Why electric eel. The most powerful discharge is from the electric eel. Electric eel - interesting facts

I was rightly reminded in the comments that despite its name, the electric eel does not belong to the order of eels, it is closer to carps and catfish.
People have known about electric fish for a long time: back in Ancient Egypt the electric ray was used to treat epilepsy, the anatomy of the electric eel gave Alessandro Volta the idea for his famous batteries, and Michael Faraday, the "father of electricity," used the same eel as scientific equipment. Modern biologists know what to expect from such fish (almost two-meter eel can generate 600 volts), in addition, it is more or less known what kind of genes form such an unusual feature - this summer a group of geneticists from the University of Wisconsin in Madison (USA) published a paper with complete sequencing of the electric eel genome. The purpose of "electrical abilities" is also clear: they are needed for hunting, for orientation in space and for protection from other predators. Only one thing remained unknown - how exactly the fish use their electric shock, what strategy they use.

Now we are going to find out about it...

First, a little about the main character.

in mysterious and muddy waters The Amazon hides many dangers. One of them is the electric eel (lat. Electrophorus electricus) is the only representative of the order of electric eels. It is found in the northeast of South America and is found in small tributaries of the middle, as well as the lower reaches of the powerful Amazon River.

The average length of an adult electric eel is a meter and a half, although sometimes three-meter specimens are also found. This fish weighs about 40 kg. Her body is elongated and slightly flattened laterally. Actually, this eel does not really look like a fish: there are no scales, only caudal and pectoral fins, and plus everything, it breathes atmospheric air.

Photo 3.

The fact is that the tributaries where the electric eel lives are too shallow and muddy, and the water in them is practically devoid of oxygen. Therefore, nature has awarded the animal with unique vascular tissues in the oral cavity, with the help of which the eel absorbs oxygen directly from the outside air. True, for this he has to rise to the surface every 15 minutes. But if an eel suddenly finds itself out of water, it can live for several hours, provided that its body and mouth do not dry out.

The color of electric coal is olive brown, which allows it to remain unnoticed by potential prey. Only the throat and lower part of the head are bright orange, but this is unlikely to help the unfortunate victims of the electric eel. As soon as he shudders with his whole slippery body, a discharge is formed, with a voltage of up to 650V (mostly 300-350V), which instantly kills all small fish nearby. The prey falls to the bottom, and the predator picks it up, swallows it whole and anoints itself nearby to rest a bit.

Photo 4.

electric eel has special organs, consisting of numerous electric plates - modified muscle cells, between the membranes of which a potential difference is formed. Organs occupy two-thirds of the body mass of this fish.

However, an electric eel can generate discharges with a lower voltage - up to 10 volts. Since he has poor eyesight, he uses them as a radar to navigate and search for prey.

Electric eels can be enormous, reaching up to 2.5 meters in length and 20 kilograms in weight. They live in the rivers of South America, for example, in the Amazon and Orinoco. They feed on fish, amphibians, birds and even small mammals.

Because the electric eel absorbs oxygen directly from atmospheric air, he has to very often rise to the surface of the water. He should do this at least once every fifteen minutes, but it usually happens more often.

To date, there are few known cases of people dying after an encounter with an electric eel. However, numerous electrical shocks can lead to respiratory or heart failure, which can cause a person to drown even in shallow water.

Photo 5.

His entire body is covered with special organs, which consist of special cells. These cells are sequentially connected to each other by means of nerve channels. In the front of the body "plus", in the back "minus". Weak electricity is formed at the very beginning and, passing successively from organ to organ, it gains strength in order to strike as efficiently as possible.

The electric eel himself believes that he is endowed with reliable protection, so he is in no hurry to give up even to a larger opponent. There were cases when eels did not give in even to crocodiles, and people should avoid meeting with them at all. Of course, it is unlikely that the discharge will kill an adult, but the sensations from it will be more than unpleasant. In addition, there is a risk of loss of consciousness, and if you are in the water, you can easily drown.

Photo 6.

The electric eel is very aggressive, it attacks immediately and is not going to warn anyone of its intentions. The safe distance from a meter-long eel is at least three meters - this should be enough to avoid a dangerous current.

In addition to the main organs that generate electricity, the eel also has one more, with the help of which it reconnoiters the environment. This kind of locator emits low-frequency waves, which, returning, notify their owner of obstacles ahead or the presence of suitable living creatures.

