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Subclass lungfish. Lung-breathing fish: representatives, examples, photos Name of fish breathing with lungs and gills


Structure Lungfish reach 12 m in length, have an elongated body covered with a tile-shaped cycloid bone scales. They do not have separate dorsal and anal fins: they merge with a large diphycercal caudal fin. The paired fins are shaped either as wide lobes or as long cords.


The notochord persists throughout life, and the vertebral bodies do not develop, but there are cartilaginous upper and lower arches and ribs. The skull, unlike all other bony fish, is autostylic, cartilaginous, but complicated by chondral and integumentary bones. Secondary jaws are absent. Gill arches, including four or five pairs, cartilaginous. The shoulder girdle is well developed, cartilaginous, but covered with false bones. The pelvic girdle is in the form of an unpaired cartilaginous plate. The paired fins are cartilaginous, like a biserial archipterygium. In a typical form, bi-serial fins are found in ceratodes, and in two other modern lungfish, fins are in the form of thread-like appendages. The external skeleton of both paired and unpaired fins consists of dissected horn rays.


The brain is characterized by a significant size of the forebrain, which is divided into two hemispheres not only outside, but also inside, so that there are two independent lateral ventricles. The midbrain is relatively small. The cerebellum is extremely poorly developed, which is associated with the low mobility of the lungfish.













Crossword 1. What do lungfish have besides gills? 2. In what period did lungfish appear? 3. In what water bodies do they live? 4. What fish has only one lung?









We are all used to the fact that fish should live only in water, and land animals, on land. All this is true, but not entirely. Nature is very resourceful. She was able to create lung-breathing creatures that feel great both in water and on land. Let's look at a simple example that concerns the life of some fish during the African drought. At this time, the area of ​​water bodies here decreases by a third. An example is Lake Chad. It would seem that all the fish locked in drying puddles must certainly die, but this does not happen. They burrow into clay capsules and feel great there.

The secret of such endurance is quite simple. Protopterus, as this fish is called, is a lungfish. In addition to the gills, he has a semblance of lungs with which he can breathe atmospheric air. In fact, this is a somewhat modified swim bladder, densely braided with blood vessels. Filled with air, it releases oxygen into the blood.

Scientists zoologists were able to detect two circles of blood circulation in the protopterus. One by one, venous blood moves, which enters the right side of the heart. Oxygenated blood (pulmonary) is sent to the left heart ventricle. It oxygenates the head and main organs of the fish. Venous blood, from the right heart ventricle, is sent to the lungs, where it is enriched with oxygen.

Lungfish represented by six types. The most popular are: Australian horntooth, African protopterus, American flake. All of them are freshwater fish.

In the northeast of Australia, you can find the Australian horntooth. The fish is quite large. The weight adult reaches 10 kilograms. Its body is covered with a series of large scales and has powerful, flipper-like fins. The color is uniform, from brown to gray-blue. The belly is almost white.

The horntooth lives in fresh water bodies, with a lot of vegetation. He cannot be constantly under water, and therefore emerges every half an hour, and greedily swallows air with his mouth, while making characteristic sounds. Having replenished the supply of oxygen, he again dives to the depth.

At the bottom, the horntooth "stands" motionless, leaning on massive fins. While hunting, it “walks” or “crawls” slowly, trying to find invertebrates. Shows special activity only when danger arises. In this case, he uses his powerful tail and quickly swims away from the predator.

During a drought, the horntooth finds a hole with the remains of water and burrows into the silt. There is practically no oxygen there, as we understand it, which leads to the death of ordinary river inhabitants. Horntooth, thanks to its pulmonary respiration, manages to survive. Although, if the puddle dries up completely, then the horntooth will also die.

With the onset of the rainy season, spawning begins at the horntooth. The female lays large eggs in aquatic vegetation, which outwardly resemble frog eggs. On the 10th day, larvae hatch from them, which do not have external gill slits. During the first week they are inactive. Their fins appear only on the 14th day. From this time on, they begin to behave more actively, and to full life will be ready by the end of the third month.

