Conclusion about the formation of reflexes in fish. Conditions for the development of conditioned reflexes in fish. Retrospective of the study of the reflex activity of fish

Conditioned fish reflexes. The continuous neural tube of vertebrates creates the most favorable conditions for the connection of all parts of the nervous system. Its leading department - the brain concentrates the functions of controlling behavior, and in it the structures that carry out conditioned reflexes receive extraordinary development.

Whoever keeps fish in an aquarium knows how easy it is to teach them to swim to the surface when the owner makes movements with his fingers, with which a pinch of food is usually poured into the water. The sight of a person's hand approaching the surface of the water, which previously elicited a defensive flight response, now becomes a signal of a conditioned food reflex. Aquarium fish can develop a variety of conditioned food reflexes, for example, to lighting a certain place in an aquarium, accompanied by feeding in this place, to tapping on the aquarium wall, if accompanied by feeding, etc.

In the natural environment, the ability to develop new behavioral skills helps fish to adapt to changing living conditions.

The resulting new conditioned reflexes are stronger than many innate instincts and can change them and even completely suppress them. For example, if a predatory pike is placed in the same aquarium with its usual victim - crucian carp, separating them with a glass partition, then the pike will attack the crucian. However, after repeated painful blows of the snout against the glass, it stops trying to grab the prey. If we now remove the partition, then the pike and crucian carp will calmly “swim” next to each other.

The fact is that fry bred under artificial conditions at a fish hatchery, when they enter an open reservoir, river or lake, die in masses from predators, since a safe life in industrial pools did not give them a reason to develop protective behavior. An increase in the survival rate of fry of valuable species of commercial fish can be achieved by artificially developing in them conditioned defensive reflexes to the species of predatory fish.

To develop such reflexes, a stuffed animal, reproducing the figure of a predatory fish, was lowered into the pool with fry, and an electric current was passed through the water or beaten on its surface. After a series of such combinations, only the appearance of a figure of a predator put the fry to flight. The practical significance of this method of increasing the productivity of fish farming can be judged from the results of an experiment carried out in one of the pond farms in Karelia. A pre-calculated number of valuable fish fry and one predator, the chub, were released into the fenced area of ​​the pond. After 1-2 days, we counted how many fry survived.

It is known that amateur fishermen, in order to ensure a good catch in their favorite gestures, especially in quiet backwaters, systematically bring and throw into the water leftovers and everything that can be edible for fish. It is possible that in this way the fish develop conditioned food reflexes that attract them to the place of feeding. Recently, there have been reports that some coastal fisheries are feeding fish in certain areas in order to increase their catch.

Conditioned reflexes of birds. The everyday observation that "the crow is afraid of the bush" speaks of a good ability to develop conditioned reflexes. This ability of the bird is already at an early age. For example, chickens quickly imitate a pecking mother hen, and rhythmic tapping becomes a signal for them to peck food. In this way, the feeding activity of weak chicks can be encouraged.

Cases are described when chickens, hunting for flies, grabbed a wasp or a bee and, once stung, were no longer mistaken. Other observations have shown that chickens quickly learn to distinguish edible caterpillars from non-edible caterpillars by shape and color. If the chickens are fed only from the hands, then they stop responding to the clucking of the chicken and run after their breadwinner with a squeak.

Week-old chickens can develop a variety of food and defensive conditioned reflexes to light, sound and other signals. However, subtle discrimination of these signals is achieved only at the age of 2-3 weeks. Adult chickens quickly adapt to the daily routine in the hen house and gather at the feeders exactly at the feed time.

Since the main signal for the activity of chickens is light.

Even more interesting theoretical and practical results were obtained in experiments with the transformation of one natural day into two artificial ones. To do this, lighting and darkening were alternated in the poultry house during each day in the following order: 0-4 hours - a normal night, from 4 to 12 hours - a bright day, from 12 to 16 hours - a blackout, creating a "second night", after which From 16:00 to 24:00 late at night, artificial lighting maintained the atmosphere of a bright "second day". The hens grown under these conditions adopted the new regimen and in two "light days" during the day they managed to eat more feed, gain more live weight, and many of them began to lay eggs twice a day. As a result, the productivity of chickens has increased markedly.

Young birds learn to find their way to their nest, primarily by visual cues. They circle over it for a long time, remembering the characteristic features of the surrounding landscape. The ability of pigeons to return home even from afar has been used since ancient times in the form of pigeon mail. Pigeon mail has not lost its significance to our time, especially in military affairs: it is devoid of the main drawback of radio communications, in which messages are easily intercepted, and the location of the transmitter is accurately determined by direction finding. About a million carrier pigeons participated in World War I. In the Second World War, the British Air Force alone had several tens of thousands of carrier pigeons "in service".

Conditioned reflexes in rodents. The house mouse learns, with the help of complex tricks, to get food for itself and escape from the dangers that await it at every turn as a result of persecution by humans, cats, etc. The life of mice and rats in the winding paths of the underground has developed in them the ability to quickly navigate them and remember everything inputs and outputs. Therefore, various experiments on the psychology of learning are performed on laboratory white rats, measuring the time required to find a way out of the tangled roads, the labyrinth.

To study the properties of higher nervous activity in mice, rats, rabbits, conditioned reflexes to light, sound, olfactory and other signals are developed in special chambers. If a food reflex is developed, then the feeder opens on a signal, and if a defensive reflex is developed, then an electric current is connected to the metal floor grate. In this way, the properties of conditioned reflexes, their changes under various influences on the animal's body (physical work, drugs, hunger, etc.) are studied.

Features of the way of life of mice and rats in the dark nooks and crannies of the underground are reflected in the fact that they form conditioned reflexes to sound signals much more easily than to visual signals. However, they also develop visual conditioned reflexes well. This can be used to show an effective "putting mice on a train" experience. If some of the white tame rats or mice are marked with red paint and fed only in red trailers, and the rest - in white ones, then when the train arrives, they will scatter to "their" trailers,

The behavior of beavers, known for their valuable fur, reaches high perfection. They build dams with amazing skill, raising the water level in the river. (It is known that beaver dwellings have an underwater entrance.) At the same time, old beavers teach young ones the most effective methods of gnawing and felling trees, cutting them, rafting to the construction site and laying them in the body of the dam. All these works are carried out unanimously by all members of the colony under the guidance of leaders. The "language" of beavers is interesting. By whistling they call each other out of their dwellings, they exchange throat sounds when they are felling trees, etc. Depending on local conditions, the size of the river, the condition of the banks and other circumstances, beavers choose different methods and means of construction, erecting complex hydraulic structures. Conditioned reflexes of ungulates. Pigs can develop a variety of conditioned reflexes from an early age. This is used, for example, in order to collect piglets after a walk. It is enough for the pig shed to give a certain signal for several days before each feeding (to hit the bottom of the bucket, like a drum), and at this signal the piglets will run together to the feeders from all over the pen.