Photo 7.

Zoologist Kenneth Catania ( Kenneth Catania) from Vanderbilt University (USA), observing electric eels that lived in a specially equipped aquarium, noticed that fish can discharge their battery in three different ways. The first is low-voltage impulses intended for orientation on the ground, the second is a sequence of two or three high voltage impulses, lasting several milliseconds, and finally, the third way is a relatively long burst of high-voltage and high-frequency discharges.

When an eel attacks, it sends a lot of volts to the prey at a high frequency (method number three). Three or four milliseconds of such processing is enough to immobilize the victim - that is, we can say that the eel uses a remote electric shock. Moreover, its frequency is much higher artificial devices: for example, the Taser remote shocker delivers 19 pulses per second, while the eel - as many as 400. Having paralyzed the victim, he must, without wasting time, quickly grab it, otherwise the prey will come to its senses and swim away.

Photo 8.

In an article in Science Kenneth Catania writes that the "live stun gun" works in the same way as an artificial one, causing a strong involuntary muscle contraction. The mechanism of action was determined in a peculiar experiment, when a fish with a destroyed spinal cord was placed in an eel aquarium; they were separated by an electrically permeable barrier. The fish could not control the muscles, but they contracted on their own in response to electrical impulses from outside. (An eel was provoked to a discharge by throwing worms at it as food.) If a fish with a destroyed spinal cord was also injected with the nerve agent curare, then the electricity from the eel had no effect on it. That is, the target of electrical discharges was precisely the motor neurons that control the muscles.

Photo 9.

However, all this happens when the eel has already determined its prey. And if the prey hid? By the movement of water, then you will no longer find it. In addition, the eel itself hunts at night, and at the same time it cannot boast of good eyesight. To find prey, it uses discharges of the second kind: short sequences of two or three high-voltage pulses. Such a discharge imitates the signal of motor neurons, causing all the muscles of a potential victim to contract. The eel, as it were, orders it to reveal itself: a muscle spasm passes through the body of the victim, it begins to twitch, and the eel catches the vibrations of the water - and understands where the prey hid. In a similar experiment with a fish with a damaged spinal cord, it was separated from an eel by an already electrically impervious barrier, but the eel could feel the waves of water from it. At the same time, the fish was connected to a stimulator, so that its muscles contracted at the request of the experimenter. It turned out that if the eel emitted short “detection pulses”, and at the same time the fish was forced to twitch, then the eel attacked it. If the fish did not answer in any way, then the eel, of course, did not react to it in any way - it simply did not know where it was.

In general, the electric eel exhibits a rather sophisticated hunting strategy. Sending from time to time external environment"Pseudo-muscular" discharges, it makes hidden victims discover themselves, then swims to where the waves propagate in the water, and gives another discharge that paralyzes the prey. In other words, the eel simply takes control of the prey's muscles, telling them to move or freeze when it needs to.

Photo 11.

Photo 12.

Photo 13.

Dominic Statham

Photo ©depositphotos.com/Yourth2007

Electrophorus electricus) lives in the dark waters of swamps and rivers in the northern part of South America. This is a mysterious predator with complex system electrolocation and capable of moving and hunting in low visibility conditions. By using "electroreceptors" to detect distortions in the electric field caused by his own body, he is able to detect potential prey while remaining undetected himself. It immobilizes the victim with a powerful electric shock, strong enough to stun such large mammal like a horse, or even kill a person. With its elongated, rounded body shape, the eel resembles the fish we usually call the moray eel (order Anguilliformes); however, it belongs to a different order of fish (Gymnotiformes).

Fish that can detect electric fields are called electroreceptive, but capable of generating powerful electric field, such as electric eel, are called electrogenic.

How does an electric eel generate such a high electrical voltage?

electric fish are not the only ones capable of generating electricity. In fact, all living organisms do this to one degree or another. The muscles in our body, for example, are controlled by the brain with electrical signals. The electrons produced by bacteria can be used to generate electricity in fuel cells called electrocytes. (see table below). And although each of the cells carries a small charge, due to the fact that thousands of such cells are assembled in a series, like batteries in a flashlight, voltages up to 650 volts (V) can be generated. If these rows are arranged in parallel, an electric current of 1 ampere (A) can be obtained, which gives an electric shock of 650 watts (W; 1 W = 1 V × 1 A).

