In an aquatic environment, living organisms can breathe. Features of the aquatic living environment
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 aquatic environment are suspended and unable to withstand 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 water makes a filtration type of nutrition possible, i.e., filtering, 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 high density 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. great depths there are no plants, and deep-water animals live in complete darkness.
The temperature regime in reservoirs is milder than on land. Because of high heat capacity 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 polluted or heated. Therefore, there are sometimes death in reservoirs - mass death 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 - 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 contains a lot of oxygen, a lot of light, more sudden changes temperatures in time and space, pressure differences are much weaker and moisture deficiency often occurs. Although many species can fly, small insects, spiders, microorganisms, seeds and spores of plants are carried by air currents, feeding and reproduction of organisms occurs on the surface of the earth or plants. In such a low-density environment as air, organisms need support. Therefore land plants mechanical tissues are developed, and in terrestrial animals the internal or external skeleton is more pronounced than in 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 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, appropriate behavior also contributes to maintaining water balance. 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 others also play an important role in the life of terrestrial organisms. environmental factors, such as air composition, winds, terrain 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.
The soil is thin layer 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 particles can also inhabit the soil. aquatic organisms. 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 cases - 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
Within the biosphere we can distinguish four main habitats. These are the aquatic environment, the terrestrial air environment, the soil and the environment formed by living organisms themselves.
Water environment
Water serves as a habitat for many organisms. From water they obtain all the substances necessary for life: food, water, gases. Therefore, no matter how diverse aquatic organisms are, they all must be adapted to the main features of life in the aquatic environment. These features are determined by physical and chemical properties water.
Hydrobionts (inhabitants of the aquatic environment) live in both fresh and salt water and are divided into \(3\) groups according to their habitat:
- plankton - organisms living on the surface of water bodies and passively moving due to the movement of water;
- nekton - actively moving in the water column;
- benthos - organisms that live at the bottom of reservoirs or burrow into silt.
Many small plants and animals constantly hover in the water column, living in a suspended state. The ability to soar is ensured not only by the physical properties of water, which has a buoyant force, but also special devices the organisms themselves, for example, by numerous outgrowths and appendages, significantly increasing the surface of their body and, therefore, increasing friction with the surrounding fluid.
The body density of animals such as jellyfish is very close to that of water.
Moreover, their characteristic body shape, reminiscent of a parachute, helps them stay in the water column.
Active swimmers (fish, dolphins, seals, etc.) have a spindle-shaped body and limbs in the form of flippers.
Their movement in the aquatic environment is facilitated, in addition, due to the special structure of the outer covers, which secrete a special lubricant - mucus, which reduces friction with water.
Water has a very high heat capacity, i.e. property of accumulating and retaining heat. For this reason, there are no sharp temperature fluctuations in water, which often occur on land. Very deep waters can be very cold, but thanks to the constant temperature, animals have been able to develop a number of adaptations that ensure life even in these conditions.
Animals can live at vast ocean depths. Plants survive only in the upper layer of water, where the radiant energy necessary for photosynthesis enters. This layer is called photic zone .
Since the surface of the water reflects most of the light, even in the most transparent ocean waters the thickness of the photic zone does not exceed \(100\) m. Animals of great depths feed either on living organisms or the remains of animals and plants that constantly fall down from the upper layer.
Like terrestrial organisms, aquatic animals and plants breathe and require oxygen. The amount of oxygen dissolved in water decreases with increasing temperature. Moreover, oxygen dissolves less well in sea water than in fresh water. For this reason water open sea The tropical zone is poor in living organisms. And, on the contrary, polar waters are rich in plankton - small crustaceans on which fish and large cetaceans feed.
The salt composition of water is very important for life. The \(Ca2+\) ions are of particular importance for organisms. Clams and crustaceans need calcium to build their shells or shells. The concentration of salts in water can vary greatly. Water is considered fresh if one liter contains less than \(0.5\) g of dissolved salts. Sea water It is characterized by constant salinity and contains on average \(35\) g of salts per liter.
Ground air environment
The terrestrial air environment, mastered in the course of evolution later than the aquatic environment, is more complex and diverse, and it is inhabited by more highly organized living organisms.
The most important factor in the life of the organisms living here are the properties and composition of the surrounding air masses. The density of air is much lower than the density of water, so terrestrial organisms have highly developed supporting tissues - the internal and external skeleton. The forms of movement are very diverse: running, jumping, crawling, flying, etc. Birds and some types of insects fly in the air. Air currents carry plant seeds, spores, and microorganisms.