Sheep and goats develop complex food conditioned reflexes, which have been studied both in the laboratory and in natural conditions. Salivation was studied in sheep that were transferred from stall keeping to grazing.

In the first two days, neither the path to the pasture, nor even the proximity to grazing sheep did not cause salivation in the experimental sheep. On the third day, her mouth watered at the sight of sheep grazing. Then conditioned reflexes were formed to the view of the pasture, the way to it, and after two months it was enough to take the sheep out of the stall into the corridor, as she already began to salivate.

According to the signals of the natural environment, sheep develop adaptive conditioned reflexes that cause changes in the metabolism in the body. The view of grass bending from the wind enhances the formation of heat, and bright sunlight reduces heat production. This regulation of metabolism allows the sheep to endure both winter blizzards and summer heat in the open field.

Of great importance for increasing the milk yield of cows are the conditioned reflexes of milk production and milk ejection, which are developed in them by the conditions of keeping and milking. A certain daily routine, a constant milking time, the same milkmaid become signals that reflexively excite the mammary glands in advance. Everything that interferes with the manifestation of this reflex - noise and disorder, rough handling of the cow, untimely milking, frequent change of milkmaids - leads to a decrease in milk yield even in highly productive cows. The practice of advanced dairy farms has shown that the use of conditioned reflex factors can be an effective means of increasing milk production.

As a result of centuries of experience in domestication and economic use, a person uses a whole range of signals to control her behavior. Well-known verbal commands are reinforced by musculoskeletal stimulation through the reins and whip for a draft horse, rein, shankel (the inner part of the rider's lower leg facing the horse) and spurs for a riding horse. During circus training, music is often used as signals for horse movements, in the rhythm of which the horse "dances".

The horse has a delicate hearing and sense of smell, well oriented on the ground. Therefore, if you get lost, for example, in a snowstorm, you can let it find its own way by the smell of housing brought from afar or the sounds of barking dogs that are inaudible to us.

In our country, serious work is underway to tame the inhabitant of the northern forests - the mighty elk, which is able to overcome swamps and impassability, unbearable for a horse. However, the most interesting prospects open up in the use of moose as dairy animals.

Zaletova V.D. one

Tavchenkova O.N. one

1 Municipal Autonomous General Educational Institution "Secondary School No. 5 of Chelyabinsk", MAOU "Secondary School No. 5 of Chelyabinsk"

The text of the work is placed without images and formulas.
The full version of the work is available in the "Job Files" tab in PDF format

Introduction

Many people mistakenly believe that fish are stupid and unreceptive creatures. Indeed, some initially purchase an aquarium as a purely decorative item. However, watching fish, many aquarists come to the conclusion that fish are not just interior decoration, they are living creatures, interesting in their behavior. Relevance work lies in the fact that the experiment on the development of a conditioned reflex in aquarium fish teaches us to be attentive to living creatures that inhabit the world around us, helps us to establish ways of interacting with living organisms. This knowledge, in turn, enables us to make the environment of living beings more comfortable, to respond to the needs of those whose lives depend on our behavior.

Target work: to study the development of a conditioned reflex in different types of aquarium fish.

An object research: aquarium fish.

Subject research: conditioned reflexes in fish.

Hypothesis research: suppose that with the help of the knowledge gained during the experiment, it is possible to develop conditioned reflexes of fish.

In accordance with the goal and hypothesis, the following tasks:

to study the behavior of fish, their conditioned and unconditioned reflexes;

identify and describe the fish that live in my aquarium;

conduct experiments on the development of conditioned reflexes in fish.

The work used the following methods research: study of scientific literature and Internet materials, description, observation, analysis.

Theoretical significance work lies in the fact that its results can be presented at the lessons of the surrounding world when studying fish.

We believe that the results of the study are practical value- assistance in organizing the most comfortable habitat for aquarium fish.

Fish behavior. Conditioned and unconditioned reflexes

Fish are vertebrates that live in water. The living conditions of fish and their behavior are interrelated. Each species of fish has innate and acquired reactions to the surrounding world. The level of development of these reactions is determined by the degree of development in the process of evolution of the sense organs and the central nervous system.

The activity of all organs of the body in fish and the organism as a whole is regulated by the nervous system. It consists of nervous tissue, brain and spinal cord.

The fish brain consists of olfactory parts, forebrain hemispheres, diencephalon with pituitary gland, visual parts (midbrain), cerebellum and elongated brain.

Fish have a well-developed memory, they can remember their owners, distinguish them from other people.

Vision is of great importance in the life and behavior of fish. Surely, everyone noticed that when you bring food, the fish immediately come to life, follow the movement of the hand. The cornea of ​​the fish eye is slightly convex, the lens is spherical in shape, there are no eyelids. The pupil is unable to contract and enlarge. Due to the contraction of the muscles of the falciform process, the lens of the eye can move back, thus, adaptation and adjustment of the vision of fish is achieved. Fish distinguish the brightness of light, select the most optimal zones for this type. Most fish see the tone of an object.

The olfactory organs of fish are located in the nostrils, which are simple depressions with a mucous membrane penetrated by branching of nerves coming from the olfactory part of the brain. With the help of signals coming through the nostrils, the fish can catch the aroma of food or the enemy at a fairly decent distance.

The organs of taste in fish are represented by taste buds. It is curious that in most types of fish papillae are located not only in the mouth, but also on the antennae, head and sides of the body, right up to the caudal peduncle.

A lot of fish have a well-developed sense of touch, in particular this applies to most bottom fish and inhabitants of muddy water. The antennae of fish are their organs of touch. With antennae, fish feel various objects and animals, find food, and navigate the terrain.

Fish do not have external ears. The organs of hearing are represented by the inner ear. The inner ear consists of three semicircular canals with ampullae, an oval sac and a round sac with a projection (lagena). Sounds enable fish to navigate in the water, detect food, escape from opponents, and attract individuals of the opposite sex.

Despite the famous saying, fish are not so dumb. Of course, it is unlikely that fish will be able to please us with melodic harmonies. The sounds made by some fish can be clearly heard by a person at a great distance. Sounds vary in pitch and intensity. Generally, fish use sound signals during the breeding season.

In the skin of the lateral surface there is a unique sense organ - the lateral line. As a rule, the lateral line is a system of depressions or channels in the skin of the head and body with nerve endings in depth. The entire system is connected by nerves to the inner ear. It is designed to perceive low-frequency vibrations, which makes it possible to detect moving objects. Thanks to the line, the fish acquires data on the flow and direction of water, its chemical composition, pressure, and “feels” infrasounds.

Fish change data and do it using a variety of signals: sound, visual, electrical and others. For fish that live in schools, interaction is essential: it can help discover food, escape from predators, select a mate, and do other things that are significant for fish.

Types of aquarium fish to watch

Guppy(lat. Poecilia reticulata) is a freshwater viviparous fish. The size of males is 1.5-4 cm; slender; thoroughbred individuals often with long fins; the color is often bright. The size of females is 2.8-7 cm; fins are always proportionately smaller than those of males; females from natural habitats and many breeds are gray with a pronounced rhombic grid of scales, for which the species got its name: reticulum from lat. - mesh, mesh.

