The overall feature of plankton plants and animals. The behavior of planktonic organisms. Schedule of heavenly expanses

The ocean vegetable life is concentrated only in the highest, illuminated water layer. It would seem here that there must be all the time planting planktonic organisms to be closer to the food source. However, in fact, the behavior of the sea zooplankton is much more complicated than it can be assumed. The overwhelming majority of its representatives feed on algae only at night, and during the day they are hiding in dark depths.

Throughout a bright day in the upper styometer layer, where photosynthesis occurs, there are almost algae. How much I fix the special device - the plankton network - sea water, only greenish-brown algae suspension is invariably in its cup. As soon as the sun goes beyond the horizon and in the upper layers of sea water comes darkness, the wraps begin to work hard with their antennas and limbs and rush up. Along with them, Salpi, Fish Fish, and the whole company in full dark is thrown on algae. Behind the plant, small and large plankton predators follow the plant, and the fish are more larger. With the approach of dawn, the whole zooplankton is immersed in depth, and by the beginning of the day the illuminated area of \u200b\u200bthe ocean will be empty again.

At the dawn of marine biology, when the plankton network was invented, people immediately drew attention to good catches at night and bad day. Initially, it was assumed that planktonic organisms in the daylight see the network and flee from it. At night, the network is not visible and therefore brings a rich catch. Of course, fish, squid, large wipes capable of active swimming, as a rule, do not fall into the plankton network, as they are really scared. But this cannot be treated with plankton animals, which passively move from place to place, dried by trends.

When the reality of the daily vertical movements of Plankton became apparent, it was necessary to explain the cause of this strange phenomenon. Initially, it was suggested that plankton's wraps, while remaining in the afternoon in a dark depth, easier savage from predators, which are easily discovered in their light. So, many terrestrial herbal animals are spent in the saving grounds of the forest and go to graze only under the cover of night darkness. This analogy may be shaped, but not founded.

Known a number of plankton rates emitting bright phosphorescent light. They seem to be deliberately signing predators about their whereabouts, with such lats and in the day in the depths of the sea, and at night near its surface. In addition, not all uniforms of plankton animals find their victim through vision. Music whales, as you know, discover the accumulations of food objects by echolocation. For them, it is absolutely indifferent, lit by the sun's wraps or dwine. Then a hypothesis was put forward, according to which plants at photosynthesis isolated some substances, harmful to zooplankton. However, after careful experiments, this assumption was not confirmed.

It turned out that the daily movement of up-down do not necessarily end up at the surface of the sea. There are many plankton organisms that spend the night at a depth of 500 - 200 meters, and in the afternoon they fall per kilometer and more. They do not penetrate at all in the layer, where photosynthesis occurs, and never see light, but nevertheless make significant vertical movements.

Thus, it seems that each type of plankton and pelagic (also living in the thickness of water, but capable of active movement) animals dwells within certain depth borders. At night, they hold close to the bottom, and in the day near the upper border, making it up and down during the day. It is clear that in the movements of all these animals, the degree of illumination plays the dominant role.

It is observed that during complete solar eclipses, zooplankton begins. The light seems to scare off plankton animals, and the darkness attracts. But then why the masses of plankton organisms, rising at night to the surface of the ocean, accumulate in the rays of bright lamps, lowered overboard? Why do flies of fish and squid rush to this stream of light? The feasibility of such actions could not be explained.

Some experts, for example, English hydrobiologist Alec Lori, tried to link the movement of plankton animals not with light, but with a temperature. The idea is as follows. At low temperature, life processes go slower, energy consumption decreases. Therefore, plankton and keeps in cold depths, economically spending nutrients, and at night quickly penetrates the feed fields, eats and goes back to the coolness. Among other things, the viscosity of cold water is higher than warm. It means that in the cold zone of Plankton's organisms in the cold zone, to preserve their position in space, it is necessary to spend less energy than if they lived in warm surface waters.

Maybe A. Laurie to a certain extent of rights, although water viscosity changes are so insignificant that it is unlikely that they can play a significant role in the adaptations of plankters. The fact is that this theory does not explain in any way, why the lifting and descent are confined to changing the intensity of light and are committed at a certain time of the day, and not as planktonic organisms will feel hunger. The slender picture of the general ideas about the daily vertical movement of plankton was completely broken by the opening of such species that the day is carried out at the surface, and the night are descended into depth.

In the end, the English researcher D. Harris, not finding explanations by the massive daily movements of plankton, concluded that they had no adaptive importance, which is a side manifestation of the internal biological rhythm of the plankters. Just at plankton organisms, like all other plants and animals, have their own biological clocks, and their pendulum waves once a day a hundred meters up and a hundred meters down (in other or more).

Of course, in some cases, animal actions lead to clearly inappropriate, but clearly visible results. Here, during the flight from the lake, a huge flock of birds rose and the sun was eclipsed by a moment, this is not a device to protect against predators, but only a shadow from the flock. But not regular, strictly regulated over time and the distance of the movement of the huge masses of the plankton is not a shadow! The organisms themselves move! Even the trace is not indifferent to the one he is left. In the footsteps, the predator trails the victim. Even the shadow is dangerous. On her, the enemy discovers the one who throws it. Especially it is impossible to imagine that serious actions such as the transition from cold to heat, from depth to the surface and back, would be an indifferent side effect of the internal rhythm of the body. It is completely undoubted that these movements are needed, only we do not know why they are necessary. While this is one of the ocean mysteries. Maybe someone from readers of this book will be able to solve it.

If the value of the vertical movement of plankton: and for the life of the plankters themselves, it is still not entirely clear, the role of this phenomenon in the balance of the ocean, according to one of our leading planktonologists, Professor Mikhail Vinogradov is obvious. The regular movement of plankton Up-down leads to contact of the inhabitants of different depths, accelerates the process of transition of organic substances from the place of their synthesis (at the ocean surface) to the site of the main consumption (in depths and at the bottom), combines the inhabitants of the water stash and the bottom in the Unified Community.

Bathe in the sea or ocean, in the water, it is randomly used to go on fish or alga, which does not cause very unpleasant feelings, but fortunately this happens extremely rarely. In fact, most of us do not suspect that being in salty water, a person contacts every second with hundreds and thousands of organisms, which he does not see and does not feel, but at the same time they are experiencing his presence. These invisible inhabitants of the seas and oceans make up plankton - a huge number of animals and vegetable organisms that drift by flow and are not able to choose the direction of their movement in space. Rarely among them are also representatives of bigger, but there are very few among the entire plankton.

Study history

Despite the fact that this group of living organisms is mostly invisible for human eye without the use of special equipment, the biologists guess about its existence for a long time. Officially, the term "plankton" was introduced by the German oceanographer Viktor General, who devoted his whole life to the study of the nature of the Ocean nature. The word was introduced to the official dictionary of terms for almost 130 years ago - in 1887.

The word borrowed from the Greek language, which is translated as "wandering" or "wandering". This laugant reflects the way of the existence of the smallest marine inhabitants, so the term perfectly passed on and never challenged.

At the moment, planktonic organisms are a group in which scientists make annually make the largest number of discoveries of new species, previously not described by anyone.

Now from more than a million different species described only 250 thousand, the rest will have to describe future generations of oceanographers.

What consists of

The composition of the plankton is very diverse, there can be many types of bacteria, algae, intestinal, simple, crustaceans and crustaceans, mollusks, caviar and fish larvae, invertebrate larvae, etc.

Under the microscope, the microman seas and oceans looks fantastic: most microorganisms resemble reduced film representatives about the future or aliens. Many of them have a bright color, an interesting shape and unusual geometry of covers. Some are quite difficult to arrange, possess the blood and nervous system of higher animals, so it would be wrong to call them a faceless mass.

