The main components of the habitat. Aquatic habitat. aquatic life aquatic habitat environmental conditions

Aquatic habitat characteristics and features, its inhabitants.

Habitat - 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
Organismic

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 the water. The surface of the Earth is 71% filled with water, which is very important for life on the planet as a whole.

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

It has the ability to store thermal energy, due to which there are no sharp temperature drops 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 index 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 the pressure at different depths, organisms can live at certain levels.

Inhabitants and animals

To what creatures live in the water, big influence provide:

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 lives in the aquatic environment. Mammals can live both on land and in water. From freshwater, one can distinguish such as the hippopotamus, which uses water for cooling purposes, the Amazonian dolphin, which lives in the channels of the Amazon River, and the manatee, which can live in both salt and fresh waters.

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

From freshwater amphibians, various types can be distinguished: newts; salamander; frogs; worm, crayfish, lobster, and many others. Amphibians do not live in salt water due to the fact that their eggs die even in slightly saline water bodies, and amphibians live in the same place where they breed, although there are exceptions to the rule.

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

aquatic plants photo

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

There are also a lot of plants here. In freshwater reservoirs, lake reeds grow (along marshy shores), water lilies (swamps, ponds, backwaters), and calamus (in shallow water). In salt water, for the most part, algae and sea grasses (Posidonia, eelgrass) grow.

Aquatic organisms

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 current of both salty and fresh water bodies. The concept of plankton includes both plants (phytoplankton) living on the surface for the sake of sunlight, and animals (zooplankton) living in the entire water column. There are also amoebas, single-celled loners that live wherever there is water.

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 - land-air - on land and in the atmosphere, plants and animals arose and rapidly adapted to new conditions. Gradually transforming the upper layer of land - the lithosphere, they created a third habitat - the 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% of water and a very small proportion - less than 0.5%, in the 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 total number of species on Earth, respectively.

In the seas-oceans, as in the mountains, vertical zonality is expressed. The pelagial - the entire water column - and the benthal - the bottom differ especially strongly in ecology. The water column is pelagial, vertically divided into several zones: epipeligial, bathypeligial, abyssopeligial and ultraabyssopeligial(Fig. 2).

The warmest seas and oceans (40,000 species of animals) are distinguished by the greatest diversity of life in the region of the equator and the tropics; to the north and south, the flora and fauna of the seas are depleted hundreds of times. As for the distribution of organisms directly in the sea, their bulk is concentrated in the surface layers (epipelagial) and in the sublittoral zone. Depending on the way of movement and stay in certain layers, Marine life 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 also includes amphibians and many insects.

Plankton (planktos - wandering, soaring) - a set of plants (phytoplankton: diatoms, green and blue-green (fresh water only) algae, plant flagellates, peridine, etc.) and small animal organisms (zooplankton: small crustaceans, from larger ones - pteropods mollusks, jellyfish, ctenophores, some worms), living at different depths, but not capable of active movement and resistance to currents. The composition of 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, pass into the lower layers of the pelagela. Above the neuston is located pleiston - these are organisms in which the upper part of the body grows above the water, and the lower part grows in the water (duckweed - Lemma, siphonophores, etc.). Plankton plays an important role in the trophic relationships of the biosphere, since is food for many aquatic life, including the main food for baleen whales (Myatcoceti).

Benthos (benthos - depth) - bottom hydrobionts. Represented mainly by attached or slowly moving animals (zoobenthos: foraminephores, fish, sponges, coelenterates, worms, molluscs, ascidians, etc.), more numerous in shallow water. Plants (phytobenthos: diatoms, green, brown, red algae, bacteria) also enter benthos in shallow water. At a depth where there is no light, phytobenthos is absent. The stony areas of the bottom are richest in phytobenthos.

Thermal regime. The aquatic environment is characterized by a lower heat input, because a significant part of it is reflected, and an equally significant part is spent on evaporation. Consistent with the dynamics of land temperatures, the water temperature has less fluctuations in daily and seasonal temperatures. Moreover, water bodies significantly equalize the course of temperatures in the atmosphere of coastal areas. In the absence of an ice shell, the sea in the cold season has a warming effect on the adjacent land areas, in summer it has a cooling and moisturizing effect.