Air masses are constantly in motion. Air temperature can change very quickly and over large areas, so organisms living on land have numerous adaptations to withstand or avoid sudden changes in temperature.
The most remarkable of them is the development of warm-bloodedness, which arose precisely in the terrestrial air environment.
Important for the life of plants and animals chemical composition air (\(78%\) nitrogen, \(21%\) oxygen and \(0.03%\) carbon dioxide). Carbon dioxide, for example, is the most important raw material for photosynthesis. Air nitrogen is necessary for the synthesis of proteins and nucleic acids.
The amount of water vapor in the air ( relative humidity) determines the intensity of transpiration processes in plants and evaporation from the skin of some animals. Organisms living in low humidity conditions have numerous adaptations to prevent severe water loss. So, for example, at desert plants powerful root system capable of sucking water into the plant great depth. Cacti store water in their tissues and use it sparingly. In many plants, to reduce evaporation leaf blades turned into thorns. Many desert animals hibernate during the hottest period, which can last for several months.
The soil - This upper layer land transformed as a result of the activity of living beings. This is an important and very complex component of the biosphere, closely connected with its other parts. Soil life is unusually rich. Some organisms spend their entire lives in the soil, others spend part of their lives. Between the soil particles there are numerous cavities that can be filled with water or air. Therefore, the soil is inhabited by both aquatic and air-breathing organisms. Soil plays a huge role in plant life.
Living conditions in the soil are largely determined by climatic factors, the most important of which is temperature. However, as one goes deeper into the soil, temperature fluctuations become less and less noticeable: daily temperature changes quickly fade, and as the depth increases, seasonal temperature changes also fade away.
Even at shallow depths, complete darkness reigns in the soil. In addition, as you sink into the soil, the oxygen content decreases and the carbon dioxide content increases. Therefore, only anaerobic bacteria can live at a considerable depth, while in the upper layers of the soil, in addition to bacteria, fungi, protozoa, roundworms, arthropods and even relatively large animals that make passages and build shelters, for example moles, shrews, mole rats.
The environment formed by living organisms themselves
It is obvious that the living conditions inside another organism are characterized by greater constancy compared to the conditions of the external environment.
Therefore, organisms that find a place in the body of plants or animals often completely lose the organs and systems necessary for free-living species. They do not have developed sensory organs or organs of movement, but they develop adaptations (often very sophisticated) for retention in the host’s body and effective reproduction.
Sources:
Kamensky A.A., Kriksunov E.A., Pasechnik V.V. Biology. 9th grade // Bustard
Kamensky A.A., Kriksunov E.A., Pasechnik V.V. Biology. General biology(basic level) 10-11 grade // Bustard
Question 1. Name the main features of the life of organisms in the aquatic environment, in the ground-air environment, and in the soil.
The characteristics of the life of organisms in the aquatic environment, the ground-air environment and in the soil are determined by the physical and chemical properties of these living environments. These properties have a significant impact on the action of other factors inanimate nature- stabilize seasonal temperature fluctuations (water and soil), gradually change illumination (water) or completely eliminate it (soil), etc.
The hydrosphere, or the water shell of the Earth, makes up about 70% of the Earth's surface. Largest reserves waters are concentrated in the World Ocean (up to 95%), the remaining 5% are in fresh water bodies (lakes, rivers, etc.). A huge number of living organisms live in water, and their typical diversity is much higher than on land. State of the hydrosphere - most important factor, which determines the climatic conditions of various geographical areas. Water is a dense medium compared to air, which has a buoyant force and is good solvent. Therefore, many organisms living in water are characterized by poor development of supporting tissues (aquatic plants, protozoa, coelenterates, etc.), special methods of movement (hovering, jet propulsion), features of respiration and adaptations to maintain constant osmotic pressure in the cells that form their bodies.
The atmosphere, or the gas envelope of the Earth, consists of a mixture of gases: nitrogen, oxygen, carbon dioxide, ozone and inert gases. The atmosphere has a huge impact on physical, chemical and biological processes on the surface of the earth and in the aquatic environment: oxygen is necessary for all living organisms to breathe; carbon dioxide is a source of carbon during photosynthesis and chemosynthesis; Nitrogen, as a result of the activity of nitrogen-fixing bacteria, is converted into nitrates, which are absorbed by plants. The density of air is much lower than the density of water, so terrestrial organisms have highly developed supporting tissues - the internal and external skeleton.