All representatives are divided into two large groups:

- Vegetable organisms that need sunlight in order to photosynthesize. This includes diatoms, green and cinema algae. It is phytoplankton that produces a huge amount of organic matter that provides food for the overwhelming majority of water inhabitants. The abundance of phytoplankton depends on how much substances needed in the water: nitrogen, phosphorus or silicon. When viewing a droplet of sea water in a microscope, scientists can conclude the appearance of planktonic organisms to conclude from each of these substances. With the active development of phytoplankton, water strata can change their color, it is this phenomenon that causes the summer "flowering" of water.

- Living organisms that cannot move or are very limited in this regard. The species diversity is quite large, here you can meet the raffs and patterns, crustaceans, the simplest, intestinal, gorgeous mollusks, fry of fish, insect larvae, etc. Zooplankton does not depend so much from entering the thickness of the sun's rays like phytoplankton, so his representatives can not be found. Only in the surface layers, but also closer to the bottom.

Also, planktonic organisms also distinguish depending on how long they are in this group:

Goloplankton. - These representatives from birth to death are plankton and keep appropriate.
Meloplankton - We are carried out in the form of planktonic organisms, only a part of life, most often - its first period, later turning into beings that increase their weight and move freely in water. Such representatives include fish, sea worms, etc.

Dimensions

It is believed that Plankton is exclusively microscopic microorganisms that cannot be viewed with a unarmed look. It is about this that students are reported in the lessons of geography and biology, making reports and reading abstracts. In fact this is not true. The overwhelming majority of representatives of this group are really very small, but there are also those that significantly exceed the size of the human body.

femtoplankton - represented by the smallest viruses, up to 0.2 microns;
picoplankton. - It includes large bacteria and single-cell algae with a size of 0.2 to 2 microns;
nanoplankton. - large single-milking algae and colonies of bacteria measuring 2-20 μm;
microplankton - These include trashrats, the simplest and most algae in size from0.02 to 0.2 cm;
mesoplankton - This group includes crustaceans and sea animals up to 2 cm;
macroplunkton - jellyfish, shrimp and other animals from 2 to 20 cm;
megaplankton.- The largest representatives with a size of 20 cm to 2 m.

The largest in plankton are medusions of cyania with a body with a diameter of 2 m and tentacles that stretch 30 m around, as well as the colony of Piros, which form a tape with a width of 1 m and 30 m in length.

The most numerous group is organisms in the range of 0.2-2 μm, they are biomass in biomass exceeding the rest, even the largest representatives.

The picture of the dependence of the weight and size of these microorganisms is interesting. Not always big instances weigh a lot. In order to faster drifting, in the process of evolution, many devices have been produced, which do not increase body weight, but increase the ability to waters to water: inclusions of gas or drip fat, internal chambers with sea water, grown, thin and flat body, pores inside Skeleton, etc.

Biological seasons

As most of the types of wildlife, plankton has seasonal fluctuations in the number, which are due to the temperature of the habitat and the length of the daylight. During good weather conditions, heat and sufficient light, a splash of reproduction is observed, and during adverse factors, development slows down. During each season, the composition, quantity and age indicators of phytoplankton and zooplankton are changed.

The annual cycle looks like this:

In the spring, with significant warming, they begin to strengthen the algae violently, so phytoplankton develops rapidly, often causing water flowering. Since phytoplankton serves as food for many types of zooplankton, then an increase in algae invariably entails a rapid surge of active breeding of the smallest living planktonic organisms.
By the summer, the increase in the number stops and freezes at one level.
In autumn, the amount of phytoplankton and zooplankton begins to decrease, especially early this process starts in the northern waters. In the southern latitudes, autumn again provokes a reproduction outbreak, as in the spring.
In winter, the amount decreases, most of the copies go to the state of rest.

The duration of each season is associated with a geographical location, so for representatives drifting in the north, the rest period may occupy nine months a year, while in the southern regions to come down by several weeks. In the tropics, the condition and amount of phytoplankton and zooplankton all year is at a balanced state.

Where dwells

The ideal conditions for this group are considered the same as for all other living beings: heat and light of the Sun. Such conditions are in the upper layer of water, which is well warmed and passes through itself the sun rays in sufficient quantities. This is especially important for phytoplankton, the processes of vital activity directly depend on sunlight. It can be found in the surface layer of the seas and oceans in the surface layer of the seas and oceans, which has the name of the eufotic layer. At a depth of 50 m, the population density begins to decrease, and after 100 m, it is possible to meet a plankton representative only occasionally.

Wearam for plankton are tropical water areas of the ocean, therefore a tremendous species diversity and a number are concentrated in the warm waves of the Indian Ocean. Most often, the composition is diverse and overall, but some copies live without neighbors. This includes Artemia's wraps that live in waters with so high saline that it does not bring any planktonic organisms anymore.

But most often a species diversity in the sea is very extensive. The average data on the number is shown that 200 million viruses are in one glass of seawater, which infect 20 million bacteria, which are also in the same glan. Therefore, you can only imagine how much plankton we "sweep" by our body, entering the sea water.

Previously, in the northern parts of the Atlantic Ocean, Plankton did not survive due to low temperatures, but now, after 800 thousand years, he returned to these areas again. The reason for this was the melting of polar glaciers, which occurs more intensively due to global warming. The presence of food in these waters has attracted her gray whales. What other changes in nature can cause the settlement of these marine microorganisms, you can only assume.

To meet Plankton is possible not only in exotic places: he lives in any reservoirs, even in a small bucket with water, which stood at home for several days. In the aquarium it is happy to eat fish, a variety of diet and approaching it to natural. You can meet the zooplankton in the supermarket, here it will be sold under the name "Krill", which is quite tasty delicacy, highly appreciated not only by whales, but also people.

Ecological role

The value of phytoplankton and zooplankton in the life of the planet is difficult to overestimate. It is these microorganisms that were the first on Earth, which began to produce oxygen. Even now, 50% of oxygen is produced by plankton, and due to the rapid cutting of forests, this percentage increases annually, therefore the title "Light planets" can be safely transmitted by oceanic inhabitants.

Plankton consumes the organic that enters the world ocean, and if it were not for these tireless "cleaners", the water would have long become unsuitable for life. They are an initial element of the food chain, on a year round, saturating marine inhabitants and birds. Interesting is the fact that the biggest mammals of the planets are the blue whales - feed on the lowest representatives of the depths of the ocean - plankton. Many whales float after the currents in which there is a large accumulation of plankton microorganisms to always stay near the feeder.

Scientists use this group for an indirect assessment of the purity of water bodies, since in contaminated water, its representatives quickly die out.

Light miracle

Everyone knows an excellent phenomenon of sea glow, which can be observed at night, which is due to the presence of plankton photosynthesising bacteria in it. The most active in this process is observed in the warm season, at the moments of active breeding of phytoplankton. Bright glow Tourists can observe in the coastal areas of the Black Seaquators, in the Sea of \u200b\u200bAzov, oversaturated fertilizers, and in the Maldives.

The main source of the glow is cyanobacteria and dinoflates. They are able to produce as much light that even astronauts are seen in the form of blue swearing, being in orbit. A huge number of photographers seek at such a time on the coast to make their best photographs.

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The smallest organisms of water thickness unite into the concept of "plankton" (from the Greek " planktos."- soaring, wandering). The world of plankton is huge and diverse. This includes organisms inhabiting the thickness of the seas, oceans, lakes and rivers. They live everywhere where there is the slightest amount of water. It can be even the most ordinary puddles, a vase with flowers with stagnant water, fountains, etc.

The plankton community is the most ancient and important from many points of view. Plankton has about 2 billion years. They were the first organisms that once inhabited our planet. Plankton's organisms were the first to begin to supply our planet with oxygen. And now about 40% of oxygen is produced by aquatic plants and primarily plankton. Plankton is of great importance in the food balance of aquatic ecosystems, since they feed on many types of fish, whales and some birds. It is the main source of life of the seas and oceans, large lakes and rivers. The impact of plankton on water resources is so large that it can affect even the chemical composition of water.

