winds, are capable of transporting animals and plants to long distances and thereby change the composition of communities.

Pressure, apparently, is not a direct limiting factor, but it is directly related to weather and climate, which have a direct limiting effect.

Low air density causes relatively low pressure on land. Normally it is 760 mmHg. As altitude increases, pressure decreases. At an altitude of 5800 m it is only half normal.

Low pressure may limit the distribution of species in the mountains.

For most vertebrates, the upper limit of life is about 6000 m. A decrease in pressure entails a decrease in oxygen supply and dehydration of animals due to an increase in respiration rate. The limits of advancement of higher plants into the mountains are approximately the same. Somewhat more hardy are arthropods (springtails, mites, spiders), which can be found on glaciers above the vegetation line.

Lecture 3 HABITAT AND THEIR CHARACTERISTICS (2 hours)

1.Aquatic habitat

2. Ground-air habitat

3. Soil as a habitat

4.Organism as a habitat

In the process of historical development, living organisms have mastered four habitats. The first is water. Life originated and developed in water for many millions of years. The second - ground-air - plants and animals arose on land and in the atmosphere and rapidly adapted to new conditions. Gradually transforming the upper layer of land - the lithosphere, they created a third habitat - soil, and themselves became the fourth habitat.

Aquatic habitat - hydrosphere

Ecological groups of hydrobionts. The warm seas and oceans (40,000 species of animals) in the equator and tropics are characterized by the greatest diversity of life; to the north and south, the flora and fauna of the seas are hundreds of times depleted. As for the distribution of organisms directly in the sea, the bulk of them are concentrated in the surface layers (epipelagic) and in the sublittoral zone. Depending on the method of movement and stay in certain layers, marine inhabitants are divided into three ecological groups: nekton, plankton and benthos.

Nekton(nektos - floating) - actively moving large animals that can overcome long distances and strong currents: fish, squid, pinnipeds, whales. In fresh water bodies, nekton includes amphibians and many insects.

Plankton(planktos - wandering, soaring) - a collection of plants (phytoplankton: diatoms, green and blue-green (fresh water bodies only) algae, plant flagellates, peridineans, etc.) and small animal organisms (zooplankton: small crustaceans, of the larger ones - pteropods mollusks, jellyfish, ctenophores, some worms) living at different depths, but not capable of active movement and resistance to currents. Plankton also includes animal larvae, forming special group– neuston. This is a passively floating “temporary” population of the uppermost layer of water, represented by various animals (decapods, barnacles and copepods, echinoderms, polychaetes, fish, mollusks, etc.) in the larval stage. The larvae, growing up, move into the lower layers of the pelagel. Above the neuston there is a pleiston - these are organisms in which the upper part of the body grows above water, and the lower part in water (duckweed - Lemma, siphonophores, etc.). Plankton plays an important role in the trophic relationships of the biosphere, because is food for many aquatic inhabitants, including the main food for baleen whales (Myatcoceti).

Benthos(benthos – depth) – bottom hydrobionts. It is represented mainly by attached or slowly moving animals (zoobenthos: foraminephores, fish, sponges, coelenterates, worms, brachiopods, ascidians, etc.), more numerous in shallow water. In shallow water, benthos also includes plants (phytobenthos: diatoms, green, brown, red algae, bacteria). At depths where there is no light, phytobenthos is absent. Along the coasts there are flowering plants of zoster, rupiah. Rocky areas of the bottom are richest in phytobenthos.

In lakes, zoobenthos is less abundant and diverse than in the sea. It is formed by protozoa (ciliates, daphnia), leeches, mollusks, insect larvae, etc. The phytobenthos of lakes is formed by free-floating diatoms, green and blue-green algae; brown and red algae are absent.

Taking root coastal plants in lakes form clearly defined belts, the species composition and appearance of which are consistent with the environmental conditions in the land-water boundary zone. Hydrophytes grow in the water near the shore - plants semi-submerged in water (arrowhead, whitewing, reeds, cattails, sedges, trichaetes, reeds). They are replaced by hydatophytes - plants immersed in water, but with floating leaves (lotus, duckweed, egg capsules, chilim, takla) and - further - completely submerged (pondweed, elodea, hara). Hydatophytes also include plants floating on the surface (duckweed).