The range of water temperatures in the World Ocean is 38° (from -2 to +36°C), in fresh water - 26° (from -0.9 to +25°C). The water temperature drops sharply with depth. Up to 50 m, daily temperature fluctuations are observed, up to 400 - seasonal, deeper it becomes constant, dropping to + 1-3 ° С. Since the temperature regime in reservoirs is relatively stable, their inhabitants are characterized by stenothermy.

Due to the different degree of heating of the upper and lower layers during the year, ebbs and flows, currents, storms, there is a constant mixing of the water layers. The role of mixing water for aquatic life is exceptionally great, because. at the same time, the distribution of oxygen and nutrients inside the reservoirs is leveled, providing metabolic processes between organisms and the environment.

In stagnant water bodies (lakes) temperate latitudes vertical mixing takes place in spring and autumn, and in these seasons the temperature in the entire reservoir becomes uniform, i.e. comes homothermy. In summer and winter, as a result of a sharp increase in warming or cooling upper layers water mixing stops. This phenomenon is called temperature dichotomy, and the period of temporary stagnation - stagnation(summer or winter). In summer, the lighter warm layers remain on the surface, being located above the heavy cold ones (Fig. 3). In winter, on the contrary, in the bottom layer more warm water, since the temperature of surface waters directly under the ice is less than + 4 ° С and they, by virtue of physical and chemical properties water becomes lighter than water with a temperature above +4°C.

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 there is a sharp jump in temperature, and near-bottom ( hypolimnion), in which the temperature varies little during the year. During periods of stagnation, oxygen deficiency is formed in the water column - in summer in the bottom part, and in winter in the upper part, as a result of which winter period fish kills often occur.

Light mode. The intensity of light in water is greatly attenuated 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 the stronger, the lower the transparency of water, which depends on the number of particles suspended in it (mineral suspensions, plankton). It decreases with the rapid development of small organisms in summer, and in temperate and northern latitudes it also decreases in winter, after the establishment of an ice cover and covering it with snow from above.

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 clearest waters are in the Sargasso Sea: the disk is visible to a depth of 66.5 m. pacific ocean the Secchi disk is visible up to 59 m, in the Indian - up to 50, in shallow seas- up to 5-15m. The transparency of rivers is on average 1-1.5 m, and in the most muddy rivers it is only 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 penetrate. Rays of 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 becomes green at first, then blue, blue and finally blue-violet, turning into complete darkness. Accordingly, hydrobionts also change color, 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). Phytobenthos is absent at great depths.

Plants have adapted to the lack of light by developing large chromatophores and by increasing the area of assimilating organs (leaf surface index). For deep-sea algae, strongly dissected leaves are typical, leaf blades are thin, translucent. For semi-submerged and floating plants, heterophylly is characteristic - the leaves above the water are the same as those of terrestrial plants, they have a whole plate, the stomatal apparatus is developed, and in the water the leaves are very thin, consist of narrow filiform lobes.

Animals, like plants, naturally change their color with depth. In the upper layers, they are brightly colored in 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 are devoid of pigments. In the dark depths of the ocean, organisms use the 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 the viscosity of water ( 55 times higher than that of air) led to the development of special adaptations of hydrobionts :

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-bearing intercellular cavities. Characterized by active vegetative reproduction, the development of hydrochoria - the removal of flower stalks above the water and the spread 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 during movement. Adaptations have been developed to increase buoyancy: accumulations of fat in tissues, swim bladders in fish, air cavities in siphonophores. In passively swimming animals, the specific surface of the body increases due to outgrowths, spines, and appendages; the body flattens, reduction of skeletal organs occurs. Different modes of locomotion: bending of the body, with the help of flagella, cilia, jet mode of locomotion (cephalopods).

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

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

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

2) In fish of flowing waters, the body is round in diameter, and in fish that live near the bottom, like in benthic invertebrates, the body is flat. Many on the ventral side have organs of fixation to underwater objects.

Salinity of water.