The plankton includes phytoplankton, bacterioplankton and zooplankton. These are mainly small organisms, the size of which most often does not exceed tens of micrometers for algae and several centimeters for zooplankton. However, most animals have significantly smaller sizes. For example, the size of the largest freshwater daphnya reaches only 5 mm.

However, most people know about plankton quite a bit, although the number of organisms in the reservoirs is extremely large. For example, the number of bacteria in one cubic centimeter of water reaches 5-10 million cells, algae - in the same volume - dozens of hundreds of thousands, and zooplankton organisms - hundreds of copies. This is an almost invisible world. It is due to the fact that the majority of plankton organisms have very small sizes, and to consider them, a microscope is needed with a sufficiently large increase. The organisms included in the plankton are in the thickness of water in a state of passing. They cannot resist the transfer of their currents. However, this can be said about this only in general terms, since in calm water, many planktonic organisms can move (albeit slowly) in a certain direction. Algae, changing buoyancy, move vertically within a few meters. In the afternoon they are in the upper well-lit water layer, and at night they fall on three or four meters deeper, where more minerals. Zooplankton in the seas and oceans at night rises into the upper layers, where microscopic algae filters, and in the morning it is lowered to a depth of 300 meters and more.

Who is part of plankton? Most of the plankton organisms spend their entire life in the thickness of water and is not associated with a solid substrate. Although the restricted stages of many of them are settled at the bottom of the reservoir, where unfavorable conditions are losing. At the same time, among them there are also those that spend only a part of life in the thickness of water. This is Meroplankton (from Greek. " meros.» - Part). It turns out that the larvae of many bottom organisms - sea chests, stars, officers, worms, mollusks, crabs, corals and others lead a plankton lifestyle, spread out the currents and, in, ultimately, find places for further habitat, settle on the bottom and already until the end Life does not leave him. This is due to the fact that the bottom organisms are in comparison with the plankton are in a disadvantage, because relatively slowly moving from place to place. Thanks to plankton larvae, they are spread by trends over long distances, just as the seeds of land plants are spread by the wind. Some fish caviar and their larvae also lead a plankton lifestyle.

As we have already noted, most plankton organisms are real planks. In the thickness of the water, they are born, they dying there. It consists of bacteria, microscopic algae, various animals (the simplest, proofraticles, crustaceans, mollusks, terrestrial, etc.).

Planktonic organisms have developed adaptations that make it easier for them in the thickness of water. These are all sorts of growing, body seal, gas and fat inclusions, porous skeleton. At plankton mollusks there was a reduction of shells. She, unlike bottom organisms, is very thin, and sometimes - barely visible. Many planktonic organisms (such as jellyfish) have student fabrics. All this allows them without any substantive energy costs to maintain the body in the thickness of water.

Many plankton crustaceans make vertical migrations. At night, they rise to the surface, where they eat algae, and a few hundred meters fall into the dawn to dawn. There, in the darkness they are hidden from fish who eat them with pleasure. In addition, low temperature reduces metabolism, and, accordingly, energy spending on maintaining vital activity. At high depths, the density of water is higher than that of the surface, and the organisms are in a state of neutral buoyancy. This allows them without any costs to be in the thickness of water. Phytoplankton inhabited mainly surface layers of water where sunlight penetrates. After all, algae, as well as land plants, requires light for development. In the seas, they live to a depth of 50-100 m, and in fresh water reservoirs - up to 10-20 meters, which is associated with different transparency of these reservoirs.

In the oceans, the habitat of algae is the finest film of a huge thickness of the waters. However, despite this microscopic algae are the first for all aquatic organisms. As noted, their size does not exceed several dozen micrometers. Only the size of the colonies reaches hundreds of micrometers. These algae feed crustaceans. Among them, we are most famous for Krill, where there are mainly Eufauzide cancers of up to 1.5 cm. The rachkov eat plankofagi fish, and they, in turn, larger and predatory fish. Kynes feed whales that filter them in huge quantities. So, in the stomach of blue whale, a length of 26 m found 5 million of these racks.

The sea phytoplankton Plankton mainly consists of diatoms of algae and pyridine. The diatoms of algae dominate the polar and indoor marine (ocean) waters. They are so great that silicon skeletons after their die form formal deposits. The diatomaces are covered by most of the bottom of the cold seas. They run at the depths of about 4000 m and more and consist mainly of large diatoms. Small shells usually dissolve without reaching the bottom. Mineral diatomite is a product of diatom algae. The number of sash in the diatoms in some areas of the ocean reaches 100-400 million in 1 grams of il. Diatoms with time are transformed into sedimentary rocks, of which the "diatomace" or mineral diatomite is formed. It consists of the smallest porous flock shells and is used as a filtering material or sorbent. This mineral is used to make dynamite.

In 1866-1876. Swedish chemist and entrepreneur Alfred Nobel sought ways and ways to produce a potent explosive. Nitroglycerin is a very effective explosive, but it spontaneously explodes with small jogs. Having established that to prevent explosions it is enough to impregnate with liquid nitroglycerin diatomaceous land, Nobel created a safe explosive - dynamite. Thus, the enrichment of Nobel and the famous "Nobel Prizes" established by its will are obliged to be the smallest diatoms of algae.

In the warm waters of the tropics, a higher species diversity is characterized, compared with the phytoplankton of the Arctic seas. Here are the most diverse algae of Peridinea. In the sea plankton, lime buccible kokkolitoforids and silicoplagellates are widespread. Kokkolitoforids are mainly inhabited by tropical waters. Lime alive, consisting of kokkolitoforide skeletons, are widespread in the world ocean. Most often they are found in the Atlantic Ocean, where they are covered by more than 2/3 of the bottom surface. However, in Larch in large quantities, the sinks of the foraminifem belonging to zooplankton are presented.

Visual observations of marine or ocean waters allow water color to easily install the distribution of plankton. Syane and the transparency of water indicates the poverty of life; In such water, practically no one to reflect the light, except for the water itself. Blue color is the color of the sea desert, where floating organisms come across very rarely. Green color is an errorless indicator of vegetation. Therefore, when fishermen meet green water, they know: the surface layers are rich in vegetation, and where there is a lot of algae, there are always abundant animals eating them. Phytoplankton is rightly called the pasture of the sea. Microscopic algae is the main food of a large number of ocean inhabitants.

Dark green color of water speaks of the presence of a large mass of plankton. Tints of water indicate the presence of certain plankton organisms. This is very important for fishermen, since the nature of plankton determines the genus of the fish living in the area. An experienced fisherman can catch the finest shades of the color of sea water. Depending on whether it catches fish in the "green", "yellow" or "red" water, "experienced eye" can with a sufficient possible degree of probability to predict the nature and size of the catch.

In fresh reservoirs, blue-green, green, diatoms and dinophite algae predominate. Abundant development of phytoplankton (the so-called "flowering" of water) changes the color and transparency of water. In fresh reservoirs, blossoms of bluenelen are most often observed, and in the seas - periodine. The toxic substances secreted by them reduce water quality, which leads to poisoning of animals and humans, and in the seas causes the mass death of fish and other organisms.

Water coloring in certain areas or seas is sometimes characteristic that the sea was obtained by the color of water. For example, the peculiar color of the Red Sea is caused by the presence in it by the blue algae TRIPhodasimium ( Trichodesmium. egythraeum) having a pigment that gives water a reddish brown shade; Or the crimson sea is the former name of the California Gulf.

