About animals

Young Naturalist 1980-02, page 13

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Why fish an oscilloscope

V. Istomin (Young Naturalist, No. 2/1980)

When I first appeared in this laboratory, it seemed to me like a zoo. More precisely, to that pavilion of the zoo, where there are long rows of aquariums, behind the glasses of which swordsmen, guppies, crucians and carp are moving their tails with their tails. The fish kingdom also reigned here. Shelves with dozens of aquariums stretched along the walls of the laboratory, on the sandy bottom of which, as if thinking, mustachioed gudgeons stood. Each of them had its own apartment - they lived alone.

“These fish honestly work for science,” smiled a young scientist, candidate of biological sciences Vladimir Baron.

Getting acquainted with the laboratory, I looked into other rooms. And there is electronic equipment: oscilloscopes, voltmeters, high-frequency generators. Why do fish need an oscilloscope? Such a question I asked Vladimir.

“We are studying the role of electricity in their lives,” he said. - Do you know that fish can generate an electric current and are able to sense an electric field?

What scientists told me here in the laboratory of fish orientation problems at the A. N. Severtsov Institute of Evolutionary Morphology and Animal Ecology of the USSR Academy of Sciences was like science fiction.

The famous American scientist, Nobel laureate physicist R. Feynman once said: "There is practically no natural phenomenon that would not be accompanied by electricity." And in fact, electrical phenomena occur not only in inanimate nature, they are inherent in all living things. Remember the textbook fact - for the first time electricity was discovered by the Italian scientist Galmani with the help of a living organism, namely a frog.

However, man discovered electricity in fish in ancient times. Rather, I felt, not suspecting at the same time of its existence. This concept did not exist then. For example, the ancient Greeks were wary of meeting fish in water, which, as the great scientist Aristotle wrote, "makes animals numb." The fish, which caused fear on people, was an electric ramp and bore the name "dashboard". And only two hundred years ago, scientists finally understood the nature of this phenomenon.

In the nineteenth century, scientists established that all living tissues and cells are peculiar sources of electric current and that life cannot exist without electricity. Today every student knows about this. Many have heard of electric ramps and eels. But does this mean that science already knows everything about fish and there is nothing more to discover? Of course not. There are as many questions and puzzles in this area of ​​biology.

Only a decade and a half ago, the Soviet scientist P. Gulyaev for the first time managed to register a bioelectric field in the air surrounding the nerves, tissues and organs of animals and even humans using highly sensitive equipment! That is, he managed to detect such a field that surrounds, say, a current conductor. The field around living tissue was called an electroaurogram. In other words, you and I, like all running, flying, and floating animals, are original living electric generators.

Based on this discovery, another Soviet scientist A. Pressman put forward the original hypothesis according to which animals seem to be able to use weak electromagnetic fields to exchange information, to communicate with each other. Only this, the scientist claimed, can explain some of the features in the behavior of pack animals and social insects. But the hypothesis is still a hypothesis. It has not yet been established, for example, that bees are talking using an electric field. And we do not feel this field in any way. Therefore, so far it can be said with certainty that no animal on earth can sense an electric field with the help of any sensory organ. fish! And some species of fish, as it turned out, even feel it better than they see or hear. If we consider that they are the only animals on our planet that can emit a strong current and create large electrical voltages, then we have the right to say: fish are unique creatures.

“In the life of different fish, the role of electricity is different,” explained Vladimir Rustamovich Protasov, Doctor of Biological Sciences, USSR State Prize laureate, laboratory head, prominent specialist in biophysics. - The so-called high-electric fish are best known, although there are only a few species. They are called so because with the help of special organs they create powerful electric discharges in water. Freshwater eel, for example, creates a tension of such force that only a thousand batteries for a flashlight can be compared with it. With the help of such "blows" it either repels an enemy attack or paralyzes its victim. Such fish are pretty well studied by biologists. But there are species and others.

We call them low-electric. They emit relatively weak signals. These include most of all 20 thousand species of fish. The most amazing thing is that these fish do not have any special electrical organs.

Here we come to the most interesting in our story. Laboratory scientists have made many surprising discoveries over the course of several years of work. The study of low-electric fish actively began only twenty years ago. And it turned out that ordinary fish - crucians, minnows and many, many others - emit a weak electric signal and feel the electric field!

It all started with the fact that biologists discovered the strange behavior of a small freshwater fish - American catfish. It turned out that he felt the approach of a metal rod in water at a distance of several centimeters. And, let's say, reacted to her only when she touched him. The English scientist Hans Lissman came up with all sorts of tricks to trick another fish - the Nile catfish, gymnarhus. What he just did not do, and the gymnasium at a distance felt metal objects, even if they were strictly isolated from water, for example, they were enclosed in a paraffin or glass shell.