The most popular and unpretentious aquarium fish. In a home aquarium, it inhabits all layers. In captivity, it lives longer and grows larger than in nature. Aquariums most often contain various breeds of guppies or the result of their mixing.

Very peaceful and able to get along with different types of fish. It is only important to take into account the impossibility of long-term residence of guppies alone. Therefore, it is necessary to populate these fish in an aquarium in pairs or groups. The optimum constant water temperature is +24-26 °C.

Guppies are unpretentious, but they can reach their maximum bloom only under favorable conditions. The offspring of the most thoroughbred parents in bad conditions will not achieve either their brightness or their pomp of fins. Guppies can live in a glass of water, but it's more of an existence than a life.

aquarium fish sumatran barbus(lat. Puntius tetrazona, and formerly Barbus tetrazona), this is a bright and active fish that will enliven any biotope. This is a medium-sized fish, with a yellowish-red body and black stripes, for which in English he even received the name tiger barb.

It is easy to maintain and is great for aquarists of all levels. They are quite hardy, provided that the water is clean and the aquarium is balanced. In an aquarium with Sumatran barbs, it is better to plant a lot of plants, but it is important that there is also free space for swimming. However, they can gnaw tender shoots of plants, although they do this quite rarely. Apparently with an insufficient amount of plant foods in the diet.

The Sumatran barb has a tall, rounded body with a pointed head. These are medium-sized fish, in nature they grow up to 7 cm, in an aquarium they are somewhat smaller. With good care, they live up to 6 years. The body color is yellowish red, with very prominent black stripes. The fins are painted red. Also at this time, their muzzle turns red.

They eat all kinds of live, frozen or artificial food. It is advisable to feed him the most varied, to maintain the activity and health of the immune system. For example, the basis of the diet can be high-quality flakes, and additionally give live food - bloodworm, tubifex, brine shrimp and coretra. It is also desirable to add flakes containing spriulina, as they can spoil the plants.

aquarium fish neon blue or ordinary (lat. Paracheirodon innesi) has long been known and very popular. With his appearance in 1930, he created a sensation and has not lost popularity up to the present day. A flock of blue neon lights in the aquarium creates a mesmerizing view that will not leave you indifferent. These are the factors that made it so popular.

Neons feel most comfortable in a flock of 6 individuals, it is in it that the brightest color colors are revealed. Neons are very peaceful and desirable inhabitants of common aquariums, but they need to be kept only with medium-sized and equally peaceful fish. Small size and peaceful disposition, bad helpers against predatory fish!

The neon is distinguished primarily by a bright blue stripe running through the entire body, which makes it very noticeable. And in contrast to it, there is a bright red stripe that starts from the middle of the body and goes to the tail, slightly going over it.

By themselves, blue neons are wonderful and peaceful fish. They never touch anyone, they get along with any peaceful fish. But here they can just become a victim of other fish, especially if it is a large and predatory fish such as a swordfish or a green tetradon. It can be kept with large, but not predatory fish, for example, with angelfish. What kind of fish do neons get along with? With guppies, platies, cardinals, swordsmen, rainbows, barbs and tetras.

Fighting fish or cockerel(lat. Betta splendens), unpretentious, beautiful, but can kill a female and other males. It is a typical labyrinth fish, meaning it can breathe atmospheric oxygen. It was the aquarium cockerel, and even its relative, the macropod, that were among the first aquarium fish that were brought to Europe from Asia. But long before this moment, fighting fish had already been bred in Thailand and Malaysia.

The fish gained popularity for its luxurious appearance, interesting behavior and the ability to live in small aquariums. And it is also easy to breed and just as easy to cross, as a result - a lot of color variations, different in everything from color to the shape of the fins.

The cockerel is just great for beginners and those aquarists who can't afford a large aquarium. He needs the very minimum, both in volume and in nutrition. And he is unpretentious, strong, always on sale. Due to its labyrinth apparatus, it can survive in water poor in oxygen, and in very small aquariums.

It is very easy to distinguish a male from a female in cockerels. The male is larger, brighter colored, has large fins. Females are paler, smaller, fins are small, and the abdomen is noticeably rounder. In addition, she keeps modestly, trying to keep secluded corners, and not to catch the eye of the male.

Development of conditioned reflexes in aquarium fish

In the development of conditioned reflexes, fish belong to the most primitive vertebrates. However, the various members of this class provide us with remarkable examples of complex behaviors that are worth exploring.

In response to various environmental stimuli perceived by the senses, fish respond with a rather limited number of motor reactions: they swim up or swim away, dive, grab food with their mouths, avoid obstacles that interfere with swimming, etc. A light stimulus, depending on its brightness and A qualitative composition acts differently on the receptors of the eyes of the fish and causes a corresponding nerve impulse, which is transmitted along the sensory nerves to the brain, and from here reflexively rushes along the motor nerves to the skin. Pigment cells located in the skin of fish undergo changes under the influence of nerve impulses. From this, a reflex change in body color occurs.

For a successful experiment on the development of a conditioned reflex, the following requirements must be met:

1. Feed the fish at different times, otherwise a conditioned reflex is developed for a while.

2. The conditioned stimulus (knock, light) should act first.

3. The conditioned stimulus is ahead in time or coincides with the unconditioned stimulus - food (food).

4. Conditioned stimulus and feeding are combined several times.

5. A conditioned reflex is considered developed if, upon the appearance of a conditioned stimulus, the fish swim to the place where they receive food.

6. When developing various reflexes, the place of feeding must be changed.

Experience 1. Development of a conditioned food reflex when a foreign object approaches.

Fish are able to distinguish not only color, but also the shape, as well as the size of moving objects. For example, the type of tweezers from which fish take food develops a conditioned food reflex over time. At first, the fish are frightened by the tweezers submerged in water, but, each time receiving food from it, after a while they begin to trustfully swim up to the tweezers, instead of swimming away ( picture 1).

Rice. 1. Feeding with tweezers

This means that the fish have developed a conditioned reflex to the tweezers as a stimulus, coinciding with the unconditioned stimulus-food. In this case, the tweezers serve as a food signal.

Experience result:

In this experiment, tweezers serve as a food signal. The formed reflex can be preserved even in the absence of feeding, but without food reinforcement, it begins to slow down, fades away. (Table 1).

Table 1

Results of tweezing observations

The experiment started on September 18, 2017.

Output: The conditioned reflex is developed on the basis of the unconditioned reflex, having the leading influence of the conditioned stimulus - tweezers. In the fish brain, a temporary connection is established between the visual and food zones of the cerebral cortex.

In fish of the species barbus, the conditioned reflex "Reaction to tweezers" developed faster than in other inhabitants of our aquarium. There is no reaction to tweezers in snails.

Experience 2. Development of a conditioned food reflex "Reaction of fish to sound stimuli."