The high density of the aquatic environment determines the special composition and nature of changes in life-supporting factors. Some of them are the same as on land - heat, light, others are specific: water pressure (increases with depth by 1 atm for every 10 m), oxygen content, salt composition, acidity. Due to the high density of the environment, the values ​​of heat and light change much faster with an altitude gradient than on land.

Thermal mode. The aquatic environment is characterized by less heat gain, because a significant part of it is reflected, and an equally significant part is spent on evaporation. Consistent with the dynamics of land temperatures, water temperatures exhibit smaller fluctuations in daily and seasonal temperatures. Moreover, reservoirs significantly equalize the temperature in the atmosphere of coastal areas. In the absence of an ice shell, the seas have a warming effect on the adjacent land areas in the cold season, and a cooling and moistening effect in the summer.

The range of water temperatures in the World Ocean is 38° (from -2 to +36°C), in fresh water bodies – 26° (from -0.9 to +25°C). With depth, the water temperature drops sharply. Up to 50 m there are daily temperature fluctuations, up to 400 – seasonal, deeper it becomes constant, dropping to +1-3°C (in the Arctic it is close to 0°C). Because the temperature regime in reservoirs it is relatively stable; their inhabitants are characterized by stenothermism. Minor temperature fluctuations in one direction or another are accompanied by significant changes in aquatic ecosystems.

Examples: a “biological explosion” in the Volga delta due to a decrease in the level of the Caspian Sea - the proliferation of lotus thickets (Nelumba kaspium), in southern Primorye - the overgrowth of whitefly in oxbow rivers (Komarovka, Ilistaya, etc.) along the banks of which woody vegetation was cut down and burned.

Due to to varying degrees heating of the upper and lower layers throughout the year, ebbs and flows, currents, and storms constantly mix the water layers. The role of water mixing for aquatic inhabitants (aquatic organisms) is extremely important, because this evens out the distribution of oxygen and nutrients inside reservoirs, ensuring metabolic processes between organisms and the environment.

During periods of stagnation, three layers are clearly distinguished: the upper (epilimnion) with the sharpest seasonal fluctuations in water temperature, the middle (metalimnion or thermocline), in which a sharp jump in temperature occurs, and the bottom (hypolimnion), in which the temperature changes little throughout the year. During periods of stagnation, oxygen deficiency occurs in the water column - in the bottom part in summer, and in the upper part in winter, as a result of which fish kills often occur in winter. Light mode.

The intensity of light in water is greatly weakened due to its reflection by the surface and absorption by the water itself. This greatly affects the development of photosynthetic plants. The less transparent the water, the more light is absorbed. Water transparency is limited by mineral suspensions and plankton. It decreases with the rapid development of small organisms in summer, and in temperate and northern latitudes even in winter, after the establishment of ice cover and covering it with snow on top. In the oceans, where the water is very transparent, 1% of light radiation penetrates to a depth of 140 m, and in small lakes at a depth of 2 m only tenths of a percent penetrates. Rays different parts

Plants have adapted to the lack of light by developing large chromatophores, which provide a low point of compensation for photosynthesis, as well as by increasing the area of ​​assimilating organs (leaf surface index). For deep-sea algae, strongly dissected leaves are typical, the leaf blades are thin and translucent. Semi-submerged and floating plants are characterized by heterophylly - the leaves above the water are the same as those of land plants, they have a solid blade, the stomatal apparatus is developed, and in the water the leaves are very thin, consisting of narrow thread-like lobes.

Heterophylly: egg capsules, water lilies, arrow leaf, chilim (water chestnut).

Animals, like plants, naturally change their color with depth. In the upper layers they are brightly colored different colors, in the twilight zone (sea bass, corals, crustaceans) are painted in colors with a red tint - it is more convenient to hide from enemies. Deep-sea species lack pigments.

The characteristic properties of the aquatic environment, different from land, are high density, mobility, acidity, and the ability to dissolve gases and salts. For all these conditions, hydrobionts have historically developed appropriate adaptations.

2. Ground-air habitat

In the course of evolution, this environment was developed later than the aquatic environment. Its peculiarity is that it is gaseous, therefore it is characterized by low humidity, density and pressure, and high oxygen content. In the course of evolution, living organisms have developed the necessary anatomical, morphological, physiological, behavioral and other adaptations.