Natural water bodies are characterized by a certain chemical composition. Carbonates, sulfates, and chlorides predominate. In fresh water bodies, the salt concentration is not more than 0.5 ‰ (and about 80% are carbonates), in the seas - from 12 to 35 ‰ (mainly chlorides and sulfates). With a salinity of more than 40 ppm, the reservoir is called hyperhaline or oversalted.

1) In fresh water (hypotonic environment), the processes of osmoregulation are well expressed. Hydrobionts are forced to constantly remove the water penetrating into them, they are homoiosmotic (ciliates “pump” through themselves an amount of water equal to its weight every 2-3 minutes). In salt water (isotonic medium), 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, osmoregulatory functions are not developed among the inhabitants of salt water bodies, and they could not populate fresh water bodies.

2) Aquatic plants are able to absorb water and nutrients from the water - "broth", with the entire surface, therefore, their leaves are strongly dissected and conductive tissues and roots are poorly developed. The roots serve mainly to attach to the underwater substrate. Most fresh water plants have roots.

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

report on biology grade 5 on the topic of the habitat of the organism

Answers:

Every organism lives in a specific environment. Everything that surrounds a living being is called a habitat. There are four main habitats on Earth, developed and inhabited by organisms. These are water, land-air, soil and, finally, organisms (environment formed by living organisms themselves). Each habitat has its own special living conditions to which organisms adapt. This explains the great diversity of living organisms on our planet. Water serves as a habitat for many organisms. From the 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 water Water has buoyancy. 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 limbs in the form of fins or flippers. Many aquatic organisms lead a sedentary or even attached lifestyle, such as coral polyps. Water is able to accumulate and retain heat, so there are no such sharp temperature fluctuations in water as on land. Animals inhabited the entire water column, up to the deepest ocean trenches. Plants live only in the upper layers of water, where sunlight penetrates. Salt composition of water is of great importance for aquatic organisms..

You already know such concepts as "habitat" and "environment of life". You need to learn to distinguish between them. What is a "living environment"?

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

On Earth, four main environments of life can be distinguished: water, land-air, soil, living organism.

Water environment

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

Temperature regime of the aquatic environment

In water, the temperature changes to a lesser extent 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. The temperature gradually decreases with depth. At great depths, the temperature regime is relatively constant (not higher than +4 °C). In the upper layers there are daily and seasonal fluctuations (from 0 to +36 °C). Since the temperature in the aquatic environment varies within a narrow range, most hydrobionts require a stable temperature. For them, even small temperature deviations are detrimental, caused, for example, by the discharge of warm Wastewater. Hydrobionts that can exist at large fluctuations in temperature are found only in shallow water bodies. Due to the small volume of water in these reservoirs, significant daily and seasonal temperature fluctuations 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.

The day underwater is shorter than on land. In summer, at a depth of 30 m, it is 5 hours, and at a depth of 40 m, it is 15 minutes. The rapid decrease in light with depth is due to 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 transparency of water in rivers and lakes is greatly reduced due to pollution with 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 the air, so it is a limiting factor. Oxygen enters the water due to the photosynthesis of aquatic plants and the ability of atmospheric 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 ones. With oxygen deficiency, deaths are observed ( mass death aquatic organisms).

Aquatic habitat - hydrosphere

Winter freezes occur when water bodies are covered with ice. Summer - when due high temperature water reduces the solubility of oxygen. 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 in relation to it are eurybionts. But there are also stenobionts (trout, planaria, larvae of mayflies and caddis flies) 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. In water, CO2 accumulates due to the respiration of aquatic organisms, 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

Salinity of water plays an important role in the life of hydrobionts. According to the salt content, natural waters are divided into groups presented in the table:

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

Plant adaptations to life in water

All plants in the aquatic environment are called hydrophytes(from Greek. hydro- water, phyton- plant). Only algae live in salty waters. Their body is not divided into tissues and organs. Algae adapted to the change 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 with a sufficiently high intensity of sunlight. Therefore, green algae live in small fresh water bodies or in shallow sea water. 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 (porphyra, phyllophora) can live at a depth 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 freshwater bodies, the stems of higher plants have poorly developed mechanical tissue. For example, if you take a white water lily or a yellow water lily out of the water, then their stems droop and are not able to support the flowers in an upright position. Water serves as a support for them due to its high density. An adaptation to a lack of oxygen in water is the presence of aerenchyma (air-bearing tissue) in plant organs. Minerals are in the water, so the conductive and root systems are poorly developed. Roots may be completely absent (duckweed, elodea, pondweed) or serve to fix in the substrate (cattail, arrowhead, chastukha). There are no root hairs on the roots. The leaves are often thin and long or strongly dissected. The mesophyll is not differentiated. The stomata of floating leaves are on the upper side, while those immersed in water are absent. Some plants have leaves different shapes(heterophilia) depending on where they are. In water lily and arrowhead, the shape of the leaves in the water and in the air is different.