Ancient animals. They live in fresh, drying waters. In addition to gills, they have lungs developed from swim bladders. The heart has an incomplete septum in the atrium (similar to a 3-chambered one), 2 circles of blood circulation. Paired fins developed. Large animals (up to 2 m), omnivorous or predatory. 6 species have been preserved. Horntooth lives in Australia, has 1 lung. The rest have 2 lungs. neocerathod up to 170 cm, the caudal fin has 1 lobe. Lives in Africa. Lepidosiren- In South America.

Subclass crossoptera.

Representative - coelacanth. There is no lung breathing. It lives in the Indian Ocean at great depths. Paired fins are very developed. Large, predatory animals. From them originated the first terrestrial vertebrates - stegocephals, primitive amphibians.

Subclass ray-finned.

It is divided into 2 superorders:

    osteocartilaginous

    bony.

Osteocartilaginous fish have a number of primitive structural features: paired fins are located horizontally, the mouth is located below the head, the body is covered with bone ganoid scales arranged in 5 rows (bugs). The caudal fin is heterocercal (unequally lobed). The notochord is preserved throughout life, there are no vertebral bodies. The cartilaginous skull is surrounded by integumentary bones. There is a spiral valve in the intestines. Most are migratory fish. Representatives are the sturgeon detachment (sterlet, beluga, sturgeon, stellate sturgeon, paddlefish, 26 species in total). They are of great commercial importance.

Bony fish. The skeleton of the fins consists of bony rays. Main squads:

    herring

    salmon

    cyprinids

    prickly-finned

    eels

    pike

    catfish

    codfish, etc.

Class amphibians (amphibians)

The most primitive terrestrial chordates were the first to land on land, but did not lose contact with water; reproduction occurs in water. Descended from ancient lobe-finned fish. Main features:

    Ground type limbs

    The skull is movably connected to the spine

    Respiration pulmonary

    Two circles of blood circulation.

Primitive building features:

    skin naked

    Body temperature is not constant

    The development of the embryo takes place in water.

Structural features of amphibians (representative - frog).

The head is large, flat, the body is short, wide, the neck is not pronounced. There is no tail. On the sides heads the eyes are equipped with upper and lower eyelids, the mouth is large, above it there is 1 pair of nostrils connected to the oral cavity, between them there are shut-off valves. Front limbs short, have 4 fingers. The hind limbs are long, have 5 fingers, between them there is a membrane, there are no claws. The cloaca is located at the posterior end of the body. Leather frogs are naked, wet, slimy, participate in respiration, especially in winter.

Skeleton has cartilaginous elements. Spine of 9 vertebrae (1 cervical, 6 trunk, 1 sacral, 1 caudal). The vertebrae are concave in front and curved behind, consist of a body, 1 spinous and 2 transverse processes. The transverse processes are well developed, forming the lid of the body. ribs No, chest no. Scull wide, movably connected to the spine with 2 condyles. The upper jaw fuses with the skull.

The skeleton of the limbs consists of the shoulder and pelvic girdle. Shoulder girdle includes 2 shoulder blades, 2 collarbones, 2 coracoid (crow) bones, sternum and forelimb (shoulder, forearm, wrist, metacarpus, finger phalanges). Pelvic girdle consists of bones: ischium, pubis, ilium, 2 innominate and hind limbs (femur, lower leg, tarsus, metatarsus, phalanges of fingers).

muscular system. The striated muscles are especially well developed on the hind limbs. nervous system. The forebrain forms hemisphere. The organs of vision are developed - the eyes and the organs of hearing - the ears (consist of the inner and middle ear, closed by the eardrum).

digestive the system begins with the oral cavity, in it the tongue (attached by the front end), salivary glands (for wetting food), teeth (conical, serve to hold food); then comes the esophagus, stomach, small and large intestines, cloaca. Has a large liver gallbladder. They feed on insects, other invertebrates, and fish fry.