Lithosphere - hard shell Earth - includes earth's crust And top part mantle. Life in the lithosphere is mainly concentrated in its upper fertile layer - the soil, the depth of which does not exceed several meters. In the structure of the soil, several horizons are distinguished (from top to bottom): the upper one, called the decline, the next - the humus layer, which ensures soil fertility, and the third, consisting mainly of a mixture of sand and clay.
Soil is the top layer of land transformed as a result of the activity of living beings. Between the soil particles there are numerous cavities that can be filled with water or air. Therefore, the soil is inhabited by both aquatic and air-breathing organisms.
Question 2. What adaptations have organisms developed for living in an aquatic environment?
The aquatic environment is denser than the air, which determines adaptations to movement in it. Active movement in water requires a streamlined body shape and well-developed muscles (fish, cephalopods - squid, mammals - dolphins, seals).
Planktonic organisms (floating in water) have adaptations that increase their buoyancy, such as increasing the relative surface of the body due to numerous projections and setae; decrease in density due to the accumulation of fats and gas bubbles in the body (unicellular algae, protozoa, jellyfish, small crustaceans). Organisms living in an aquatic environment are also characterized by adaptations to maintain water-salt balance. Freshwater species have adaptations to remove excess water from the body. This is, for example, served by excretory vacuoles in protozoa. In salt water, on the contrary, it is necessary to protect the body from dehydration, which is achieved by increasing the concentration of salts in the body.
Another way to maintain your water-salt balance is to move to places with a favorable salinity level.
And finally, the constancy of the body’s water-salt environment is ensured by water-impermeable integuments (mammals, higher crayfish, aquatic insects and their larvae).
Plants need light energy from the Sun to live, so aquatic plants live only at those depths where light can penetrate (usually no more than 100 m). With increasing depth of habitat in plant cells, the composition of pigments that take part in the process of photosynthesis changes, which makes it possible to capture parts of the solar spectrum penetrating into the depths.
Question 3. How do organisms avoid the negative effects of low temperatures?
At low temperatures, there is a danger of metabolism stopping, so organisms have developed special adaptation mechanisms to stabilize it.
Plants are least adapted to sudden temperature fluctuations. When the temperature drops sharply below 0 °C, the water in the tissues can turn into ice, which can damage them. But plants are able to withstand small negative temperatures by binding free water molecules into complexes that are incapable of forming ice crystals (for example, by accumulating up to 20-30% sugars or fatty oils in cells). With a gradual decrease in temperature during seasonal climate changes, a period of dormancy begins in the life of many plants, accompanied by either partial or complete death of terrestrial vegetative organs (herbaceous forms), or a temporary cessation or slowdown of the main physiological processes - photosynthesis and transport of substances.
Animals have the most reliable protection Low ambient temperatures result in warm-bloodedness, but not everyone has it. The following ways of adaptation of animals to low temperatures: chemical, physical and behavioral thermoregulation.
Chemical thermoregulation is associated with an increase in heat production with decreasing temperature through the intensification of redox processes. This path requires expense large quantity energy, so animals in harsh climatic conditions need more food. This type of thermoregulation is carried out reflexively.
Many cold-blooded animals are capable of maintaining optimal temperature body due to the work of muscles. For example, in cool weather, bumblebees warm up their bodies by shivering to 32-33 °C, which gives them the opportunity to take off and feed.
Physical thermoregulation is associated with the presence in animals of special body coverings - feathers or hair, which, due to their structure, form air and environment, since it is known that air is an excellent heat insulator. In addition, many animals living in harsh climatic conditions accumulate subcutaneous fat, which also has thermal insulating properties.
Behavioral thermoregulation is associated with moving in space in order to avoid temperatures unfavorable for life, creating shelters, crowding into groups, changing activity in different time days or years.
Characteristics of the aquatic environment as the main environment of life. Properties of water. Ecological groups of aquatic plants. Adaptive features of aquatic plants. Zoning of the water environment.
Characteristics of the aquatic environment as the main living environment
In progress 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 is called the hydrosphere.
Water covers 71% of the area globe and is 1/800 of the land volume or 1370 m3. The bulk of water is concentrated in the seas and oceans - 94-98%, polar ice contains about 1.2% of water and a very small proportion - less than 0.5%, in fresh waters of rivers, lakes and swamps.
About 150,000 species of animals and 10,000 plants live in the aquatic environment, which is respectively only 7 and 8% of the total number of species on Earth. Based on this, it was concluded that evolution on land was much more intense than in water.
Properties of water
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.
