Humans have always observed nature and have tried to copy it in order to make use of its ingenuity. For example, the sonar was invented by imitating the dolphins, the camera imitating the eye, and the electric battery by copying the electric organ of the torpedo fish ( see Les Lumières ). But in one illustrious case, it was the reverse that occurred: Marconi invented the wireless telegraph (1896), the radio, without having observed it in nature. The radio does exist in nature … for 400 million years. In fact, there are more than 100 species of fish that use the radio mode to detect their prey, communicate with their congeners and locate in their environment:
The electrical component (OE), which the aptononote uses as an electrical emission antenna, is a long bundle of excitable fibers located in the dorsal portion of the tail ( see Electrical Device ). Under the influence of the pacemaker nucleus (PM) at the base of the brain ( see PM et cie ), it produces synchronous and repetitive discharges. When discharges sweep into the electrical device, the electrical current they carry generates an electric field around the fish. As the discharges of the electrical organ of the apteronote are repetitive, the electric field is undulatory. It is of low intensity: on the order of μV / cm (μ = micro = 1 millionth of …).
Electrolocation scheme of an electric fish with undulating discharge.
This field is modulated (transformed) by any surrounding thing that does not have the same resistance or the same capacitance (the impedance to summarize the two values) as water, whether animal, vegetable or mineral. The electric field is then captured on the skin surface of the animal by electroneceptors ( see Electroreceptor ).
There are different types of electroreceptors that respond differently to variations in the electric field. However, they all filter relevant information on the modulation of the electric field and send this information to a specialized area of the brain: the lateral line electrical lobe ( see ELL ). This is where the electrosensory information begins to be treated before being sent to more complex areas of the brain.
Marconi and his radio in all that?!? Well, that’s the beauty of the thing: it works exactly like a radio, more sophisticated! At the base, a radio station emits a high-speed wave, the carrier wave. The number of the radio station also refers to the frequency of the carrier wave. Then, another wave, generated by the voice of the animator or by the music, is superimposed over the carrier wave. This modulating wave is of lower frequency than the carrier wave and contains information relevant to the listener. If the station is AM, the amplitude is modulated; If the station is FM, it is the frequency that is modulated. The resulting modulated wave is then transmitted via the transmitting antenna according to its emission field (that is to say the space it can cover).
Like the radio, the apteronote emits an electric field thanks to its electrical component which serves as an antenna. For brown knife fish, this field is a high frequency wave ranging from 600Hz to 1300Hz or cycles per second. Subsequently, the surrounding objects modulate the carrier wave to give the modulated wave that returns to the electroreceptors on the surface of the skin. These filter the relevant information about the module and send this perceived information to the brain that will interpret it. But since the electrical nature of objects and animals varies in resistance and in capacitance, the modulation varies in amplitude and frequency. Otherwise, the fish-knife perceives its data in AM and FM at the same time, and knows how to dissect them correctly to survive,
Moreover, it is not alone to do so, all weakly electrically wave-emitting fish have similar properties. And they are very numerous.
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