The textbook characterizes the most important processes and trends in the socio-political, social and spiritual life of our country and the world in the 19th - early 21st centuries.
The textbook is intended for general educational institutions: schools, gymnasiums, lyceums and colleges.
The textbook is equipped with a multimedia application posted on the publisher’s website “ Russian word» - Russian-slovo.rf.
Transition to modern industrial production.
The increasing volumes of technologically complex products required not only updating the fleet of machines and new equipment, but also a more advanced organization of production.
American engineer F.W. Taylor proposed dividing the process of producing complex products into a number of relatively simple operations, performed in a clear sequence with precise adherence to the timing of the time required for each operation.
The Taylor system was first tested in practice by automaker G. Ford in 1908 during the production of the Ford T model, which he invented. It became possible to assemble machines on a continuously moving conveyor belt, which greatly speeded up the production process.
CONTENT
Introduction
Section I. RUSSIA AND THE WORLD AT THE BEGINNING OF THE XX CENTURY.
§ 1. Scientific and technological progress and a new stage of industrial development
§ 2. Modernization in Europe, the USA and Japan
§ 3. Russia at the turn of the XIX-XX centuries
§ 4. Crisis of the Empire: Russo-Japanese War and the revolution of 1905-1907.
§ 5. Political life countries after the Manifesto of October 17, 1905
§ 6. Third June monarchy and reforms of P.A. Stolypin
§ 7. Russian culture in late XIX- early 20th century
§ 8. Colonialism and the aggravation of contradictions in world development at the beginning of the 20th century
§ 9. Development paths for the countries of Asia, Africa and Latin America
§ 10. First World War
Section II. RUSSIA AND THE WORLD BETWEEN TWO WORLD WARS
§ 11. February revolution in Russia 1917
§ 12. Transfer of power to the Bolshevik Party
§ 13. Civil war and intervention
§ 14. Completion Civil War and education of the USSR
§ 15. From war communism to NEP
§ 16. Culture of the Land of Soviets in 1917-1922
§ 17. Soviet modernization of the economy. The formation of Soviet culture
§ 18. Cult of personality I.V. Stalin, mass repressions and politic system USSR
§ 19. Culture and art of the USSR in the interwar years
§ 20. Economic and political development Western Europe and America after World War I
§ 21. Weakening of colonial empires
§ 22. International relations between the two world wars
§ 23. Spiritual life and development of world culture in the first half of the 20th century
Section III. HUMANITY IN THE SECOND WORLD WAR
§ 24. From European to World War
§ 25. The initial period of the Great Patriotic War
§ 26. Anti-Hitler coalition and the 1942 campaign on the Eastern Front
§ 27. A radical change in the Great Patriotic War
§ 28. The offensive of the Red Army at the final stage of the Great Patriotic War
§ 29. Reasons, price and significance of the great Victory
Section IV. WORLD DEVELOPMENT IN THE FIRST POST-WAR DECADES
§ thirty. Soviet Union V last years life of I.V. Stalin
§ 31. First attempts at reforms and the 20th Congress of the CPSU
§ 32. Soviet society of the late 1950s - early 1960s.
§ 33. Spiritual life in the USSR in the 1940-1960s.
§ 34. Countries of Western Europe and the USA in the first post-war decades
§ 35. The fall of the world colonial system
§ 36. “Cold War” and international conflicts 1940-1970s
§ 37. Expansion of the socialist system: Eastern Europe and China
Section V. RUSSIA AND THE WORLD IN THE 1960-1990s.
§ 38. Technologies of the new era
§ 39. Formation of the information society
§ 40. The crisis of the “welfare society”
§ 41. Neoconservative revolution of the 1980s.
§ 42. USSR: from reforms to stagnation
§ 43. The deepening of the crisis in the USSR and the beginning of the policy of perestroika
§ 44. Development of glasnost and democracy in the USSR
§ 45. Crisis and collapse of Soviet society
§ 46. Science, literature and art. Sport. 1960-1980s
§ 47. Japan, newly industrialized countries and China: a new stage of development
§ 48. Socio-economic development of India, the Islamic world and Latin America in the 1950-1980s
§ 49. International relations: from detente to completion " cold war»
Section VI. RUSSIA AND THE WORLD AT THE PRESENT STAGE OF DEVELOPMENT
§ 50. Transnationalization and globalization of the world economy and their consequences
§ 51. Integration of developed countries and its results
§ 52. Russia: course of reforms and political crisis of 1993
§ 53. Social and political problems of Russia in the second half of the 1990s.