Respiratory system. Primitive lungs in the form of cellular sacs, the airways are poorly developed. The skin is involved in respiration. circulatory system: 3-chambered heart, 2 circles of blood circulation. excretory system: paired trunk kidneys, cloaca. Reproduction. At males testes, seminal ducts, wolf's canal, seminal vesicle, cloaca. Females have 2 granular ovaries, oviducts, cloaca. Fertilization external. Development with transformation. From the eggs on the 10th day, fish-shaped tadpole larvae appear, having gills and a tail. After 2-4 years they reach sexual maturity.

Classification. The class is divided into 3 divisions:

      legless

      caudate

      Lung-breathing fish and their

      DISTRIBUTION IN NATURE;

      CHARACTERISTICS OF BRUSHED FISHES;

      GENERAL CHARACTERISTICS OF CRANIALS;

      CLASSIFICATION SYSTEM OF BONE FISH.

      individual work

      student of biological faculty

      group 4120-2(b)

      Menadiyev Ramazan Ismetovich

      Zaporozhye 2012

      Kingdom Animals, animalia

      Type: Chordates, chordata

      Subtype Vertebrates, vertebrata

      Superclass: Fish, pisces

      Class: Bony fish, osteichtyes

      Superorder: lungfish, dipnoi

      Lungfish - a small ancient and very peculiar group freshwater fish, combining primitive features with features of high specialization for life in oxygen-depleted water bodies. At modern representatives most of The skeleton remains cartilaginous throughout life. A well-developed chord is preserved. The vertebral column is represented by the rudiments of the upper and lower vertebral arches. The skull is cartilaginous at the base with few integumentary bones and bony dental plates. As with cartilaginous fish, in the intestines there is a spiral valve, and in the heart - a pulsating arterial cone. These are the primitive features of the organization. Along with this, in lungfish, the palatine-square cartilage adheres directly to the skull (autostyly). The caudal fin merges with the dorsal and anal (diphycercal). Paired limbs have a wide leathery lobe. The name Lungfish speaks of the most main feature- the presence of gill and pulmonary respiration. As organs of pulmonary respiration, 1 or 2 bubbles function, opening on the ventral side of the esophagus. These formations are not homologous to the swim bladder bony fish. The nostrils are through, leading to the oral cavity and serve for pulmonary respiration. Blood enters the lungs through special vessels extending from the 4th pair of branchial arteries. The vessels are homologous to the pulmonary arteries. From the "lungs" come the vessels that carry blood to the heart (homologues of the pulmonary veins). Progressive signs of lungfish also include a strong development of the forebrain. The urogenital system is close to the urogenital system of cartilaginous fish and amphibians.

      Axial skeleton lungfish - fish largely retains primitive features: the vertebral bodies are absent, the cartilaginous bases of the upper and lower arches sit directly on the chord, which is well preserved throughout life. The skull, along with ancient features, is characterized by a peculiar specialization. In the cartilaginous cranium (neurocranum), only one pair of replacement bones (lateral occipital) develops. Available a large number of peculiar integumentary bones of the skull. The palatine cartilage fuses with the base of the skull. On the vomer, pterygopalatine bones and lower jaws sit bone chewing dental plates, formed from the fusion of numerous small teeth and very similar to cranial plates (4 plates on the upper jaw and 2 on the lower).



      cartilaginous skeleton paired fins supports almost the entire lobe of the fin, except for its outer edge, where it is supported by thin skin rays. This peculiar internal skeleton consists of a long articulated central axis, bearing in horntooths (Ceratodidae) two rows of lateral articulated cartilaginous elements, in squamosals (family Lepidosirenidae) it does not have these appendages or carries their rudiments. Internal skeleton of the fins is connected to the girdle by only one main (basal) segment of the central axis and in this respect is to a certain extent similar to the limb of terrestrial vertebrates. Unpaired fins, dorsal and anal, completely merge with the caudal fin. The latter is symmetrical, has a diphycercal structure (in many fossil lungfish, the tail was unequal-lobed - heterocercal). The scales of the ancient forms were of the "cosmoid" type; in modern lungfish, the upper enamel layer and dentin have been lost. There is an arterial cone in the heart; the intestines are equipped with a spiral valve, these are primitive signs. The genitourinary apparatus is similar to that of shark fish and amphibians: there is a common excretory opening (cloaca).

