A story about aquatic habitats. Specific properties of water as a habitat

Water environment habitat characteristics and features, its inhabitants.

Habitat is an element of the world used by living organisms for existence.

It has certain conditions and factors to which organisms living in this area must adapt.

There are 4 types:

• Ground-air
• Soil
• Water
• Organismal

According to one theory, the first organisms formed 3.7 billion years ago, according to another - 4.1 billion. The first forms of life appeared in water. The Earth's surface is 71% covered with water, which is very important for life on the planet as a whole.

Without water, plants and animals cannot exist. This is an amazing liquid that can exist in three stays. Water is part of everything; a certain percentage of it is contained in the atmosphere, soil and living organisms, minerals, and affects weather and climate.

She has the ability to store thermal energy, due to which there are no sudden temperature changes in coastal areas.

Characteristic

The aquatic environment has limited resources of both light and oxygen. The amount of air can be replenished mainly through photosynthesis. The oxygen level directly depends on the depth of the water column, because... light does not penetrate below 270 meters. It is there that red algae grow, absorbing the scattered rays of the sun and converting them into oxygen. Due to pressure at different depths, organisms can live at certain levels.

Inhabitants and animals

What creatures live in water are greatly influenced by:

• water temperature, its acidity and density;
• mobility (ebb and flow);
• mineralization;
• light mode;
• gas mode (percentage of oxygen content).

A huge variety of representatives of various species of animals and plants live in the aquatic environment. Mammals can live both on land and in water. Among freshwater animals, we can distinguish such as the hippopotamus, which uses water for cooling purposes, Amazonian dolphin, living in the beds of the Amazon River, is a manatee that can live in both salt and fresh waters.

TO marine mammals include whales, the largest animals on the planet, polar bears, which do not spend all their lives in water, but a significant part; sea ​​lions, going ashore for recreation.

Among freshwater amphibians, various species can be distinguished: newts; salamanders; frogs; worms, crayfish, lobsters, and many others. Amphibians do not live in salt water due to the fact that their eggs die even in slightly salty waters, and amphibians live in the same place where they breed, although there are exceptions to the rules.

Also, frogs cannot live in salt water due to the fact that they have very thin skin, and the salts draw moisture from the amphibian, as a result of which it dies. Reptiles inhabit both fresh and salt waters. Some species of lizards, snakes, crocodiles and turtles live there and have adapted to this environment.

aquatic plants photo

For fish, the aquatic environment is their home. They can live in salty or fresh water. Many insects such as mosquitoes, dragonflies, water striders, water spiders and the like live in aquatic environments.

There are also a large number of plants present here. In freshwater bodies of water, lake reeds (along swampy shores), water lilies (swamps, ponds, creeks), and calamus (in shallow waters) grow. In salt water, algae and sea grasses (Posidonia, eelgrass) mostly grow.

Organisms of the aquatic environment

In addition to multicellular animals, simple unicellular animals also live in water. Plankton or “wandering” cannot move independently. That is why it is carried by the currents of both salt and fresh water bodies. The concept of plankton includes plants (phytoplankton) living on the surface for the sake of sunlight and animals (zooplankton) living throughout the water column. There are also amoebas, single-celled loners that live wherever there is water.

The habitat of organisms is constantly exposed to various changing factors. Organisms are capable of reflecting environmental parameters. During historical development Three habitats were developed by living organisms. Water is the first of them. Life originated in it and developed over millions of years. Ground-air is the second environment in which animals and plants arose and adapted. Gradually transforming the lithosphere, which is the top layer of land, they created soil, which became the third habitat.

Each type of individual living in a certain environment is characterized by its own type of energy and metabolism, the preservation of which is important for its normal development. When the state of the environment threatens the body with an imbalance in the metabolism of energy and substances, the body either changes its position in space or transfers itself to a more favorable conditions, or changes metabolic activity.

Aquatic habitat

Not all factors play an equal role in the life of aquatic organisms. According to this principle, they can be divided into primary and secondary. The most important of them are the mechanical and dynamic characteristics of bottom soil and water, temperature, light, suspended and dissolved substances in water, and some others.