§ 54. Russia at the turn of the century: along the path of stabilization
§ 55. Russian Federation at the beginning of the 21st century
§ 56. Spiritual life of Russia in the modern era
§ 57. Countries of Eastern and South-Eastern Europe and the CIS states in the world community
§ 58. Countries of Asia, Africa and Latin America on modern stage development
§ 59. Russia and folding new system international relations
§ 60. Main trends in the development of world culture in the second half of the 20th century
§ 61. Global threats humanity and the search for ways to overcome them.
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- History of Russia, XX - early XXI centuries, 11th grade, Zagladin N.V., Kozlenko S.I., Minakov S.T., Petrov Yu.A., 2007
- History of Russia and the world, grade 11, Zagladin N.V., Simonia N.A., 2013
- History, History of Russia and the world, grades 10-11, Program and thematic planning of the course, Zagladin N.V., Kozlenko S.I., Zagladina Kh.T., 2012
Fish They are common in all types of reservoirs, from marine waters to the smallest ponds, eriks and rivulets. Tropics and eternal ice are also rich in unusual varieties of fish. In the reservoirs of Russia, aquatic inhabitants are very diverse and distinguished by their beauty. In the territory Russian Federation there are more than 120 thousand rivers, about 2,000,000 lakes, 12 seas, 3 oceans, and all of them are habitats fish. Even in fresh Russian reservoirs, over 450 animals have adapted to live. fish species, and many live permanently, and some arrive temporarily until a certain period.
general information
Based on the presence and nature of the rays in the fins of most bony fishes, a fin formula is compiled, which is widely used in their description and definition. In this formula, the abbreviated designation of the fin is given in Latin letters: A - anal fin (from the Latin pinna analis), P - pectoral fin (pinna pectoralis), V - ventral fin (pinna ventralis) and D1, D2 - dorsal fins (pinna dorsalis). Roman numerals indicate the numbers of prickly rays, and Arabic numerals indicate the numbers of soft rays.
The gills absorb oxygen from the water and release carbon dioxide, ammonia, urea and other waste products into the water. Bony fish have four gill arches on each side.
Gill rakers are the thinnest, longest and most numerous in fish that feed on plankton. In predators, the gill rakers are sparse and sharp. The number of rakers is counted on the first arch, located immediately under the gill cover.
The pharyngeal teeth are located on the pharyngeal bones, behind the fourth branchial arch.
When a person looks into the water from his familiar world, filled with light and air, the world in which fish live seems cold, dark, mysterious, inhabited by many strange, unusual creatures. He himself can move in this environment only with great difficulty and in a very limited space. The need to wear heavy, cumbersome equipment in order to see, breathe, stay warm and move at a speed that should seem like a snail's to a fish hides from humans some of the undoubted advantages of fish over land dwellers.
The advantages come from the very existence in the aquatic environment, which played an important role in the formation of fish. Water is not subject to sudden temperature changes and therefore can serve as an excellent habitat for cold-blooded animals. Changes in the water occur slowly and provide an opportunity to move to more suitable places or adapt to changed conditions. Problem maintaining weight own body in water it is also much easier than on land, because protoplasm has approximately the same density as water, and therefore fish in their environment are almost weightless. This means that they can get by with a simple and light skeleton and at the same time sometimes reach significant sizes. A fish as huge as a whale shark moves with the same freedom and ease as a small guppy.
But there is one essential difficulty which is connected with life in water, and which, more than anything else, has shaped fish: the incompressibility of water. Anyone who has ever waded through water just above the ankle depth has felt the difficulty that fish constantly have to overcome: when moving, the water must be moved apart, literally pushed to the side, and it immediately closes behind you again.
Flat and angular bodies have difficulty moving through such a medium (if you push a board lying on water straight down, it will inevitably wobble from side to side), so the body shape of fish is remarkably consistent with this property of water. We call this shape streamlined: sharply pointed from the head, most voluminous closer to the middle and gradually tapering towards the tail, so that the water can flow smoothly on both sides with the least turbulence and, when approaching the tail, even impart some additional push to the fast-swimming fish. Of course, there is a certain variety of shapes, but in general this is the original form for all free-swimming fish, no matter what shape they acquire in the process of evolution.