In some chemical way, that is, "to taste", the fish could not feel the metal. How then to explain her behavior? Probably, the researchers decided, it's all about electricity. And they were not mistaken. Indeed, later fish found special organs that perceived very weak electric field strength. Among them, Lorenzini's ampoules, named after the Italian scientist, are best described by biologists. They are located in the sensory system of the lateral line and are long tubes filled with a jelly-like substance. There, inside, there are sensitive cells with nerve endings. Lorenzini ampoules work like small natural galvanometers or voltmeters.

Checking the sensitivity of electroreceptors in fish, scientists conducted, for example, such an experiment. They closed the fish tank with a dark cloth or paper and drove nearby in the air with a small magnet. And the fish felt a magnetic field! Then the researchers simply drove near the aquarium with their hands. And she even reacted to such a weak bioelectric field created by the human hand.

Amazing? Yes. But scientists prefer rigorous facts and figures. Research continued, more and more complicated. Sensitive voltmeters, oscilloscopes, and other delicate instruments appeared on the arsenal of biologists. Without them, it became impossible to conduct experiments.

Fish are no worse, and sometimes even better than the most sensitive devices in the world, register an electric field and notice the slightest change in its intensity. But this is not the most striking thing that biophysicists discovered when studying low-electric fish. Fish, it turned out, are not only floating "galvanometers", but also floating "electric generators". In other words, they radiate an electric current into water and create an electric field around them, much larger in strength than what occurs around ordinary living cells.

“Our laboratory made many measurements of the strength of this electric field,” Vladimir Baron told me. - We found that fish emit both direct current and current pulses. Their voltage is measured in tenths of a volt. The nature and frequency of these impulses are different for different species of fish. And they depend on external conditions, and on the well-being of the fish itself. Speaking scientifically, from the degree of her excitement. The bioelectric field, like a conventional battery, has two poles - positive and negative. One pole is on the head, the other on the tail. Sometimes the signs of the poles change unexpectedly: the plus from the head jumps to the tail, and the minus to the head. A fish swam - and again they change.

“So,” I tell the scientist, do these fish still have some kind of electric generators, some special organs that create currents in the water?

“Oddly enough,” Vladimir answered, “they don’t have such organs.” But you know that any cells of living organisms are capable of emitting a bioelectric field. So do the fish. Only unlike other animals, these cells in the course of evolution mutated, became more powerful, and the field created by them is stronger than what occurs in ordinary cells. Fish even learned to control the current impulses that emit their cells.

- Nature, as you know, does not create anything in vain. If this is so, then why did she need to make an electric generator from gudgeon that emits currents into the water? I asked.

With electric fish, everything is clear. Strong current or voltage is their weapon. And it is useless to gudgeon. And even if he tried to defend himself with his weak current from pike, she would not even notice his "injection".

“You are right,” Vladimir smiled. - Gudgeon in this sense is defenseless. An electric shield will not help him. However, electricity plays a huge role in his life, in the life of almost all types of fish (I’m not even talking about electric fish now). The same as in our life, vision, hearing, touch, speech play. With the help of the senses, we receive information from the outside world. And the fish, as you see, also have another feeling unknown to us. It can be considered proven that they communicate using electrical signals. Have you ever noticed how simultaneously, simultaneously turns a school of fish in the water, as if someone is giving them a signal. Fish, of course, don’t tell each other at all, they say, maybe we will turn around. They just swim nearby and feel the bioelectric field of their neighbors. But if only one of them is anxious and abruptly turns, all the other fish will instantly do the same. But that is not all. Electrical signals, it turned out, are used by fish in order to mark their territory. On land, many animals leave odorous marks on their territory - they seem to say: this is mine, don’t come! Fish, on the other hand, designate the territory with their electric field. With the help of electrical signals, they seek food and prey, attract individuals of the other sex to themselves.

For example, when the gymnarhus who we have already mentioned wants to explore an unfamiliar object, it does not smell it, does not feel it, does not examine it, but swims up to it. tail. What for? And the thing is that it is on the tail of the gymnarchus that an electric organ is located, which generates current pulses with a frequency of 300 hertz. After conducting many subtle experiments and observations, scientists came to the conclusion that fish have a special mechanism for electrical location.

At first, of course, an analogy was drawn with echolocation of bats. They are known to emit ultrasound, which is reflected from obstacles and returns back to the animal.

But in fish, everything happens quite differently. Think of an ordinary electric field with two poles and a characteristic pattern of lines of force. What will happen if an object is introduced into this field that, in contrast to water, has some other electrical conductivity? Say metal? The configuration of the power lines will change. These are the changes that fish feel.