In stagnant reservoirs (lakes) of temperate latitudes, vertical mixing takes place in spring and autumn, and during these seasons the temperature throughout the reservoir becomes uniform, i.e. homothermy occurs. In summer and winter as a result of a sharp increase in heating or cooling upper layers mixing of water stops. This phenomenon is called temperature dichotomy, and the period of temporary stagnation is called stagnation (summer or winter). In summer, lighter warm layers remain on the surface, located above heavy cold ones (Fig. 2).
Figure 2. Stratification and mixing of water in the lake (after E. Ponter et al. 1982)
In winter, on the contrary, there is warmer water in the bottom layer, since the temperature directly under the ice surface waters less than +4°C and, due to the physical and chemical properties of water, they become lighter than water with a temperature above +4°C.
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 spectrum are absorbed differently in water; red rays are absorbed first. With depth it becomes darker, and the color of the water first becomes green, then blue, indigo and finally blue-violet, turning into complete darkness. Hydrobionts also change color accordingly, adapting not only to the composition of light, but also to its lack - chromatic adaptation. In light zones, in shallow waters, green algae (Chlorophyta) predominate, the chlorophyll of which absorbs red rays, with depth they are replaced by brown (Phaephyta) and then red (Rhodophyta). At great depths, phytobenthos is absent.
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).
The characteristic properties of the aquatic environment, different from land, are high density, mobility, acidity, and the ability to dissolve gases and salts.
Water is characterized by high density ( 1 g/cm3, which is 800 times the density of air) and viscosity.
Plants have very poorly developed or completely absent mechanical tissues - they rely on water itself for support. Most are characterized by buoyancy due to air-carrying intercellular cavities. Characterized by active vegetative reproduction, the development of hydrochory - the removal of flower stalks above the water and the distribution of pollen, seeds and spores by surface currents.
A characteristic feature of the aquatic environment is mobility. It is caused by ebbs and flows, sea currents, storms, and different levels of elevations of river beds.
In flowing reservoirs, plants are firmly attached to stationary underwater objects. The bottom surface is primarily a substrate for them. These are green algae (Cladophora) and diatoms (Diatomeae), and aquatic mosses. Mosses even form a dense cover on fast river riffles.
Natural bodies of water have a certain chemical composition. Carbonates, sulfates, and chlorides predominate. In fresh water bodies, the salt concentration is no more than 0.5 g/l, in the seas - from 12 to 35 g/l (ppm - tenths of a percent). When the salinity is more than 40 ppm, the water body is called hypersaline or oversaline.
In fresh water (hypotonic environment), osmoregulation processes are well expressed. Hydrobionts are forced to constantly remove water penetrating into them; they are homoyosmotic (ciliates “pump” through themselves an amount of water equal to its weight every 2-3 minutes). In salt water (isotonic environment), the concentration of salts in the bodies and tissues of hydrobionts is the same (isotonic) with the concentration of salts dissolved in water - they are poikiloosmotic. Therefore, the inhabitants of salt water bodies do not have developed osmoregulatory functions, and they were unable to populate fresh water bodies.
Aquatic plants are able to absorb water and nutrients from the water - “broth”, with their entire surface, therefore their leaves are strongly dissected and conductive tissues and roots are poorly developed. The roots serve mainly for attachment to the underwater substrate. Most freshwater plants have roots.
In water, oxygen is the most important environmental factor. Its source is the atmosphere and photosynthetic plants. When water is mixed, especially in flowing reservoirs, and as the temperature decreases, the oxygen content increases. There is enough carbon dioxide in water - almost 700 times more than in air. It is used in plant photosynthesis.
In freshwater bodies of water, the acidity of water, or the concentration of hydrogen ions, varies much more than in sea waters - from pH = 3.7-4.7 (acidic) to pH = 7.8 (alkaline). The acidity of water is largely determined by the species composition of aquatic plants. Sphagnum mosses grow in the acidic waters of swamps. The acidity of sea water decreases with depth.
Question 1. Name the main features of the life of organisms in the aquatic environment, in the ground-air environment, and in the soil.
The characteristics of the life of organisms in the aquatic environment, the ground-air environment and in the soil are determined by the physical and chemical properties of these living environments. These properties have a significant impact on the action of other factors of inanimate nature - they stabilize seasonal temperature fluctuations (water and soil), gradually change illumination (water) or completely eliminate it (soil), etc.