The body of a fish, like that of any vertebrate animal, has bilateral mirror symmetry and is built according to the same simple scheme: a hollow cylinder, open on both sides, with a food tract that stretches inside from one end to the other. The oral opening is located at the anterior end, and the anal opening is located at the opposite end. Along the upper half of the cylinder there is a spinal column, a series of bone or cartilaginous discs that give rigidity to the entire structure. In the canal formed by the vertebrae is the spinal cord, which, expanding at the anterior end, forms the focal point, or brain. The walls of the cylinder along its entire length from head to tail are divided into numerous identical segments; strong motor muscles of these segments act on the bony or cartilaginous skeleton and enable the entire body to make wave-like movements from side to side.
Since fish are cold-blooded animals, life in the aquatic environment, as already mentioned, is especially favorable for them, but still it has its limitations. When the temperature drops below what fish can tolerate, they have to leave these places - which is why many fish in the temperate zone make seasonal migrations. With a strong and sudden change in temperature, the fish become too lethargic and do not have time to leave, and if conditions do not improve, they die. Some freshwater fish, which cannot migrate when the seasons change, circumvent this danger by plunging into winter or summer hibernation - they stop eating and winter time They lie inertly at the bottom, and in the summer they bury themselves in the mud until the temperature becomes favorable again.
The circulatory system of fish is the simplest of all vertebrates. Blood travels one circuit - from the heart through the gills, where it is saturated with oxygen, to various organs and parts of the body that take up oxygen, and back to the heart. The heart itself consists of only two chambers, the atrium and the ventricle (unlike the three-chambered heart of amphibians and the four-chambered heart of mammals), and works, so to speak, in line with the entire system.
A characteristic feature of fish is their fins, large or small wing-like structures that give them stability in the water and help them move and control their movements. Most fish have two types of paired fins - pectoral fins, on the sides of the head immediately behind the gills, and ventral fins, which are usually pushed back. At the top, the dorsal fin passes through the middle of the back; it can be divided into two parts, the anterior spiny one and the posterior soft one. On the ventral side of the body anus there is an anal fin, and at the very end there is a caudal fin.
All fins have their own special purpose; they are all mobile and driven by muscles located inside the fish’s body. The dorsal and pectoral fins, acting together, play a major role in creating stability. The dorsal fin, pointing straight up, acts as a stabilizer to keep the fish upright; The pectoral fins, spread to the sides, help maintain balance and make turns. The pelvic fins are also used as stabilizers. The tail serves for control and in the fastest fish it also plays the role of a stabilizer and engine. The fish hits it forcefully from side to side, and the entire back part of its body makes wave-like swimming movements. In fast swimmers, the dorsal and anal fins are pressed against the body or even retracted into special recesses, which increases streamlining.
The location and structure of fins in fish can be very diverse. In most benthic species, the paired fins are very close together and the abdominal pair, strongly shifted towards the head, is sometimes even located in front of the pectoral fins, directly under the lower jaw. This arrangement allows the head and gills to be kept above the bottom surface. In other fish, the pelvic fins are greatly reduced or even completely disappeared, for example in eels. In triggerfish and other more or less disc-shaped fish, the pectoral fins take on the full or partial role of motors. In the sea cock, which leads a bottom-dwelling lifestyle, the lower rays of the pectoral fins are separated and act like the legs of an insect. And the pectoral fins of the striped lionfish serve it mainly for camouflage: their long and widely spread rays resemble a bunch of algae among the coral reefs where this fish lives.
The body shape of the fish also differs markedly from each other. The most amazing changes occurred with those of them that almost always lie at the bottom: they became flat. Some fish lie on their belly and are flattened on top, while others lie on their sides and are flattened on the sides. Flattening in such fish occurs during the growth of juveniles and ends with the unusual process of moving the eyes to one, upper, side of the head. Winter flounder ( Pseudopleuro-nectus americanus), for example, lies on its left side, and its eyes are on the right side, while its close relative, the summer flounder ( Paralichthys dentatus), on the contrary, the eyes are on the left side, since she lies on the right side.
