Giant fish and dwarf fish. Chordates. vertebrates. fish. Restoration of the joints

Slide 10

manta ray

There are giants among stingrays. The manta ray lives in the tropical waters of the Atlantic, Pacific and Indian oceans. It often reaches a length of 6 meters, and its weight exceeds four tons. Fishermen call the manta the sea devil. And not in vain. There are cases when a huge stingray, caught on a hook, jumped out of the water and, falling into a boat with fishermen, drowned it.

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Beluga

Everyone knows the Caspian Beluga. After sharks and gigantic rays, this is the most big fish. In 1926, a beluga weighing 1228 kilograms was caught near the Biryuchaya Spit, one caviar in it turned out to be 246 kilos, but in 1827 a beluga weighing 1440 kilograms was caught - the largest ever caught.

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Slide 14

• Beluga too predatory fish. It feeds on roach and herring, but sometimes large fish and young seals are found in its stomach. They hunt the beluga with nets, but they also catch it with ropes and even on a piece of white oilcloth wrapped around a hook.
• Almost the same size reaches the closest Amur relative of the beluga Kaluga - a thunderstorm of Far Eastern salmon.

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Tuna

In the warm waters of the Atlantic and Pacific Oceans, in the Mediterranean and Black Seas, tuna is found. This big fish, over 3 meters long and weighing up to 600 kilograms. Tuna is famous for its tender and fatty meat: according to some, it resembles pork, according to others, chicken. Tuna is sometimes even called sea chicken.

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Slide 18

Of the freshwater fish, the largest is our European catfish. Once I managed to see a catfish weighing 21 pounds (336 kilograms), he was caught in the Dnieper near Smolensk.

Slide 19

catfish

Slide 20

Slightly inferior in size to catfish freshwater fish South America arapaima. Each scale is almost the size of a saucer for jam. Arapaima meat is highly valued by the local population. They hunt for it with a spear or a gun, less often they catch it with a bait.

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Arapaima

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The moon-fish reaches almost a ton, although it does not exceed 2.5 meters in length. This is a stump fish. They usually say about such: what is along, then across. Moonfish can be found in all oceans.

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moon fish

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The halibut flounder is found in the Barents Sea. One adult halibut can serve as a meal for at least 500 people. After all, such a flounder weighs 200 or even 300 kilograms, and its length is 4-6 meters.

Slide 25

Halibut

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The belt-fish, or, as it is also called, the oar king, looks completely different. The body of this fish is ribbon-like, it weighs about 100 kilograms and reaches a length of 6-7 meters. The homeland of the belt-fish is the Atlantic and Indian oceans. She is called the herring king because she often moves along with a school of herring, and on her head she has a corolla resembling a crown.

Slide 27

Herring king

Slide 28

Pike are also large, reaching 2.5 meters in length and 60-70 kilograms of weight. The largest specimens are found in the reservoirs of the North and in the lower reaches of the Dnieper. In Valdai Lake, I managed to catch a pike weighing 28 kilograms on the track. She was as tall as me - 1 meter 80 centimeters.

As in other classes of animals, vertebrates and invertebrates, there are species characterized by different sizes. Among the fish there are real dwarfs and monstrous giants.

In the Philippine Islands, between the South China Sea And Pacific Ocean, there is a tiny lake goby mystichthys, whose length is 1–1.5 centimeters. This goby is found in large flocks. The inhabitants of the islands catch it and eat it. The mystichthys goby is considered the smallest animal of all vertebrates in the world.

There are dwarf fish in European waters, in particular in Soviet ones. In the Black, Azov and Caspian Seas, Berg's goby is found, the length of which barely reaches three centimeters. This is the smallest vertebrate animal within the USSR. In the figure, the goby is shown almost 5 times enlarged.

In our waters, marine and fresh, there are many fish 5–10 centimeters in size. Baikal goby stone sculpin usually has a length of 8 centimeters, and only occasionally come across specimens up to 14 centimeters long. This fish most of the time swims among the stones, here it feeds, and here it breeds.

Small size and stickleback fish. It is very abundant in lakes, rivers and brackish coastal areas of the seas. The Aral nine-spined stickleback is only 5–6 centimeters long. There are so many sticklebacks in our water bodies that it could become commercial fish. In Finland and other Baltic countries, stickleback is caught and processed to produce fat for technical purposes and flour for livestock and poultry feed.

Some herrings, minnows, bleaks, verkhovka, gudgeon, plucked fish, etc. should also be attributed to small fish species. Pinchovka got its Russian name for the sharp thorns located near the eyes; With these spines, the fish is quite sensitively pricked (pinched).

In stories about animals special interest cause large individuals. We are surprised big sizes fish, and we try to learn more about their life.

The real giants must be recognized by some cartilaginous fish, sharks. In the northern regions Atlantic Ocean, partly in the Barents Sea, there is a gigantic shark. Its length is over 15 meters. Despite such a gigantic size, this shark is reputed to be a rather peaceful animal. It feeds mainly on small fish and other small marine organisms, but on occasion it also eats the corpses of large marine animals, even whales. When hunting for a giant shark, accidents can occur, as it has such huge force that with the blows of the tail is capable of breaking the boat.