As you know, fish do not have an external or middle ear. Their organ of hearing (and balance) is only the inner ear, which is characterized by a relatively simple structure. The endings of the auditory nerve come to the inner ear. The question of whether fish hear or are deaf has long been debatable. Now it can be considered proven that fish perceive sounds, but only if the latter pass through the water. In essence, fish cannot pick up sound as vibrations of the air: for this it would be necessary to have a more complex auditory apparatus (tympanic membrane, auditory ossicles), which in the process of evolution appeared only in amphibians, but it is absent in fish. The sound vibrations arising in the air of the fish are able to perceive in the form of vibrations of water particles if they are set in motion under the influence of air sound waves. Therefore, fish do not hear in the same way as terrestrial animals. Out of the water, the fish become deaf and do not react even to the strongest sounds. We conducted an experiment on the development of a conditioned reflex to tapping, accompanying the feeding of fish with light blows of a solid object against the walls of the aquarium ( figure 2).

Rice. 2. Feeding with tapping

Experience result:

As a result, for about a week, with just one tapping (without feeding), the fish swim up to the place where they usually received food ( table 2).

table 2

Results of the tapping experience

The experiment started on September 26, 2017.

Output: In barb and neon fish, the conditioned reflex “Feeding with tapping” developed faster than in fish of other species. No feeding response with tapping in snails. The knocking reflex developed in the fish on the 6th day.

Experience 3. Development of a conditioned food reflex with a light stimulus.

The development of the eyes, their size and position on the head of the fish are directly dependent on the conditions of its life. So, for example, in bottom fish, which observe the approach of prey from below, the eyes are located on the upper part of the head (catfish); in fish lying on the bottom on one side, the eyes move to the side of the body that is turned upwards (flounder). In conditions of deep-sea habitat, where light hardly penetrates, the organs of vision of fish are either reduced or increased in size. In the first case, this is the result of a decrease in visual function, and in the second, its increase. With a complete loss of vision in some deep-sea fish, the photosensitivity of their skin increases as a compensatory adaptation to orientation in the specific conditions of a dimly lit zone of a reservoir. The development of luminous organs in deep-sea fishes has the same biological significance in some cases, although their role is not exhausted by this. It should be noted that the fish have a positive reaction to light. They swim to those places that are well lit by the sun. Their natural food is concentrated here - numerous small crustaceans that feed on phytoplankton (free-floating algae, whose life depends on solar radiation). Since plankton as an unconditioned food stimulus acted on fish every time in combination with sunlight, the latter received in their life the value of the food signal ( figure 3) .

Rice. 3. Feeding with light stimulus

We conducted an experiment on feeding fish in the presence of a light stimulus: each time we fed, we turned on the light in the aquarium.

Experience result:

One must think that at first the fish developed a conditioned food reflex to light, but over time, repeating many times in a number of generations, this reflex was inherited and turned into an innate biologically useful reaction - phototaxis, which became a means for fish to find food. This phototaxis has recently been successfully used in fishing, attracting fish with the help of electric lamps and other light sources. Commercial reconnaissance using light also gives good results. In this case, a person controls the historically established instinct of fish (the desire for light) in his own interests to the detriment of their life, which indicates the relative nature of the expediency of innate reactions ( table 3).

Table 3

Results of the feeding experiment with light stimulus

The experiment started on October 1, 2017.

Output: Barb and cockerel fish react to light faster than other fish. No reaction feeding with light in snails, weak reaction in guppies.

Conclusion

As a result of the work done, it turned out that the aquarium is a small world that gives a unique opportunity to bring a piece of nature into the house, where everything is coordinated, lives in harmony, develops, changes, revealing itself to the observer.

In highly organized animals with a central nervous system, there are two groups of reflexes: unconditioned (congenital) and conditioned (acquired). Reflexes are of great adaptive importance for maintaining the integrity of the body, full functioning and constancy of the internal environment. In aquarium fish, you can develop all kinds of conditioned reflexes to various stimuli: time, light, color and shape of objects, etc.

During the experiment, we made the following conclusions.

To develop a conditioned reflex in aquarium fish, certain conditions must be met.

During the experiment, conditioned reflexes were developed in aquarium fish guppies, barbs, neon, cockerel to sound, light and feeding with tweezers.

Faster than others, fish develop a reflex to sound.

Conditioned reflexes contribute to the adaptation of organisms to environmental conditions (in this case, feeding conditions).

The degree of response and the ability to learn differ significantly among representatives of different families and even species of aquarium fish. When studying the behavior of fish in an aquarium, the level of adaptation in such species as the barb, cockerel and neon turns out to be high. There are no reactions to external stimuli in aquarium snails.

Tapping on the wall of the aquarium became a stronger stimulus, and therefore the conditioned reflex developed faster.

Thus, the hypothesis of the study that we can develop conditioned reflexes in fish was confirmed, the purpose and objectives of the study were fulfilled.

In this paper, an example of the development of only some conditioned reflexes is considered. The acquired knowledge gives rise to a wide range of opportunities for scientific knowledge of the laws of nature and the improvement of one's own knowledge.

Watching the fish, as well as writing a research paper, taught me how to independently work with information sources (books, the Internet), process information, and keep a diary of observations. In the future, I would like to continue to observe the fish, try to develop new reflexes in them, learn to understand their needs.

Many people say that it is not interesting to keep fish because they cannot be trained. But training is based on the development of a conditioned reflex. And my observations of fish confirmed that they can develop conditioned reflexes.

Bibliographic list

Ziper, A.F. Management of the behavior of animals and birds. Reflexes in the life of animals [Text]. - Access mode: http://fermer02.ru/animal/296-refleksy-v-zhizni-zhivotnykh.html

Pleshakov, A.A. From earth to sky. Atlas-determinant: book. for students beginning class [Text] / A.A. Pleshakov. - M.: Education, 2016. - 244 p.

Rules for the development of conditioned reflexes [Text]. - Access mode: http://www.medicinform.net/human/fisiology8_1.htm

Sereev, B.F. Entertaining physiology [Text] / B.F. Sergeev. - M.: Bustard, 2004. - 135 p.

I know the world: Children's Encyclopedia: Animals [Text, drawing]. - M .: OOO "Publishing house AST", 2001. - 223 p.

Questions about the sensitivity of fish, their behavioral reactions to capture, pain, stress are constantly raised in scientific specialized publications. Do not forget about this topic and magazines for amateur anglers. True, in most cases, publications highlight personal fabrications about the behavior of a particular species of fish in stressful situations for them.

This article continues the topic raised by the author in the last issue of the journal (No. 1, 2004)

Are fish primitive?

Until the end of the 19th century, fishermen and even many biologists were firmly convinced that fish were very primitive, stupid creatures that did not have not only hearing, touch, but even a developed memory.

Despite the publication of materials refuting this point of view (Parker, 1904 - on the presence of hearing in fish; Zenek, 1903 - observations of the reaction of fish to sound), even in the 1940s, some scientists adhered to the old views.

