Scientists have been observing the behavior of snakes for a long time. The main organs for reading information are thermal sensitivity and smell.

The sense of smell is the main organ. The snake constantly works with a forked tongue, taking samples of air, soil, water and objects surrounding the snake.

Thermal sensitivity. A unique sense organ possessed by snakes. allows you to "see" mammals on the hunt even in complete darkness. In the viper, these are sensory receptors located in deep grooves on the muzzle. A snake like a rattlesnake has two large spots on its head. The rattlesnake not only sees warm-blooded prey, it knows the distance to it and the direction of movement.
The eyes of the snake are covered with completely fused transparent eyelids. Vision different types the kite may vary, but serves primarily to track the movement of prey.

All this is interesting, but what about hearing?

It is absolutely known that snakes do not have hearing organs in the usual sense for us. The tympanic membrane, auditory ossicles and cochlea, which transmit sound through nerve fibers to the brain, are completely absent.


However, snakes can hear, or rather, feel, the presence of other animals. The feeling is transmitted through the vibrations of the ground. So reptiles hunt and hide from danger. This ability to perceive danger is called vibrational sensitivity. Vibration of the snake is felt by the whole body. Even very low sound frequencies are transmitted to the snake through vibration.

More recently, a sensational article by zoologists from the Danish Aarhus University (Aarhus University, Denmark) has appeared, which investigated the effect on the neurons of the python brain from a speaker turned on in the air. It turned out that the basics of hearing in the experimental python are present: there is an inner and outer ear, but there is no eardrum - the signal transmission goes directly to the skull. It was possible to fix even the frequencies "heard" by the bones of the python: 80-160 Hz. This is an extremely narrow low frequency range. Man, as you know, hears 16-20000 Hz. However, whether other snakes have similar abilities is not yet known.

Organs that allow snakes to "see" thermal radiation, give an extremely blurry image. Nevertheless, a clear thermal picture of the surrounding world is formed in the snake's brain. German researchers have figured out how this can be.

Some species of snakes have the unique ability to capture heat radiation, allowing them to "look at" the world in absolute darkness. True, they “see” thermal radiation not with their eyes, but with special heat-sensitive organs (see figure).

The structure of such an organ is very simple. Near each eye is a hole about a millimeter in diameter, which leads into a small cavity of about the same size. On the walls of the cavity there is a membrane containing a matrix of thermoreceptor cells approximately 40 by 40 cells in size. Unlike rods and cones in the retina, these cells do not respond to the "brightness of light" of heat rays, but to local temperature membranes.

This organ works like a camera obscura, a prototype of cameras. A small warm-blooded animal against a cold background emits "heat rays" in all directions - far infrared radiation with a wavelength of about 10 microns. Passing through the hole, these rays locally heat the membrane and create a "thermal image". Due to the highest sensitivity of receptor cells (a temperature difference of thousandths of a degree Celsius is detected!) and good angular resolution, a snake can notice a mouse in absolute darkness from a fairly large distance.

From the point of view of physics, just a good angular resolution is a mystery. Nature has optimized this organ so that it is better to "see" even weak heat sources, that is, it simply increased the size of the inlet - the aperture. But the larger the aperture, the more blurry the image turns out (we are talking, we emphasize, about the most ordinary hole, without any lenses). In the situation with snakes, where the aperture and depth of the camera are approximately equal, the image is so blurred that nothing but “there is a warm-blooded animal somewhere nearby” can be extracted from it. However, experiments with snakes show that they can determine the direction of a point source of heat with an accuracy of about 5 degrees! How do snakes manage to achieve such a high spatial resolution with such a terrible quality of "infrared optics"?

Since the real “thermal image”, the authors say, is very blurry, and the “spatial picture” that appears in the animal’s brain is quite clear, it means that there is some intermediate neuroapparatus on the way from the receptors to the brain, which, as it were, adjusts the sharpness of the image. This apparatus should not be too complicated, otherwise the snake would "think" over each image received for a very long time and would react to stimuli with a delay. Moreover, according to the authors, this device is unlikely to use multi-stage iterative mappings, but rather is some kind of fast one-step converter that works on forever hardwired in nervous system program.

In their work, the researchers proved that such a procedure is possible and quite real. They conducted mathematical modeling of how a "thermal image" appears, and developed an optimal algorithm for repeatedly improving its clarity, dubbing it a "virtual lens".

In spite of loud name, the approach they used, of course, is not something fundamentally new, but just a kind of deconvolution - the restoration of an image spoiled by the imperfection of the detector. This is the reverse of motion blur and is widely used in computer image processing.