With the help of electrical signals, fish can even “talk” in a special way. Acne, for example, at the sight of food, begins to generate current pulses of a certain frequency, thereby attracting its counterparts. And if two fish are placed in one aquarium, the frequency of their electric discharges immediately increases. Opposing fish determine the strength of their opponent by the strength of the signals emitted by him. In short, there have been many observations of this kind. Scientists have even hypothesized that marine fish use their ability to sense weak electrical signals to navigate the ocean during a migration of thousands of kilometers.

But why all the same fish, only they? Why don't other animals have this feeling? There are two explanations so far. First: the special physical properties of water. She is a wonderful guide. Especially sea water. Electric waves and currents propagate in it, without attenuation, over distances of thousands of kilometers. Low-frequency electric current can go around the entire oceans. Therefore, it is not surprising that the fish living in the water during evolution have developed mechanisms for generating and recording electrical signals. The second reason is the physiological structure of the fish muscles, which over time have become living electrical generators.

What can a person learn from all these unusual fish qualities? A lot of things. Bionics, as you know, draws original ideas from nature. The scientist will notice something unusual in nature, in living organisms - and transfer it to technology. For example, electric fish generators. These are almost perfect batteries! They are durable, small in size, able to quickly accumulate a lot of energy. If it were possible to understand in more detail the mechanism of their work, there would be a revolution in technology.

Features of the reaction of fish to electrical signals have become the basis for the development of a wide variety of devices.

You can copy in fish their ability to locate and underwater communication. Such a connection would be significantly better than currently used sonar echolocation. After all, I remind you that there are no barriers to an electrical signal in water; it can even come out of the water, unlike sound. Orientation problems laboratory specialists have developed a compact system for wireless communication between a fishing vessel and a trawl. The current pulses in this case control various devices located on the trawl.

WHY DO FISH AN OSCILLOGRAPH?

When I first appeared in this laboratory, it seemed to me like a zoo. More precisely, to that pavilion of the zoo, where there are long rows of aquariums, behind the glasses of which the swordsmen, guppies, crucians and carp are moving their tails with their tails. Here, too, reigned "fish kingdom." Shelves with dozens of aquariums stretched along the walls of the laboratory, on the sandy bottom of which, as if thinking, mustachioed gudgeons stood. Each of them had its own apartment - they lived alone.

“These fish honestly work for science,” smiled a young scientist, candidate of biological sciences Vladimir Baron.

Getting acquainted with the laboratory, I looked into other rooms. And there is electronic equipment: oscilloscopes, voltmeters, high-frequency generators. Why do fish need an oscilloscope? Such a question I asked Vladimir.

“We are studying the role of electricity in their lives,” he said. - Do you know that fish can generate an electric current and are able to sense an electric field?

What scientists told me here in the laboratory of fish orientation problems at the A. N. Severtsov Institute of Evolutionary Morphology and Animal Ecology of the USSR Academy of Sciences was like science fiction.

The famous American scientist, Nobel laureate physicist R. Feynman once said: "There is practically no natural phenomenon that would not be accompanied by electricity." And in fact, electrical phenomena occur not only in inanimate nature, they are inherent in all living things. Remember the textbook fact - for the first time electricity was discovered by the Italian scientist Galvani with the help of a living organism, namely a frog.

However, man discovered electricity in fish in ancient times. Rather, I felt, not suspecting at the same time of its existence. This concept did not exist then. For example, the ancient Greeks were wary of meeting fish in the water, which, as the great scientist Aristotle wrote, “makes animals numb.” The fish that caused fear on people was an electric stingray and bore the name

"Torpedo". And only two hundred years ago, scientists finally understood the nature of this phenomenon.

In the nineteenth century, scientists established that all living tissues and cells are a kind of source of electric current and that life cannot exist without electricity. Today every student knows about this. Many have heard of electric ramps and eels. But does this mean that science already knows everything about fish and there is nothing more to discover? Of course not. There are as many questions and puzzles in this area of ​​biology.

Only a decade and a half ago, the Soviet scientist P. Gulyaev for the first time managed to register a bioelectric field in the air surrounding the nerves, tissues and organs of animals and even humans using highly sensitive equipment! That is, he managed to detect such a field that surrounds, say, a current conductor. The field around living tissue was called an electro-aurogram. In other words, you and I, like all running, flying, and floating animals, are original living electric generators.

Based on this discovery, another Soviet scientist A. Pressman put forward the original hypothesis according to which animals seem to be able to use weak electromagnetic fields to exchange information, to communicate with each other. Only this, the scientist claimed, can explain some of the features in the behavior of pack animals and social insects. But the hypothesis is still a hypothesis. It has not yet been established, for example, that the bees "talk" using an electric field. And we do not feel this field in any way. therefore

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