Even larger sharks are found in tropical seas.

There are also giants among our sturgeon (cartilaginous fish). Fishermen caught beluga weighing more than one and a half tons. Belugas weighing one ton and are currently no exception.

At strong winds from the south, the water in the coastal sections of the Volga rises so much that it floods large expanses of the delta. These shallow waters are visited by fish, including beluga. With a rapid decline in water, clumsy beluga sometimes remain in drying lowlands. Once I was an eyewitness of how a happy Astrakhan, what is called with bare hands I took a live beluga almost on land, weighing more than 500 kilograms, in which there was a lot of top quality caviar.

Amur beluga - Kaluga weigh over a ton. At the sight of such giants, one is surprised not so much by the length of their body as by their weight.

Sturgeon and stellate sturgeon are also large fish. The Baltic Sea sturgeon reaches the largest size; its weight is up to 160 kilograms. There are cases when sturgeons were caught weighing up to 280 kilograms with a body length of three and a half meters.

In June 1930, a female sturgeon 265 centimeters long and weighing 128 kilograms was caught in the southern part of Lake Ladoga. A rare specimen was skinned and transferred to the Zoological Museum of the Academy of Sciences (in Leningrad) for making a stuffed animal. The Ladoga fishermen informed us that another large sturgeon was caught in the Volkhov Bay almost at the same time - a male, somewhat smaller than the female. This fact is worth mentioning: it can be assumed that a pair of sturgeon was heading to the Volkhov River for spawning. The fishermen, who did not want to miss such prey, did not think that these fish could give more than a million fry (sturgeons). I will also talk about the Baltic sturgeon in other parts of the book, this fish is worth taking special care of.

In the rivers of tropical America lives one of the largest bony fish- arapaima. Its length is up to 4 meters, weight 150-200 kilograms. They hunt it with rods and arrows. Arapaima meat is considered delicious.

Aral catfish often weighs up to 2 centners. Even larger catfish (up to 3 centners) come across in the Dnieper. The Caspian catfish weighs over 160 kilograms. The longest catfish is 5 meters.

You have probably heard about the huge pikes weighing 50-80 kilograms, hunting for waterfowl and animals caught in the water. In the stories, the pike is represented as a greedy freshwater shark. There is a lot of fantastic in this, but a lot of it is fair. Indeed, occasionally there are pikes weighing about 50 kilograms and more than 1.5 meters long.

In the Amur, among the cyprinids, which are considered to be medium-sized fish, there are specimens reaching two meters in length and 40 kilograms in weight.

The well-known cod of the North Atlantic usually has a body length of 50–70 centimeters and a weight of 4–7 kilograms. But in 1940, a cod 169 centimeters long and weighing 40 kilograms was caught in the Barents Sea.

Who would have guessed that among the herring fish, which we consider small, there are also giants! Such is the Atlantic tarpoon. Its length is up to 2 meters, weight is up to 50 kilograms. This fish is found in the Atlantic, Pacific and Indian oceans, sometimes it enters rivers. Commercial fishermen and angler anglers also hunt for tarpoons. Who is not flattered to fish out such a "herring"! Interestingly, when this fish is dragged out of the water, it performs such a trick - it jumps with a hook to a height of 2-3 meters above the water.

Take a look at the picture. What a monster the hammerhead shark looks like! Russian name this animal is quite consistent with the shape of its body. Hammer fish, reaching a length of 3-4 meters, is considered one of the most terrible ocean predators, dangerous for humans. The hammerhead fish is found in tropical seas, but it is also found off the coast of Europe, keeping mainly near the bottom.

Fish adaptability

The amazing variety of shapes and sizes of fish is explained by long history their development and high adaptability to the conditions of existence.

The first fish appeared several hundred million years ago. Now existing fish bear little resemblance to their ancestors, but there is a certain similarity in the shape of the body and fins, although the body of many primitive fish was covered with a strong bony shell, and highly developed pectoral fins resembled wings.

The oldest fish died out, leaving their traces only in the form of fossils. From these fossils, we make guesses, assumptions about the ancestors of our fish.

It is even more difficult to talk about the ancestors of fish that left no traces. There were also fish that had no bones, no scales, no shells. Similar fish still exist. These are lampreys. They are called fish, although, in the words of the famous scientist L. S. Berg, they differ from fish, like lizards from birds. Lampreys do not have bones, they have one nasal opening, the intestines look like a simple straight tube, the mouth is in the form of a round sucker. In the past millennia, there were many lampreys and related fish, but they are gradually dying out, giving way to more adapted ones.

Sharks are also fish ancient origin. Their ancestors lived more than 360 million years ago. The internal skeleton of sharks is cartilaginous, but there are solid formations in the form of spikes (teeth) on the body. In sturgeons, the body structure is more perfect - there are five rows of bone bugs on the body, there are bones in the head section.

According to the numerous fossils of ancient fish, one can trace how the structure of their body developed and changed. However, it cannot be assumed that one group of fish directly converted to another. It would be a gross mistake to say that sturgeons originated from sharks, and bony ones came from sturgeons. We must not forget that, in addition to the named fish, there were a huge number of others, which, unable to adapt to the conditions of the nature surrounding them, died out.