Among the fish flattened on top - angler. This fish rarely moves and catches its prey using its own fishing rod with bait - a fleshy lump on a thin flexible rod hanging from its head. Its close relative, the clownfish, is more active: its pectoral fins have turned into a special kind of limbs, and with their help it moves in leaps.
The various rays are essentially sharks that have transitioned to a sedentary bottom life and become flat. While swimming, their wide pectoral fins make wave-like movements and the fish seem to float in the water. In many stingrays, the tail is extended like a whip and has no motor power.
Even in water, there are other modes of movement besides swimming, and fish use them all to varying degrees. They crawl along the bottom like gurnards and dolgoopers, and can even emerge from the water onto the shore, like the mudskipper does. The Malayan slider and Chinese snakehead easily walk along the ground from pond to pond, crawling in exactly the same movements as most fish swim. In order not to tip over, the crawler supports its narrow, nimble body pectoral fins like props.
Some fish can also move through the air, albeit over short distances. The Mississippi pike skims the surface of the water using its tail like the propeller of an outboard motor. But flying fish really fly - they can fly through the air for almost a full minute and, if a strong wind blows, they rise to a height of three to six meters and glide over the waves on large front fins extended like wings. There are biplane flying fish, those that use their pectoral and pelvic fins to fly, there are monoplane flying fish, which fly only on their pectoral fins, and there is even a freshwater type of fish that flies like birds, flapping their pectoral fins over the water surface.
One remarkable feature of fish immediately attracts attention: from head to tail, fish are covered with a flexible, usually, shell made of round overlapping bone plates, or scales. These scales are strengthened in the inner layer of the skin and form the protective cover necessary for fish. In addition to the armor of scales, the fish is also protected by a layer of mucus, which is secreted by numerous glands scattered throughout the body. Mucus, which has antiseptic properties, protects fish from fungi and bacteria, and also lubricates the surface of the body. The differences in the size and thickness of the scales can be very significant - from the microscopic scales of the common eel to the very large, palm-sized scales of the three-meter long barbel that lives in Indian rivers. Only a few species of fish, such as lampreys, have no scales at all. In some fish, the scales merged into a solid, motionless shell like a box, like in boxfishes, or formed rows of closely connected bony plates, like in seahorses and pipefish.
The scales grow as the fish grows, and some fish have distinct annual and seasonal markings on their scales. The substance necessary for growth is secreted by a layer of skin covering the scales on the outside and grows along its entire edge. Since in temperate zones scales grow fastest in summer time When there is more food, the age of the fish can sometimes be determined by the number of growth rings on the scales.
The mouth of a fish is the only instrument for capturing food, and in all species of fish it is perfectly adapted for its task. The parrot fish, as already mentioned, has developed a real beak for pinching off plants and corals; The small American gerbil is equipped with a digging tool - a hard, sharp protrusion on the lower jaw, with which it digs through the sand in search of small crustaceans and worms.
In fish that feed near the surface, the mouth is usually directed upward, and the lower jaw is sometimes strongly elongated, as, for example, in half-snouts. Bottom-dwelling fish such as stargazers and monkfish, which grab prey floating above them, also have their mouths pointing upward. And in those fish that look for food at the bottom, for example, stingrays, haddock and the common chukuch, the mouth is located on the underside of the head.
Well, how does a fish breathe? To maintain life, she, like all animals, of course, needs oxygen - in fact, her respiratory process is not so different from the breathing of terrestrial animals. To extract oxygen dissolved in water, fish force water through their mouths, pass it through the gill cavity, and push it out through openings located on the sides of their heads. The gills act in much the same way as the lungs. Their surface is permeated with blood vessels and covered with a thin layer of skin that forms folds and plates, the so-called gill filaments, which increase the absorption surface. The entire gill apparatus is enclosed in a special cavity, covered by a bony shield, the operculum.
The gill apparatus is characterized by high functional adaptability, so that some fish can even obtain the oxygen they need not only from water, but also from atmospheric air. Common carp, for example, in hot weather summer months when the pond dries out or lacks oxygen, it captures air bubbles and holds them in the mouth next to the wet gills. The slider, snakehead and Indian catfish have special air cavities with folded walls near the gills. Lungfish, if necessary, use fully developed lungs with the same network of blood vessels as those of frogs and newts. In some ancient fish, the rudimentary lung, which later turned into a swim bladder, is still connected to the esophagus, and in essence these fish - mud fish, armored pike - have spare lungs.