A peculiar color of water gives some attributable dinoflagellates (for example, Gonyaulax and Gymnodinium) in tropical and moderate warm waters, these creatures sometimes multiply so quickly that the sea becomes red. Fishermen call this phenomenon "Red Tide". Huge clusters of dinoflagellats (up to 6 million cells in 1 liter of water) are extremely poisonous, so many organisms die during the "red tide". These algae are not only poisonous in themselves; They distinguish poisonous substances that are then accumulated in organisms eating dinoflagels. Any creature, whether it is a fish, a bird or a person, eating such an organism, gets dangerous poisoning. Fortunately, the phenomenon of "red tide" is local in nature and happens not often.

Water seas are painted not only by the presence of algae, but also zooplankton. Most Eupauzide are transparent and colorless, but some of them are painted in bright red color. Such evafauxides dwell in the colder northern and southern hemispheres and sometimes accumulate in such quantities that all the sea is painted in red.

Not only microscopic plankton algae, but also various particles of organic and inorganic origin give water. After a strong rain of the river, many mineral particles bring, because of which the water acquires various shades. So, clay particles, brought by the River Juanhe, give the yellow sea to the appropriate shade. River Juanhe (from Kit. - Yellow River) for his turbidity and received its name. Many rivers and lakes contain such a number of humic compounds that their water becomes dark - brown and even black. Hence the names of many of them: Rio-Negro - in South America, Black Volta, Niger - in Africa. Many of our rivers and lakes (and the cities located on them) because of the color of water are the names "Black".

In fresh water, staining of water due to the development of algae is more common and more intense. The mass development of algae causes the phenomenon of "flowering" of water bodies. Depending on the composition of phytoplankton, water is painted into different colors: from green algae Eudorina, Pandorina, Volvox - in green; from Asterionella's diatoms, Tabellaria, Fragilaria - yellowish-brown color; From Zhutikov DinoBryon - in greenish, euglena - in green, synura - in brown, trachelomonas - in yellowish brown colors; From dinofite ceratium - in yellow-brown color.

The total biomass of phytoplankton is small as compared with the biomass of the zooplankton feeding to them (respectively, 1.5 billion tons and more than 20 billion tons). However, due to the rapid reproduction of algae, their products (harvest) in the ocean almost 10 times more than the total products of the entire living population of the ocean. The development of phytoplankton largely depends on the content of mineral substances in surface waters, such as phosphates, nitrogen compounds and others. Therefore, in the seas, the most abundantly develops algae in areas of raising deep waters rich in minerals. In fresh water bodies, the flow of mineral fertilizers, various domestic and agricultural, drain, leads to the massive development of algae, which adversely affects the quality of water. Microscopic algae feeds small planktonic organisms, which in turn serve as more large organisms and fish. Therefore, in the areas of the greatest development of phytoplankton, many zooplankton and fish.

The role of bacteria in plankton is large. They mine organic compounds (including various pollutants) of water bodies and again include them in biotic circulation. Bacteria themselves are food for many zooplankton organisms. The number of plankton bacteria in the seas and pure fresh water reservoirs does not exceed 1 million cells in one millilitress of water (one cubic centimeter). In most fresh water bodies, their number changes in the range of 3-10 million cells in one millilitress of water.

A.P.Sadchikov,
professor MSU named after M.V. Lomonosov, Moscow Society Tests of Nature
(http: //www.moIP.mSU.rU)

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How to find out where the birds spent the winter? How to study the paths for which they flew?

For centuries, Europeans did not suspect the long flight of birds and were convinced that in winter they are hiding in secluded and inaccessible places where they are doing unfavorable days in a state of lethargy. This opinion existed until the XVIII century.

Even the great Swedish naturalist Karl Linney wrote: "Every autumn, when it starts to get cold, swallows are looking for refuge in reeds of rivers and lakes." Later, scientists discovered the migratory paths of various types of birds and caused them to map of the globe. And they helped the scientists in this light rings worn on the paws of birds.

The idea of \u200b\u200bringing birds was born in 1899. She rightfully belongs to the Danish teacher Martensen. He first began to ring birds to find out if they fly away. Martensen put on his feet 102 various birds lightweight aluminum rings on which engraved their address. Each ring had its own serial number, which could be clarified which bird, what date and where it was caught.

Of the 102 birds surrounded by Martensen, 9 were killed next year in Western Europe. The idea of \u200b\u200bsuch a kind of "certification" of birds was accepted by scientists of the whole world. So it was the beginning of the scientific ringing of birds. Now almost all countries of the world have created special centers of bird ringing.

However, in 1740, the Italian scholar of the Spolancing "Rolled" birds, tie red ribbons on their feet. Now the ringing of birds in different institutes is conducted according to the method of Martensen. The ring with the name and address of the institution, the leading ring, and the ordinal number of the bird is put on the leg of the caught living bird. Most often, the rings put on the legs of chicks that have not yet learned to fly. In a special diary, a bird's species, rings number, date and place where it was causing.

The collapsed birds often fall into the hands of people, most often hunters and nature lovers. The brilliant ring immediately rushes into the eye, and in the address of the dialing center there are reports of catching birds, and if it is killed, then the ring is sent there, which is put in a regular envelope along with information about time, place and circumstances of bird production.

Suppose the ring was put on the chick of Aist in Bulgaria, and then received it from Egypt. So, the stork flew to winter in Africa. Next, we get a second letter with a similar ring from another stork, stolen, too, in Bulgaria. This time the ring was removed in Equatorial Africa. It turns out that he flew over Egypt and continued his way.

This method helped undoubtedly to establish that storks winter a thousand kilometers from their native places in southern Africa. In the same way, they found out that our swallows winter south of the equator, from Tanzania to Guinea. And our cuckoo, it turns out, a big traveler - it visits the winter of the Arab countries and the oasis of Sahara, Jungle Sudan and even reaches Mozambique.

Thanks to the ringing, we know that some species are returned in the spring in those nests in which they spent last year, for example, storks, swallows, starlets and other birds. It turns out each small ring, put on the leg of a bird, is a valuable scientific document. He tells us about the path where our winged friends are moving. In many countries, hundreds and thousands of birds are surrounded every year.

Character, deadlines and path of jambs of fish are studied using observations from sushi, from ships and aircraft. But the main method of studying the migration of fish is marking. It provides the best results. The study of fish biology, including their migration, scientists are engaged in scientists of many special scientific institutions around the world. Submitted by the International Council for the Study of the Seas, in Copenhagen, for the period 1925-1951, more than 5 million fish were labeled by scientists from various countries, mainly migratory species.

Typically, the brand is attached to the body of the fish with a nylon thread and special clamps. It is fixed near the spinal fin. On the brand, as well as on the ring, the address of the scientific institute, which labeled the fish, and the corresponding number is indicated. Fish marking data is entered into the appropriate diary.

Recently, the labeling of fish with hydrostatic stamps, which are transparent plastic tubes are practiced. The note is inserted in them, where the following data is noted: the address by which the note found, and the information about the date and place of fish. On the light on transparent celluloid, you can read: "Cut the edge, a letter inside." The text of the note is written in several languages.

With the help of the labeling, information on the migration of whales was collected. The first ideas about their paths were obtained with direct observation from the shore and with whaling ships. The success of the whaling fishery is directly dependent on the migration of whales, from knowledge, where and what time they are. Migration travels affect the number of subcutaneous fat.

When whales are sent in the fall from areas of nutrition to the reproduction areas, the fat layer in animals reaches the greatest thickness, in the spring, when returning, it becomes very thin. The most complete information about whale biology was obtained by playing. Whales marked with various types of tags, shooting them into the subcutaneous fatty layer of garpared weapons.

Scientists of a number of countries have developed a lot of strength to study the migrations of butterflies. At the beginning of the 20th century, American entomologists began to study the monarch butterfly flight - a classic traveler. Soon the flights of butterflies began to study in Europe. Some countries have created special entomological stations to explore their routes.