How does an eel manage to avoid electrocuting itself?

Photo: CC-BY-SA Steven Walling via Wikipedia

Scientists do not know exactly how to answer this question, but the results of some interesting observations can shed light on this issue. First, the vital organs of an eel (such as the brain and heart) are located near the head, away from the organs that generate electricity, and are surrounded by fatty tissue that can act as insulation. The skin also has insulating properties, since it has been observed that eels with damaged skin are more susceptible to self-stunning by electric shock.

Secondly, eels are able to inflict the most powerful electric shocks at the time of mating, without harming the partner. However, if another eel is hit with the same force outside of the mating season, it can kill it. This suggests that eels have some kind of defense system that can be turned on and off.

Could the electric eel have evolved?

It is very difficult to imagine how this could happen during minor changes, as required by the process proposed by Darwin. If shock wave was important from the very beginning, instead of stunning, it would warn the victim of danger. Moreover, in order to develop the ability to stun the victim in the course of evolution, the electric eel would have to simultaneously develop a system of self-defense. Every time a mutation appeared that increased the strength of the electric shock, another mutation should have arisen that improved the electrical insulation of the eel. It seems unlikely that one mutation would be enough. For example, in order to move the organs closer to the head, it would take a whole series of mutations that had to occur at the same time.

Although few fish are capable of stunning their prey, there are many species that use low voltage electricity for navigation and communication. Electric eels belong to a group of South American fish known as knifefish (family Mormyridae) that also use electrolocation and are thought to have developed this ability along with their South American cousins. Moreover, evolutionists are forced to claim that the electrical organs in fish evolved independently eight times. Given the complexity of their structure, it is already striking that these systems could have developed at least once in the course of evolution, not to mention eight.

Knife-cutters from South America and chimaeras from Africa use their electrical organs to locate and communicate, and use a series of various kinds electroreceptors. In both groups there are species that produce electric fields of different complex shapes waves. Two types of knives Brachyhypopomus benetti and Brachyhypopomus walteri so similar to each other that they could be attributed to the same type, however, the first of them produces a constant voltage current, and the second - a current AC voltage. evolutionary history becomes even more remarkable if you dig even deeper. To ensure that their electrolocation devices do not interfere with each other and do not interfere, some species use special system, with which each of the fish changes the frequency of the electrical discharge. It is noteworthy that this system works in almost the same way (using the same computational algorithm) as that of a glass knifemaker from South America ( Eigenmannia) and African fish aba-aba ( Gymnarchus). Could such an interference elimination system have evolved independently in the course of evolution in two separate groups of fish living on different continents?

Masterpiece of God's Creation

The power unit of the electric eel eclipsed all human creations with its compactness, flexibility, mobility, environmental safety and the ability to self-heal. All parts of this apparatus are perfectly integrated into the polished body, which gives the eel the ability to swim with high speed and agility. All the details of its structure - from tiny cells that generate electricity, to the most complex computer complex, analyzing the distortions of the electric fields produced by the eel, indicate the intention of the great Creator.

How does an electric eel generate electricity? (popular science article)

Electric fish generate electricity in a similar way to the way the nerves and muscles in our body do. Inside electrocyte cells, special enzymatic proteins called Na-K ATPase pump out sodium ions through the cell membrane, and absorb potassium ions. ('Na' is the chemical symbol for sodium and 'K' is the chemical symbol for potassium. 'ATP' stands for adenosine triphosphate, the energy molecule used to power the pump.) An imbalance between potassium ions inside and outside the cell results in a chemical gradient that again pushes potassium ions out of the cell. Similarly, an imbalance between sodium ions creates a chemical gradient that draws sodium ions back into the cell. Other proteins embedded in the membrane act as channels for potassium ions, pores that allow potassium ions to leave the cell. As positively charged potassium ions accumulate on the outside of the cell, an electrical gradient builds up around the cell membrane, with the outside of the cell having a more positive charge than the inside. Pumps Na-K ATPase (sodium-potassium adenosine triphosphatase) are constructed in such a way that they select only one positively charged ion, otherwise the negatively charged ions would also begin to flow, neutralizing the charge.