Aquatic environmental factors

Aquatic habitats, the so-called hydrosphere, occupy up to 71% of the entire planet's area. The volume of water is almost 1.46 billion cubic meters. km. Of these, 95% are the World Ocean. consists of glacial (85%) and underground (14%). Lakes, ponds, reservoirs, swamps, rivers and streams occupy a little more than 0.6% of total number fresh water, 0.35% is contained in soil moisture and atmospheric vapor.

The aquatic habitat is inhabited by 150 thousand species of animals (which is 7% of all living creatures on Earth) and 10 thousand species of plants (8%).

Near the equator and tropical zones The world of animals and plants is the most diverse. When moving away from these belts in the northern and southern directions high-quality composition aquatic organisms are becoming poorer. Organisms of the World Ocean are concentrated mainly near the coast. Life is practically absent in open waters located far from the coast.

Properties of water

Determine the vital activity of living organisms in it. Among them, thermal properties are primarily important. These include high heat capacity, low thermal conductivity, high latent heat of evaporation and melting, and the property of expansion before freezing.

Water is an excellent solvent. In a dissolved state, all consumers absorb inorganic and organic matter. The aquatic habitat facilitates the transport of substances within organisms; breakdown products are also released with water.

High water holds living and inanimate objects and fills capillaries, due to which land plants feed.

Water clarity promotes photosynthesis great depths.

Ecological groups of organisms in the aquatic environment

• Benthos are those organisms that are attached to the ground, lie on it or live in the sediment (phytobenthos, bacteriobenthos and zoobenthos).
• Periphyton - animals and plants that are attached or held to the stems and leaves of plants or to any surfaces that rise above the bottom and float with the flow of water.
• Plankton are free-floating plant or animal organisms.
• Nekton are actively swimming organisms with streamlined body shapes, not connected to the bottom (squids, pinnipeds, etc.).
• Neuston - microorganisms, plants and animals that live at the surface of the water between the aquatic and air environment. These are bacteria, protozoa, algae, larvae.
• Plaiston is aquatic organisms that are partly found in water and partly above its surface. These are swallowtails, siphonophores, duckweed and arthropods.

The inhabitants of rivers are called potambionts.

Aquatic habitats are characterized by unique living conditions. The distribution of organisms is greatly influenced by temperature, light, water currents, pressure, dissolved gases and salts. Living conditions in sea and continental waters are sharply different. is a more favorable environment, close to Continental waters are less favorable for their inhabitants.

According to the majority of authors studying the origin of life on Earth, the evolutionarily primary environment for life was the aquatic environment. We find a lot of indirect confirmation of this position. First of all, most organisms are not capable of active life without water entering the body or, at least, without maintaining a certain fluid content inside the body. The internal environment of the organism, in which the main physiological processes occur, obviously still retains the features of the environment in which the evolution of the first organisms took place. Thus, the salt content in human blood (maintained at a relatively constant level) is close to that in ocean water. The properties of the aquatic oceanic environment largely determined the chemical and physical evolution of all forms of life. Perhaps the main distinguishing feature of the aquatic environment is its relative conservatism. For example, the amplitude of seasonal or daily temperature fluctuations in the aquatic environment is much smaller than in the land-air environment. Bottom topography, differences in conditions at different depths, the presence of coral reefs, etc. create a variety of conditions in the aquatic environment. Features of the aquatic environment stem from physical and chemical properties water. Thus, the high density and viscosity of water are of great environmental importance. Specific gravity water is comparable to that of the body of living organisms. The density of water is approximately 1000 times higher than the density of air. Therefore, aquatic organisms (especially actively moving ones) encounter a large force of hydrodynamic resistance. For this reason, the evolution of many groups of aquatic animals went in the direction of the formation of body shapes and types of movement that reduce drag, which leads to a decrease in energy costs for swimming. Thus, a streamlined body shape is found in representatives of various groups of organisms living in water - dolphins (mammals), bony and cartilaginous fish. The high density of water is also the reason that mechanical vibrations propagate well in the aquatic environment. This was of great importance in the evolution of sensory organs, spatial orientation and communication between aquatic inhabitants. The speed of sound in the aquatic environment, four times greater than in air, determines the higher frequency of echolocation signals. Due to the high density of the aquatic environment, its inhabitants are deprived of the obligatory connection with the substrate, which is characteristic of terrestrial forms and is associated with the forces of gravity. Therefore, there is a whole group of aquatic organisms (both plants and animals) that exist without an obligatory connection with the bottom or other substrate, “floating” in the water column. Electrical conductivity opened up the possibility of the evolutionary formation of electrical sense organs, defense and attack.