      Despite the fact that, according to modern views, lungfish represent a side branch of the main "trunk" of aquatic vertebrates, interest in this amazing group of animals does not wane, since it can be used to trace the evolutionary attempts of nature to carry out the transition of vertebrate animals from aquatic existence to terrestrial and from gill to pulmonary respiration.

      3 orders: Horn-toothed (ceratodiformes ) – 1 type; Scaly, Bipulmonary, (Lepidosirenidae) - 5 species. Dipteriformes ( Dipteridiformes) are extinct.

      Order Dipteriformes (Dipteridiformes). This includes extinct lungfish, from the Middle and Upper Devonian, distributed throughout fresh water bodies of all the globe. By the end Paleozoic era died out. They are characterized by cosmoid scales, varying degrees of ossification of the brain skull and a wide variety of integumentary bones, reduction of secondary jaws, the presence of conical teeth in some species that have not merged into dental plates, the presence of rudiments of vertebral bodies, and the independence of unpaired fins. Apparently, they lived in reservoirs rich in aquatic vegetation, eating inactive animals and plants.

      Paleozoic forms probably already had pulmonary respiration and, at least in some species, the ability to fall into a state of a kind of hibernation when water bodies dried up (fossil "cocoons" were found in Permian deposits).

      Detachment Horn-toothed, or One-lung (Ceratcdiformes). The brain skull is cartilaginous, with slight ossifications. Integumentary bones are few. There are no secondary jaws. Dental plates with few thick, slightly tuberculate ridges. The paired biserial fins are well developed. There is only one lung with a weakly cellular inner wall. Scales bony, large. Apparently, they separated from the dipteridians at the end of the Devonian, but the most ancient remains are known only from the Lower Triassic. AT mesozoic era met in all continental reservoirs; many fossil species have been described.

      Now only one species lives - cattail - Neoceratodus forsteri. It is found in a small area of ​​Western Australia. Reaches a length of up to 1.5 m and a mass of over 10 kg. Lives in rivers slow flow overgrown with aquatic and emersed vegetation. The period of drought, when the rivers become shallow, is experienced in the preserved pits with water. Periodically, every 40-50 minutes, it rises, exhales air from the lung with noise and, having taken a breath, sinks to the bottom. When the pit dries completely, it dies.

      It feeds by moving slowly near the bottom and eating invertebrates; the intestines are usually full of finely abraded plant debris, but vegetation is believed to be poorly digested. Large, up to 6-7 mm in diameter, caviar is deposited on aquatic plants. After 10-12 days, a fry hatches with a large yolk sac. It breathes with gills and usually lies on the bottom, only occasionally moving a short distance. After resorption of the yolk sac, they become more mobile and stay in creeks, feeding on filamentous algae. The pectoral fins appear on the 14th day after hatching (probably from this time the lung begins to function); abdominal - after about 2.5 months. Horntooths were vigorously exterminated due to tasty meat; fishing was facilitated by the low mobility of the fish. Horntooths are now under protection; attempts are being made to reacclimatize them in other water bodies of Australia.

      Order Bipulmonary(Lepidosireniformes). The brain skull is cartilaginous, with slight ossifications. Integumentary bones are few. There are no secondary jaws. Dental blades with sharp cutting ridges. The bones of the operculum are noticeably reduced. Paired fins look like long tentacles; their skeleton is formed only by a dissected central axis. Small cycloid scales are deeply embedded in the skin. Lungs - paired, slightly cellular. Development with metamorphosis: larvae develop external skin gills, which disappear with the onset of lung function. Like the one-lungs, apparently, they separated from some diptheridians at the end of the Devonian - the beginning of carboniferous period. A few fossils have been found in the Permian deposits of the United States and on the Russian platform.

      Protopterus.