However, the swim bladder of modern fish, if present, no longer performs respiratory functions, but acts as an improved lifting balloon. The bladder is located in the abdominal cavity below the spine and is an airtight sac equipped with glands that can, if necessary, extract gas directly from the bloodstream of the fish and fill the bladder with it. The amount of gas is adjusted with great precision, and the fish receives just the lift it needs to stay at its usual horizon, whether near the surface or at a depth of four hundred meters. Many fish that live at great depths or lead a benthic lifestyle do not need a swim bladder and do not have one. The swim bladder limits the ability of the fish to move arbitrarily to any depth, since adaptation to depth and pressure occurs gradually. Most fish living at significant depths cannot rise to the surface because their swim bladder would swell to an unbearable size for the fish - if such a fish is caught with a fishing rod and pulled out of the water, the swollen bladder can squeeze out its stomach through the mouth. There are fish, such as the mackerel family, with very little or no bladder. For them there is no such limitation, and they can forage at different depths. However, they pay a high price for this: in order not to drown, they need to be in continuous motion.
There are fish that live alternately in fresh and salt water; they have special difficulties - salt barriers that they need to overcome. Because fish live in water, they need to maintain a balance between the salts dissolved in their blood and lymph and the salts that may (or may not) be in the water around them. In freshwater fish, the concentration of salts in the blood is higher than in the surrounding waters, and therefore water constantly strives to penetrate the fish’s body through the skin, gill membranes, mouth and others. open areas bodies. Under such unrelenting pressure, the fish must constantly secrete water in order to maintain proper balance. U sea fish the difficulty is just the opposite: they constantly release water into saltier water environment and therefore must absorb it all the time so as not to wrinkle, like baked apple. And to release excess salts that come with the water, marine fish have special cells on their gill filaments.
Since the aquatic environment is so different from the air, we have the right to ask ourselves how the fish's senses operate to notify it of where it is and what is happening around it. What does the fish see? How does she hear? Does she have a sense of smell like ours, a sense of taste, a sense of touch?
We can answer that fish have all these five senses, and in addition they have one more, truly sixth sense, which allows them to very subtly perceive the slightest change in the movement of water around them. This sixth sense is unique to fish (This system of organs is also characteristic of amphibians living in water), and its organs are located in a system of canals under the skin.
Let's start, however, with the organ of vision - it functions in fish in the same way as in humans, with the difference that fish that feed themselves above the surface of the water have to deal with the phenomenon of refraction. Due to the refraction of light rays when they pass from air to water (or vice versa), objects observed in water appear displaced if you do not look at them directly from above. A man who wants to hit a fish with an arrow from a bow must aim much lower than where he sees it, otherwise he will miss, and long practice has taught him to do this. In the same way, a trout, an eared perch or a salmon, preparing to grab an insect fluttering over their pond, must jump out of the water somewhat ahead of the intended target - and long ago in the process of evolution this skill turned into a reliable skill based on instinct.
Fish that feed in water do not have to overcome this difficulty, because light travels in a straight line in the same way as in the air. There are, however, other factors that influence the mechanism of visual perception in their underwater world, and therefore the structure of their eyes. Chief among these factors are the amount of light available underwater and the limit of visibility due to the fact that even the clearest water cannot compare with air.
The absence of bright light in the underwater world has contributed to a significant simplification in the structure of the eyes of most fish in comparison with the eyes of land animals: they can do with little or no contraction of the iris, they also do not need eyelids, because water constantly washes away foreign particles from their eyes . They have an iris - a metallic ring around the dark pupil, but to regulate the amount of light rays entering the eye, it does not need to expand and contract to the same extent as our iris, so in most fish it is motionless.
Since visibility underwater does not exceed thirty meters at best (and often much less), fish do not need to adjust their eyes to too great a difference in distances. Almost all the time they have to look at objects only in close proximity, and the structure of their eyes corresponds to this. Their lens is not a lens with adjustable curvature, like the human eye, but an incompressible ball. In the normal position of the fish’s eye, it sees only close objects, but if it is necessary to look at an object located at a far distance, a special muscle tightens the lens.
There is another, more important reason for the spherical shape of the fish's lens, and this again has to do with refraction.