Question 7. Ground-air environment of life. The ground-air environment is characterized by a huge variety of living conditions, ecological niches and organisms inhabiting them. It should be noted that organisms play a primary role in shaping the conditions of the land-air environment of life, and above all, the gas composition of the atmosphere. Almost all the oxygen in the earth's atmosphere is of biogenic origin. The main features of the ground-air environment are the large amplitude of changes in environmental factors, the heterogeneity of the environment, the action of gravitational forces, and low air density. A complex of physical-geographical and climatic factors characteristic of a certain natural zone leads to the evolutionary formation of morphophysiological adaptations of organisms to life in these conditions, a diversity of life forms. The high oxygen content in the atmosphere (about 21%) determines the possibility of the formation of a high (energy) level metabolism. The atmospheric air is characterized by low and variable humidity. This circumstance largely limited (limited) the possibilities of mastering the ground-air environment, and also directed the evolution of water-salt metabolism and the structure of the respiratory organs.

Question 8. Soil as a living environment . Soil is the result of the activity of living organisms. The organisms that populated the ground-air environment led to the emergence of soil as a unique habitat. Soil is a complex system including a solid phase (mineral particles), a liquid phase (soil moisture) and a gaseous phase. The relationship between these three phases determines the characteristics of the soil as a living environment. An important feature of the soil is also the presence of a certain amount of organic matter. It is formed as a result of the death of organisms and is part of their excreta (secretions). Conditions soil environment habitats are determined by such soil properties as its aeration (that is, saturation with air), humidity (presence of moisture), heat capacity and thermal regime (daily, seasonal, annual temperature variations). The thermal regime, in comparison with the ground-air environment, is more conservative, especially on great depth. In general, the soil has fairly stable living conditions. Vertical differences are also characteristic of other soil properties, for example, light penetration naturally depends on depth. Many authors note the intermediate position of the soil living environment between aquatic and ground-air environment. Soil can harbor organisms that have both aquatic and airborne respiration. The vertical gradient of light penetration in soil is even more pronounced than in water. Microorganisms are found throughout the entire thickness of the soil, and plants (primarily root systems) are associated with external horizons. Soil organisms are characterized by specific organs and types of movement (burrowing limbs in mammals; the ability to change body thickness; the presence of specialized head capsules in some species); body shape (round, volcanic, worm-shaped); durable and flexible covers; reduction of eyes and disappearance of pigments. Among soil inhabitants, saprophagy is widely developed - eating the corpses of other animals, rotting remains, etc.

HABITAT AND THEIR CHARACTERISTICS

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

Water covers 71% of the earth's area. The bulk of water is concentrated in the seas and oceans - 94-98%, in polar ice contains about 1.2% 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 only 7 and 8% of the world's population, respectively. total number species of the Earth.

In the seas-oceans, as in the mountains, vertical zoning is expressed. The pelagic - the entire water column - and the benthic - the bottom - differ especially greatly in ecology. The water column, the pelagic zone, is vertically divided into several zones: epipeligal, bathypeligal, abyssopeligal and ultraabyssopeligal(Fig. 2).