      All species, when the reservoir dries up, burrow into the ground, experiencing a dry period. For example, protopterus, when the water level drops to 5-10 cm, digs a hole. The soil is captured by the mouth, crushed and thrown out through the gill slits. Having dug out a vertical passage, the fish expands its end into the chamber, in which it is located, sharply bending the body and putting its head up. When the water level drops, the soil closes the entrance to the hole, and the fish seals this plug with movements of the head from the inside. At big fish The camera is located at a depth of up to half a meter. Due to the hardening of the skin mucus around the fish, a cocoon tightly adjacent to the skin is formed (its wall thickness is only 0.05-0.06 mm); and the upper part of the cocoon forms a thin tube through which air penetrates to the head of the fish. In this state, the fish remains up to next period rains, about 6-9 months (in the experiment under laboratory conditions, the fish hibernated for more than four years and woke up safely). During hibernation, the intensity of metabolism sharply decreases. Apparently, not only fat, but also muscles serve as an energy reserve. During a 6-month hibernation, the fish loses up to 20% of its original weight. The products of nitrogen metabolism during the period of active life are excreted from the body mainly in the form of ammonia, and when they fall into a stupor, they turn into urea, which is less toxic compared to ammonia, and are not excreted, but accumulate, amounting to 1-2% of the mass of the fish by the end of hibernation; the mechanisms that provide resistance to such high concentrations of urea have not yet been elucidated. When the reservoirs are filled during the rainy season, the soil gradually soaks, the water fills the air chamber, and the fish, breaking through the cocoon, sticks out its head, inhaling the air every 5-10 minutes, and after a few hours, when the water covers the bottom of the reservoir, it leaves the hole. Soon, urea is excreted through the gills and kidneys. During hibernation, the formation of reproductive products occurs. A month and a half after leaving hibernation, reproduction begins. The male at the bottom of the reservoir among the thickets of vegetation digs a horseshoe-shaped hole with two entrances, at the bottom of which the female lays up to 5 thousand eggs with a diameter of 3-4 mm. After 7-9 days, the eggs hatch into larvae with a large yolk sac and 4 pairs of feathery external gills. With the help of a special cement gland, the larvae are attached to the walls of the nesting hole. The entire period of incubation and the first weeks of the life of the larvae, the male is near the nest and actively defends it, rushing even at an approaching person. After 3-4 weeks, the yolk sac is completely absorbed, a pair of external gills is reduced (the rest are absorbed more slowly), and the larva leaves the hole, starting to feed actively. If necessary, it rises to the surface for swallowing. atmospheric air. The ability to burrow into the ground during drought, form a cocoon and hibernate, the larvae acquire at a length of 4-5 cm. 2-3 weeks after leaving hibernation (after filling the reservoir with water), the fish begin to breed. The male digs a vertical burrow, sometimes bending horizontally towards the end. Some burrows reach 1.5 m in length and 15-20 cm in width. At the end of the hole, the fish drags leaves and grass, on which the female spawns eggs 6-7 mm in diameter. The male remains in the burrow guarding the eggs and hatched fry. At this time on his pelvic fins branching leathery outgrowths 5–8 cm long, abundantly supplied with capillaries, develop. It was assumed that these outgrowths contribute to the saturation of water in the nesting chamber with oxygen. Other ichthyologists believe that these outgrowths compensate for the inability to use pulmonary respiration in the burrow. After a period of reproduction, these outgrowths resolve. The mucus secreted by the skin of the male has a coagulating effect and cleans the nest water from turbidity. The larvae hatched from the eggs have 4 pairs of strongly branching external gills and a cement gland, with which they are attached to the walls of the nest. Approximately one and a half months after hatching (with a length of 4-5 cm), the larvae leave the hole, begin to feed actively and can breathe with their lungs, while the external gills dissolve.

      The areas of distribution of these relic forms - South America, tropical africa and Australia - indicate the great antiquity of the group.

      Lungfish have only been found in the last century. Until that moment, no one had seen them live. Ideas about them were limited only to the found ancient remains. Their structural features determined such interesting name. Let's see what kind of fish is lungfish and what is so special about it. The fact is that representatives of this class can breathe not only with gills, but also with lungs.