The main means of study was the labeling: a completely thin and lightweight aluminum plate is attached to the butterfly wing, which glitters in the sun, attracting attention. She does not interfere with the flight. The microscopic label indicates the address of the station or researcher. West German Entomologist Herbert Rere marched in this way 60,000 cabbagers. From the released butterflies, RR received about 20 plates, one of which was found at a distance of 80 km from the release place.

Today apply the latest ways of marking. For example, fish are labeled with radioactive isotopes. Modern technique gives more and more means, with which you can trace the paths of migratory animals. To establish the migration path of sea turtles that swim thousands of kilometers to reproduction places, scientists resorted to the original method of laugh.

On the back of a huge turtle weighing 150 kg put a special radio transmitter, the signals of which gave the opportunity to trace her route across the ocean. Today and on some ornithological stations, instead of a ring, a miniature radio transmitter is strengthened on his back, with which they determine where it is located.

Recently, in some countries, the routes of migratory birds are studying with radar. Observations for migratory birds are kept in the same way as behind aircraft. The radar screen marks flying birds, the space in which they are located and the direction of flight. Large birds appear on the screen as small bright dots, and small noticeable only when there are many of them.

With the help of a radar, observations can be embraced quite large spaces and huge amounts of migratory birds. The study of radar snapshots showed that birds fly over huge spaces and not a firmly specified path, but on a very wide front. The exception is white storks and some predatory birds flying through strictly defined places and using scientists, ascending air flows that facilitate flight.

With the help of the radar, a lot of valuable data was collected, indicating that migratory birds in the afternoon are focused on the Sun, and at night on the stars. With a lot of clouds, they often begin to rush, circling, changing the direction, sometimes come down from the course, but as soon as the stars become visible again, the ability of birds to the orientation is immediately restored, and they take the right course again. So the devices serving on Earth military and civil aviation helps ornithologists.

The study of random and periodic wing wanders is not only theoretical, cognitive interest to specialists, but has a huge nationality value. For example, the study of the mass flight of locusts and other pest insects has long been put on a strictly scientific basis. A special research institute has been created in London, which studies issues related to locust flights.

Underwater travelers

The lower representatives of the animal world are also susceptible to regular movements that are similar to the migrations of higher organisms. There are two types of plankton movements: horizontal and vertical.

The horizontal movement of zoo and phytoplankton organisms is called still passive migration. Because of the limited possibility of movement, planktonic organisms travel often not in their will, and they are passionate about various water currents.

Planktonic organisms form clusters with a total weighing up to several million tons. Sometimes they move on hundreds and thousands of kilometers; The speed with which the flow carries the aqueous organisms is sometimes very large. For example, some equatorial flows have an average speed of about 100 km per day, and the atlantic flow rate of Golf Stream is about 250 km per day! Pedestrian would not have got angry.

The vertical movements of plankton organisms are active and sometimes reach a distance of up to 500 m. If you compare this distance with the miniature sizes of the organisms themselves, then vertical migrations are truly long journey. In various stages of its development, planktonic organisms dwell at different depths of the water basin. Adult shapes inhabit mainly the depths of the sea, and eggs and organisms at an early stage of development are surviving surface layers. At various depths, some male and female individuals of the same kind are also inhabited.

The movement of the simplest organisms are in close relationship with their reproduction cycles. Very interesting in this regard sea worms Palolo from the Nareid group, which at a certain time associated with the phases of the moon, go to the upper layers of water for breeding. These worms are found in indisclous quantities in the Pacific Ocean near Samoa Islands, Fiji and Tonga of the Polynesian Group. Usually they inhabit the cracks of coral reefs, making moves in coral formations.

In the fall (in October - November), after a week after the full moon they float on the surface of the sea. At this time, at the rear end of the body of the females, you can see a bag full of brown eggs; Men's germ green. Ripe eggs, climbed from the mother body, swim freely. Their fertilization is accomplished passively, by the waves. The front parts of the body of worms (red) remain in water, they have the ability to regenerate - restore lost parts of the body.

Residents of the islands appreciate Palolo as a special delicacy. The islanders know the time in which Palolo will appear on the surface of the ocean, with an accuracy of one day. At this time, they go out into the sea on their boat wetted from wood, even before sunrise, they stop near the reefs and wait patiently with the grids in the hands of the appearance of sea worms.

Usually, the output of worms on the surface lasts two hours, then the bags of females burst, and the sex products are floating out. In the clock, when Palolo appears, the sea on huge areas literally tears from their countless set, becoming dark green. In the continuation of the whole week, the natives fell: eating worms with raw or prepare delicious and nutritious dishes.

Large importance for vertical distribution of life in water bodies is, as well as the temperature and pressure of water. Nevertheless, the distribution of zooplankton at different depths of the sea is not a constant phenomenon, in various parts of the day it changes due to the vertical migration of organisms. The amplitude of movements in various organisms usually varies from 200 to 300 m.

Research has been established that the main reason that causes them to perform such long journeys over one day is related to nutrition. Surface layers of water, especially to a depth of 25 cm, thick are inhabited by various types of bacteria, phytoplankton and other microscopic organisms - the main food of zooplankton.

Most plankton animals at night rises to the surface of the water, and during the day it goes into the depths of the aquatic layers, although food is enough upstairs. The reason for this is studied not enough, most likely, in deep and dark layers, animals are saved from enemies.

In addition to daily, part of the plankton makes seasonal migrations. For example, the sea crustacean Calanus Finmarchius spends several months at a depth, and the rest of the time rises and lives in the upper layers of the sea. It is assumed that this is due to the change in the intensity of light and temperature. Studies have established that some marine organisms that cannot carry high temperatures in the surface layers of the sea regularly make seasonal migrations, adhering to the summer of cool deep layers, and in the fall and winter - superficial. Some species can and daily and seasonal migrations.

From marine invertebrates migrate and some migrate and iglobler migrate, which with the approach of spring come to the coastal strip, where eggs are laying. Pursuing the migratory fish herds in continuation of 4 months, the Pacific squid, for example, passes the distance of up to 8000 km.

One of the surprising phenomena of wildlife is undoubtedly massive fishing of fish. And indeed, it is difficult to imagine how in a strictly defined, as if the "appointed" hundreds of thousands of thousands and even millions of fish of one species leave the invalid herds wide ocean expanses and are rolled into the distant and most disastrous way.

More than 2000 km need to meet the flow of the river, overcome countless hazardous thresholds and waterfalls to achieve a place where you can take the caviar. No one will show them the way they must pass once in their lives. And yet the fish unmistakably reach their native places where the caviar droop and die. Of course, not all fish travel. It turns out that there are such species that never leave their native reservoirs, no matter how small they are.

In fish, like plankton animals, distinguish two types of migration: passive and active. Fish Fish, for example, never move against the current, as too weak to overcome it. Therefore, caviar, fry and young are transferred to close or distant distances with various water flows. Passive migration is observed in the juicing herring.

Every spring adult fish living in the northern regions of the Atlantic Ocean are sent to the shores of Norway, where I caviar. The seaside course refers to the hatched fir to the shores of the Scandinavian Peninsula, for the distance 800-1000 km from the place of birth. Similar migrations and fry of herring, hatched in the Murmansk coast area.

The larvae of acne - lepticephali, insignificant in size and almost deprived of the organs of active movement, make one of the most ambitious passive migrations. They pass 7-8 thousand km from Sargassov Sea, where they are removed, to the coast of Europe, fascinated by the powerful movement of golf stream. There are many and actively migrant. They are wound independently, but adhering to a certain direction related to reproduction, nutrition and wintering. Pisces are taking both accidental migrations, for example, with suddenly changing conditions.