Modern fish also adapt to natural conditions, and in the process of this, slowly, sometimes imperceptibly, their lifestyle and body structure change.

An amazing example of high adaptability to environmental conditions is represented by lungfish. Ordinary fish breathe with gills, which consist of gill arches with gill rakers and gill filaments attached to them. Lung-breathing fish, on the other hand, can breathe with both gills and "lungs" - peculiarly arranged swim bladders. The lung bubble of lungfish is replete with folds and partitions with many blood vessels. It resembles the lungs of amphibians.

How to explain this structure of the respiratory apparatus in lungfish? These fish live in shallow water bodies, which dry out for quite a long time and become so poor in oxygen that breathing with gills becomes impossible. Then the inhabitants of these reservoirs - lungfish - switch to breathing with lungs by swallowing outside air. When the reservoir completely dries up, they burrow into the silt and experience drought there.

There are very few lungfish left: one genus in Africa (protopterus), another in America (lepidosiren) and a third in Australia (neoceratod, or scaly).

Protopterus inhabits fresh water bodies Central Africa and is up to 2 meters long. During the dry period, it burrows into the silt, forming a chamber (“cocoon”) of clay around itself, and hibernates. In such a dry nest, it was possible to transport protopterus from Africa to Europe.

Lepidosiren inhabits the swampy waters of South America. When reservoirs are left without water during a drought lasting from August to September, lepidosiren, like protopterus, burrows into silt, falls into a stupor, and its life is supported by an insignificant amount of air penetrating here. Lepidosiren is a large fish, reaching 1 meter in length.

The Australian flake is somewhat larger than the lepidosiren, lives in quiet rivers, heavily overgrown with aquatic vegetation. At a low water level (during dry times), grass begins to rot in the river, oxygen in the water almost disappears, then the flake passes to breathing atmospheric air.

All listed lungfish are consumed by the local population for food.

Each biological feature has some significance in the life of a fish. What kind of appendages and adaptations do fish have for protection, intimidation, attack! A wonderful device has a small bitter fish. By the time of reproduction, a long tube grows in the female bitterling, through which she lays eggs in the cavity of a bivalve shell, where the eggs will develop. This is similar to the habits of a cuckoo, throwing its eggs into other people's nests. It is not so easy to get mustard caviar from hard and sharp shells. And the bitter man, having dumped his care on others, hurries to put away his cunning device and again walks in the free space.

In flying fish, capable of rising above the water and flying over fairly long distances, sometimes up to 100 meters, the pectoral fins have become like wings. Frightened fish jump out of the water, spread their wings and rush over the sea. But an air walk can end very sadly: birds of prey often attack the little birds.

Flies are found in the temperate and tropical parts of the Atlantic Ocean and the Mediterranean Sea. Their size is up to 50 centimeters.

Longfins living in tropical seas are even more adapted to flying; one species is also found in the Mediterranean Sea. Longfins are similar to herring: the head is sharp, the body is oblong, the size is 25–30 centimeters. The pectoral fins are very long. Longfins have huge swim bladders (the length of the bladder is more than half the length of the body). This device helps the fish stay in the air. Longfins can fly over distances exceeding 250 meters. When flying, the fins of longfins, apparently, do not wave, but act as a parachute. The flight of a fish is similar to the flight of a paper dove, which is often launched by children.

Jumping fish are also wonderful. If in flying fish the pectoral fins are adapted for flying, then in jumpers they are adapted for jumping. Small jumping fish (their length is not more than 15 centimeters), living in coastal waters mainly of the Indian Ocean, can leave water for quite a long time and get their own food (mainly insects), jumping on land and even climbing trees.

The pectoral fins of jumpers are like strong paws. In addition, the jumpers have another feature: the eyes placed on the head outgrowths are mobile and can see in the water and in the air. During a land journey, the fish tightly covers the gill covers and thus protects the gills from drying out.

No less interesting is the creeper, or climbing perch. This is a small (up to 20 centimeters) fish that lives in fresh waters India. main feature its consists in the fact that it can crawl away on land to a long distance from water.

Creepers have a special supra-gill apparatus, which the fish uses when breathing air in cases where there is not enough oxygen in the water or when it moves overland from one reservoir to another.

Aquarium fish macropods, fighting fish and others also have a similar supragillary apparatus.

Some fish have luminous organs, allowing them to quickly find food in the dark depths of the seas. Luminous organs, a kind of headlights, in some fish are located near the eyes, in others - at the tips of the long processes of the head, and in others, the eyes themselves emit light. An amazing property - the eyes both illuminate and see! There are fish that radiate light with their whole body.

On page 31, a fish is depicted luring its prey to itself with a branched, sea grass-like head process. Cunning angler!

In tropical seas, and occasionally in the waters of the Far Eastern Primorye, one can find interesting sticky fish. Why such a name? Because this fish is able to stick, stick to other objects. There is a large suction cup on the head, with the help of which the stick sticks to the fish.