In the analysis carried out, however, important nuance: the law of deconvolution did not need to be guessed, it could be calculated from the geometry of the sensitive cavity. In other words, it was known in advance what kind of image a point source of light would give in any direction. Thanks to this, a completely blurred image could be restored with very good accuracy (ordinary graphic editors with a standard deconvolution law would not have coped with this task even close). The authors also proposed a specific neurophysiological implementation of this transformation.

Whether this work said some new word in the theory of image processing is a moot point. However, it undoubtedly led to unexpected conclusions regarding neurophysiology " infrared vision» at snakes. Indeed, the local mechanism of "normal" vision (each visual neuron picks up information from its own small area on the retina) seems so natural that it is difficult to imagine anything much different. But if snakes really use the described deconvolution procedure, then each neuron that contributes to the whole picture of the surrounding world in the brain receives data not from a point at all, but from a whole ring of receptors passing through the entire membrane. One can only wonder how nature has managed to construct such a "non-local vision" that compensates for the defects of infrared optics with non-trivial mathematical transformations of the signal.

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    For some reason, it seems to me that the inverse transformation of a blurry image, provided that there is only a two-dimensional array of pixels, is mathematically impossible. My understanding is that computer sharpening algorithms simply create the subjective illusion of a sharper image, but they cannot reveal what is blurred in an image.

    Is not it?

    In addition, the logic from which it follows that a complex algorithm would make the snake think is incomprehensible. As far as I know, the brain is a parallel computer. A complex algorithm in it does not necessarily lead to an increase in time costs.

    It seems to me that the refinement process should be different. How was the accuracy of infrared eyes determined? Certainly, by some action of the snake. But any action is long and allows for correction in its process. In my opinion, a snake can "infrasee" with the accuracy that is expected and start moving based on this information. But then, in the process of movement, constantly refine it and come to the final as if the overall accuracy was higher.

    Answer

    • I answer point by point.

      1. The inverse transformation is a sharp image acquisition (which would be created by an object with an eye-type lens), based on the existing blurry one. At the same time, both pictures are two-dimensional, there are no problems with this. If there are no irreversible distortions during blurring (such as a completely opaque barrier or signal saturation in some pixel), then blurring can be thought of as a reversible operator acting in the space of two-dimensional images.

      There are technical difficulties with regard to noise, so the deconvolution operator looks a little more complicated than described above, but nevertheless it is derivable unambiguously.

      2. Computer algorithms improve sharpness by assuming the blur was Gaussian. After all, they do not know in detail those aberrations, etc., that the filming camera had. Special programs However, they are capable of more. For example, if when analyzing images of the starry sky
      a star enters the frame, then with its help you can restore sharpness better than standard methods.

      3. A complex processing algorithm - this meant multi-stage. In principle, images can be processed iteratively by running the image over and over again in the same simple chain. Asymptotically, it can then tend to some "ideal" image. So, the authors show that such processing, at least, is not necessary.

      4. I don't know the details of experiments with snakes, I'll have to read them.

      Answer

      • 1. I did not know this. It seemed to me that blurring (lack of sharpness) is an irreversible transformation. Suppose there is some kind of blurry cloud objectively present in the image. How does the system know that this cloud should not be sharpened and that this is its true state?

        3. In my opinion, an iterative transformation can be implemented by simply making several layers of neurons connected in series, and then the transformation will take place in one step, but be iterative. How many iterations you need, so many layers to make.

        Answer

        • Here is a simple blur example. Given a set of values ​​(x1,x2,x3,x4).
          The eye sees not this set, but the set (y1,y2,y3,y4) obtained in this way:
          y1 = x1 + x2
          y2 = x1 + x2 + x3
          y3 = x2 + x3 + x4
          y4 = x3 + x4

          Obviously, if you know the blur law in advance, i.e. linear operator (matrix) of the transition from x to y, then you can count inverse matrix transition (the law of deconvolution) and for the given players to restore x. If, of course, the matrix is ​​invertible, i.e. there are no irreversible distortions.

          About several layers - of course, this option cannot be dismissed, but it seems so uneconomical and so easily violated that one can hardly expect evolution to choose this path.

          Answer

          "Obviously, if you know the blurring law in advance, i.e. the linear operator (matrix) of the transition from x to y, then you can calculate the inverse transition matrix (deconvolution law) and restore x from the given y. If, of course, the matrix is ​​invertible, i.e. there are no irreversible distortions." Don't confuse math with measurements. The masking of the lowest charge by the errors is not linear enough to spoil the result of the inverse operation.