Animals in the ground-air environment move on the soil or through the air (birds, insects), and plants take root in the soil. In this regard, animals developed lungs and trachea, and plants developed a stomatal apparatus, i.e. organs with which the land inhabitants of the planet absorb oxygen directly from the air. Skeletal organs have developed strongly, ensuring autonomy of movement on land and supporting the body with all its organs in conditions of insignificant environmental density, thousands of times less than water. Ecological factors in the ground-air environment differ from other habitats in the high intensity of light, significant fluctuations in temperature and air humidity, the correlation of all factors with geographic location, changing seasons and time of day. Their effects on organisms are inextricably linked with air movement and position relative to the seas and oceans and are very different from the effects in the aquatic environment (Table 1).

Habitat conditions for air and water organisms

(according to D.F. Mordukhai-Boltovsky, 1974)

Important (certain quantities required)

Many of the adaptations were discussed above as examples in characterizing abiotic environmental factors. Therefore, there is no point in repeating ourselves now, since we will return to them in practical classes.

Animals are spread over almost the entire surface of the Earth. Due to their mobility, ability to adapt evolutionarily to colder living conditions, due to their lack of direct dependence on sunlight, animals occupied more habitats than plants. However, it should be remembered that animals depend on plants, since plants serve as a source of food for them (for herbivores, and predators eat herbivores).

Here in the context of animal habitats we will understand animal living environment.

In total, four animal habitats can be distinguished. These are 1) ground-air, 2) water, 3) soil and 4) other living organisms. Speaking about the ground-air environment of life, it is sometimes divided into ground and, separately, air. However, even flying animals sooner or later land on the ground. In addition, while moving on the ground, the animal is also in the air. Therefore, the ground and air environments are combined into one ground-air environment.

There are animals that live in two environments at once. For example, many amphibians (frogs) live both in water and on land, a number of rodents live in the soil and on the surface of the earth.

Ground-air habitat

The land-air environment contains the most animal species. The land turned out to be, in a sense, the most convenient environment for their life. Although in evolution, animals (and plants) arose in water and only later came to the surface.

Most worms, insects, amphibians, reptiles, birds and mammals live on land. Many species of animals are capable of flight, so they spend part of their lives exclusively in the air.

Animals of the land-air environment are usually characterized by high mobility and good vision.

The land-air environment is characterized by a wide variety of habitat conditions (tropical forests and temperate climate, meadows and steppes, deserts, tundras and much more). Therefore, animals in this living environment are characterized by great diversity; they can differ greatly from each other.

Aquatic habitat

The aquatic habitat differs from the air habitat in its greater density. Here animals can afford to have very massive bodies (whales, sharks), as the water supports them and makes their bodies lighter. However, it is more difficult to move in a dense environment, which is why aquatic animals most often have a streamlined body shape.

Almost no sunlight penetrates into the depths of the sea, so deep-sea animals may have poorly developed visual organs.

Aquatic animals are divided into plankton, nekton and benthos. Plankton floats passively in the water column (for example, unicellular organisms), nekton- these are actively swimming animals (fish, whales, etc.), benthos lives on the bottom (corals, sponges, etc.).

Soil habitat

Soil as a habitat is characterized by very high density and lack of sunlight. Here animals do not need organs of vision. Therefore, they are either not developed (worms) or reduced (moles). On the other hand, temperature changes in the soil are not as significant as on the surface. The soil is home to many worms, insect larvae, and ants. There are also soil inhabitants among mammals: moles, mole rats, and burrowing animals.

There are several main living environments on planet Earth:

water

ground-air

soil

living organism.

Aquatic living environment.

Organisms that live in water have adaptations that are defined physical properties water (density, thermal conductivity, ability to dissolve salts).

Due to the buoyant force of water, many small inhabitants of the aquatic environment are suspended and are not able to resist currents. The collection of such small aquatic inhabitants is called plankton. Plankton includes microscopic algae, small crustaceans, fish eggs and larvae, jellyfish and many other species.

Plankton

Planktonic organisms are carried by currents and are unable to resist them. The presence of plankton in the water makes a filtration type of nutrition possible, i.e., straining, using various devices, small organisms and food particles suspended in water. It is developed in both floating and sessile bottom animals, such as crinoids, mussels, oysters and others. A sedentary life would be impossible for aquatic inhabitants if there were no plankton, and this, in turn, is possible only in an environment with sufficient density.

The density of water makes active movement in it difficult, so fast-swimming animals, such as fish, dolphins, squids, must have strong muscles and a streamlined body shape.