Not only does the sticky use free transport, the fish also receive a “free” lunch, eating the remnants of the table of their drivers. The driver, of course, is not very pleasant to travel with such a “rider” (the length of the stick reaches 60 centimeters), but it is not so easy to get rid of it either: the fish sticks tightly.

Shore dwellers use this ability to trap turtles. A cord is tied to the tail and the fish is put on the turtle. The sticky quickly sticks to the turtle, and the fisherman lifts the sticky together with the prey into the boat.

In the fresh waters of the basins of the tropical Indian and Pacific Oceans live small fish archers. The Germans call them even more successfully - "Schützenfish", which means shooter fish. The archer, swimming near the shore, notices an insect sitting on the coastal or water grass, draws water into his mouth and lets a stream into his "trading" animal. How not to call a archer a shooter?

Some fish have electrical organs. Known American electric catfish. The electric stingray lives in the tropical parts of the oceans. Electric shocks can knock a grown man off his feet; small aquatic animals often die from the blows of this stingray. The electric stingray is a rather large animal: up to 1.5 meters in length and up to 1 meter in width.

Strong electric shocks are also capable of inflicting an electric eel, reaching 2 meters in length. One german book frenzied horses are depicted, which were attacked in the water by electric eels, although there is a considerable share of the artist's imagination here.

All of the above and many other features of fish have been developed over thousands of years as necessary means of adapting to life in the aquatic environment.

It is not always so easy to explain why one or another device is needed. Why, for example, does a carp need a strong serrated ray of a fin if it helps to entangle fish in nets? Why do we need such long tails for a wide-mouthed and a whistle? Undoubtedly, this has its own biological meaning, but not all the mysteries of nature have been solved by us. We have given a very small number of interesting examples, but they all convince of the expediency of various adaptations of animals.

In flounder, both eyes are on the same side of the flat body - on the one that is opposite to the bottom of the reservoir. But they will be born, come out of eggs, flounders with a different arrangement of eyes - one on each side. In larvae and fry of flounder, the body is still cylindrical, and not flat, as in adult fish. The fish lies on the bottom, grows there, and its eye from the bottom side gradually passes to the upper side, on which both eyes eventually end up. Surprising but understandable.

The development and transformation of the eel is also surprising, but less understood. The eel, before acquiring its characteristic serpentine form, undergoes several transformations. At first it looks like a worm, then it takes the form of a tree leaf and, finally, the usual shape of a cylinder.

In an adult eel, the gill slits are very small and tightly covered. The expediency of this device is that tightly covered gills dry out much more slowly, and with moistened gills, an eel can remain alive for a long time without water. There is even a rather plausible belief among the people that the eel crawls through the fields.

Many fish are changing before our eyes. The offspring of large crucian carp (weighing up to 3–4 kilograms), transplanted from the lake into a small low-feeding pond, grows poorly, and adult fish look like “dwarfs”. This means that the adaptability of fish is closely related to high variability.

These properties can be used to the advantage National economy– when selecting and deriving the most valuable breeds fish. The time is not far off when not only aquarium fish, but also those that are now commercial (bream, pike perch, whitefish and even sturgeon).

Facts found in nature indicate that fish have many advantages over other vertebrates for all sorts of experiments. First of all, fish have great survivability. It is not so rare to find fish without this or that fin, with a crippled spine, with an ugly snout, etc., but this does not prevent them from having a normal general state of health.

The pink salmon that I discovered in the Tatar Strait without one pectoral fin came into the river with normally developed eggs, that is, it was fully prepared for spawning, although it made its long journey along the sea and along the river, moving on one side. This could be judged by the abnormally developed (altered) other pectoral fin.

But so far, fish farmers are far behind livestock breeders in the domestication of economically valuable breeds, and in this respect they have a lot of work to do.

In the Philippine Islands, between the South China Sea and the Pacific Ocean, there is a tiny lake goby mystichthys, whose length is 1-1.5 centimeters. This goby is found in large flocks. The inhabitants of the islands catch it and eat it. The mystichthys goby is considered the smallest animal of all vertebrates in the world.

There are dwarf fish in European waters, in particular in Soviet ones. In the Black, Azov and Caspian Seas, Berg's goby is found, the length of which barely reaches three centimeters. This is the smallest vertebrate animal within the USSR. In the figure, the goby is shown almost 5 times enlarged.

In our waters, marine and fresh, there are many fish 5–10 centimeters in size. Baikal goby stone sculpin usually has a length of 8 centimeters, and only occasionally come across specimens up to 14 centimeters long. This fish most of the time swims among the stones, here it feeds, and here it breeds.

Small size and stickleback fish. It is very abundant in lakes, rivers and brackish coastal areas of the seas. The Aral nine-spined stickleback is only 5–6 centimeters long. There are so many sticklebacks in our water bodies that it could become a commercial fish. In Finland and other Baltic countries, stickleback is caught and processed to produce fat for technical purposes and flour for livestock and poultry feed.

Some herrings, minnows, bleaks, verkhovka, gudgeon, plucked fish, etc. should also be attributed to small fish species. Pinchovka got its Russian name for the sharp thorns located near the eyes; With these spines, the fish is quite sensitively pricked (pinched).

