Ichthyologists long been established that the electrical sensitivity of fish is not fiction. Fish of some species are capable of feeling powerful electrical discharges to protect or attack, while the other, much more numerous species, and creating electrical discharges very weak, although prolonged.
Studying this phenomenon in more detail, scientists have found that the second type of fish used pulsating field to determine the location of their victims. Fish nocturnal and live in muddy waters in order to guide and links. What is the role of the electric fields in the life of the most common and accessible to angler’s fish species?
Among modern animals electrical organs are only in fish. In the process of evolution, they have developed a number of representatives of the two groups: plate-gill (cartilaginous fish) and four groups of bony. These include all kinds of detachment beak inhabiting the waters of Africa. The detachment carp fish from South America. As well as sturgeon, sea Perciformes, many freshwater catfish species.he intensity of the electric field created by all of these fish can be divided into:
- Types of creating around him a strong electric field. This electric rays, common stingrays, electric eels, electric catfish.
- Types of creating around him pulsating electric fields. These include gimnarhi, mormirusy, gimnotusy, gnatonemusy.
- Non-electric types, which include all other fish that do not have specialized electric generator systems. Many fish from this group of electrical sensitivity by using specialized receptors low frequency and high frequency receptors. Electric organs are 500 species of fish, that is, approximately 2% of the total in its class.
- Electricity nonelectric fish
Detailed studies of electrical discharges of freshwater and saltwater fish found ability to "non-electrical" fish generate weak electrical discharges. The researchers also found that the level of non-electric fish in the majority of neuromuscular origin, arise as a result of motor reactions in the aggressive-defensive situations.
When producing food, spawning situations (courtship and finding a partner). The amplitude of such discharges is in the range of 100-200 mV at a distance of 5-10 cm from the fish. Interestingly, different fish different frequency, duration and intensity of the discharge to a large extent depend on the temperature, salinity, and water chemistry.
Electrical receptors are classified into several types, differing in frequency characteristics. The so-called Ampoule electrical receptors spontaneously generate their own action potentials, the rhythm of which changes in external electric fields. By allowing the fish to sense the geomagnetic field and those of biological origin.
Their frequency range - 0.1-50 Hz. The so-called, electric fields of electrical receptors poryadka50-2000 frequency range Hz. These receptors are inherent locator systems murmured gimnotovyh and who have normal receptors and ampoule type. It is proved that hypersensitivity ampulir receptors at low frequencies allows the fish to feel at a distance of a few centimeters in the low-frequency component of the electrical pulses generated not electric organs and normal neuron-motor systems of fish and other aquatic animals.
When fear reactions, respiratory movements of the gill apparatus, and more. Now scientists are looking for electrical receptors in "non-electrical" fish. Perhaps they will be fundamentally new structure bodies are not yet known to science.
According to many scientists, have no electrical fish instead of electrical receptors act neuromasts and other cells of the lateral line. Including scattered throughout the body, and concentrated in the head. From our non-electric fish record is common eel (not to be confused with the electric eel).
This member of the family anguillidae distributed along the European coast from the White to the Black Sea, as well as in West Africa and the Mediterranean, reaching 1.5 m in length. Back in 1970, it was found that the eel able to produce excitation level several mill volts. Upon the spoil, discharged discharge characteristic of 2-3 mV.
In the aquarium, it takes a certain territory and protect it from neighbors is much more important than the ability of fish to produce no electric discharges, and their increased electrical sensitivity. Acne just has high electrical sensitivity, which is 0.67 mV / cm in the sea water and fresh - 0.067 mV / cm.
On the basis of this version was put forward that the migration of eel uses its geo-electric field ocean orientation. Also eel ordinary electric fields at sea lampreys were found. Further studies showed that almost all the fish creates around itself a kind of electric field.
Of course, it is different forces at different fish species. For example, pike discharge time 34-92 ms, with a frequency range of 63-403 Hz. rudd discharges are 8-10 ms duration in the frequency range of 52-160 Hz. Interestingly, the night of fish and predators emit a stronger electrical signals and are more active than peaceful day fish.
But at the same time and prey, and peaceful fish electrical activity is expressed in constant pulsed electric field. Scientists came to the conclusion that peace and fish during their joint power and prey during the persecution there is a sharp increase in electric discharges. Several times increased electrical sensitivity.
Electrical sensitivity, the ability to produce discharges in non-electric fish varies depending on the species, size and properties of water. It should be understood that in the truest sense of the electrical receptors in most fish our waters there. But at the same time, even in such fish found an opportunity to feel the electric field.
In seawater, the sensitivity of the same fish increases several times. The electric field feel good pike, walleye, perch, carp, crucian carp, catfish, eel, gudgeon, rudd, salmon, sturgeon, herring, flounder and many other fish. And the fish that are not on the list, most likely just have not studied enough.
The electrical sensitivity of the fish, researchers detected by measuring the heart rate of the electrocardiogram records in response to the conditioned stimulus - a weak electric field. It is very important what kind of water is carried out in experience. If the sea, the sensitivity is ten times higher.
Electrical sensitivity of fish use for orientation in the oceans and seas, as well as communicative, food, defensive, spawning, territorial and schooling behavior. In the attack on other individuals. Not only is acne vulgaris, but the majority of freshwater fish having electrical sensitivity, which allows them to obtain biologically valuable information on the background and the natural electric fields.
To navigate in space, to find prey, communicate with each other in advance to leave the danger zone. In addition, fish can feel other people (from other fish or aquatic animals) electric fields or to receive information about what is happening around them, and to change the configuration of their own field.
Electric fish sensitivity strongly depends on the age and size of the fish species, water conductivity and temperature. In recent years, many researchers are engaged in the electrical sensitivity of fish. Environmental services are fighting with power in this regard.
After all, if exceeded permissible values of the electric and magnetic fields, the current density in space, the fish appears stable reaction repelling or immobilization reaction. If the threshold is reached immobilization occurs in fish muscle paralysis and breathing. That may, depending on the residence time in the electric field area lead to their death.
When the fish gets into the zone of inhomogeneous electromagnetic field AC, once traced the characteristic behavior of the fish zone, specific to each species. Simply put, the influence of electricity in the water to attract the fish can be, but you can scare or even kill. Depending on the intensity of the electric field in the defense reaction may be fish or fright response, or it will attract them.
For example, metal spinners protrude in an aqueous medium as some small galvanic electricity producers. And although their electric effect is not the strongest factor in attracting the fish, however it should be taken into account. For example, it is useful to know the composition of the metal (or rather, an alloy), which is made from baubles to predict its galvanic opportunities.