Since the lens contains a substance almost the same density as water, light penetrating from the surrounding aquatic environment into the lens, does not refract - according to the laws of optics, this means that for a clear image of an object on the retina, the curvature of the lens must be significant, and the ball has the greatest curvature. But, as some scientists believe, even with such curvature the image is not truly clear, and it is possible that the fish, even under the most favorable conditions, does not see objects under water clearly enough.
But fish have an advantage that land animals do not: they can see in more than one direction at the same time. Their eyes are not located in front, but usually on the sides of the head, and what each eye sees is recorded in the brain on the opposite side, that is, objects on the right are recorded by the visual center located on the left side of the brain, and vice versa.
This monocular vision of the fish has its limitations, especially in judging distance. Nevertheless, it is not at all impossible that there is a relatively narrow space directly in front of the fish that both eyes can see at the same time, therefore, fish have to some extent binocular vision (and therefore a sense of perspective), such as we have. Indeed, when something to the side attracts the fish’s attention, it seems as if it is really trying to make up for its monocular vision: it quickly turns so that the object is in the field of vision of both eyes and it would be possible to better estimate the distance to it.
DOUBLE VISION. The eyeball of four-eyed birds living in the Central and South America, is designed so that the fish can simultaneously and equally clearly see both in the water and above its surface. Both eyes of the four-eyed fish are located at the top of the head, and it can swim with them half out of the water. True, from time to time she has to dive to wet the upper, “above-water” part of the eye.
The extent to which fish can distinguish colors is unknown. The main tone of the underwater world of fish is greenish-blue, since all other colors are absorbed and disappear already at a short distance from the surface. The perception of color is therefore not particularly important for fish; The only exceptions are those fish that swim close to the surface. However, we do know that all fish except sharks can perceive some colors. Microscopic examination of the fish's retina showed that it contains cones, color-detecting nerve cells, and rods, which function primarily at night and are insensitive to color.
But what significance color has in the everyday life of fish remains a mystery. Some fish prefer one color to another: trout, for example, distinguish artificial flies by color. If a darkened aquarium is illuminated with all the colors of the spectrum, the fish will swim to the green and yellow stripes and stop there, but if only red is left, they will behave as if in the dark.
Bright and sharply contrasting colors, of course, can be a certain means of identifying each other for fish, but here again we are not sure that this is what actually happens. The bright, colorful outfit of some tropical fish makes one naturally think that it must have some significance for other inhabitants of the underwater world. For example, does a shark recognize a pilot fish by the contrasting transverse stripes on its dark back and sides? This would explain to us why such a small fish, a little more than twenty centimeters long, can fearlessly swim next to its huge and voracious companion and he will never swallow it by mistake.
It is also possible that bright colors serve identification mark, warning about the inedibility or toxicity of fish. There are fish that probably do not represent tasty prey for other fish, and in the shallow waters of tropical coral reefs, where visibility under water is relatively high, the bright coloring, which so clearly distinguishes them from their underwater counterparts, can serve as protection.
In any case, it seems likely that some species of fish recognize each other by their colors. In their greenish-blue world, a bright color catches the eye faster than a gray, barely noticeable shadow flashing somewhere nearby. This guess is supported by the fact that most species of fish that usually swim in dense schools are rarely brightly colored, while fish that live separately, among a rather monotonous color environment, usually have a noticeable appearance, and other individuals of this species can identify them.
The colors themselves are produced by a layer of cells in the skin under transparent scales. These cells are called chromatophores, or flower carriers, and contain various grains of pigment.
These are primarily orange, yellow and red pigments, very similar to the pigments in red or yellow flower. Then there is the black pigment, which is essentially waste from the body and can be found in more than just the skin ( internal organs fish with black skin also, as a rule, have a black shell), and finally, the substance guanine, contained in the form of crystals, which, depending on their number and location, can give white, silver or rainbow colors. When combined with black pigment, guanine produces blue and green metallic tints.
Of course, the main thing in the coloring of most fish is its protective properties. The protective coloring of fish that live in the upper layers of the sea - a dark back and a white or silvery bottom - makes them inconspicuous, no matter where you look at them. The camouflage of bottom-dwelling fish is very skillful - their color matches the color of the bottom or, like the zigzag pattern of camouflaged warships, breaks up the contours of the fish’s body. To this “breaking” coloring is added the so-called “deceptive” coloring, which completely changes the appearance of the fish.