Greatest variety Life is distinguished by warm seas and oceans (40,000 species of animals) in the equator and tropics; to the north and south, the flora and fauna of the seas is 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 life are divided into three environmental 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 a 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 is located plaiston - these are organisms in which top part The body grows above water, and the lower one grows in water (duckweed - Lemma, siphonophores, etc.). Plankton plays important role in the trophic connections of the biosphere, because is food for many aquatic life, 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, mollusks, 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. Rocky areas of the bottom are richest in phytobenthos.

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 ground temperatures, water temperature has smaller 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. Since the temperature regime in reservoirs is relatively stable, their inhabitants tend to stenothermicity.

Due to to varying degrees warming up the upper and lower layers Throughout the year, the ebb and flow of tides, currents, and storms constantly mix the water layers. The role of water mixing for aquatic inhabitants is extremely important, because at the same time, the distribution of oxygen and nutrients within reservoirs is equalized, ensuring metabolic processes between organisms and the environment.

In stagnant bodies of water (lakes) temperate latitudes In spring and autumn, vertical mixing takes place, and during these seasons the temperature throughout the entire reservoir becomes uniform, i.e. comes homothermy. In summer and winter, as a result of a sharp increase in heating or cooling of the upper layers, the mixing of water stops. This phenomenon is called temperature dichotomy, and the period of temporary stagnation is stagnation(summer or winter). In summer, lighter warm layers remain on the surface, located above heavy cold ones (Fig. 3). In winter, on the contrary, in the bottom layer there is more warm water, since directly under the ice the temperature 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.

During periods of stagnation, three layers are clearly distinguished: the upper (epilimnion) with the most dramatic seasonal fluctuations in water temperature, the middle (metalimnion or thermocline), in which there is a sharp jump in temperature, and bottom ( hypolimnion), in which the temperature varies 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 absorption of light is stronger, the lower the transparency of the water, which depends on the number of particles suspended in it (mineral suspensions, plankton). It decreases with rapid development small organisms in summer, and in temperate and northern latitudes– also in winter, after the ice cover has been established and covered with snow on top.

Transparency is characterized by the maximum depth at which a specially lowered white disk with a diameter of about 20 cm (Secchi disk) is still visible. The most clear waters- in the Sargasso Sea: the disk is visible to a depth of 66.5 m. B Pacific Ocean the Secchi disk is visible up to 59 m, in the Indian Sea - up to 50 m, in shallow seas - up to 5-15 m. The transparency of rivers is on average 1-1.5 m, and in the most muddy rivers just a few centimeters.

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 from different parts of the 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 adapted to the lack of light by developing large chromatophores, as well as 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.

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. In the dark depths of the ocean, organisms use light emitted by living beings as a source of visual information. bioluminescence.

High density(1 g/cm3, which is 800 times the density of air) and water viscosity ( 55 times higher than that of air) led to the development of special adaptations of aquatic organisms :

1) Plants have very poorly developed or completely absent mechanical tissues - they are supported by water itself. 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.

2) In animals living in the water column and actively swimming, the body has a streamlined shape and is lubricated with mucus, which reduces friction when moving. Developed devices to increase buoyancy: accumulations of fat in tissues, swim bladders in fish, air cavities in siphonophores. In passively swimming animals, the specific surface area of ​​the body increases due to outgrowths, spines, and appendages; the body is flattened, and skeletal organs are reduced. Different ways locomotion: bending of the body, with the help of flagella, cilia, reactive mode of locomotion ( cephalopods).

In benthic animals, the skeleton disappears or is poorly developed, body size increases, vision reduction is common, and tactile organs develop.

Currents. A characteristic feature of the aquatic environment is mobility. It is caused by ebbs and flows, sea currents, storms, at different levels elevation marks of river beds. Adaptations of hydrobionts:

1) In flowing reservoirs, plants are firmly attached to stationary underwater objects. The bottom surface is primarily a substrate for them. These are green and diatoms, water mosses. Mosses even form a dense cover on fast riffles of rivers. In the tidal zone of the seas, many animals have devices for attaching to the bottom ( gastropods, barnacles), or hide in crevices.