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

Animal adaptations to life in the water

In the aquatic environment animal world richer than vegetable. Thanks to their independence from sunlight, animals inhabited the entire water column. According to the 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, larvae of some invertebrates. All their adaptations are aimed at increasing the buoyancy of the body:

an increase in the surface of the body due to flattening and elongation of the shape, the development of outgrowths and setae;
a decrease in body density due to the 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 the nekton are fish, cetaceans, pinnipeds, cephalopods. To resist the current, they are helped by adaptations to active swimming and a decrease in body friction. Active swimming is achieved due to well-developed muscles. In this case, the energy of the ejected jet of water, bending of the body, fins, flippers, etc. can be used.
skin scales and mucus.

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

Adaptations of benthic organisms are aimed at reducing buoyancy:

weighting of the body due to shells (molluscs), chitinous covers (crayfish, crabs, lobsters, spiny lobsters);
fixation at the bottom with the help of fixation organs (suckers in leeches, hooks in caddis 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 distinguished - neuston. Neuston- organisms associated with the surface film of water and living permanently or temporarily on this film or up to 5 cm deep from its surface. Their body is not wetted because its density is less than that of water. Specially arranged limbs allow you to move on the surface of the water without sinking (water strider bugs, whirlwind beetles). A peculiar group of aquatic organisms is also periphyton— organisms that form a fouling film on underwater objects. Representatives of the periphyton are: algae, bacteria, protists, crustaceans, bivalves, oligochaetes, bryozoans, sponges.

On planet Earth, there are four main environments of life: water, land-air, soil and living organism. In the aquatic environment, oxygen is the limiting factor. According to the nature of adaptations, aquatic inhabitants are divided into ecological groups: plankton, nekton, benthos.

Minsk Educational Institution “Gymnasium No. 14”

Abstract on biology on the topic:

“ WATER IS A HABITAT”

Prepared by a student of 11 "B" class

Maslovskaya Evgeniya

Teacher:

Bulva Ivan Vasilievich

1. Aquatic habitat - hydrosphere.

2. Water is a unique environment.

3. Ecological groups of hydrobionts.

4. Modes.

5. Specific adaptations of hydrobionts.

6. Filtration as a type of food.

7. Adaptation to life in drying up reservoirs.

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 the 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. These ratios are constant, although in nature, without ceasing, there is a water cycle (Fig. 1).

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

In the seas-oceans, as in the mountains, vertical zonality is expressed. The pelagial - the entire water column - and the benthal - the bottom differ especially strongly in ecology.

The water column is pelagial, vertically divided into several zones: epipeligial, bathypeligial, abyssopeligial, and ultraabyssopeligial (Fig. 2).

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

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

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

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

- bathyal - a steep decrease in land (mainland slope),

- abyssal - a smooth lowering of the bottom of the ocean bed; the depth of both zones together reaches 3-6 km.

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

2. Water is a unique medium.

Water is a completely unique medium in many ways. The water molecule, which consists of two hydrogen atoms and one oxygen atom, is remarkably stable. Water is the only compound of its kind that simultaneously exists in a gaseous, liquid and solid state.

Water is not only a life-giving source for all animals and plants on Earth, but is also a habitat for many of them. Among them, for example, are numerous species of fish, including crucians that inhabit 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 with 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 whole lives in water, while others are in the aquatic environment only at the beginning of their lives. This can be seen 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 examine. These include numerous algae and bacteria. Their number is measured in millions per cubic millimeter of water.