Now it is a well-known fact that fish, like other vertebrates, are perfectly oriented in space and receive information about their surrounding aquatic environment using the organs of sight, hearing, touch, smell, and taste. Moreover, in many ways the sense organs of "primitive fish" can argue even with the sensory systems of higher vertebrates, mammals. For example, in terms of sensitivity to sounds ranging from 500 to 1000 Hz, the hearing of fish is not inferior to the hearing of animals, and the ability to pick up electromagnetic waves and even use their electroreceptor cells and organs to communicate and exchange information is generally a unique ability of some fish! And the “talent” of many species of fish, including the inhabitants of the Dnieper, to determine the quality of food due to ... the touch of a fish to a food object with a gill cover, fins and even a tail fin?!

In other words, today no one, especially experienced amateur fishermen, will be able to call representatives of the fish tribe creatures “stupid” and “primitive”.

Popular about the nervous system of fish

The study of the physiology of fish and the characteristics of their nervous system, behavior in natural and laboratory conditions has been carried out for a long time. The first major work on the study of the sense of smell in fish, for example, was carried out in Russia as early as the 1870s.

The brain in fish is usually very small (in a pike, the brain mass is 300 times less than body weight) and is arranged primitively: the forebrain cortex, which serves as an associative center in higher vertebrates, is completely undeveloped in bony fish. In the structure of the fish brain, a complete separation of the brain centers of different analyzers was noted: the olfactory center is forebrain, visual - middle, the center for the analysis and processing of sound stimuli perceived by the lateral line, - cerebellum. The information received by different fish analyzers at the same time cannot be processed in a complex way, therefore fish cannot “think and compare”, much less “think” associatively.

However, many scientists believe that bony fish ( which include almost all of our inhabitants of fresh waters - R. N. ) have memory- the ability to figurative and emotional "psychoneurological" activity (albeit in its most rudimentary form).

Fish, like other vertebrates, due to the presence of skin receptors, can perceive various sensations: temperature, pain, tactile (touch). In general, the inhabitants of the kingdom of Neptune are champions in terms of the number of peculiar chemical receptors they have - taste kidneys. These receptors are the endings of the facial ( presented in the skin and on the antennae), glossopharyngeal ( in the mouth and esophagus), wandering ( in the oral cavity on the gills), trigeminal nerves. From the esophagus to the lips, the entire oral cavity is literally strewn with taste buds. In many fish, they are on the antennae, lips, head, fins, scattered throughout the body. Taste buds inform the host about all substances dissolved in water. Fish can taste even those parts of the body where there are no taste buds - with the help of ... their skin.

By the way, thanks to the work of Koppania and Weiss (1922), it turned out that freshwater fish (golden carp) can regenerate a damaged or even cut spinal cord with complete restoration of previously lost functions.

Human activity and conditioned reflexes of fish

A very important, practically dominant, role in the life of fish is played by hereditary And non-hereditary behavioral reactions. Hereditary include, for example, the obligatory orientation of fish with their heads towards the current and their movement against the current. From non-hereditary interesting conditional And unconditioned reflexes.

During life, any fish gains experience and "learns". Changing her behavior in any new conditions, developing a different reaction - this is the formation of the so-called conditioned reflex. For example, it has been established that during experimental fishing for ruff, chub, and bream with a fishing rod, these freshwater fish developed a conditioned defensive reflex as a result of 1-3 observations of the capture of fellow flocks. Interesting fact: it is proved that even if the same bream over the next, say, 3-5 years of its life, fishing tackle does not come across on the way, the developed conditioned reflex (capturing brothers) will not be forgotten, but only slowed down. Seeing how a spotted brother “soars” to the surface of the water, the wise bream will immediately remember what to do in this case - run away! Moreover, to disinhibit the conditioned defensive reflex, only one glance will be enough, and not 1-3! ..

A huge number of examples can be cited when the formation of new conditioned reflexes in relation to human activity was observed in fish. It is noted that in connection with the development of spearfishing, many large fish have accurately recognized the distance of a speargun shot and do not let a diver get closer than this distance. This was first written by J.-I. Cousteau and F. Dumas in the book "In the World of Silence" (1956) and D. Aldridge in "Spearfishing" (1960).

Many anglers are well aware that defensive reflexes to hook tackle, to swinging a rod, walking along the shore or in a boat, fishing line, bait are very quickly created in fish. Predatory fish unmistakably recognize many types of spinners, "learned by heart" their vibrations and vibrations. Naturally, the larger and older the fish, the more conditioned reflexes (read - experience) it has accumulated, and the more difficult it is to catch it with “old” gear. Changing the fishing technique, the range of lures used for a while dramatically increase the catches of anglers, but over time (often even within one season), the same pike or pike perch “master” any new items and put them on their “black list”.

Do fish feel pain?

Any experienced fisherman who fishes different fish from a reservoir can already tell at the stage of hooking which inhabitant of the underwater kingdom he will have to deal with. Strong jerks and desperate resistance of pike, powerful "pressure" to the bottom of the catfish, the practical absence of resistance from pike perch and bream - these "calling cards" of fish behavior are immediately identified by skilled fishermen. Among fishing enthusiasts, there is an opinion that the strength and duration of the struggle of fish directly depends on its sensitivity and the degree of organization of its nervous system. That is, it is understood that among our freshwater fish there are species that are more highly organized and "neurally sensitive", and that there are also fish that are "rough" and insensitive.

This point of view is too straightforward and essentially wrong. To know for sure whether our inhabitants of water bodies feel pain and how exactly, let us turn to rich scientific experience, especially since the specialized “ichthyological” literature since the 19th century provides detailed descriptions of the physiology and ecology of fish.

INSERT. Pain is a psychophysiological reaction of the body that occurs with strong irritation of sensitive nerve endings embedded in organs and tissues.

TSB, 1982

Unlike most vertebrates, fish cannot communicate the pain they feel by screaming or moaning. We can judge the pain feeling of fish only by the protective reactions of its body (including characteristic behavior). Back in 1910, R. Gofer found that a pike at rest, with artificial skin irritation (prick), produces a tail movement. Using this method, the scientist showed that the "pain points" of the fish are located on the entire surface of the body, but they were most densely located on the head.

Today it is known that due to the low level of development of the nervous system, pain sensitivity in fish is low. Although, undoubtedly, a spotted fish feels pain ( remember the rich innervation of the head and mouth of fish, the taste buds!). If the hook has stuck into the gills of the fish, the esophagus, the periorbital region, its pain in this case will be stronger than if the hook had pierced the upper / lower jaw or caught on the skin.

INSERT. The behavior of fish on the hook does not depend on the pain sensitivity of a particular individual, but on its individual reaction to stress.

It is known that the pain sensitivity of fish strongly depends on the water temperature: in pike, the rate of nerve impulse conduction at 5°C was 3-4 times lower than the rate of excitation conduction at 20°C. In other words, caught fish are 3-4 times more sick in summer than in winter.