In some cases, migratory fish pass more than 2,000 km, and Nerd, for example, is making wandering in the upper river Yukon on Alaska, overcoming 3,600 km, and at a speed of 30-40 km per day. Sometimes such travels continue all months. Caspian Beluga passes from the Caspian Sea to the upper river Ufimka 2950 km. Caspian sturgeon, whose spawning site is in the headwaters of Kama, swim 2500 km.

Some fish, especially Pacific salmon, prolonged wandering so dedicts that after spawning they are almost not able to actively move. The question arises, what is rational fish in these distant migrations? On this question, science still did not give a complete and exhaustive response. And yet it can be said that, dying, fish provide good conditions to the fools that will get out of fertilized caviar. Parents die for the life of their offspring.

Among the numerous species of fish, the most distant travel is taking European river eel. This fish is born in the depths of the ocean and soon leaves in freshwater pools - in the rivers and lakes. When sex maturity comes (approximately 8-12 years old), it again begins uncontrollably in the sea, overcoming from 7 to 8 thousand km; It goes first in the Atlantic Ocean, then in Sargassovo Sea, where at a depth of about 1000 m mosses caviar and there, where he was born, dies from exhaustion.

Amphibians and reptiles are wage

Interesting observations of migration of some amphibians made biologist V. Beshkov, Researcher of the Zoological Institute of the Bulgarian Academy of Sciences. With the playing, it found that a herbal frog in search of a suitable place for wintering was 120 km. He observed how the frogs of this species committed migration to reproduce a distance of 60-70 m from the coast of the river Super, since they lacked comfortable for reproduction of places.

In the process of research of biology and behavior of various types of amphibians, it has established that long-term migrations to reproduction places makes a gray toad. He observed the movement of the toad from the low-lying areas of Vitosha (Forest in Bayan) to almost the area of \u200b\u200bVauses in Sofia.

Toads go to the places of ikrometania from April 1 to April 15 and remain there 15 days, after which they return to the Forest Bayan. Peskkov also watched the toad of this species, leaving the spring from the sublime places of jacket (rocky and anhydrous terrain) to the river Zabanitsa to postpone the caviar there. Gray toads are taking vertical migrations to a distance of up to 300 m. After reproduction, they return to where they came from.

The Zabs Beskov hatched in the forest near the cliffs in early October. But the toads make movements not only for short distances. There are cases when they traveled to continue the week to reach the swamps or puddles, in which Icru was postponed. Traveling these amphibians only at night, and sleep. Unmistakable instinct always tells them the right path, they never come down from the way to the water reservoir to which they are sent.

Among the amphibian migrations for a short distance are committed by some types of tritons. Finding Tritons at a distance of a kilometer from the reservoir is not uncommon.

Traveling to the places of wintering is taking and reptiles. For example, some vichuks crawl more than a kilometer to get to a comfortable place in the roots of a dry tree or in some career, where they accumulate in a set. And crocodiles wake up from one reservoir to another. There are cases when the densely populated swamp in India was abandoned by dangerous inhabitants, as it washed.

Crocodiles crawled, without disassembled roads, through thickets and the field, even got into one village, where they scattered through the streets, filled into the courtyards, and some climbed into the wells, putting a population into horror: in the morning, people at every step stumbled on terrible aliens. On the next night, the crocodiles left the village, continuing the way.

Long migrations are taking a giant sea turtle, which in the continuation of the millennium lay eggs into coastal sand on certain islands. Green Brazilian Turtle, for example, you need to overcome about 2,500 km to reach the isoth Asuncion, where it puts eggs. Prolonged wanderings to reproduction places are made by other sea turtles - Ridlea, common in the Atlantic Ocean from Canada to the Caribbean.

Migrations of these turtles for a long time remained a mystery for scientists. Only in 1947 it was established that every year in April - May and before June about 40 thousand skulls of this species float from different sides of the vast ocean to their favorite beach to postpone the eggs.

Schedule of heavenly expanses

Everyone knows the accuracy with which migratory birds leave the autumn of native places, going to the south, and in the spring they return home to postpone the eggs and bring offspring. This rhythm is so strictly observed by various types of birds, which in India, for example, in ancient times, some months of the year were even called from certain types of migratory birds.

Birds are undoubtedly the record holders in the animal world, as they commit the most distant travel. The absolute record belongs to the polar cracker, which every year overcomes the path from the Arctic to Antarctica and back!

The famous American ornithologist J. Odubon described his observations of the packs of wandering pigeons, which flew through Ohio in the fall of 1813. He calculated that the pack had more than 1.1 billion pigeons. It would be difficult to believe it if there were no other evidence. Alexander Wiilen, who watched in 1832 by a flock of wandering pigeons in Kentucky, argued that its number was determined at 2,330,70,000 individuals.

Let us leave such an accurate figure on the conscience of eyewitness, but this is not the main thing. Unfortunately, the human greed caused that these birds whose flocks reached such astronomical numbers, no longer exist. They were barbarices destroyed in the XIX century because of tasty meat. The last bird of this species died in 1914 in Zoological Garden in Cincinnati.

What speed migratory birds are flying? Wild ducks, for example, - at an average rate of 70-80 km / h, swallows - 55-60 km / h; There is also a minor-like message that the city carved in England, after 24 hours, was caught in the United States, flying 3,500 km per day. It should be noted that the direction of the wind has a large influence on the flight speed.

A bird that flies at a winding time at a speed of 40 km / h, and with a passing wind 50 km / h, with the compere significantly reduces the speed. Especially reduces the flight speed of a pushing wind. The height on which the migratory flocks fly, too different. For example, small singing birds are usually flying no more than 100 meters from the ground; Skvorts, crows, drosses prefer height in 150-500 m, and storks 900-1300 m.

Many birds achieve such a height, where a person could not be without an oxygen apparatus. This applies to those species of birds that are forced to overcome high mountain arrays during migrations. Over the Himalayas observed and photographed small birds flying from India to Siberia. And the English observer Harisen photographed from the aircraft to the flock of wild geese, flew over the Himalayas at an altitude of 9500 m. Most of the migratory birds bypass mountain ranges, adhering to river valleys and gorges.

Migrations are observed in some types of low-flying birds. Penguins, for example, sometimes overcome the distance of up to 2000 km, moving "on foot", gliding on the abdomen on the outstanding hilly sites or climb across the ocean. With the onset of winter from all over Antarctica, they are rolled to the north, sometimes reaching the southern shores of Africa and South America.

Some representatives of the group running birds, such as ostriches, cover the "walk" distance of 1000 km, moving in a precisely specific direction.

It should be noted that different birds make flights at different times of the day. Day predators and a number of other birds fly solely during the day, some swamp and waterfowl - at any time of the day. Many migratory birds during the flight are followed by a certain "Stroy", for example, the cranes fly by the Wedge, geese with a variete, and small birds are widely unfolded. Some birds make flights in full silence, others (cranes, swans, wild ducks and many others) make characteristic sounds that serve as apparently to transfer various information.

Watching birds is a phenomenon that people paid attention to many years ago. It is known that various legends of the ancient Ellala and Rome are associated with birds and their flights, it is mentioned in the ancient Egyptian legends. In the ancient anthem that came to us, such words are found: "They fly to the south over you, they guard you from the hot wind ..."

This is also said in the Bible Prophets of Jiequi and Jeremia. Aristotle, the greatest scientist-encyclopedist and philosopher-naturalist of ancient Greece, in his diversity "History of Animals" also took a big place to birds. In it, along with naive and erroneous ideas, many and accurate information about their flights. Millennies people collected data on bird flights, but so far this phenomenon is not fully studied.

By the time of departure, the birds are divided by sodium basic groups. The first is birds that begin to prepare for the departure long before the occurrence of an unfavorable period. Cuckoo, for example, flies from our country at the end of July or early August, when a lot of food and warmth.