In stories about animals, large individuals are of particular interest. We are surprised by the large size of fish, and we try to learn more about their life.

Some cartilaginous fish, sharks should be recognized as real giants. In the northern regions of the Atlantic Ocean, and partly in the Barents Sea, there is a gigantic shark. Its length is over 15 meters. Despite such a gigantic size, this shark is reputed to be a rather peaceful animal. It feeds mainly on small fish and other small marine organisms, but on occasion it also eats the corpses of large marine animals, even whales. When hunting for a gigantic shark, accidents can occur, since it has such great strength that it can break the boat with tail blows.

Even larger sharks are found in tropical seas.

There are also giants among our sturgeon (cartilaginous fish). Fishermen caught beluga weighing more than one and a half tons. Belugas weighing one ton and are currently no exception.

With strong winds from the south, the water in the coastal sections of the Volga rises so much that it floods large expanses of the delta. These shallow waters are visited by fish, including beluga. With a rapid decline in water, clumsy beluga sometimes remain in drying lowlands. Once I was an eyewitness of how a happy Astrakhan with what is called with his bare hands took a live beluga, weighing more than 500 kilograms, in which there was a lot of top quality caviar, almost on land.

Amur beluga - Kaluga weigh over a ton. At the sight of such giants, one is surprised not so much by the length of their body as by their weight.

Sturgeon and stellate sturgeon are also large fish. The Baltic Sea sturgeon reaches the largest size; its weight is up to 160 kilograms. There are cases when sturgeons were caught weighing up to 280 kilograms with a body length of three and a half meters.

In June 1930, a female sturgeon 265 centimeters long and weighing 128 kilograms was caught in the southern part of Lake Ladoga. A rare specimen was skinned and transferred to the Zoological Museum of the Academy of Sciences (in Leningrad) for making a stuffed animal. The Ladoga fishermen informed us that another large sturgeon was caught in the Volkhov Bay almost at the same time - a male, somewhat smaller than the female. This fact is worth mentioning: it can be assumed that a pair of sturgeon was heading to the Volkhov River for spawning. The fishermen, who did not want to miss such prey, did not think that these fish could give more than a million fry (sturgeons). I will also talk about the Baltic sturgeon in other parts of the book, this fish is worth taking special care of.

One of the largest bony fish, the arapaima, lives in the rivers of tropical America. Its length is up to 4 meters, weight 150-200 kilograms. They hunt it with rods and arrows. Arapaima meat is considered delicious.

Aral catfish often weighs up to 2 centners. Even larger catfish (up to 3 centners) come across in the Dnieper. The Caspian catfish weighs over 160 kilograms. The longest catfish is 5 meters.

You have probably heard about the huge pikes weighing 50-80 kilograms, hunting for waterfowl and animals caught in the water. In the stories, the pike is represented as a greedy freshwater shark. There is a lot of fantastic in this, but a lot of it is fair. Indeed, occasionally there are pikes weighing about 50 kilograms and more than 1.5 meters long.

In the Amur, among the cyprinids, which are considered to be medium-sized fish, there are specimens reaching two meters in length and 40 kilograms in weight.

The well-known cod of the North Atlantic usually has a body length of 50–70 centimeters and a weight of 4–7 kilograms. But in 1940, a cod 169 centimeters long and weighing 40 kilograms was caught in the Barents Sea.

Who would have guessed that among the herring fish, which we consider small, there are also giants! Such is the Atlantic tarpoon. Its length is up to 2 meters, weight is up to 50 kilograms. This fish is found in the Atlantic, Pacific and Indian oceans, sometimes it enters rivers. Commercial fishermen and angler anglers also hunt for tarpoons. Who is not flattered to fish out such a "herring"! Interestingly, when this fish is dragged out of the water, it performs such a trick - it jumps with a hook to a height of 2-3 meters above the water.

Take a look at the picture. What a monster the hammerhead shark looks like! The Russian name of this animal is consistent with the shape of its body. Hammer fish, reaching a length of 3-4 meters, is considered one of the most terrible ocean predators, dangerous for humans. The hammerhead fish is found in tropical seas, but it is also found off the coast of Europe, keeping mainly near the bottom.

Next we will talk about other large fish.
Fish adaptability
The amazing variety of shapes and sizes of fish is explained by the long history of their development and high adaptability to the conditions of existence.

The first fish appeared several hundred million years ago. Now existing fish bear little resemblance to their ancestors, but there is a certain similarity in the shape of the body and fins, although the body of many primitive fish was covered with a strong bony shell, and highly developed pectoral fins resembled wings.

The oldest fish died out, leaving their traces only in the form of fossils. From these fossils, we make guesses, assumptions about the ancestors of our fish.

It is even more difficult to talk about the ancestors of fish that left no traces. There were also fish that had no bones, no scales, no shells. Similar fish still exist. These are lampreys. They are called fish, although, in the words of the famous scientist L. S. Berg, they differ from fish, like lizards from birds. Lampreys do not have bones, they have one nasal opening, the intestines look like a simple straight tube, the mouth is in the form of a round sucker. In the past millennia, there were many lampreys and related fish, but they are gradually dying out, giving way to more adapted ones.