      Who are lungfish?

      Representatives of this superorder of lobe-finned fish have both gill and pulmonary respiration. This is the nature of their structure. AT modern world the subclass lungfish, whose representatives are divided into two orders - horn-toothed and dilung-shaped, is quite rare. Individuals related to it live only in Africa, Australia and South America.

      In addition to the usual gills, they also have lungs (one or two), which are a modified swim bladder. Through its walls, penetrated by capillaries, in fact, gas exchange occurs. Fish take in air to breathe through their mouths as they rise to the surface. In the atrium they have a septum, which continues in the ventricle. Blood through the veins comes from the organs and enters the right side of the atrium, as well as the right half of the ventricle. The blood coming from the lung goes to the left side of the heart. Interestingly, further oxygenated lung blood is coming mainly in those vessels that pass through the gills to the head and various organs. And its second part from the right side of the heart, also passing through the gills, ends up in a vessel leading to the lung. It turns out that oxygen-rich and poor blood is still partially mixed in the vessels and the heart. So, we can talk about the primitive rudiments of two circles of blood circulation in lungfish.

      ancient lungfish

      Lungfish are representatives of a very ancient group. Their remains are found among the sediments (Paleozoic era). Enough long time such fish were known only from fossilized remains. And in 1835, it was discovered that the protopter, which lives in Africa, is a lungfish.

      The lungfish subclass, whose representatives have survived to this day, consists of only six species:

      1. The Australian horntooth is a detachment of one-lungs.
      2. American flake from the order of two-lungs.
      3. Four varieties of Protopterus from Africa (two-lungs).

      Apparently, they all, together with their ancestors, belong to

      Australian horntooth

      Australian lungfish are lungfish. They are found in a very small area of ​​the Mary and Burnett river basins in northeastern Australia. It is up to 175 centimeters long and weighs more than ten kilograms.

      The large body of the horned tooth is flattened on the sides and covered with large scales. Large paired fins look like flippers. The color of the body of the horned tooth varies from red-brown to bluish-gray, and the belly is certainly a light shade.

      The fish lives in slow-flowing rivers, where surface and underwater thickets are present. Every fifty minutes, the horntooth rises to the surface and noisily expels air from the lung. At the same time, he emits not the groan, not the grunt, which is heard far enough away. Inhaling fresh air, the fish again sinks to the bottom.

      Habitat of the rosogub

      The horntooth spends most of its time at the bottom, lying on its belly or standing on flipper-like fins. To search for food, he begins to crawl slowly. The fish also swim very slowly. However, if you scare her, then she begins to quickly work with her tail, thereby accelerating her movement.

      During periods of drought, when the rivers become completely shallow, horntooths lie in preserved pits with water. AT hot water deprived of oxygen, the whole fish dies, and it itself turns into a smelly, dirty slurry. In such conditions, only lung-breathing fish survive, whose representatives are able to breathe with their lungs. However, if the water evaporates completely, then the horntooths still die, because, unlike their South American and African relatives, they do not know how to hibernate.

      Fish spawning falls during the rainy season, when the rivers overflow with water. The horntooth lays large eggs on algae. After 12 days, larvae appear, which, until the moment of resorption of the yolk sac, are at the bottom, sometimes moving slightly over short distances.

      It is believed that on the 14th day after the birth of the fry, their lung begins to function. Horntooths are very tasty, and it is very easy to catch them. This is what led to a sharp reduction in their numbers. Currently, they are under protection, in addition, attempts are being made to relocate them to other Australian reservoirs.

      Protoptera - African lungfish

      Protopters are also lungfish. They live in Africa and have filiform fins. Of the four species living on the continent, the largest - a large protopter - reaches a length of more than one and a half meters. The average length of the fish is about thirty centimeters. Fish swim like eels, wriggling their bodies. But the filamentous fins help them move along the bottom. An interesting fact is that the skin of the fins is rich in receptors. As soon as the fin touches something edible, the fish immediately grabs its prey. Periodically, the protopter floats up and inhales fresh air. Protopters live in central regions Africa. What places do lungfish choose to live? Representatives of this species prefer rivers and lakes in swampy areas, which are annually flooded during rains and dry up during droughts. During the dry season, the water level drops from five to ten centimeters. At this time, the protopters begin to dig holes for themselves.