Other interesting property water is to acquire 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 the same property, ice floats on the surface of the water, forming a protective layer on lakes, rivers and coastal areas. And the same property contributes to the thermal stratification of water layers and the seasonal turnover of water masses in lakes in areas with a cold climate, which is very important for the life of aquatic organisms. The density of water makes it possible 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 hovering 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" it is mainly the so-called protective system or carbonic acid complex, consisting of carbonic acid salt, carbonate and bicarbonate. This factor determines whether the water is acidic, neutral, or basic based on its pH value, which chemically means the proportion of hydrogen ions contained in the water. Neutral water has a pH of 7, lower values indicate that the water is acidic, and higher values indicate that it is alkaline. In limestone areas, the water of lakes and rivers usually has elevated pH values compared to water bodies in those places where the limestone content in the soil is negligible.

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

3. Ecological groups of hydrobionts.

Ecological groups of hydrobionts. The warmest seas and oceans (40,000 species of animals) are distinguished by the greatest diversity of life in the region of the equator and the tropics; to the north and south, the flora and fauna of the seas are depleted hundreds of times. As for the distribution of organisms directly in the sea, their bulk is concentrated in the surface layers (epipelagial) and in the sublittoral zone. Depending on the mode of movement and stay in certain layers, marine life is 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 also includes amphibians and many insects.

Plankton (planktos - wandering, soaring) - a collection of plants (phytoplankton: diatoms, green and blue-green (fresh water only) algae, plant flagellates, peridinea, etc.) and small animal organisms (zooplankton: small crustaceans, from larger ones - pteropods, jellyfish, ctenophores, some worms), living at different depths, but not capable of active movement and resistance to currents. The composition of 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, pass into the lower layers of the pelagela. Above the neuston is the pleuston - these are organisms in which the upper part of the body grows above the water, and the lower part grows in the water (duckweed - Lemma, siphonophores, etc.). Plankton plays an important role in the trophic relationships of the biosphere, since is food for many aquatic life, including the main food for baleen whales (Myatcoceti).

Benthos (benthos - depth) - hydrobionts of the bottom. Represented mainly by attached or slowly moving animals (zoobenthos: foraminephores, fish, sponges, coelenterates, worms, brachiopods, ascidians, etc.), more numerous in shallow water. Plants (phytobenthos: diatoms, green, brown, red algae, bacteria) also enter benthos in shallow water. At a depth where there is no light, phytobenthos is absent. Along the coasts there are flowering plants of zoster, rupee. The stony 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 the lakes is formed by free-swimming diatoms, green and blue-green algae; brown and red algae are absent.

Rooting coastal plants in lakes form distinct belts, species composition and whose appearance is 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, calla, reeds, cattail, sedges, trichaetes, reeds). They are replaced by hydatophytes - plants submerged in water, but with floating leaves (lotus, duckweed, egg-pods, chilim, takla) and - further - completely submerged (weeds, 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 the change in life-supporting factors. Some of them are the same as on land - heat, light, others are specific: water pressure (with depth increases by 1 atm for every 10 m), oxygen content, salt composition, acidity. Due to the high density of the medium, heat and light values change much faster with the height gradient than on land.

4. Modes.

Temperature regime water bodies are more stable than on land. It's connected with physical properties water, especially high specific heat capacity, due to which the receipt or release of a significant amount of heat does not cause too sharp temperature changes. The amplitude of annual temperature fluctuations in the upper layers of the ocean is no more than 10-150С, in continental water bodies - 30-350С. Deep layers of water are characterized by constant temperature. In equatorial waters mean annual temperature surface layers + 26 ... + 270С, in polar - about 00С and below. Thus, in reservoirs there is a fairly significant variety of 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 the outer and deep waters is stronger.

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

Aquatic life environment

From an ecological point of view, the environment is natural bodies and phenomena with which the organism is in direct or indirect relations. Habitat is a part of nature that surrounds living organisms (individual, population, community) and has a certain impact on them.

On our planet, living organisms have mastered four main habitats: aquatic, terrestrial-air, soil and organismal (i.e., formed by living organisms themselves).

Aquatic life environment

The aquatic environment of life is the most ancient. Water ensures the flow of metabolism in the body and the normal functioning of the body as a whole. Some organisms live in water, others have adapted to a constant lack of moisture. The average water content in the cells of most living organisms is about 70%.