Most of the electric eel's body is made up of electrical organs. The main organ and the Hunter organ are responsible for the production and accumulation electric charge. The Sachs organ generates a low voltage electric field that is used for electrolocation.

The chemical gradient acts to push the potassium ions out, while the electrical gradient pulls them back in. At the moment of balance, when the chemical and electrical forces cancel each other out, there will be about 70 millivolts more positive charge on the outside of the cell than on the inside. Thus, inside the cell is a negative charge of -70 millivolts.

However, more proteins embedded in the cell membrane provide channels for sodium ions - these are pores that allow sodium ions to enter the cell again. Normally, these pores are closed, but when the electrical organs are activated, the pores open, and sodium ions with a positive charge again enter the cell under the influence of a chemical potential gradient. AT this case balance is achieved when a positive charge of up to 60 millivolts is collected inside the cell. There is a total voltage change from -70 to +60 millivolts, and this is 130 mV or 0.13 V. This discharge occurs very quickly, in about one millisecond. And since there are approximately 5000 electrocytes in a series of cells, due to the synchronous discharge of all cells, up to 650 volts (5000 × 0.13 V = 650) can be generated.

Pump Na-K ATPase (sodium-potassium adenazine triphosphatase). For each cycle, two potassium ions (K+) enter the cell and three sodium ions (Na+) leave the cell. This process is driven by the energy of ATP molecules.

Glossary

An atom or molecule that carries an electrical charge due to an unequal number of electrons and protons. An ion will be negatively charged if it contains more electrons than protons, and positively charged if it contains more protons than electrons. Potassium (K+) and sodium (Na+) ions have a positive charge.

Gradient

A change in some quantity when moving from one point in space to another. For example, if you move away from a fire, the temperature drops. Thus, the fire generates a temperature gradient that decreases with distance.

electrical gradient

The gradient of change in the magnitude of the electric charge. For example, if there are more positively charged ions outside the cell than inside the cell, an electrical gradient will flow across the cell membrane. Due to the fact that the same charges repel each other, the ions will move in such a way as to balance the charge inside and outside the cell. The movement of ions due to the electrical gradient occurs passively, under the influence of electrical potential energy, and not actively, under the influence of energy coming from external source, for example from an ATP molecule.

chemical gradient

Chemical concentration gradient. For example, if there are more sodium ions outside the cell than inside the cell, then the sodium ion chemical gradient will pass through the cell membrane. Due to the random movement of ions and collisions between them, there is a tendency for sodium ions to move from higher concentrations to lower concentrations until a balance is established, that is, until the same number of sodium ions are on both sides of the membrane. This happens passively, as a result of diffusion. The movements are due to the kinetic energy of the ions, not to the energy received from an external source such as an ATP molecule.

The family contains only one genus with a single species, the electric eel (Electrophorus electricus). Electric eels inhabit the shallow rivers of northeastern South America and tributaries of the middle and lower Amazon.

In these slow-flowing, heavily overgrown, silty water bodies, a sharp lack of oxygen often occurs. Probably, it was this circumstance that caused the development of special sections of vascular tissue in the oral cavity of the electric eel, which allows it to absorb oxygen directly from atmospheric air. To capture a new portion of air, the eel must rise to the surface of the water at least once every 15 minutes, but usually it does this somewhat more often. If the electric eel is deprived of such an opportunity, then it will die and, paradoxically as it sounds in relation to the fish, it will drown. The ability of the electric eel to use atmospheric oxygen for breathing allows it to stay out of water for several hours without any harm to itself, but only if its body and oral cavity remain moist. This feature not only ensures the survival of eels in extremely adverse conditions existence, but also makes them extremely convenient laboratory animals for experiments.

Electric eels are large fish average length adults is 1-1.5 m, and the largest of the known specimens reached almost three meters in length. The skin of the electric eel is naked, without scales; the body is strongly elongated, rounded in the anterior part and somewhat laterally compressed in the posterior part. Spinal and pelvic fins the electric eel does not, and the pectorals are very small and, apparently, play only the role of stabilizers during the movement of the fish. The main organ of movement of the eel is a huge anal fin, numbering up to 350 rays and stretching from the anus to the end of the tail. With the help of wave-like movements of the fin, the eel can move forward and backward, up and down with equal ease.