Sharks are also fish of the most ancient origin. Their ancestors lived more than 360 million years ago. The internal skeleton of sharks is cartilaginous, but there are solid formations in the form of spikes (teeth) on the body. In sturgeons, the body structure is more perfect - there are five rows of bone bugs on the body, there are bones in the head section.

According to the numerous fossils of ancient fish, one can trace how the structure of their body developed and changed. However, it cannot be assumed that one group of fish directly converted to another. It would be a gross mistake to say that sturgeons originated from sharks, and teleosts from sturgeons. We must not forget that, in addition to the named fish, there were a huge number of others, which, unable to adapt to the conditions of the nature surrounding them, died out.

Modern fish also adapt to natural conditions, and in the process, slowly, sometimes imperceptibly, their lifestyle and body structure change.

An amazing example of high adaptability to environmental conditions is represented by lungfish. Ordinary fish breathe with gills, which consist of gill arches with gill rakers and gill filaments attached to them. Lung-breathing fish, on the other hand, can breathe with both gills and "lungs" - peculiarly arranged swim bladders. The lung bubble of lungfish is replete with folds and partitions with many blood vessels. It resembles the lungs of amphibians.

How to explain this structure of the respiratory apparatus in lungfish? These fish live in shallow water bodies, which dry out for quite a long time and become so poor in oxygen that breathing with gills becomes impossible. Then the inhabitants of these reservoirs - lungfish - switch to breathing with the lungs, swallowing the outside air. When the reservoir completely dries up, they burrow into the silt and experience drought there.

There are very few lungfish left: one genus in Africa (protopterus), another in America (lepidosiren) and a third in Australia (neoceratod, or scaly).

Protopterus inhabits fresh water bodies of Central Africa and has a length of up to 2 meters. During the dry period, it burrows into the silt, forming a chamber (“cocoon”) of clay around itself, and hibernates. In such a dry nest, it was possible to transport protopterus from Africa to Europe.

Lepidosiren inhabits the swampy waters of South America. When reservoirs are left without water during a drought lasting from August to September, lepidosiren, like protopterus, burrows into silt, falls into a stupor, and its life is supported by an insignificant amount of air penetrating here. Lepidosiren is a large fish, reaching 1 meter in length.

The Australian flake is somewhat larger than the lepidosiren, lives in quiet rivers, heavily overgrown with aquatic vegetation. At a low water level (during dry times), grass begins to rot in the river, oxygen in the water almost disappears, then the flake passes to breathing atmospheric air.

All listed lungfish are consumed by the local population for food.

Each biological feature has some significance in the life of a fish. What kind of appendages and adaptations do fish have for protection, intimidation, attack! A wonderful device has a small bitter fish. By the time of reproduction, a long tube grows in the female bitterling, through which she lays eggs in the cavity of a bivalve shell, where the eggs will develop. This is similar to the habits of a cuckoo, throwing its eggs into other people's nests. It is not so easy to get mustard caviar from hard and sharp shells. And the bitter man, having dumped his care on others, hurries to put away his cunning device and again walks in the free space.

In flying fish, capable of rising above the water and flying over fairly long distances, sometimes up to 100 meters, the pectoral fins have become like wings. Frightened fish jump out of the water, spread their wings and rush over the sea. But an air walk can end very sadly: birds of prey often attack the little birds.

Flies are found in the temperate and tropical parts of the Atlantic Ocean and the Mediterranean Sea. Their size is up to 50 centimeters.

Longfins living in tropical seas are even more adapted to flying; one species is also found in the Mediterranean Sea. Longfins are similar to herring: the head is sharp, the body is oblong, the size is 25–30 centimeters. The pectoral fins are very long. Longfins have huge swim bladders (the length of the bladder is more than half the length of the body). This device helps the fish stay in the air. Longfins can fly over distances exceeding 250 meters. When flying, the fins of longfins, apparently, do not wave, but act as a parachute. The flight of a fish is similar to the flight of a paper dove, which is often launched by children.

Jumping fish are also wonderful. If in flying fish the pectoral fins are adapted for flying, then in jumpers they are adapted for jumping. Small jumping fish (their length is not more than 15 centimeters), living in coastal waters mainly of the Indian Ocean, can leave water for quite a long time and get their own food (mainly insects), jumping on land and even climbing trees.

The pectoral fins of jumpers are like strong paws. In addition, the jumpers have another feature: the eyes placed on the head outgrowths are mobile and can see in the water and in the air. During a land journey, the fish tightly covers the gill covers and thus protects the gills from drying out.

No less interesting is the creeper, or climbing perch. This is a small (up to 20 centimeters) fish that lives in the fresh waters of India. Its main feature is that it can crawl away on land for a long distance from the water.

Creepers have a special supra-gill apparatus, which the fish uses when breathing air in cases where there is not enough oxygen in the water or when it moves overland from one reservoir to another.

Aquarium fish macropods, fighting fish and others also have a similar supragillary apparatus.