Specific properties of water as a habitat

A characteristic feature of the aquatic environment is its high density; it is 800 times greater than the density of the air environment. In distilled water, for example, it is 1 g/cm3. With an increase in salinity, the density increases and can reach 1.35 g/cm 3 . All aquatic organisms experience high pressure, increasing by 1 atmosphere for every 10 m of depth. Some of them, for example, anglerfish, cephalopods, crustaceans, starfish and others, live at great depths at a pressure of 400...500 atm.

The density of water provides the ability to rely on it, which is important for non-skeletal forms of aquatic organisms.

The biont of aquatic ecosystems is also affected by the following factors:

1. concentration of dissolved oxygen;

2. water temperature;

3. transparency, characterized by a relative change in the intensity of the light flux with depth;

4. salinity, that is, the percentage (by weight) of salts dissolved in water, mainly NaCl, KC1 and MgS0 4;

5. the availability of nutrients, primarily compounds of chemically bound nitrogen and phosphorus.

The oxygen regime of the aquatic environment is specific. There is 21 times less oxygen in water than in the atmosphere. The oxygen content in water decreases with increasing temperature, salinity, depth, but increases with increasing flow velocity. Among hydrobionts, there are many species belonging to euryoxybionts, i.e., organisms that can tolerate low oxygen content in water (for example, some types of mollusks, carp, crucian carp, tench, and others).

Stenoxibionts, such as trout, mayfly larvae, and others, can exist only at a sufficiently high saturation of water with oxygen (7...11 cm 3 /l), and therefore are bioindicators of this factor.

The lack of oxygen in water leads to catastrophic deaths (winter and summer), accompanied by the death of aquatic organisms.

The temperature regime of the aquatic environment is characterized by relative stability compared to other environments. In fresh water bodies of temperate latitudes, the temperature of the surface layers ranges from 0.9 °C to 25 °C, i.e. the amplitude of temperature changes is within 26 °C (except for thermal sources, where the temperature can reach 140 °C). At a depth in fresh water bodies, the temperature is constantly equal to 4 ... 5 ° C.

The light regime of the aquatic environment differs significantly from the ground-air environment. There is little light in water, as it is partially reflected from the surface and partially absorbed when passing through the water column. The passage of light is also hindered by particles suspended in water. In deep reservoirs, in connection with this, three zones are distinguished: light, twilight and the zone of eternal darkness.

According to the degree of illumination, the following zones are distinguished:

littoral zone (water column where sunlight reaches the bottom);

limnic zone (water column to a depth where only 1% of sunlight penetrates and where photosynthesis fades);

euphotic zone (the entire illuminated water column, including the littoral and limnic zones);

profundal zone (bottom and water column where sunlight does not penetrate).

In relation to water, the following ecological groups are distinguished among living organisms: hygrophiles (moisture-loving), xerophiles (dry-loving) and mesophiles (intermediate group). In particular, among plants, hygrophytes, mesophytes and xerophytes are distinguished.

Hygrophytes are plants of moist habitats that do not tolerate water deficiency. These include, for example: pondweed, water lily, reed.

Xerophytes plants of dry habitats, able to tolerate overheating and dehydration. There are succulents and sclerophytes. Succulents are xerophytic plants with succulent, fleshy leaves (for example, aloe) or stems (for example, cacti) in which water storage tissue is developed. Sclerophytes are xerophytic plants with hard shoots, due to which, with a water deficit, they do not have an external wilting pattern (for example, feather grass, saxaul).

Mesophytes of plants of moderately humid habitats; intermediate group between hydrophytes and xerophytes.

About 150,000 species of animals live in the aquatic environment (which is about 7% of their total number) and 10,000 plant species (which is about 8% of their total number). Organisms that live in water are called hydrobionts.

Aquatic organisms according to the type of habitat and lifestyle are combined into the following ecological groups.

Plankton are suspended organisms floating in the water, passively moving due to the current. There are phytoplankton (single-celled algae) and zooplankton (single-celled animals, crustaceans, jellyfish, etc.). a special variety plankton is an ecological group of neuston - inhabitants of the surface film of water at the border with the air (for example, water striders, bedbugs, and others).