The coloration of adult electric eels is olive brown, the underside of the head and throat is bright orange, the edge of the anal fin is light, and the eyes are emerald green. The coloration of young fish is lighter, ocher, sometimes with a marbled pattern.

Most interesting feature electric eels are huge electrical organs that occupy about 4/5 of the body length. The positive pole of the "battery" lies in the front of the body of the eel, the negative - in the back, that is, the opposite of what occurs in African electric catfish. The highest discharge voltage, according to observations in aquariums, can reach 650 V, but usually it is less, and in meter-long fish, on average, it does not exceed 350 V. The current strength, however, is not very high - only 0.5-0.75 Ah, so even a six-hundred-volt discharge cannot cause a fatal shock in a person. True, as the fish grows, the current strength increases significantly (up to 2 A), and it is difficult to say what the result of an electric shock from a three-meter fish may be.

The main electrical organs are used by the eel to protect itself from enemies and to paralyze its prey, which are mainly small fish. In addition to powerful high-voltage organs, electric eels have two more types of low-voltage organs. The purpose of one of them is unclear; we only know that it acts in connection with the main "battery". The second type of "auxiliary" electric organ plays the role of a locator, which serves to detect obstacles in the path of movement, and in old fish to search for food, since with age, the eyesight of electric eels apparently deteriorates sharply. The frequency of such location discharges at calm state fish does not exceed 20-30 per second, but when excited, it can reach 50.

Almost nothing is known about the reproduction and development of electric eels, as well as other hymnoid fish. According to a few observations, by the time of reproduction, electric eels leave their usual habitats and return to them, accompanied by grown-up juveniles, which begin to lead an independent lifestyle, reaching a length of 10-12 cm.

Electric eels are successfully kept in captivity and often serve as decorations for large public aquariums. It is not recommended to change the water in the aquarium frequently. Otherwise, electric eels develop ulcers on their bodies and die. This phenomenon seems to be due to the fact that the mucus secreted by eels contains some kind of antibiotic, which, accumulating in the water, protects the fish from ulcers.

Electrical organs are paired formations in a number of fish that are capable of generating electrical discharges; serve for defense, attack, intraspecific signaling and orientation in space. They evolved independently in several unrelated groups of freshwater and marine fish. Were widely represented in fossil fish and jawless; known to over 300 modern species. The location, shape and structure of these organs in different species are varied. They can be located symmetrically on the sides of the body in the form of kidney-like formations ( electric ramps and electric acne) or subcutaneous thin layer (electric catfish), filamentous cylindrical formations (mormyrids and hymnotids), in the infraorbital space (American stargazer), can be, for example, up to 1/6 (electric rays) and 1/4 (electric acne and catfish) masses of fish. Each organ consists of numerous electric plates assembled in columns - modified (flattened) muscle, nerve or glandular cells, the membranes of which are electrical generators. The number of plates and columns in the organs different types fish are different: the electric stingray has about 600 columns arranged in the form of a honeycomb of 400 plates each, the electric eel has 70 horizontally placed columns of 6000 each, the electric catfish electric plates, about 2 million, are randomly distributed. The potential difference developed at the ends of the organs with an open electrical circuit can reach 1200 V (electric eel), and the discharge power in a pulse is up to 1.5 kW. The latter applies, of course, to a closed circuit when the fish is in the water.

Very powerful discharges in the electric stingray Torpedo occidentalis, which lives in the ocean. Salty water conducts electricity better.

Discharges are emitted in series, the form, duration and sequence of which depend on the degree of excitation and the type of fish. The pulse repetition rate is related to their purpose (for example, an electric ray emits 10-12 "defensive" and from 14 to 562 "hunting" pulses per second, depending on the size of the victim). The voltage in the discharge ranges from 220 (electric ramps) to 600 V (electric eels). Fish that have electric organs tolerate without harm the voltages that kill fish that do not have them (electric eel - up to 220 V). electrical discharges big fish dangerous to humans.

Electric eel (lat. Electrophorus electricus) is one of the few fish that has developed the ability to generate electricity, allowing not only to help in orientation, but also to kill.

Many fish have special organs that generate a weak electric field to navigate and search for food (for example, elephant fish). But not everyone has the opportunity to hit their victims with this electricity, as an electric eel does!

For biologists, the Amazonian electric eel is a mystery. It combines a variety of characteristics that often belong to different fish.