2) In fish of running waters, the body is round in diameter, and in fish that live near the bottom, as in benthic invertebrate animals, the body is flat. Many have attachment organs to underwater objects on the ventral side.

Salinity of water.

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 ‰ (and about 80% are carbonates), in the seas - from 12 to 35 ‰ (mainly chlorides and sulfates). When the salinity is more than 40 ppm, the water body is called hypersaline or oversaline.

1) 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.

2) Aquatic plants are able to absorb water and nutrients from 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.

Typically maritime and typically freshwater species– stenohaline, do not tolerate significant changes in water salinity. There are few euryhaline species. They are common in brackish waters (freshwater pike perch, pike, bream, mullet, coastal salmon).

5th grade biology report on the topic of an organism’s habitat

Answers:

Each organism lives in a specific environment. Everything that surrounds Living being, called the habitat. There are four main habitats on Earth that have been developed and inhabited by organisms. These are water, ground-air, soil and, finally, organisms (the environment formed by living organisms themselves). Each habitat has its own special living conditions to which organisms adapt. This explains the wide variety of living organisms on our planet. Water serves as a habitat for many organisms. From water they get everything they need for life.

Aquatic habitat.

Aquatic organisms are very diverse, but all their structural features and adaptations are determined by physical and chemical properties waterWater has a buoyant force. This property allows many organisms to float in the water column. These include both small plants and animals, and fairly large organisms, such as jellyfish. Active swimmers (fish, dolphins, whales, etc.) have a streamlined body shape, and their limbs are in the form of fins or flippers. Many aquatic organisms lead a sedentary or even attached lifestyle, for example, coral polyps. Water is able to accumulate and retain heat, so there are no such sharp temperature fluctuations in water as on land. Animals have populated the entire thickness of the water, right down to the deepest ocean depressions. Plants live only in the upper layers of water, where sunlight penetrates. The salt composition of water is of great importance for aquatic organisms.

You already know such concepts as “habitat” and “living environment”. You need to learn to distinguish them. What is “living environment”?

The living environment is a part of nature with a special set of factors, for existence in which different systematic groups organisms have formed similar adaptations.

There are four main environments of life on Earth: aquatic, ground-air, soil, and living organisms.

Water environment

The aquatic living environment is characterized by high density, special temperature, light, gas and salt regimes. Organisms that live in aquatic environments are called hydrobionts(from Greek hydor- water, bios- life).

Temperature regime of the aquatic environment

In water, the temperature changes less than on land, due to the high specific heat capacity and thermal conductivity of water. An increase in air temperature of 10 °C causes an increase in water temperature of 1 °C. With depth, the temperature gradually decreases. At great depths, the temperature regime is relatively constant (no higher than +4 °C). In the upper layers, daily and seasonal fluctuations are observed (from 0 to +36 °C). Since the temperature in the aquatic environment varies within a narrow range, most aquatic organisms require a stable temperature. Even small temperature deviations caused, for example, by enterprises discharging warm water are harmful to them. Wastewater. Hydrobionts that can exist under large temperature fluctuations are found only in small bodies of water. Due to the small volume of water in these reservoirs, significant daily and seasonal temperature changes are observed.

Light regime of the aquatic environment

There is less light in water than in air. Part sun rays is reflected from its surface, and part is absorbed by the water column.

A day under water is shorter than a day on land. In summer, at a depth of 30 m it is 5 hours, and at a depth of 40 m - 15 minutes. The rapid decrease of light with depth is associated with its absorption by water.

The boundary of the photosynthesis zone in the seas is at a depth of about 200 m. In rivers it ranges from 1.0 to 1.5 m and depends on the transparency of the water. The clarity of water in rivers and lakes is greatly reduced due to pollution by suspended particles. At a depth of more than 1500 m there is practically no light.