Scientists are sure that the furious resistance of the pike or the passivity of the zander, the bream on the hook during the fight, is only to a small extent due to pain. It has been proven that the reaction of a particular fish species to capture depends more on the severity of the stress received by the fish.

Fishing as a deadly stress factor for fish

For all fish, the process of catching them by an angler, playing them is the strongest stress, sometimes exceeding the stress of fleeing from a predator. For anglers who practice the “catch and release” principle, it will be important to know the following.

Stress reactions in the body of vertebrates are caused by catecholamines(adrenaline and noradrenaline) and cortisol, which operate during two different but overlapping periods of time (Smith, 1986). Changes in the body of fish caused by the release of adrenaline and noradrenaline occur in less than 1 second and last from several minutes to hours. Cortisol causes changes that start in less than 1 hour and sometimes last weeks or even months!

If the stress on the fish is prolonged (for example, during a long haul) or very intense (strong fright of the fish, aggravated by pain and, for example, lifting from a great depth), in most cases the caught fish is doomed. She will surely die within a day, even being released into the wild. This statement has been repeatedly proven by ichthyologists in natural conditions (see "Modern Fishing", No. 1, 2004) and experimentally.

In the 1930s-1940s. Homer Smith stated the lethal stress response of the anglerfish to being caught and placed in an aquarium. In a frightened fish, the excretion of water from the body with urine increased sharply, and after 12-22 hours it died ... from dehydration. The death of fish came much faster if they were injured.

A few decades later, fish from American fish ponds were subjected to rigorous physiological studies. Stress in fish caught during planned activities (replanting spawners, etc.) was due to increased activity of fish during seine pursuit, attempts to escape from it, and short-term stay in the air. The caught fish developed hypoxia (oxygen starvation) and, if they still had a loss of scales, the consequences in most cases were lethal.

Other observations (for brook trout) showed that if a fish loses more than 30% of its scales when caught, it dies on the very first day. In fish that lost part of their scale cover, swimming activity faded, individuals lost up to 20% of their body weight, and the fish quietly died in a state of mild paralysis (Smith, 1986).

Some researchers (Wydowski et al., 1976) noted that when trout were caught with a rod, the fish were less stressed than when they lost their scales. The stress reaction proceeded more intensively at high water temperatures and in larger individuals.

Thus, an inquisitive and scientifically "savvy" angler, knowing the peculiarities of the nervous organization of our freshwater fish and the possibility of acquiring conditioned reflexes, learning ability, their attitude to stressful situations, can always plan their vacation on the water and build relationships with the inhabitants of the Neptune kingdom.

I also sincerely hope that this publication will help many anglers to effectively use the rules of fair play - the principle of "catch and release" ...

behavioral acts that promote passive and active migration. All fish are characterized by a food-procuring instinct, although it can be expressed in very different forms of behavior. The possessive instinct, expressed in the protection of territory and shelters, upholding the sole right to a sexual partner, is far from known for all species, sexual - for all, but its expression is very different.

Complexes of simple behavioral acts that have a certain sequence and purposefulness are sometimes called dynamic stereotypes - for example, a certain series of actions when obtaining a discrete portion of food, going to a shelter, building a nest, caring for protected eggs. The dynamic stereotype also combines congenital and acquired forms of behavior.

Acquired forms of behavior are the result of an organism's adaptation to changing environmental conditions. They allow you to acquire cost-effective, time-saving standard reactions. In addition, they are labile, that is, they can be redone or lost as unnecessary.

Different pisciformes have different complexity and development of the nervous system, so the mechanisms for the formation of acquired forms of behavior are different for them. For example, acquired responses in lampreys, although they are formed with 3-10 combinations of conditioned and unconditioned stimuli, are not developed during the time interval between them. That is, they are based on persistent sensitization of receptor and nerve formations, and not on the formation of connections between the centers of conditioned and unconditioned stimuli.

The training of laminabranchs and teleosts is based on true conditioned reflexes. The rate of development of simple conditioned reflexes in fish is approximately the same as in other vertebrates - from 3 to 30 combinations. But not every reflex can be worked out. Food and defensive motor reflexes are the most well studied. Defensive reflexes in the laboratory are studied, as a rule, in shuttle chambers - rectangular aquariums with an incomplete partition that allows you to move from one half of the chamber to the other. As a conditioned stimulus, an electric light bulb or a sound source of a certain frequency is most often used. As an unconditioned stimulus, an electric current from a network or battery with a voltage of 1-30 volts, supplied through flat electrodes, is usually used. The current is turned off as soon as the fish moves to another compartment, and if the fish does not leave, then after a certain time - for example, after 30 seconds. The number of combinations is determined when the fish performs the task in 50 and 100% of cases with a sufficiently large number of experiments. Food reflexes are usually developed for any action of the fish by rewarding the issuance of a portion of food. The conditioned stimulus is a light being turned on, a sound being emitted, an image appearing, etc. In this case, the fish should come to the feeder, press the lever, pull the bead, etc.

It is easier to develop an "environmentally adequate" reflex than to force the fish to do something that is not characteristic of it. For example, it is easier to make an eared perch, in response to a conditioned stimulus, grab a tube from which feed paste is squeezed out of its mouth than to throw a float from below. It is easy to develop in a loach the reaction of leaving to another compartment, but it is not possible to make it move while a conditioned and even unconditioned stimulus is acting - such a movement is not characteristic of this species, which is characterized by hiding after a jerk. Persistent attempts to make the loach constantly move along the annular channel lead to the fact that it stops moving and only flinches from electric shocks.

It should be said that the "abilities" of the fish are very different. What works with some instances doesn't work with others. A. Zhuikov, studying the development of defensive reflexes in juvenile salmon grown at a fish hatchery, divided the fish into four groups. In some fish, it was not possible at all to develop a motor defensive reflex in 150 experiments, in another part the reflex was developed very quickly, the third and fourth groups of experimental fish acquired the skill of accurately avoiding electric shock with an intermediate number of lamp ignitions. Studies have shown that fish that learn easily are significantly better at avoiding predators, while those that learn poorly are doomed. After the release of salmon from the hatchery, after a period of time sufficient to undergo rigorous selection when living together with predators (fish and birds), the learning ability of the survivors is much higher than that of the original material, since the "incapable" become the food of predators.

The simplest form of learning is habituation to an indifferent stimulus. If at the first demonstration of a frightening stimulus, for example, a blow to the water, the wall of an aquarium, a defensive reaction arises, then with repeated repetition, the reaction to it gradually weakens and, finally, completely stops. Fish become accustomed to a variety of stimuli. They get used to living in conditions of industrial noise, periodic drawdown of the water level, eye contact with a predator, fenced off by glass. In the same way, the developed conditioned reflex can be inhibited. With repeated presentation of a conditioned stimulus without reinforcement by an unconditioned stimulus, the conditioned reflex disappears, but after some time the "deception" is forgotten, and the reflex may spontaneously arise again.