Sometimes surrounding objects are imitated not only in color, but also in shape. The Amazonian leaf fish surprisingly resembles a leaf floating in the water. Fish can even change their camouflage at different stages of their lives - in the tropical waters off the coast of Florida there are, for example, fish that when young take the shape and color of a mangrove pod lying on a white sandy bottom, but when they outgrow the pod, so to speak, This camouflage becomes useless; the fish then go into deeper waters, becoming striped. One of the most skilled masters of camouflage is the common flounder; it can imitate stones, sand, and dark silt with the ease of a chameleon.
Camouflage can even affect the structure of the fish. The Sargassum clown sea is covered with skin projections like threads and patches that imitate the algae where it hides, and the rag seahorse has long shoots similar to sea grass leaves that it clings to.
Most fish retain the same basic color throughout their lives, but for some it changes with age. Young salmon and trout are streaked with dark stripes, but in adult fish the stripes disappear. Male salmon, trout, stickleback and many other fish change color during the breeding season. One day, Dr. William Beebe discovered coral fish that changed color combinations seven times in one day.
Even males and females can differ in their coloring. The male minnows, or lyre fish, and the European wrasse look like exotic birds with brilliant plumage, while the females of both species are completely inconspicuous. There are fish that become darker at night or, like barracuda, take on a completely different color. Many fish change color when scared or caught on a hook.
After death, the color of the fish usually changes immediately and often becomes completely different from what it was during life. The most amazing changes are probably happening with the bright green and gold sea bream, or sea bream. During the death throes, the green and gold colors turn into blue and pure white, and then gradually, when the last convulsions stop, the whole body acquires a dull brownish-olive hue.
For a long time, scientists have been studying the hearing of fish, trying to find out whether they can perceive sounds. It was believed that they could not, and that what we call the ear serves simply as an organ of balance in fish. But since some fish do make sounds underwater (these can be call and response signals during the mating season or identification signals), it is logical to conclude that they still perceive them. Most likely, when sound waves are perceived, the swim bladder serves as a resonator. Since they do not have an eardrum and auditory ossicles of the inner ear, which represent the true hearing apparatus of higher animals, it is believed that the role of the hearing organ, which perceives sound in the form of wave vibrations, in some fish is performed by the swim bladder and the so-called Weberian apparatus - a series of small bones connecting the swim bladder with the area of the inner ear. Some fish are, of course, very sensitive to vibrations, including simple water movement. They can hear the sound of a propeller at a great distance, and the steps of a person on the shore, which very slightly shake the earth and thus the water, are quite enough to scare away the trout in the pond. The tactile sensitivity in fish is carried out by nerve endings distributed throughout the skin. Most of them are on the head and around the lips, and in many fish they are also located on special antennae. Cod and mullet examine the bottom with rather short antennae sitting on the chin; Catfish have very long mustaches.
Almost all fish are characterized by a finely developed sense of smell. They have nostrils somewhat similar to ours - a pair of small indentations that open outward and are located directly on the snout, lined inside with folded tissue, which greatly increases their surface. This tissue contains nerve cells that perceive odor.
The sense of smell in most fish is so developed that when looking for food, it means much more to them than vision. Sharks can smell blood from afar and appear near a wounded fish or animal out of nowhere. Sports anglers have successfully used fish blood to attract bluefish and other predatory fish. If you pour just one glass of water into a pool with lampreys, in which another fish was swimming, the lampreys will immediately become wary and begin to look for the source of this suddenly pleasant aroma.
As for taste sensitivity, it probably does not play a big role in the life of fish. First of all, none of them, with the exception of lungfish, have taste organs in the mouth. They have taste buds, but they are located on the head, body, tail, modified fins or antennae, and therefore if the fish taste food, it happens before it gets into their mouth. Many fish simply swallow food, it goes directly into the stomach and is digested there.
The most remarkable feature of the fish is its unique “sixth sense”, which allows it to subtly perceive all movements and currents of water. The most perfectly arranged system of channels under the skin is quite clearly indicated on the sides of the fish as a series of scales of a different shape from the rest. This is the side line. In the main channel, specialized sensory organs are located at a certain distance from each other. The same channels spread throughout the head.