Gas regime of the aquatic environment

In the aquatic environment, the oxygen content is 20-30 times less than in air, so it is a limiting factor. Oxygen enters water due to photosynthesis of aquatic plants and the ability of air oxygen to dissolve in water. When water is stirred, the oxygen content in it increases. The upper layers of water are richer in oxygen than the lower layers. With oxygen deficiency, death occurs ( mass death aquatic organisms).

Aquatic habitat - hydrosphere

Winter freezes occur when bodies of water are covered with ice. Summer - when due high temperature water, the solubility of oxygen decreases. The reason may also be an increase in the concentration of toxic gases (methane, hydrogen sulfide) formed during the decomposition of dead organisms without access to oxygen. Due to the variability of oxygen concentration, most aquatic organisms are eurybionts in relation to it. But there are also stenobionts (trout, planaria, mayfly and caddisfly larvae) that cannot tolerate a lack of oxygen. They are indicators of water purity. Carbon dioxide dissolves in water 35 times better than oxygen, and its concentration in it is 700 times higher than in air. CO2 accumulates in water due to the respiration of aquatic organisms and the decomposition of organic residues. Carbon dioxide provides photosynthesis and is used in the formation of calcareous skeletons of invertebrates.

Salt regime of the aquatic environment

The salinity of water plays an important role in the life of aquatic organisms. Based on salt content, natural waters are divided into groups presented in the table:

In the World Ocean, salinity averages 35 g/l. The highest salt content is in salt lakes (up to 370 g/l). Typical inhabitants of fresh and salt waters are stenobionts. They cannot tolerate fluctuations in water salinity. There are relatively few eurybionts (bream, pike perch, pike, eel, stickleback, salmon, etc.). They can live in both fresh and salt water.

Adaptations of plants to life in water

All plants in the aquatic environment are called hydrophytes(from Greek hydor- water, phyton- plant). Only algae live in salt waters. Their body is not divided into tissues and organs. The algae adapted to changes in the composition of the solar spectrum depending on the depth by changing the composition of their pigments. When moving from the upper layers of water to the deep ones, the color of the algae changes in the sequence: green - brown - red (the deepest algae).

Green algae contain green, orange and yellow pigments. They are capable of photosynthesis under sufficiently high intensity sunlight. Therefore, green algae live in small fresh water bodies or in shallow sea waters. These include: spirogyra, ulotrix, ulva, etc. Brown algae, in addition to green, contain brown and yellow pigments. They are able to capture less intense solar radiation at a depth of 40-100 m. Representatives of brown algae are fucus and kelp, which live only in the seas. Red algae (porphyry, phyllophora) can live at depths of more than 200 m. In addition to green, they have red and blue pigments that can capture even slight light at great depths.

In fresh water bodies, in the stems of higher plants, it is poorly developed mechanical fabric. For example, if you remove a white water lily or a yellow water lily from the water, their stems droop and are not able to support the flowers in an upright position. They rely on water due to its high density. An adaptation to the lack of oxygen in water is the presence of aerenchyma (air-bearing tissue) in plant organs. Minerals are found in water, so conductive and root system. Roots may be absent altogether (duckweed, elodea, pondweed) or serve to anchor them in the substrate (cattail, arrowhead, chastuha). There are no root hairs on the roots. The leaves are often thin and long or heavily dissected. Mesophyll is not differentiated. The stomata of floating leaves are on the upper side, while those of leaves submerged in water are absent. Some plants are characterized by the presence of leaves different shapes(heterophily) depending on where they are located. Water lilies and arrowheads have different leaf shapes in water and in air.

Pollen, fruits and seeds of aquatic plants are adapted to dispersal by water. They have cork outgrowths or strong shells that prevent water from getting inside and rotting.

Adaptations of animals to life in water

In the aquatic environment animal world richer than vegetable. Thanks to their independence from sunlight, the animals populated the entire thickness of the water. By type of morphological and behavioral adaptations They are divided into the following ecological groups: plankton, nekton, benthos.