Like many eels, it needs to breathe atmospheric oxygen to live. He spends most of his time at the bottom, but rises every 10 minutes to swallow oxygen, so he gets more than 80% of the oxygen he needs.

Despite its eel-like shape, the electric one is closer to the knifefish that lives in South Africa.

Video - electric eel kills a crocodile:

The South American electric eel was first described in 1766. This is very common freshwater fish who lives in South America along the entire length of the Amazon and Orinoco rivers.

Habitat in places with warm but muddy water - tributaries, streams, ponds, even swamps. Places with low oxygen content in the water do not frighten the electric eel, as it is able to breathe atmospheric oxygen, for which it rises to the surface every 10 minutes.

This is a nocturnal predator, which has a very poor eyesight and it relies more on its electric field, which it uses to orient itself in space. In addition, with its help, he finds and paralyzes prey.

Juvenile electric eels feed on insects, but adults eat fish, amphibians, birds, and even small mammals that have wandered into the pond.

Life is also made easier for them by the fact that in nature they have almost no natural predators. An electric shock of 600 volts to an electric eel can not only kill a crocodile, but even a horse.

Description

The body is elongated, cylindrical. This is very big fish In nature, eels can grow up to 250 cm long and weigh more than 20 kg. In the aquarium, they are usually smaller, about 125-150 cm.

At the same time, they can live for about 15 years. Generates a discharge with a voltage of up to 600 V and a current of up to 1 A.

The eel does not have a dorsal fin, instead it has a very long anal fin which it uses for swimming. The head is flattened, with a large square mouth.

The body color is mostly dark gray with an orange throat. Juveniles are olive brown with yellow spots.

Level electric current, which can produce eel, is much higher than that of other fish of its family. He produces it with the help of big organ, consisting of thousands of elements that produce electricity.

In fact, 80% of his body is covered with such elements. When he is resting, there is no discharge, but when he is active, an electric field is generated around him.

Its usual frequency is 50 kilohertz, but it is capable of generating up to 600 volts. This is enough to paralyze most fish, and even an animal the size of a horse, it is just as dangerous for humans, especially residents of coastal villages.

He needs this electric field for orientation in space and hunting, of course, for self-defense. It is also believed that with the help of an electric field, males look for females.

Two electric eels in the same aquarium usually do not get along, they begin to bite each other and shock. In this regard, and his way of hunting, as a rule, only one electric eel is kept in the aquarium.

Difficulty in content

As a rule, he is quite unpretentious, possesses good appetite and eats almost all types of protein feed. As already mentioned, it can generate current up to 600 volts, so only experienced aquarists need to keep it.

Most often it is kept either by very enthusiastic hobbyists, or in zoos and at exhibitions.

Feeding

The electric eel is a predator, it eats everything it can swallow. In nature, it is usually fish, amphibians, small mammals.

Juveniles eat insects, but adult fish prefer fish. At first, they need to be fed live fish, but they are also able to eat protein foods such as fish fillets, shrimp, mussel meat, etc.

They quickly understand when they will be fed and rise to the surface to beg for food. Never touch them with your hands, this can lead to a severe electric shock!

Electric eel eats goldfish:

The electric eel is a very large fish that conducts most time at the bottom of the aquarium. It needs a volume of 800 liters or more so that it can move freely and turn around. Remember that even in captivity, eels grow over 1.5 meters!

Juveniles grow rapidly and gradually require more and more volume. Be prepared that you will need an aquarium from 1500 liters, and even more to keep a couple.

Because of this, the electric eel is not very popular and is kept mostly in zoos. And yes, it still shocks, it can easily poison a careless owner into a better world.

This massive fish that leaves a lot of waste needs a very powerful filter. Better external, as the fish easily breaks everything that is inside the aquarium.

Since he is practically blind, he does not like bright light, but he likes twilight and many shelters. Temperature for content 25-28C, hardness 1 - 12 dGH, ph: 6.0-8.5.

Compatibility

The electric eel is not aggressive, but due to the way it hunts, it is only suitable for solitary keeping.

Sex differences

Mature females are larger than males.

Breeding

It does not breed in captivity. The electric eel has a very interesting way breeding. The male builds a saliva nest during the dry season, and the female lays her eggs in it.

A lot of caviar, thousands of eggs. But, the first fry that appear begin to eat this caviar.

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