Scientists have yet to reveal all the secrets of the lateral line, but it is already clear that its main function is related to capturing the movement of water. If the base of the nerve running from the lateral line to the brain is cut, the fish clearly loses the ability to respond to disturbances in the water or changes in the direction of the flow. Apparently, it is this special sensory organ that allows the coral fish to shoot like an arrow through a narrow crevice, which it probably does not see properly, or allows fish to bypass obstacles invisible in muddy water during floods. And, probably, it is the lateral line that allows huge schools of fish of many thousands of individuals to swim in such a coordinated formation.
Anyone who has ever fished or seen others fish has probably wondered whether fish feel pain. This question is too difficult to give a clear answer to. Pain is not only a physical, but also a mental reaction, and we cannot find out from the fish exactly what it feels. But we can be almost sure that fish do not feel pain mentally.
Well, do they experience physical pain? In humans, pain is generated in the cerebral cortex as a result of information sent by sensory nerves, but fish do not have a formation comparable to the human cerebral cortex, or any other part of the brain that would perform its functions.
The strength of stimulation of certain sensory organs necessary to cause the sensation of pain is called the pain threshold. In some animal species, as well as in individual individuals, it is much higher than in others. The lower we go down the evolutionary ladder, the higher the pain threshold becomes, the more irritation is needed to cause a pain reaction. We can be quite sure that it is high in fish. In response to too much irritation, they simply leave or try to get away.
This is why a fish can calmly swim away with a hook in its mouth or a harpoon in its back, but a wounded shark will continue to attack even if its fellows are tearing out its entrails.
Fish classification(from Latin classis - category - class and ..., fication) - this is, simply put, the division of fish according to their lifestyle, structural features, method of reproduction and appearance. There are a variety of classifications, and the aquarist needs to know the main ones.
Let's start with the fact that of all vertebrates, fish are the most numerous animals in terms of the number of species. If you combine all mammals, birds, amphibians and reptiles, then the number of their species will be less than fish, of which there are over 20 thousand species!
Fish inhabit almost all bodies of water globe. Through evolution, these animals adapted to various living conditions, which led to the emergence of many of their species. They are all combined into one general class"fish".
According to this system, the class of “fish” is divided into subclasses, subclasses, in turn, into orders, orders into suborders, suborders include superfamilies, superfamilies - families, families - subfamilies, subfamilies - genera, which already include species.
The Latin name for fish usually has a specific ending. Thus, an order, as a rule, ends in -formes, a suborder in -oidei, the name of a superfamily is written with the ending -oidae, a family ends in -idae, and a subfamily in -ini.
Other not specified systematic units fish classification do not have a specific ending and can end in different ways.
Fish classification is carried out as follows. Very similar species of fish in structure and lifestyle, as well as in their relationship, are combined into a genus. A genus, in turn, belongs to a subfamily, a subfamily belongs to a specific family, and so on. In some cases, species are also divided into subspecies.
The scientific name of the fish is indicated on the letter in two words. The first of these is the genus, and the second is the species name. In addition, the surname of the author who first described this species is indicated, as well as the year in which the description was created, if this year, of course, is known.
For example, the Latin name for fish zebrafish looks like this: Brachydanio rerio Hamilton-Buchanan, where Brachydanio is the name of the genus, rerio is the name of the species, and Hamilton-Buchanan, respectively, is the surname of the author.
In addition to the division described above, there are other fish classification. First of all, fish are always divided according to their habitat into marine and freshwater species.
Then, according to the method of reproduction, they are divided into viviparous and egg-bearing.
Next, and no less important, classify fish according to what is optimal for their life temperature conditions: Fish are warm-water, tropical and cold-water. Typically, aquariums contain tropical species, which are easiest to create suitable temperature conditions.
There is also fish classification according to their shape and structural features of the body. Usually, there is no separate Latin name in this case, but aquarists call different shapes types of fish by breeds.
For example, if the fish is called zebrafish veil, then such fish have elongated fins that look like a veil.
Besides, classify fish depending on the color form. In general, it might look something like this: black fork guppy, where guppy is the name of the fish species, black is the color of the body and fins, forked is the forked shape of the caudal fin.
Aquarists can call these same guppies, for example, “black prince,” although this species is exactly what scientists call it. fish classification not described or “patented”, but aquarists themselves came up with the name for the fish after they developed this form.