      The fish absorbs the soil with its mouth, and then crushes it and throws it out through the gills. The hole is a vertical passage, at the end of which there is a chamber, where, in fact, the protopter is located, bent in half and exposing its head.

      Until the water is completely dry, the fish rises to breathe. And then liquid sludge is sucked into the hole, blocking the exit. Then the protopter can't get out. He just pokes his muzzle into the plug of silt, lifting it up. After drying, it becomes porous and allows oxygen to pass through, which makes it possible for fish to survive while hibernating.

      The water in the burrow gradually becomes very viscous due to the mucus secreted by the protopter. The soil gradually dries out more and more, and the water level in the hole drops. As a result, the vertical stroke is filled with air. Bending over, the fish freezes in the lower chamber. A cocoon of mucus forms around her body. It is in this state that the protopter is waiting for the rainy period, which comes only after 6 - 9 months.

      Behavior of fish during the dry season

      Lungfish are quite interesting in their behavior and living conditions. Representatives (photos are given in the article) of this group participated in laboratory studies. So, the protopters were kept in hibernation for more than four years, and at the end of the research they woke up safely.

      During hibernation in fish, metabolic processes are greatly reduced. Nevertheless, in six months, protopters lose up to 20 percent of their mass. Energy in the body comes from the breakdown of muscle tissue, therefore ammonia accumulates in the body. During the active period of the existence of fish, it calmly goes outside, but during hibernation it turns into a very toxic urea, the concentration of which is quite high. But the poisoning of the body does not occur. How such stability arises has not yet been clarified.

      With the beginning of the rainy season, a gradual soaking of the soil begins, water fills the hole, the protopter, breaking the cocoon, periodically sticks out its head and inhales the air. As soon as the water completely covers the bottom of the reservoir, the fish will leave the hole. After a month and a half, the protopters will begin the breeding season. At this time, the male digs a new norm in the thickets and lures the female there, who will lay up to 5 thousand eggs. And after 7 days the larvae will appear. And after another 4 weeks, the fry begin to feed on their own and leave the mink. For some time they swim next to her, hiding at the slightest danger. Throughout this period, the male is always near the hole and protects it from enemies.

      Protopter dark

      Considering the topic "Lung-breathing fish: representatives, names", it is necessary to recall one more representative of this class - the dark protopter. It lives in the basin of the Congo and Ogowe rivers, preferring wetlands in which the underground water level is maintained even during a period of drought. When the water begins to decrease in the river, the fish burrows into the bottom silt, reaching underground water. There, the protopter spends the entire dry period, while not creating a cocoon, periodically it rises to the surface to inhale air.

      The hole of the fish is an inclined course and a chamber at the end. Fishermen say that such a shelter serves the protopter for five to ten years. Spawning also takes place in the same burrow. Males prepare for this event in advance by building up a mound of mud around it, which can reach one meter in height.

      Lungfish, briefly described by us in the article, have always attracted the attention of scientists, they are so unusual and interesting. Protopters have interested researchers in sleeping pills. Biochemists in Sweden and England tried to isolate substances from fish organisms that enable them to hibernate. And here's what's interesting: when the extract from the brain of sleeping fish was injected into the blood of laboratory rats, the body temperature of the subjects began to drop sharply, they fell asleep very quickly, almost instantly. Sleep lasted up to 18 hours. Upon awakening, the rats failed to detect any sign artificial sleep. The substance did not give any adverse reactions.

      American flake, or lepidosiren

      The considered examples of lungfish clearly demonstrate their adaptability to living conditions that are completely unsuitable for habitation. And yet, even under such circumstances, thanks to the ability to breathe in two ways, the fish feel great.