Plankton(from Greek planktos- soaring, wandering) - organisms that live in the water column and move under the influence of its current. These are small crustaceans, coelenterates, and the larvae of some invertebrates. All their adaptations are aimed at increasing the buoyancy of the body:

1. increase in body surface due to flattening and lengthening of the shape, development of outgrowths and bristles;
2. decrease in body density due to reduction of the skeleton, the presence of fat drops, air bubbles, and mucous membranes.

Nekton(from Greek nektos- floating) - organisms that live in the water column and lead an active lifestyle. Representatives of nekton are fish, cetaceans, pinnipeds, and cephalopods. They are able to resist the current by adapting to active swimming and reducing body friction. Active swimming is achieved through well-developed muscles. In this case, the energy of the ejected stream of water, bending of the body, fins, flippers, etc. can be used. Adaptation helps reduce body friction: streamlined body shape, elasticity skin, availability on
skin scales and mucus.

Benthos(from Greek benthos- depth) - organisms living at the bottom of a reservoir or in the thickness of the bottom soil.

Adaptations of benthic organisms are aimed at reducing buoyancy:

1. weighting of the body due to shells (mollusks), chitinized integuments (crayfish, crabs, lobsters, lobsters);
2. fixation on the bottom with the help of fixation organs (suction cups in leeches, hooks in caddisfly larvae) or a flattened body (stingrays, flounder). Some representatives burrow into the ground (polychaete worms).

In lakes and ponds, another ecological group of organisms is identified - neuston. Neuston- organisms associated with the surface film of water and living permanently or temporarily on this film or up to 5 cm in depth from its surface. Their body is not wetted because its density is less than that of water. Specially designed limbs allow them to move along the surface of the water without plunging (water strider bugs, spinning beetles). A unique group of aquatic organisms is also periphyton— organisms that form a fouling film on underwater objects. Representatives of periphyton are: algae, bacteria, protists, crustaceans, bivalves, oligochaete worms, bryozoans, sponges.

There are four main living environments on planet Earth: aquatic, land-air, soil and living organisms. In the aquatic environment, oxygen is the limiting factor. Based on the nature of their adaptations, aquatic inhabitants are divided into ecological groups: plankton, nekton, and benthos.

Minsk Educational Institution “Gymnasium No. 14”

Abstract on biology on the topic:

“ WATER - HABITAT”

Prepared by a student of grade 11 “B”

Maslovskaya Evgenia

Teacher:

Bulva Ivan Vasilievich

1. Aquatic habitat – hydrosphere.

2. Water – unique environment.

3. Ecological groups of hydrobionts.

4. Modes.

5. Specific adaptations of hydrobionts.

6. Filtration as a type of nutrition.

7. Adaptation to life in drying up water bodies.

8. Conclusion.

1. Aquatic environment - hydrosphere

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. Water covers 71% of the area globe and makes up 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. These relationships are constant, although in nature the water cycle continues without ceasing (Fig. 1).

About 150,000 species of animals and 10,000 plants live in aquatic environments, representing only 7 and 8% of the total number of species on Earth, respectively. Based on this, it was concluded that evolution on land was much more intense than in water.

In the seas-oceans, as in the mountains, vertical zoning is expressed. The pelagic - the entire water column - and the benthic - the bottom - differ especially greatly in ecology.

The water column, the pelagial, is vertically divided into several zones: epipeligal, bathypeligal, abyssopeligal and ultraabyssopeligal (Fig. 2).

Depending on the steepness of the descent and the depth at the bottom, several zones are also distinguished, which correspond to the indicated pelagic zones:

- littoral - the edge of the coast, flooded during high tides.

- supralittoral - the part of the coast above the upper tidal line, where the surf splashes reach.

- sublittoral - a gradual decrease in land to 200m.

- bathyal - steep depression of land (continental slope),

- abyssal - a gradual decrease in the bottom of the ocean floor; the depth of both zones together reaches 3-6 km.

- ultra-abyssal - deep-sea depressions from 6 to 10 km.

2. Water is a unique environment.

Water is a completely unique medium in many respects. The water molecule, consisting of two hydrogen atoms and one oxygen atom, is surprisingly stable. Water is a unique compound that exists simultaneously in gaseous, liquid and solid states.