Mako shark

Due to the high density of water, pressure increases greatly with depth. Deep-sea inhabitants are able to withstand pressure that is thousands of times higher than on the land surface.

Light penetrates water only to a shallow depth, so plant organisms can only exist in the upper horizons of the water column. Even in the most clean seas photosynthesis is possible only to depths of 100-200 m. At greater depths there are no plants, and deep-water animals live in complete darkness.

The temperature regime in reservoirs is milder than on land. Due to the high heat capacity of water, temperature fluctuations in it are smoothed out, and aquatic inhabitants do not face the need to adapt to severe frosts or forty-degree heat. Only in hot springs can the water temperature approach the boiling point.

One of the difficulties in the life of aquatic inhabitants is the limited amount of oxygen. Its solubility is not very high and, moreover, decreases greatly when the water is contaminated or heated. Therefore, in reservoirs there are sometimes starvation - mass death of inhabitants due to a lack of oxygen, which occurs for various reasons.

Fish kill

The salt composition of the environment is also very important for aquatic organisms. Marine species cannot live in fresh waters, and freshwater ones - in the seas due to disruption of cell function.

Ground-air environment of life.

This environment has a different set of features. It is generally more complex and varied than aquatic. It has a lot of oxygen, a lot of light, sharper changes in temperature in time and space, significantly weaker pressure drops, and moisture deficiency often occurs. Although many species can fly, and small insects, spiders, microorganisms, seeds and plant spores are carried by air currents, feeding and reproduction of organisms occurs on the surface of the ground or plants. In such a low-density environment as air, organisms need support. Therefore, terrestrial plants have developed mechanical tissues, and terrestrial animals have a more pronounced internal or external skeleton than aquatic animals. The low density of air makes it easier to move around in it. About two-thirds of land inhabitants have mastered active and passive flight. Most of them are insects and birds.

Black kite

Caligo butterfly

Air is a poor conductor of heat. This makes it easier to conserve heat generated inside organisms and maintain a constant temperature in warm-blooded animals. The very development of warm-bloodedness became possible in a terrestrial environment. The ancestors of modern aquatic mammals - whales, dolphins, walruses, seals - once lived on land.

Land dwellers have a wide variety of adaptations related to providing themselves with water, especially in dry conditions. In plants it is powerful root system, a waterproof layer on the surface of leaves and stems, the ability to regulate water evaporation through stomata. In animals, these are also different structural features of the body and integument, but, in addition, maintaining water balance Corresponding behavior also contributes. They can, for example, migrate to watering holes or actively avoid particularly drying conditions. Some animals can live their entire lives on dry food, such as jerboas or the well-known clothes moth. In this case, the water needed by the body arises due to oxidation components food.

Camel thorn root

Many other environmental factors also play an important role in the life of terrestrial organisms, such as air composition, winds, and the topography of the earth's surface. Weather and climate are especially important. The inhabitants of the land-air environment must be adapted to the climate of the part of the Earth where they live and tolerate variability in weather conditions.

Soil as a living environment.

Soil is a thin layer of land surface, processed by the activity of living beings. Solid particles are permeated in the soil with pores and cavities, filled partly with water and partly with air, so small aquatic organisms can also inhabit the soil. The volume of small cavities in the soil is a very important characteristic of it. In loose soils it can be up to 70%, and in dense soils - about 20%. In these pores and cavities or on the surface of solid particles live a huge variety of microscopic creatures: bacteria, fungi, protozoa, roundworms, arthropods. Larger animals make passages in the soil themselves.

Soil inhabitants

The entire soil is penetrated by plant roots. Soil depth is determined by the depth of root penetration and the activity of burrowing animals. It is no more than 1.5-2 m.

The air in soil cavities is always saturated with water vapor, its composition is enriched in carbon dioxide and depleted in oxygen. In this way, the living conditions in the soil resemble the aquatic environment. On the other hand, the ratio of water and air in soils is constantly changing depending on weather conditions. Temperature fluctuations are very sharp at the surface, but quickly smooth out with depth.

The main feature of the soil environment is the constant supply of organic matter, mainly due to dying plant roots and falling leaves. It is a valuable source of energy for bacteria, fungi and many animals, so soil is the most life-rich environment. Her hidden world is very rich and diverse.

Living organisms as a living environment.

Wide tapeworm