During the development of conditioned reflexes in fish, the phenomena of summation and differentiation may occur. Numerous experiments are an example of summation, when a reflex, developed to one sound frequency or to one color of a light source, manifested itself upon presentation of other sound frequencies or colors. Differentiation occurs in the presence of the resolving power of the receptor organs in fish: if food reinforcement is given at one frequency and pain at another, then differentiation occurs. The fish manage to develop reflexes of the second order, that is, reinforcement is given after the light source is turned on only if it is preceded by a sound stimulus. The reaction in this case is observed directly to the sound without waiting for the light. In the development of chain reflexes, fish are inferior to higher animals. For example, in children, reflexes up to the sixth order can be observed.

CONDITIONAL REFLECTOR ACTIVITY OF FISH

In the process of evolution, animals have developed a special mechanism that makes it possible to respond not only to conditioned stimuli, but also to a mass of indifferent (indifferent) stimuli. Coinciding in time with unconditioned stimuli. Thanks to this mechanism, the appearance of indifferent stimuli signals the approach of those agents that are of biological significance. The connection of the animal with the outside world is expanding. The animal gets the opportunity to better adapt to the conditions of the external environment. Therefore, conditioned reflexes are necessary for life.

IP Pavlov pointed out that during the formation of a conditioned reflex in the cerebral cortex, the nervous connection between the excited centers of the conditioned and unconditioned stimulus is closed.

The cortex of the cerebral hemispheres of higher vertebrates (neopalhum), which is formed in the process of phylogenesis from the forebrain and is of exceptional importance for the formation of conditioned connections, is still absent in fish. It has been proven that the middle and diencephalon play an important role in the formation of conditioned reflexes. In this regard, the ability of fish to engage in conditioned reflex activity has been established by numerous studies by various authors. goby, cod, etc.) are capable of developing conditioned reflexes (or, in the terminology of German authors, “training”) to a wide variety of stimuli.

At the same time, it should be noted that it was only in the works of Frolov that a deep analysis of the specific features of the conditioned reflex activity of fish was given, proceeding from the patterns discovered by IP Pavlov;

MOSCOW STATE UNIVERSITY OF APPLIED BIOTECHNOLOGY.

DEPARTMENT OF ANATOMY, PHYSIOLOGY AND ANIMAL HUSBANDRY.

Coursework in Physiology and Ethology

farm animals.

« Conditioned reflex activity of fish

and its impact on productivity»

Written by: 2nd year student of group 9

Faculty of Veterinary and Sanitary Kochergin-Nikitsky K.

Lecturer: Rubekin E. A.

Moscow 2000-2001

PLAN.

I Introduction

II main part

A retrospective of the study of the reflex activity of fish.

Conditioned reflex activity of fish.

The influence of conditioned reflex activity on the productivity of fish

III Conclusion.

Among the many sections of the comparative physiology of vertebrates, a special place is occupied by the physiology of fish, which is rapidly developing both in our country and abroad. The growing interest of researchers in the physiological and biochemical foundations of fish life is determined by several reasons.

First, fish are the most numerous group of vertebrates in terms of species. The modern world ichthyofauna is represented by more than 20,000 species, the vast majority of which (95%) belong to bony fish. In terms of the total number of fish species, they significantly outnumber amphibians, reptiles, birds and mammals combined (about 18,000 species), and the process of describing fish species is still far from complete, since descriptions of new dozens of fish species appear every year and painstaking work continues to clarify species independence. many "subspecies" with the involvement of modern methods of biochemical systematics.

Secondly, fish are taxonomically very heterogeneous groups of aquatic vertebrates. Fish is the same collective concept as "terrestrial vertebrates", consisting of several classes. The macroheterogeneity of fish is recognized today by most ichthyologists-systematists, and the only question is how many classes are included in the superclass of fish? According to L. S. Berg, there are 4 classes: cartilaginous, chimeras, lungfish and higher fish, and, according to T. S. Russ and G. L. Lindberg, there are only 2 classes: cartilaginous and bony fish. It should, perhaps, be noted that the division of fish into classes, even in our time, is carried out exclusively according to morphological characters, without taking into account modern data of evolutionary physiology, biochemistry and molecular biology.

Thirdly, fish are the most ancient group of vertebrates, the phylogenetic history of which is at least 3 times longer than that of birds and mammals. In addition, within each of the two main classes of fish (cartilaginous and bony), there are evolutionarily older and younger orders, or the so-called progressive and primitive. All this is of great interest to specialists in the field of evolutionary physiology and biochemistry and makes fish an obligatory object of evolutionary physiological research in the understanding of L. A. Orbeli (1958), i.e., in the development of problems of the evolution of functions and functional evolution.

Fourth, fish are an extremely ecologically diverse group of vertebrates. As a result of a long adaptive evolution, they have mastered almost all ecological niches in the oceans, seas, lakes and rivers, adapted to living in mountain lakes and the deepest oceanic depressions, in drying up reservoirs and underground caves, in arctic waters and hot springs. In other words, fish are an indispensable object of ecological and physiological research, the focus of which is on the physiological and biochemical mechanisms of adaptation to ever-fluctuating environmental factors.

Fifth, and this is especially important, fish are of great economic importance as a source of food protein for humans and farm animals. Recall that today, of the total amount of protein consumed by mankind, terrestrial ecosystems provide about 98%, water - 2%, that is, almost 50 times less. At the same time, however, it should be borne in mind that the share of animal protein of “terrestrial” origin is only 5% (the remaining 93% are vegetable protein), and animal protein of “aquatic” origin is 1.9%, i.e. 30% of the animal protein consumed by mankind. As the world's population increases, the need for animal protein will constantly increase and in the future it will not be possible to satisfy them at the expense of "land animal husbandry". The growing shortage of food protein makes us face the need to further increase the volume of fish catch in the World Ocean, which, however, has already reached 90 million tons per year, i.e., has come close to the level of the maximum possible catch (about 100-120 million tons per year), the excess of which will inevitably lead to catastrophic consequences. Therefore, the main increase in fish production in the World Ocean and inland waters can only be obtained through the development of maritime and aquaculture on an unprecedented scale, as well as the artificial reproduction of the most valuable fish species by obtaining viable juveniles in fish hatcheries with their subsequent release to feeding pastures in natural areas. reservoirs. In addition to meeting the need for protein, a person also uses fish products such as fish oil (obtained from cod liver) as a source of vitamin D in medicine and animal husbandry. In medicine, drugs derived from sharks are used. In animal husbandry - fishmeal. Everyone knows such products as salmon and sturgeon caviar.