Astricted storks and swallows relatively early. Birds that come to the second group fly away after the appearance of the first signs of changing weather, i.e. When the air temperature decreases and reducing the number of food. Among such birds there are many insectivores: starlings, Slavs, etc. The third group is ranked with birds, which are flying late in the fall, when the living conditions become unbearable for them, for example, wild ducks and geese.

However, sometimes not all birds of the same species and not even all individuals are migrated by the same population. Some fly away, while others remain within the number of nesting areas. "Almighty" migratory instinct on them is not valid. In cities in warm winters, near the garbage containers, you can see the remaining wintering races.

Still not allowed completely issues related to navigation and orientation of birds during flight. Nevertheless, these observations and experiments suggest that their vision is played by the main role in the orientation of birds, which is well developed in all feathered.

Not only terrestrial, but also celestial landmarks are of great importance for bird orientation: in the daytime - the sun, at night - the moon and the stars. It is also established that with night flights, birds are focused mainly on the polar star. Some researchers adhere to the opinions that during distant flights, birds are guided by the magnetic field of the Earth.

Traveling mammals

Migrations observed in mammals are two species: non-periodic and periodic. Indirectural migrations are often associated with disadvantage of food or with overpopulation of their habitat. The behavior of animals is changing, and, in the end, they leave the region, i.e. Migrate.

A characteristic example of mass migration is the grand migration of mouse-like rodents in the so-called "mouse years". For example, in 1727, countless hordes of rats from the Kazakh steppes crossed the Volga. In subsequent years, animals settled all over Europe, spreading illness and damage to the population. Such travels from time to time are taken by other mice-like rodents - various types of field mice, water rats, lemmings and many others.

The classic example of spontaneous and irregular migrations represent the movement of lemmings. These animals are in length of 15 cm, and they live in Asia, Europe, America. On the European continent are found mainly on the Scandinavian and Kola Peninsula. Periodically gathering in inconspicuous quantities, the lemmings leave the areas of their habitat and the huge live stream move along the tundra, as if trying to reach the horizon line.

Sometimes they leave for hundreds of kilometers from native places. The lemmings are followed by wolves and foxes, which during this period feed solely by them. The animals can become prey and fish, bears, wolves, sands, as well as domestic cats and dogs. At the time of movement over them, Owls, crows, cauldons, seagulls and other feathers are spinning, which attracts light and delicious mining. But nothing can stop the lemmings in their spontaneous movement forward: neither enemies that are destroyed in many of them, no river and mountains.

Going on this campaign, the animals are guarding themselves to peculiar suicide. Having reached the sea coast, they do not stop, do not return back, and in some inexplicable blindness are thrown into the fusion of the water of the surf. The probability of salvation is negligible. Only a minor part of the lemmingly manifests "prudence" and, clogging on the shore, rushes further along his edge until it finds the right place.

The main reason for the mass travels of lemming is a strong increase in their numbers. It has been established that in some years these animals are fruitful especially intensively: instead of two times a year, the female brings three, and sometimes four times. At the same time, the number of kids in the litter is greater than usual. As a result of this, "hunt for changing places" occurs. It is known that migratory lemming groups consist mainly of young animals, but only 20% of them reaches puberty.

Migration Antelope GNU in Africa

Some zoologists believe that lemmings have a congenital migration instinct, but it is manifested only during the years when the conditions mentioned above are above.

Mass non-periodic wanders are taking proteins. Usually, these cute animals are not prone to distant movements, but with disadvantage of food they are massively, thousands of individuals, leave the constant habitats and move on hundreds and thousands of kilometers from him. With these natural relocations, the bugly proteins are usually stopped before any obstacles.

Sideways or groups of animals, stringly fly from a tree to a tree, moving from one forest to another, twisted rivers and lakes, littered villages and cities. Without a stop, they move forward and forward until the forest is reached, where a lot of food, not frightening neither people nor animal enemies.

Proteins are moving at a speed of 3-4 km / h, however, the total speed of movement depends on the number of rehabilitary animals. The more numerous accumulation of migratory protein, the faster they move forward, as in a short time they destroy food reserves and they need to find new feeds rather. When resettlement, proteins do not adhere to the general group, like some other mammals (reindeer, bison, lemmings, etc.). And although they travel in one direction, but often do not see each other. Brem described the case when in 1896 the huge accumulation of protein moved through the Nizhny Tagil (Ural).

The bulk of the crossing animals took place 8 km from the city, and the flank detachments of this "army" defended 16 km from each other. One part of the protein passed through the city; The animals were fearlessly jumping through the streets, ran into the courtyards, drove through the windows into the rooms, lasted on the trees and roofs. Dogs with dispersion crushed animals, people killed them, but proteins were not deviated from the selected path, moving forward uncontrollably.

Three days continued the procession. Even the turbulent and wide Chusovaya River did not stop the animal immigrants. The proteins fearlessly entered cold and stormy waters and swam on the opposite shore. "There is no more beautiful spectacle," wrote a well-known researcher Siberia Midddorf, - than the flotilla of a squad, swimming a wide river.

Their tails sticking out of the water are similar to ship sails. " The journey of the protein that Brem wrote, continued until the animals fell into the forest, where they had enough for all foods. Sometimes the front, which moves proteins, reaches 300 km, and the number of migratory animals is determined by tens, and sometimes hundreds of thousands of individuals.

Mass migrations are taking both texts. Instinct awakens in the fall - also due to an increase in the number of animals in a given area and an increasing disadvantage of food. By the sword of individual individuals, it was found that some of the songs migrate to a distance of 2000 km from the place of marking. Often, during these wanders, the beasts fall on the drifting ice of the Northern Ocean and reach the most distant from the continent of the islands.

Indirectional migrations commit all the well-known gophers. In the area where these animals appear, they become dangerous pests of field crops. In the middle of the XIX century in the region of Schleswig (Germany), these rodents were not at all. They appeared there unknown from where, in large quantities, and quickly became the scourge of agriculture in the area.

Of all the representatives of the animal world, the most significant horizontal migrations make marine mammals, mainly whales, seals and sea seals. Movement of whales and lastonods are determined by their features of their nutrition, and some species are associated with the peculiarities of the reproduction.

Migrations of different types of whales have a different character. In whales living in the northern seas, they are very limited. The species that adhere to the bays and coastal zones migrate mainly in the northern and southern directions, and the animals rarely go to the open sea.

Whales that live in open marine spaces are moved during migrations in a strictly defined circular direction, adhering to the ocean flow. At the beginning of the summer, these animals hold the path to the north, and at the beginning of the winter (with the occurrence of large cold weather and when accumulating ice in the northern seas), they will be drunk in the opposite direction, south, bypassing the equator.

However, not all whales migrate in strictly certain seasons of the year. Only humpback whales are the greatest accuracy. Representatives of the satuled whales of the southern hemisphere are sent in summer to the south, in the cold water of the Antarctic, rich in food at this time, and in winter they return to the north, in warm tropical and subtropical water. Here they feed down poorly or do not take food at all.

Long Travel Makes Blue Whale, the largest animal of the Earth. The case is known when the blue whales sailed about 500 km in 32 days, in another case, 88 days about 800 km. The recorded record distance from the place of marking for Blue Whale is 1600 km.

Regular seasonal migration makes small polysya. It spends the winter in the northern waters of the Atlantic Ocean, and in the spring it is sent to distant wanders, reaching Svalbard and the Barents Sea.

The females of some kinds of whales penetrate through the Gibraltar Strait in the Mediterranean Sea. According to Zoologist P.U. Puzanova, in 1880 one of the whales penetrated through the Bosphorus and Dardanelles in the Black Sea, armed stranded in shallow water near Batumi. His skeleton is now stored in the Tbilisi Museum.