Nekton Animals actively moving in the water (fish, amphibians, cephalopods, turtles, cetaceans, etc.). Active swimming of aquatic organisms united in this ecological group directly depends on the density of water. Rapid movement in the water column is possible only in the presence of a streamlined body shape and highly developed muscles.

Benthos are organisms living on the bottom and in the ground, it is divided into phytobenthos (attached algae and higher plants) and zoobenthos (crustaceans, mollusks, starfish, etc.).

Aquatic inhabitants are amazing animals that have subjugated stormy seas and majestic oceans. The inhabitants of the aquatic environment are a colorful and numerous world, including aquarium fish. They are all so different. Some of them are simply huge, while others are so small that they are almost invisible. Some aquatic inhabitants are fierce predators that pose a great threat, while some, on the contrary, are friendly and do not pose a danger.

Everyone was in a dolphinarium or oceanarium. But everyone who is represented there is the inhabitants of the vast expanses, living in the harsh conditions of the water element. Below you will find articles about the diverse inhabitants of the water world, in which you will learn a lot of new and interesting things about them.

The big blue whale is the giant of the planet Earth. Description and photo of the blue whale

The blue whale or blue whale is a marine animal that is a representative of the order of cetaceans. The blue whale belongs to the baleen whales of the minke whale genus. The blue whale is the most big whale on the planet. In this article you will find a description and photo blue whale, you will learn a lot of new and interesting things about the life of this huge and amazing animal.

The seahorse is an incredible creature. Description and photo of a seahorse

Seahorse - fish small size, which is a representative of the Needle family from the order Stingle-like. Studies have shown that the seahorse is a highly modified needlefish. Today, the seahorse is a fairly rare creature. In this article you will find a description and photo of a seahorse, learn a lot of new and interesting things about this extraordinary creature.

Water as a habitat has a number of specific properties, such as high density, strong pressure drops, relatively low oxygen content, strong absorption of sunlight, etc. Reservoirs and their individual sections differ, in addition, in the salt regime, the speed of horizontal movements (currents) , the content of suspended particles. For the life of benthic organisms, the properties of the soil, the mode of decomposition of organic residues, etc. are important. Therefore, along with adaptations to general properties of the aquatic environment, its inhabitants must also be adapted to a variety of particular conditions. The inhabitants of the aquatic environment received in ecology common name hydrobionts. They inhabit the oceans, continental waters and groundwater. In any reservoir, zones can be distinguished according to the conditions.

Consider the basic properties of water as a habitat.

Density of water - this is a factor that determines the conditions for the movement of aquatic organisms and pressure at different depths. Density natural waters containing dissolved salts, may be more, up to 1.35 g/cm 3 . Pressure increases with depth by approximately 101.3 kPa (1 atm) on average for every 10 m.

In connection with a sharp change in pressure in water bodies, hydrobionts are generally more easily tolerated than terrestrial organisms by pressure changes. Some species, distributed at different depths, endure pressure from several to hundreds of atmospheres. For example, holothurians of the genus Elpidia live in the area from coastal zone to the zone of greatest ocean depths, 6-11 km. However, most of the inhabitants of the seas and oceans live at a certain depth.

The density of water makes it possible to lean on it, which is especially important for non-skeletal forms. The density of the medium 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 hydrobionts - plankton("planktos" - soaring). Plankton includes unicellular and colonial algae, protozoa, jellyfish, various small crustaceans, larvae of bottom animals, fish eggs and fry, and many others.

The density and viscosity of water greatly affect the possibility of active swimming. Animals capable of fast swimming and overcoming the force of currents are combined into an ecological group. nekton("nektos" - floating). Representatives of nekton are fish, squid, dolphins. Rapid movement in the water column is possible only in the presence of a streamlined body shape and highly developed muscles.

1. Oxygen mode. In oxygen-saturated water, its content does not exceed 10 ml per 1 liter, which is 21 times lower than in the atmosphere. Therefore, the conditions for the respiration of hydrobionts are much more complicated. Oxygen enters the water mainly due to the photosynthetic activity of algae and diffusion from the air. Therefore, the upper layers of the water column, as a rule, are richer in this gas than the lower ones. With an increase in temperature and salinity of water, the concentration of oxygen in it decreases.