      The class lungfish, whose representatives we have discussed above, also includes the American flake, which lives in the Amazon basin. The length of the fish reaches 1.2 meters. It lives, as a rule, in temporary reservoirs, which are flooded during the rainy season or floods. The flake feeders feed on various animal foods, mainly molluscs. They may also eat plant foods. When the reservoir dries up, the fish lie on the bottom of the hole and clog it with a cork. However, they do not form cocoons. Sleeping fish are surrounded by mucus and moistened by groundwater. The basis, unlike the protopter, is stored fat.

      A couple of weeks after the flooding of the reservoir, the American flake begins to multiply. The male digs a hole, which can reach one and a half meters in length. In its very depths, he drags grass and leaves, on which the females throw eggs. The male stays in the burrow and guards the young. During this period, outgrowths appear on his ventral fins. Some ichthyologists say that these are temporary external gills for additional respiration. Others believe that with the help of these growths, the fish partially gives up the oxygen taken when it rises to the surface of the reservoir. Whether this is true or not is not known for sure. However, after the breeding season, the outgrowths disappear.

      Lungfish. Representatives: coelacanth

      Another representative of lungfish is coelacanths (coelacanths). They are very few in number and covered with a mysterious veil. They live near However, local fishermen have mined them in the entire history of no more than two hundred pieces. The length of the fish is from 43 to 180 centimeters, and the mass reaches 95 kg. An interesting fact is that all coelacanths were caught from September to April, and in the dark. Fishermen caught them with bait from squid or pieces of fish. Fishing rods were cast to decent depths (from 150 to 400 meters). Attempts were made to catch the coelacanth with traps or trawls, but nothing came of it. Perhaps this is due to the difficult topography of fish habitats.

      Latimeria is a lungfish. She has enough interesting structure. For example, she has no vertebrae. The spine is formed by an elastic thick rod. serving as lung for lungfish, reduced to a small tube. The eyes of the coelacanth are adapted to living in the dark. The biology of coelacanth has been studied very little. In general, lungfish are very interesting in terms of their habitat. Representatives (a list of them was given by us in the article) of this class are quite unique. There are not many of them left on earth. Moreover, due to good palatability they are still being exterminated.

      But as for the coelacanth, it is not so easy to catch it. Scientists suggest that it lives among the basalt rocks of the Comorian Rocks at great depths. Those rare specimens that caught the bait of fishermen, of course, were subjected to close examination. So, in their stomachs were found the remains deep sea fish living at a depth of 500 to a thousand meters. Most likely, the coelacanth leads a sedentary life, although, as we have already said about the lungfish, they can make sharp throws, thanks to their strong tail. Movable paired fins help them squeeze through the crevices of the rocks. Latimeria does not tolerate bright sunlight and high temperature surface layers of water.

      The last representative on earth

      In fact, coelacanth is the only type of coelacanth fish that has survived to this day. Their discovery is comparable only to the discovery of a living dinosaur.

      Of course, the coelacanth is very different from its ancient predecessors, which once inhabited the shallow waters of the coastal zone and fresh water. Such conclusions were made by scientists on the basis of fossils found. By the way, with the help of the same fossils, experts concluded that the ancient coelacanths lived 400 million years ago, which means even before the advent of dinosaurs.

      Latimeria is the only representative of the cross-finned fish on earth. Its discovery was the largest find in the zoological field in the twentieth century. It happened in 1938. Fishermen in Indian Ocean caught a very large unknown fish with quite aggressive behavior. Its study led to a stunning discovery - that this is the last representative of the lobe-finned fish on earth, which were previously considered extinct for a long time.

      Coelacanth habitats have been established over the years. It gradually became clear that she lives near the three Comoros, as well as off the coast of southern Mozambique and the southwestern coast of Madagascar. And in 1998, a fish population was discovered off the Indonesian coast.

      Currently, scientists are talking about two types of coelacanths - Indonesian and Kamor. How many fish there are off the coast of Indonesia is unknown, but about two hundred individuals live near the Comoros. All coelacanths are under close control. Catching this fish is strictly prohibited.