Regular seasonal migrations sometimes are sometimes characteristic of many lobs. One of the Schedule of this detachment of animals is a Greenland seal. In summer, these animals move to the areas of floating ice western regions of the Arctic Ocean, where they eat hard, and in the winter they come far to the south - to the throat of the White Sea.

Here, seals appear in huge quantities, forming three separate herds - Newfoundland, Janmaienne and Belomorsk, who have hundreds of thousands and even millions of animals. Here, seals give birth and climb babies, linen. Later, they are together returning to the Arctic Waters of the Ocean.

It is interesting to note that the Mentioned herdland seals are not only kept in various districts, but are not mixed during migrations. For many years of observations and the labeling of a large number of individuals, Norwegian researchers found that there is a partial exchange of individuals of only Jan-Mayensky and the Belomorsk Stud.

Far seasonal migrations make sea seals. In the summer, they are going to thousands of individuals in the northern part of the Pacific Ocean, mainly on the island of Profit and the Commander Islands. The old males sail here at the beginning of May, a few weeks earlier than females.

Here the cats multiply and keep until the end of August. In the autumn, the flock from the Commander Islands floats to the Japanese Sea, and the profitable winters off the coast of Southern California. Females, unlike males, winter in more southern regions and migrations swim huge distances - up to 5000 km.

The plankton crustaceans in fresh waters are eaten fish, as well as a number of relatively small invertebrate predators (branching crustaceans Leptodora Kindti,many weary crustaceans, non-applicant mosquito larvae ChaoBorus. and etc.). At the attackers to the "peaceful" zooplankton of fish and invertebrate predators, various strategies of hunting and different most preferred mining.

In the process of fishing, fish usually rely on vision, trying to choose the production of maximum size for them: for grown fish it is usually the largest of plankton animals found in fresh waters, including invertebrate predators-planktonophages. Invertebrate predators attack mainly on small or medium-sized plankton animals, because they simply cannot cope with large. In the process of hunting, invertebrate predators are oriented, as a rule, with the help of mechanoreceptors, and therefore many of them, unlike fish, can attack their victims and in complete darkness. Obviously, invertebrate predators themselves, being the largest representatives of plankton, can easily become victims of fish. Apparently, so they "not beneficial" to be particularly large, although it would allow to expand the dimensional range of their potential victims.

To protect against invertebrate predators, the plankton animals are more profitable to have larger sizes, but at the same time the danger is immediately increasing, and therefore easily affordable prey for fish. The compromise solution of these seemingly incompatible, the requirements would be an increase in real sizes, but due to any transparent increases that do not make their owners are particularly noticeable. Indeed, in the evolution of different groups of plankton animals, there is an occurrence of such "mechanical" means of protection against invertebrate predators. So branching Holopedium Gibberum. Forms around his body a spherical chatter shell (Fig. 51), which, being absolutely colorless, does not make it particularly noticeable for fish, but at the same time protects against invertebrate predators (for example, from larvae ChaoBorus), Since they are just hard to grab such a sacrifice. Protective function can also be performed by various rates of pecite of Daphny and Kolovoltovka, and, as it turned out, some of these formations are developing in victims under the influence of certain substances allocated nearby predators. At first, such a phenomenon was found (Beauchamp, 1952; Gilbert, 1967) at Kolovoltov: Female Victims - Koverts Brachionus (BRACHIONUS CALYCIFLORUS), grown in water, in which previously contained prepocriters of the kind of asplan ASPLANCHNA SPP.), produced young with particularly long side spikes of the shell (see Fig. 51). These spikes strongly interfered asplanms to collect brachyonuses, since those literally stood up their throat across them.

Later, various bodies induced by predators were discovered in crustaceans. So, in the presence of predatory larvae ChaoBorus. In young individuals Daphnia Pulex grown on the dorsal side "dentum" growing, significantly reduced the likelihood of successful eating them by these predators (Krueger, Dodson, 1981; Havel, Dodson, 1984), and some Australian Daphnia Carinata. in the presence of predatory bedbugs Anisops Calcareus. (Sea. Notonectidae) On the dorsal side, a transparent comb was formed, apparently, also having a hard predator in setting and eating production (see Fig. 51).

From most fish, such growers cannot protect, and therefore, with plankton crustaceans, if there are extremely important in the water reservoir, it is extremely important to keep imperceptibility and (or) to avoid immediate meetings with them, especially in a good light. As the concentration of planktonic crustaceans is maximal at the surface, it is not surprising, how often we find the existence of vertical daily migrations, expressing as a rise in the rich surface layers and lowering the day in layers, deeper, where weak illumination, as well as the possibility Reduce the local density by scattering in a larger volume prevent the rejection of their fish.

Vertical migrations themselves require certain energy costs. In addition, a small amount of food and a low temperature at great depths lead to a decrease in the intensity of reproduction and slowing the development of the racks, and therefore, ultimately to reduce the speed of their population growth. This negative consequence of vertical migrations is usually considered as a "fee" for protection against predators. The question of whether it is worth "paying" to protect against predators, it may be solved in different ways in evolution. For example, in the deep Bodhen lake in the south of the Federal Republic of Germany, two externally similar species of Daphnes live: Daphnia Galeata. and Daphnia Hyalina, Moreover, the first species is constantly held in the upper, heated layers of the water strata (Epilimnion), and the second - in the summer and autumn makes migration, rising into Epilimnion at night and dropping at great depths (in the hypolimnion) during the day. The concentration of food of both types of Daphnia (mainly it is small plankton algae) is quite high in the epilimnion and very low in the hypolimnion. The temperature in the middle of summer in Epilimnion reaches 20 °, and in the hypolimnion, it hardly reaches 5 °. Researchers from Germany X. County and V. Lampert (Stich, Lampert, 1981, 1984), detailed by the Daphny of the Lake of the Lake, suggested that migrations D. Hyalina. allow it to greatly avoid the press of fish (sigov and perch), and D. Galeata, Staying all the time in Epilimnion, in conditions of a strong press of fish capable of withstanding him a very high birth rate. Its hypothesis about different strategies for the survival of these Daphnia X. County N V. Lampert were tested in the laboratory when in the absence of a predator for both species imitated the conditions for permanent stay in the ephylimnion (constantly supported high temperature and large amounts of food) and vertical migration conditions (changing in During the day, the temperature regime and the changing amount of food). It turned out that in such artificially created conditions of Epilimnion, both types felt well and had a high birth rate. In the case of imitating the conditions of vertical migration, the survival and intensity of the reproduction of both species were significantly lower, but it is interesting that D. Hyalina. characterized at the same time much better survival and reproduction indicators than D. Galeata. When simulating the same epilimnion conditions, some advantage (though, insignificant) turned out to be D. Galeata. Thus, the differences in the space-time distribution of these types of Daphnia responded to the differences in their physiological features.

In favor of the assumption that it was the press of fish-planktonophages that is a factor responsible for the emergence of vertical migrations from plankton animals, the data obtained by the Polish hydrobiologist M. Glyavich (Gliwicz, 1986) also testify. Surveying a number of small lakes in the tatras, Glyavich discovered that the most common representative of weary crustaceans in them Cyclops ABYSSORUM. Makes daily vertical migrations in those lakes where there are fish, but does not make any fish where the fish are missing. Interestingly, the degree of severity of vertical migrations of cyclops in one or another concrete reservoir depended on how long the permanent fish population exists in it. In particular, weak migrations are marked in one lake, which fish were listed only 5 years before the survey, and significantly stronger where the fish appeared 25 years ago. But the most clearly migration of cyclops was expressed in that lake, where the fish are as far as known, there were a very long time, apparently, have already been several millennia. Another additional argument in favor of the hypothesis discussed is the fact of the absence of a lack of cyclop migration in 1962, just a few years after the launch of the fish there, and the presence of a clear migration of them in 1985 after 25 years coexistence with fish.

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