Some fish have luminous organs that allow them to quickly find food in the dark depths of the seas. Luminous organs, a kind of headlights, in some fish are located near the eyes, in others - at the tips of the long processes of the head, and in others, the eyes themselves emit light. An amazing property - the eyes both illuminate and see! There are fish that radiate light with their whole body.

On page 31, a fish is depicted luring its prey to itself with a branched, sea grass-like head process. Cunning angler!

In tropical seas, and occasionally in the waters of the Far Eastern Primorye, one can find interesting sticky fish. Why such a name? Because this fish is able to stick, stick to other objects. There is a large suction cup on the head, with the help of which the stick sticks to the fish.

Not only does the sticky use free transport, the fish also receive a “free” lunch, eating the remnants of the table of their drivers. The driver, of course, is not very pleasant to travel with such a “rider” (the length of the stick reaches 60 centimeters), but it is not so easy to get rid of it either: the fish sticks tightly.

Shore dwellers use this ability to trap turtles. A cord is tied to the tail and the fish is put on the turtle. The sticky quickly sticks to the turtle, and the fisherman lifts the sticky together with the prey into the boat.

In the fresh waters of the basins of the tropical Indian and Pacific Oceans, small archer fish live. The Germans call them even more successfully - "Schützenfish", which means shooter fish. The archer, swimming near the shore, notices an insect sitting on the coastal or water grass, draws water into his mouth and lets a stream into his "trading" animal. How not to call a archer a shooter?

Some fish have electrical organs. Known American electric catfish. The electric stingray lives in the tropical parts of the oceans. Electric shocks can knock a grown man off his feet; small aquatic animals often die from the blows of this stingray. The electric stingray is a rather large animal: up to 1.5 meters in length and up to 1 meter in width.

Strong electric shocks are also capable of inflicting an electric eel, reaching 2 meters in length. A German book depicts mad horses being attacked by electric eels in the water, although there is no small part of the artist's imagination here.

All of the above and many other features of fish have been developed over thousands of years as necessary means of adapting to life in the aquatic environment.

It is not always so easy to explain why one or another device is needed. Why, for example, does a carp need a strong serrated ray of a fin if it helps to entangle fish in nets? Why do we need such long tails for a wide-mouthed and a whistle? Undoubtedly, this has its own biological meaning, but not all the mysteries of nature have been solved by us. We have given a very small number of interesting examples, but they all convince of the expediency of various adaptations of animals.

In flounder, both eyes are on the same side of the flat body - on the one that is opposite to the bottom of the reservoir. But they will be born, come out of eggs, flounders with a different arrangement of eyes - one on each side. In larvae and fry of flounder, the body is still cylindrical, and not flat, like in adult fish. The fish lies on the bottom, grows there, and its eye from the bottom side gradually passes to the upper side, on which both eyes eventually end up. Surprising but understandable.

The development and transformation of the eel is also surprising, but less understood. The eel, before acquiring its characteristic serpentine form, undergoes several transformations. At first it looks like a worm, then it takes the form of a tree leaf and, finally, the usual shape of a cylinder.

In an adult eel, the gill slits are very small and tightly covered. The expediency of this device is that tightly covered gills dry out much more slowly, and with moistened gills, an eel can remain alive for a long time without water. There is even a rather plausible belief among the people that the eel crawls through the fields.

Many fish are changing before our eyes. The offspring of large crucian carp (weighing up to 3-4 kilograms), transplanted from the lake into a small pond with little food, does not grow well, and adult fish look like “dwarfs”. This means that the adaptability of fish is closely related to high variability.

These properties can be used in the interests of the national economy - in the selection and breeding of the most valuable fish species. The time is not far off when not only aquarium fish will be domestic, but also those that are now commercial (bream, pike perch, whitefish and even sturgeon).

Facts found in nature indicate that fish have many advantages over other vertebrates for all sorts of experiments. First of all, fish have great survivability. It is not so rare to find fish without this or that fin, with a crippled spine, with an ugly snout, etc., but this does not prevent them from having a normal general state of health.

The pink salmon that I discovered in the Tatar Strait without one pectoral fin came into the river with normally developed eggs, that is, it was fully prepared for spawning, although it made its long journey along the sea and along the river, moving on one side. This could be judged by the abnormally developed (altered) other pectoral fin.

But so far, fish farmers are far behind livestock breeders in the domestication of economically valuable breeds, and in this respect they have a lot of work to do.

Dwarf and giant fish

In the class of fish, as in other classes of animals, vertebrates and invertebrates, there are species characterized by different sizes. Among the fish there are real dwarfs and monstrous giants.

In the Philippine Islands, between South China Sea and the Pacific Ocean, there is a tiny lake goby mystichthys, whose length is 1–1.5 centimeters. This goby is found in large flocks. The inhabitants of the islands catch it and eat it. The mystichthys goby is considered the smallest animal of all vertebrates in the world.

There are dwarf fish in European waters, in particular in Soviet ones. In the Black, Azov and Caspian Seas, Berg's goby is found, the length of which barely reaches three centimeters. This is the smallest vertebrate animal within the USSR. In the figure, the goby is shown almost 5 times enlarged.