Water is a dense medium compared to air, has a buoyant force and is a good solvent. Therefore, many organisms living in water are characterized by poor development of supporting tissues (aquatic plants, protozoa, coelenterates, etc.), special methods of movement (hovering, jet propulsion), and features of respiration and adaptation. We aim to maintain a constant osmotic pressure in the cells that form their bodies.
The density of air is much lower than the density of water, so terrestrial organisms have highly developed supporting tissues - the internal and external skeleton.
Soil is the top layer of land, transformed as a result of the vital activity of living beings. Between the soil particles there are numerous cavities that can be filled with water or air. Therefore, the soil is inhabited by both aquatic and air-breathing organisms.
Question 2. What adaptations have organisms developed for living in an aquatic environment?
The aquatic environment is denser than the air, which determines adaptations to movement in it.
For active movement in water, a streamlined body shape and well-developed muscles are required (fish, cephalopods - squid, mammals - dolphins, seals).
Planktonic organisms (floating in water) have adaptations that increase their buoyancy, such as increasing the relative surface of the body due to numerous projections and bristles; decrease in density due to the accumulation of fats and gas bubbles in the body (single-cell algae, protozoa, jellyfish, small crustaceans).
Organisms living in an aquatic environment are also characterized by adaptations to maintain water-salt balance. Freshwater species have adaptations to remove excess water from the body. This is, for example, served by excretory vacuoles in protozoa. In salt water, on the contrary, it is necessary to protect the body from dehydration, which is achieved by increasing the concentration of salts in the body.
Another way to maintain your water-salt balance is to move to places with a favorable level of salinity.
And finally, the constancy of the body’s water-salt environment is ensured by water-impermeable integuments (mammals, higher crayfish, aquatic insects and their larvae).
Plants need the light energy of the Sun to live, so aquatic plants live only at those depths where light can penetrate (usually no more than 100 m). With increasing depth of habitat in plant cells, the composition of pigments that take part in the process of photosynthesis changes, which makes it possible to capture parts of the solar spectrum penetrating into the depths.
Question 3. How do organisms avoid the negative effects of low temperatures?
At low temperatures, there is a danger of metabolism stopping, which is why organisms have developed special adaptation mechanisms to stabilize it.
Plants are least adapted to sudden temperature fluctuations. When the temperature drops sharply below 0°C, the water in the tissues can turn into ice, which can damage them. But plants are able to withstand small negative temperatures by binding free water molecules into complexes that are incapable of forming ice crystals (for example, by accumulating up to 20-30% sugars or fatty oils in cells).
With a gradual decrease in temperature in the process of seasonal climatic changes, a period of dormancy begins in the life of many plants, accompanied by either partial or complete death of terrestrial vegetative organs (herbaceous forms), or a temporary cessation or slowdown of the main physiological processes - photosynthesis and transport of substances.
In animals, the most reliable protection against low environmental temperatures is warm-bloodedness, but not all have it. The following ways of adaptation of animals to low temperatures can be distinguished: chemical, physical and behavioral thermoregulation.
Chemical thermoregulation is associated with an increase in heat production with a decrease in temperature through the intensification of redox processes. This path requires the expenditure of a large amount of energy, so animals in harsh climatic conditions need more food. This type of thermoregulation is carried out reflexively.
Many cold-blooded animals are able to maintain optimal body temperature through muscle work. For example, in cool weather, bumblebees warm up their bodies by shivering to 32-33 °C, which gives them the opportunity to take off and feed. Material from the site
Physical thermoregulation is associated with the presence in animals of special body coverings - feathers or hair, which, due to their structure, form air gap between the body and the environment, since it is known that air is an excellent heat insulator. In addition, many animals living in harsh climatic conditions accumulate subcutaneous fat, which also has thermal insulating properties.
Behavioral thermoregulation is associated with moving in space in order to avoid temperatures unfavorable for life, creating shelters, crowding into groups, changing activity at different times of the day or year.
Question 4. What are the main features of organisms that use the bodies of other organisms as a habitat?
The living conditions inside another organism are characterized by greater constancy compared to the conditions of the external environment, therefore organisms that find a place in the body of plants or animals often completely lose the organs and systems necessary for free-living species (sense organs, organs - movements, digestion, etc.), but at the same time they develop adaptations for retention in the host’s body (hooks, suction cups, etc.) and effective reproduction.
Didn't find what you were looking for? Use the search
On this page there is material on the following topics:
- 6.1. biosphere. living environment summary
- biosphere living environment test with answers
- features of living environments in comparison
- name the main features of the life of organisms in the aquatic environment, in the land-air environment, and soil
- characteristics of plants living in aquatic environments