          Answer

      • "3. In my opinion, an iterative transformation can be implemented by simply making several layers of neurons connected in series, and then the transformation will take place in one step, but be iterative. How many iterations are needed, so many layers can be made." No. next layer starts processing AFTER the previous one. The pipeline does not allow you to speed up the processing of a specific piece of information, except when it is used in order to entrust each operation to a specialized performer. It allows you to start processing the NEXT FRAME before the previous one is processed.

      Answer

"1. The inverse transformation is a sharp image (which would be created by an object with an eye-type lens), based on the existing blurry one. At the same time, both images are two-dimensional, there are no problems with this. If there are no irreversible distortions during blurring (such as completely opaque barrier or saturation of the signal in some pixel), then the blur can be thought of as a reversible operator acting in the space of two-dimensional images. No. Blurring is a reduction in the amount of information, it is impossible to create it anew. You can increase the contrast, but if it's not just about adjusting the gamma, it's only at the cost of noise. When blurring, any pixel is averaged over its neighbors. FROM ALL SIDES. After that, it is not known where exactly something was added to its brightness. Either to the left, or to the right, or from above, or from below, or diagonally. Yes, the direction of the gradient indicates where the main additive came from. There is exactly as much information in this as in the most blurry picture. That is, the resolution is low. And the little things are only better masked by noise.

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It seems to me that the authors of the experiment simply "spawned extra entities." Is there absolute darkness in the real habitat of snakes? - as far as I know, no. And if there is no absolute darkness, then even the most blurry "infrared image" is more than enough, its entire "function" is to give the command to start hunting "approximately in such and such a direction", and then the most ordinary vision comes into play. The authors of the experiment refer to the too high accuracy of the choice of direction - 5 degrees. But is it really a great accuracy? In my opinion, under no conditions - neither in a real environment, nor in a laboratory - will hunting be successful with such "accuracy" (if the snake only orients itself in this way). If we talk about the impossibility of even such "accuracy" due to a too primitive processing device infrared radiation, then here, apparently, one can disagree with the Germans: the snake has two such "devices", and this gives it the opportunity to "on the move" determine "right", "left" and "straight" with further constant direction correction up to until the moment of visual contact. But even if the snake has only one such "device", then in this case it will easily determine the direction - by the temperature difference on different areas"membrane" (it is not for nothing that it captures changes in thousandths of a degree Celsius, for some reason it is necessary!) Obviously, an object located "directly" will be "displayed" by a picture of more or less equal intensity, located "on the left" - by a picture with greater intensity of the right "part", located "on the right" - a picture with a greater intensity of the left side. Only and everything. And no complicated German innovations are needed in the snake nature developed over millions of years :)

Answer

"It seems to me that the process of precision should be different. How was the accuracy of the work of infrared eyes established? Certainly, by some action of the snake. But any action is long-term and allows for correction in its process. In my opinion, the snake can "infra-see" with that accuracy, which is expected and start moving based on this information. But then, in the process of moving, constantly refine it and come to the final as if the overall accuracy was higher. " That's just a mixture of a balometer with a light-recording matrix, and so it is very inertial, and from the heat of the mouse it frankly slows down. And the snake's throw is so swift that the vision on cones and rods does not have time. Well, maybe it’s not the fault of the cones directly, where the accommodation of the lens slows down, and processing. But even the whole system works faster and still does not have time. The only thing Possible Solution with such sensors - make all decisions in advance, using the fact that there is enough time before the throw.

Answer

"In addition, the logic is not clear, from which it follows that a complex algorithm would make a snake think. As far as I know, the brain is a parallel computer. A complex algorithm in it does not necessarily lead to an increase in time costs." To parallelize a complex algorithm, you need a lot of nodes, they are of decent size and slow down already because of the slow passage of signals. Yes, this is not a reason to refuse parallelism, but if the requirements are very strict, then the only way keep within the time when processing large arrays in parallel - use so many simple nodes that they cannot exchange intermediate results with each other. And this requires hardening the entire algorithm, since they will no longer be able to make decisions. And sequentially, it will also be possible to process a lot of information in the only case - if the only processor is fast. And this also requires a hard algorithm. The level of implementation is hard and so.

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>German researchers have figured out how this can be.



but the cart, it seems, is still there.
You can immediately propose a couple of algorithms that, perhaps, will solve the problem. But will they be relevant to reality?