In our waters, marine and fresh, there are many fish 5–10 centimeters in size. Baikal goby stone sculpin usually has a length of 8 centimeters, and only occasionally come across specimens up to 14 centimeters long. This fish most of the time swims among the stones, here it feeds, and here it breeds.

Small size and stickleback fish. It is very abundant in lakes, rivers and brackish coastal areas of the seas. The Aral nine-spined stickleback is only 5–6 centimeters long. There are so many sticklebacks in our water bodies that it could become a commercial fish. In Finland and other Baltic countries, stickleback is caught and processed to produce fat for technical purposes and flour for livestock and poultry feed.

Some herrings, minnows, bleaks, verkhovka, gudgeon, plucked fish, etc. should also be attributed to small fish species. Pinchovka got its Russian name for the sharp thorns located near the eyes; With these spines, the fish is quite sensitively pricked (pinched).

In stories about animals, large individuals are of particular interest. We are surprised by the large size of fish, and we try to learn more about their life.

Some cartilaginous fish, sharks should be recognized as real giants. In the northern regions of the Atlantic Ocean, and partly in the Barents Sea, there is a gigantic shark. Its length is over 15 meters. Despite such a gigantic size, this shark is reputed to be a rather peaceful animal. It feeds mainly on small fish and other small marine organisms, but on occasion it also eats the corpses of large marine animals, even whales. When hunting for a gigantic shark, accidents can occur, since it has such great strength that it can break the boat with tail blows.

Even larger sharks are found in tropical seas.

There are also giants among our sturgeon (cartilaginous fish). Fishermen caught beluga weighing more than one and a half tons. Belugas weighing one ton and are currently no exception.

With strong winds from the south, the water in the coastal sections of the Volga rises so much that it floods large expanses of the delta. These shallow waters are visited by fish, including beluga. With a rapid decline in water, clumsy beluga sometimes remain in drying lowlands. Once I was an eyewitness of how a happy Astrakhan with what is called with his bare hands took a live beluga, weighing more than 500 kilograms, in which there was a lot of top quality caviar, almost on land.

Amur beluga - Kaluga weigh over a ton. At the sight of such giants, one is surprised not so much by the length of their body as by their weight.

Sturgeon and stellate sturgeon are also large fish. The Baltic Sea sturgeon reaches the largest size; its weight is up to 160 kilograms. There are cases when sturgeons were caught weighing up to 280 kilograms with a body length of three and a half meters.

In June 1930, a female sturgeon 265 centimeters long and weighing 128 kilograms was caught in the southern part of Lake Ladoga. A rare specimen was skinned and transferred to the Zoological Museum of the Academy of Sciences (in Leningrad) for making a stuffed animal. The Ladoga fishermen informed us that another large sturgeon was caught in the Volkhov Bay almost at the same time - a male, somewhat smaller than the female. This fact is worth mentioning: it can be assumed that a pair of sturgeon was heading to the Volkhov River for spawning. The fishermen, who did not want to miss such prey, did not think that these fish could give more than a million fry (sturgeons). I will also talk about the Baltic sturgeon in other parts of the book, this fish is worth taking special care of.

One of the largest bony fish, the arapaima, lives in the rivers of tropical America. Its length is up to 4 meters, weight 150-200 kilograms. They hunt it with rods and arrows. Arapaima meat is considered delicious.

Aral catfish often weighs up to 2 centners. Even larger catfish (up to 3 centners) come across in the Dnieper. The Caspian catfish weighs over 160 kilograms. The longest catfish is 5 meters.

You have probably heard about the huge pikes weighing 50-80 kilograms, hunting for waterfowl and animals caught in the water. In the stories, the pike is represented as a greedy freshwater shark. There is a lot of fantastic in this, but a lot of it is fair. Indeed, occasionally there are pikes weighing about 50 kilograms and more than 1.5 meters long.

In the Amur, among the cyprinids, which are considered to be medium-sized fish, there are specimens reaching two meters in length and 40 kilograms in weight.

The well-known cod of the North Atlantic usually has a body length of 50–70 centimeters and a weight of 4–7 kilograms. But in 1940, a cod 169 centimeters long and weighing 40 kilograms was caught in the Barents Sea.

Who would have guessed that among the herring fish, which we consider small, there are also giants! Such is the Atlantic tarpoon. Its length is up to 2 meters, weight is up to 50 kilograms. This fish is found in the Atlantic, Pacific and Indian oceans, sometimes it enters rivers. Commercial fishermen and angler athletes also hunt for tarpoons. Who is not flattered to fish out such a "herring"! Interestingly, when this fish is dragged out of the water, it performs such a trick - it jumps with a hook to a height of 2-3 meters above the water.

Take a look at the picture. What a monster the hammerhead shark looks like! The Russian name of this animal is consistent with the shape of its body. Hammerhead fish, reaching a length of 3-4 meters, is considered one of the most terrible ocean predators, dangerous to humans. The hammerhead fish is found in tropical seas, but is also found off the coast of Europe, keeping mainly near the bottom.