Water is not only a life-giving source for all animals and plants on Earth, but is also a habitat for many of them. These include, for example, numerous species fish, including crucian carp, inhabiting the rivers and lakes of the region, as well as aquarium fish in our homes. As you can see, they feel great among aquatic plants. Fish breathe through gills, extracting oxygen from the water. Some fish species, such as macropods, breathe atmospheric air, so they periodically rise to the surface.

Water is the habitat of many aquatic plants and animals. Some of them spend their entire lives in water, while others are in the aquatic environment only at the beginning of their lives. You can verify this by visiting a small pond or swamp. In the water element you can find the smallest representatives - single-celled organisms, which require a microscope to view. These include numerous algae and bacteria. Their number is measured in millions per cubic millimeter of water.

Other interesting property water consists in acquiring a very dense state at a temperature above the freezing level; for fresh water, these parameters are 4 °C and 0 °C, respectively.

Water as a habitat (page 1 of 3)

This is critical for the survival of aquatic organisms during the winter. Thanks to this same property, ice floats on the surface of the water, forming a protective layer on lakes, rivers and coastal areas. And this same property contributes to the thermal stratification of water layers and the seasonal turnover of water masses in lakes in areas with cold climates, which is very important for the life of aquatic organisms. The density of water provides the ability to lean on it, which is especially important for non-skeletal forms. The support of the environment serves as a condition for soaring in water, and many hydrobionts are adapted precisely to this way of life. Suspended organisms floating in water are combined into a special ecological group of aquatic organisms - plankton.

Completely purified water exists only in laboratory conditions. Any natural water contains many different substances. In "raw water" this is mainly the so-called protective system or carbon dioxide complex, consisting of salt carbonic acid, carbonate and bicarbonate. This factor allows you to determine the type of water - acidic, neutral or basic - based on its pH value, which from a chemical point of view means the proportion of hydrogen ions contained in the water. Neutral water has a pH=7, lower values ​​indicate increased acidity water, and higher levels - because it is alkaline. In limestone areas, the water of lakes and rivers usually has higher pH values ​​compared to reservoirs in places where the limestone content in the soil is insignificant

If the water of lakes and rivers is considered fresh, then sea ​​water called salty or brackish. There are many intermediate types between fresh and salt water.

3. Ecological groups of hydrobionts.

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) are 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) is a collection of plants (phytoplankton: diatoms, green and blue-green (fresh water bodies only) algae, plant flagellates, peridinea, etc.) and small animal organisms (zooplankton: small crustaceans, of the larger ones - pteropods, jellyfish, ctenophores, some worms), living at different depths, but not capable of active movement and resistance to currents. Plankton also includes animal larvae, forming a 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) – hydrobionts of the bottom. 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. Found along the coasts flowering plants zoster, rupee. 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 zones, 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 the altitude gradient than on land.

4. Modes.

Temperature reservoirs are more stable than on land. It's connected with physical properties water, primarily high specific heat capacity, due to which the receipt or release significant amount heat does not cause too sudden changes in temperature. Amplitude annual fluctuations temperatures in the upper layers of the ocean are no more than 10-150C, in continental waters - 30-350C. Deep layers of water are characterized by constant temperature. In equatorial waters average annual temperature surface layers +26...+270С, in polar layers - about 00С and below. Thus, there is quite a significant diversity in reservoirs temperature conditions. Between the upper layers of water with seasonal temperature fluctuations expressed in them and the lower ones, where the thermal regime is constant, there is a zone of temperature jump, or thermocline. The thermocline is more pronounced in warm seas, where the temperature difference between external and deep waters is stronger.

Due to the more stable temperature regime of water, stenothermy is common among aquatic organisms to a much greater extent than among the land population. Eurythermal species are found mainly in shallow continental reservoirs and in the littoral zone of seas of high and temperate latitudes, where daily and seasonal temperature fluctuations are significant.