Answer

  • > I would like at least indirect evidence that it is so, and not otherwise.

    Of course, the authors are careful in their statements and do not say that they have proved that this is how infravision works in snakes. They only proved that resolution of the "paradox of infravision" does not require too large computational resources. They only hope that similarly the organ of snakes works. Whether this is true or not, physiologists must prove.

    Answer

    > There are so-called. binding problem, which is how a person and an animal understand that sensations in different modalities (sight, hearing, heat, etc.) refer to the same source.

    In my opinion, there is a holistic model in the brain real world, rather than separate fragments-modalities. For example, in the brain of an owl there is a "mouse" object, which has, as it were, corresponding fields that store information about how the mouse looks, how it sounds, how it smells, and so on. During perception, the stimuli are converted into terms of this model, that is, the "mouse" object is created, its fields are filled with squeak and appearance.

    That is, the question is not how the owl understands that both the squeak and the smell belong to the same source, but how the owl CORRECTLY understands separate signals?

    Recognition method. Even signals of the same modality are not so easy to attribute to one object. For example, a mouse tail and mouse ears could well be separate items. But the owl does not see them separately, but as parts of a whole mouse. The thing is that she has a prototype of a mouse in her head, with which she compares the parts. If the parts "fit" on the prototype, then they make up the whole, if they don't fit, then they don't.

    This is easy to understand from your own example. Consider the word "KNOWN". Let's look at it carefully. In fact, it's just a collection of letters. Even just a collection of pixels. But we cannot see it. The word is familiar to us, and therefore the combination of letters inevitably evokes in our brain an integral image, from which it is downright impossible to get rid of.

    So is the owl. She sees a ponytail, sees ears, about in a certain direction. Sees characteristic movements. He hears rustling and squeaking from about the same direction. He smells a special smell from that side. And this familiar combination of stimuli, just like the familiar combination of letters for us, evokes the image of a mouse in her brain. The image is integral, located in the integral image of the surrounding space. The image exists independently and, according to owl observations, can be very much refined.

    I think the same goes for snakes. And how in such a situation it is possible to calculate the accuracy of only one visual or infra-visual analyzer, I do not understand.

    Answer

    • It seems to me that image recognition is a different process. It's about not about the snake's reaction to the image of a mouse, but about the transformation of spots in the infra-eye into the image of a mouse. Theoretically, one can imagine a situation where a snake does not infra-see a mouse at all, but immediately rushes in a certain direction if its infra-eye sees circular circles of a certain shape. But this seems unlikely. After all, it is the profile of the mouse that the earth sees with its NORMAL eyes!

      Answer

      • It seems to me that the following might be happening. There is a bad image on the infraretina. It transforms into a vague image of a mouse, enough for the snake to recognize the mouse. But there is nothing "wonderful" in this image, it is adequate to the abilities of the infra-eye. The snake starts an approximate throw. In the process of throwing, her head moves, the infra-eye shifts relative to the target and generally approaches it. The image in the head is constantly supplemented and its spatial position is specified. And the movement is constantly being corrected. As a result, the final throw looks like the throw was based on incredibly accurate information about the position of the target.

        It reminds me of watching myself, when sometimes I can catch a fallen glass just like a ninja :) And the secret is that I can only catch the glass that I dropped myself. That is, I know for sure that the glass will have to be caught and I start the movement in advance, correcting it in the process itself.

        I also read that similar conclusions were drawn from observations of a person in zero gravity. When a person presses a button in weightlessness, he must miss upwards, since the forces habitual for a weighing hand are incorrect for weightlessness. But a person does not miss (if he is attentive), precisely because the possibility of correction "on the fly" is constantly built into our movements.

        Answer

"There is a so-called binding problem, which is how a person and an animal understand that sensations in different modalities (sight, hearing, heat, etc.) refer to the same source.
There are many hypotheses http://www.dartmouth.edu/~adinar/publications/binding.pdf
but the cart, it seems, is still there.
You can immediately propose a couple of algorithms that, perhaps, will solve the problem. But will they be relevant to reality?" But it looks like it. Do not react to cold leaves, no matter how they move and look, but if there is a warm mouse somewhere, attack something that looks like a mouse in optics and when this falls into the scope. Or some kind of very wild processing is needed. Not in the sense of a long sequential algorithm, but in the sense of the ability to draw patterns on nails with a janitor's broom. Some Asians even know how to hard it so that they manage to do billions of transistors. And that one more sensor.