Respiration of hydrobionts is carried out either through the surface of the body, or through specialized organs - gills, lungs, trachea. In this case, covers can serve additional body breathing. For example, loach fish consumes on average up to 63% of oxygen through the skin. Many sedentary and inactive animals renew the water around them, either by creating its directed current, or by oscillatory movements contributing to its mixing. For this purpose, bivalve mollusks use cilia lining the walls of the mantle cavity; crustaceans - the work of the abdominal or thoracic legs. Leeches, larvae of ringing mosquitoes (bloodworms) sway the body, leaning out of the ground.

Mammals that have passed in the process of evolutionary development from a land to aquatic way of life, for example, pinnipeds, cetaceans, water beetles, mosquito larvae, usually retain an atmospheric type of breathing and therefore need contact with the air.

Lack of oxygen in water sometimes leads to catastrophic phenomena - death, accompanied by the death of many aquatic organisms. Winter freezes are often caused by the formation of ice on the surface of water bodies and the termination of contact with air; summer - by an increase in water temperature and a decrease in the solubility of oxygen as a result.

2. Salt mode. Maintaining the water balance of hydrobionts has its own specifics. If for terrestrial animals and plants it is most important to provide the body with water in conditions of its deficiency, then for hydrobionts it is no less important to maintain a certain amount of water in the body when it is in excess. environment. An excessive amount of water in the cells leads to a change in their osmotic pressure and a violation of the most important vital functions. Therefore, freshwater forms cannot exist in the seas, marine ones cannot tolerate desalination. If the salinity of the water is subject to change, the animals move in search of a favorable environment.
3. Temperature regime water bodies, as already noted, is more stable than on land. The amplitude of annual temperature fluctuations in the upper layers of the ocean is no more than 10-15 °С, in continental water bodies - 30-35 °С. Deep layers of water are characterized by constant temperature. In equatorial waters, the average annual temperature of the surface layers is +26-27 °С, in polar waters - about 0 °С and lower. In hot terrestrial springs, the water temperature can approach +100 °C, and in underwater geysers at high pressure on the ocean floor, a temperature of +380 °C has been recorded. But along the vertical, the temperature regime is diverse, for example, seasonal temperature fluctuations appear in the upper layers, and the thermal regime is constant in the lower layers.
4. Light mode. There is much less light in water than in air. Part of the rays incident on the surface of the reservoir is reflected into the air. The reflection is stronger the lower the position of the Sun, so the day under water is shorter than on land. The rapid decrease in the amount of light with depth is due to its absorption by water. Rays with different length waves are absorbed differently: red ones disappear close to the surface, while blue-green ones penetrate much deeper. This affects the color of hydrobionts, for example, with depth, the color of algae changes: green, brown and red algae, which specialize in capturing light with different wavelengths. The color of animals changes with depth in the same way. Many deep organisms do not have pigments.

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

Thus, the properties of the environment largely determine the ways of adaptation of its inhabitants, their way of life and ways of using resources, creating chains of cause-and-effect dependencies. Thus, the high density of water makes the existence of plankton possible, and the presence of organisms floating in the water is a prerequisite for the development of a filtration type of nutrition, in which a sedentary lifestyle of animals is also possible. As a result, a powerful mechanism of self-purification of water bodies of biospheric significance is formed. It involves a huge number of hydrobionts, both benthic (living on the ground and in the soil of the bottom of water bodies) and pelagic (plants or animals living in the water column or on the surface), from unicellular protozoa to vertebrates. For example, only planktonic marine copepods (Calanus) are able to filter the waters of the entire World Ocean in a few years; approximately 1.37 billion km 3. Disturbance of the activity of filter feeders by various anthropogenic influences poses a serious threat to maintaining the purity of waters.

Questions and tasks for self-control

1. List the main properties of the aquatic habitat.
2. Explain how the density of water determines the shape of animals capable of fast swimming.
3. Name the reason for blockages.
4. What phenomenon is called "bioluminescence"? Do you know living organisms that have this property?
5. What ecological role do filter feeders play?