Humanity has been engaged in fish farming, in particular the pond cultivation of carp, for more than 2000 years, but more empirically than on a scientific basis. This is due to the fact that a person receives the bulk of seafood through hunting, and not breeding. In the current century, the intensive development of fish farming has shown that the solution of these large-scale fishery problems is possible only on the basis of a comprehensive study of the main objects of fish farming and fishing, on a deep understanding of the general patterns and mechanisms of interaction of fish with the main factors of the aquatic environment that determine the normal course of life in natural and artificial conditions. , without the knowledge of which neither the rational establishment of fish farming nor the management of managed fisheries in natural reservoirs are inconceivable.

Retrospective of the study of the reflex activity of fish

So, fish is the most numerous, extremely diverse in terms of phylogenetic age, living conditions, lifestyle and level of development of the nervous system, a group of vertebrates perfectly adapted to the environment, which is also of great economic importance as a source of food protein.

The foundations of domestic fish physiology were laid in the 20-40s of the current century by the studies of X. S. Koshtoyants, E. M. Kreps, Yu. P. Frolov, P. A. Korzhuev, S. N. Skadovsky, A. F. Karpevich, G. S. Karzinkin, G. N. Kalashnikov, N. L. Gerbilsky, V. S. Ivlev, E. A. Veselov, V. A. Pegelya, T. M. Turpaeva, N. V. Puchkov and many others. It was during these years that the first data were obtained on the physiology of blood, digestion, respiration, osmoregulation, reproduction and behavior, as well as on the metabolism of fish and the influence of individual factors of the aquatic environment on it. These were the first steps towards the physiological "identification" of fish, revealing their characteristics in comparison with other classes of vertebrates, as well as differences between groups of fish of different phylogenetic age.

Acquired forms of behavior are usually opposed to innate responses, although a sharp line between such forms of behavior may not always be drawn, since an innate response in its original, primitive form can be developed even in the embryonic period (Hind, 1975). Complex complexes of long-term motivated behavior, usually referred to as instincts, contain elements in which the role of innate reactions is undoubted, but also acquired forms of behavior are also undoubted. It is customary to call the instinct of self-preservation, which is inherent in almost the entire period of life, although to varying degrees. This instinct is expressed in various forms of defensive behavior, primarily passive-defensive. Anadromous fish are characterized by a migratory instinct - a system of behavioral acts that promotes passive and active migrations. All fish are characterized by a food-procuring instinct, although it can be expressed in very different forms of behavior. The possessive instinct, expressed in the protection of territory and shelters, upholding the sole right to a sexual partner, is far from known for all species, sexual - for all, but its expression is very different.

Complexes of simple behavioral acts that have a certain sequence and purposefulness are sometimes called dynamic stereotypes - for example, a certain series of actions when obtaining a discrete portion of food, going to a shelter, building a nest, caring for protected eggs. The dynamic stereotype also combines innate and acquired forms of behavior.

Acquired forms of behavior are the result of an organism's adaptation to changing environmental conditions. They allow you to acquire cost-effective, time-saving standard reactions. In addition, they are labile, that is, they can be redone or lost as unnecessary.

Different pisciformes have different complexity and development of the nervous system, so the mechanisms for the formation of acquired forms of behavior are different for them. For example, acquired reactions in lampreys, although they are formed with 3-10 combinations of conditioned and unconditioned stimuli, are not developed during the time interval between them. That is, they are based on persistent sensitization of receptor and nerve formations, and not on the formation of connections between the centers of conditioned and unconditioned stimuli.

The training of laminabranchs and teleosts is based on true conditioned reflexes. The rate of development of simple conditioned reflexes in fish is approximately the same as in other vertebrates - from 3 to 30 combinations. But not every reflex can be developed. Food and defensive motor reflexes are the most well studied. Defensive reflexes in laboratory conditions are studied, as a rule, in shuttle chambers - rectangular aquariums with an incomplete partition that allows one to move from one half of the chamber to the other. As a conditioned stimulus, an electric light bulb or a sound source of a certain frequency is most often used. As an unconditioned stimulus, an electric current from a network or a battery with a voltage of 1-30 volts, supplied through flat electrodes, is usually used. The current is turned off as soon as the fish moves to another compartment, and if the fish does not leave, then after a certain time - for example, after 30 seconds. The number of combinations is determined when the fish performs the task in 50 and 100% of cases with a sufficiently large number of experiments. Food reflexes are usually developed for any action of the fish by rewarding the issuance of a portion of food. The conditioned stimulus is a light being turned on, a sound being emitted, an image appearing, etc. In this case, the fish should come to the feeder, press the lever, pull the bead, etc.

It is easier to develop an "environmentally adequate" reflex than to force the fish to do something that is not characteristic of it. For example, it is easier to make an eared perch, in response to a conditioned stimulus, grab a tube from which feed paste is squeezed out of its mouth than to throw a float from below. It is easy to develop in a loach the reaction of leaving to another compartment, but it is not possible to make it move while a conditioned and even unconditioned stimulus is acting - such a movement is not characteristic of this species, which is characterized by hiding after a jerk. Persistent attempts to force the loach to constantly move along the annular channel lead to the fact that it stops moving and only flinches from electric shocks.

It should be said that the "abilities" of the fish are very different. What works with some instances doesn't work with others. A. Zhuikov, studying the development of defensive reflexes in juvenile salmon grown at a hatchery, divided the fish into four groups. In some fish it was not possible at all to develop a motor defensive reflex in 150 experiments, in another part the reflex was developed very quickly, the third and fourth groups of experimental fish acquired the skill of accurately avoiding electric shock during an intermediate number of lamp ignitions. Studies have shown that fish that learn easily are significantly better at avoiding predators, while those that learn poorly are doomed. After salmon chicks are released from the hatchery, after a period of time sufficient to undergo rigorous selection while living with predators (fish and birds), the learning ability of the survivors is much higher than that of the original material, since the "incapable" become food for predators.

The simplest form of learning is getting used to an indifferent stimulus. If at the first demonstration of a frightening stimulus, for example, a blow to the water, the wall of an aquarium, a defensive reaction arises, then with repeated repetition, the reaction to it gradually weakens and, finally, completely stops. Fish get used to a variety of stimuli. They get used to living in conditions of industrial noise, periodic drawdown of the water level, eye contact with a predator, fenced off by glass. In the same way, the developed conditioned reflex can be inhibited. With repeated presentation of a conditioned stimulus without reinforcement by an unconditioned stimulus, the conditioned reflex disappears, but after some time the "deception" is forgotten, and the reflex may spontaneously arise again.

During the development of conditioned reflexes in fish, the phenomena of summation and differentiation may occur. An example of summation is provided by numerous experiments, when a reflex developed to one sound frequency or to one color of a light source manifested itself upon presentation of other sound frequencies or colors. Differentiation occurs in the presence of the resolving power of the receptor organs in fish: if food reinforcement is given at one frequency and pain at another, then differentiation occurs. In fish, it is possible to develop second-order reflexes, that is, reinforcement is given after the light source is turned on only if it is preceded by a sound stimulus. The reaction in this case is observed directly to the sound without waiting for the light. In the development of chain reflexes, fish are inferior to higher animals. For example, in children, reflexes up to the sixth order can be observed.