Answer

>in the brain there is a holistic model of the real world, and not separate fragments-modalities.
Here is another hypothesis.
Well, how about without a model? There is no way without a model. Of course, simple recognition in a familiar situation is also possible. But, for example, for the first time having got into the workshop, where thousands of machines are working, a person is able to distinguish the sound of one particular machine.
The trouble may lie in the fact that different people use different algorithms. And even one person can use different algorithms in different situations. With snakes, by the way, this is also not excluded. True, this seditious thought can become a tombstone for statistical methods of research. What psychology cannot bear.

In my opinion, such speculative articles have a right to exist, but at least they need to be brought to the scheme of an experiment to test a hypothesis. For example, based on the model, calculate the possible trajectories of the snake. And let physiologists compare them with real ones. If they understand what it's about.
Otherwise, as with the binding problem. When I read another unsubstantiated hypothesis, it only causes a smile.

Answer

  • > Here is another hypothesis.
    Strange, I did not think that this hypothesis is new.

    In any case, it has confirmation. For example, amputees often claim to still feel them. For example, good motorists claim to "feel" the edges of their car, the position of the wheels, and so on.

    This suggests that there is no difference between the two cases. In the first case, there is an innate model of your body, and sensations only fill it with content. When the limb is removed, the model of the limb still exists for some time and causes sensations. In the second case, there is a purchased car model. From the car, there are no direct signals to the body, but indirect signals. But the result is the same: the model exists, is filled with content and is felt.

    Here, by the way, good example. Let's ask the motorist to run over a pebble. He will hit very accurately and will even say whether he hit or not. This means that he feels the wheel by vibrations. Does it follow from this that there is some kind of "virtual vibrolens" algorithm that restores the image of the wheel based on vibrations?

    Answer

It is rather curious that if the light source is 1, and is quite strong, then the direction to it is easy to determine even with eyes closed- you need to turn your head until the light begins to shine equally in both eyes, and then the light is in front. There is no need to come up with some super-duper neural networks to restore the image - everything is just awful, and you can check it yourself.

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They do not have ears, but they react to every rustle. They don't have a nose, but they can sniff with their tongue. They can live for months without food and still feel great.
They are hated and deified, they are worshiped and destroyed, they are prayed to and with all this they are endlessly afraid. The Indians called them holy brothers, the Slavs - ungodly creatures, the Japanese - celestials of unearthly beauty ...
Snakes are not at all the most poisonous creatures on Earth, as most people think. On the contrary, the title of scary killer belongs to small South American leaf-climbing frogs. Moreover, according to statistics, every year more people die from bee stings than from snake stings.
snakes contrary to terrible myths about aggressive reptiles, the first to attack people and pursue them in a blind desire to sting, in fact - terribly shy creatures. Even among giant snakes, an attack on a person is an accidental and extremely rare phenomenon.


Seeing a person, the same vipers will first of all try to hide, hide, and they will definitely warn about their aggression, which is manifested, by hissing and false throws. By the way, the terrifying sweeps of the snake's tongue are not a threatening gesture at all. So the snake... sniffs the air! The most amazing way learn information about surrounding objects. In a couple of strokes, the tongue conveys the collected information to the sensitive serpentine palate, where it is recognized. And also a snake - and this coincides with Chinese myths- very prudent: she will never waste her poison in vain. She needs him herself - for real hunting and for defense. Therefore, most often the first bite is not poisonous. Even the king cobra often makes a blank bite.
It is the Indians who consider her a goddess endowed with great intelligence and wisdom.
By the way, it is cowardice that makes snakes and even spitting cobras feign death! In the face of a threat, these tricksters twist and fall on their backs, their mouths wide open and emitting unpleasant odors. All these subtle manipulations make the snake unattractive as a snack - and predators, disdainful of "carrion", go away. The Calabar boa acts even wiser: its blunt tail is very similar to the head. Therefore, sensing danger, the boa curls up into a ball, exposing its tail instead of a vulnerable head in front of the predator.
In fact, snakes that love to pretend to be dead are extremely tenacious creatures. There is a known case when an exhibit of a desert snake came to life in the British Museum! A copy that did not show signs of life was glued to a stand, and after a couple of years something was suspected. Peeled off, placed in warm water: the snake began to move, and then eat with pleasure and lived for another two happy years.
No matter how attractive the legends about the bewitching snake look, in fact, these reptiles do not know how to hypnotize. The look of the snake is unblinking and fixed because it has no eyelids. Instead, there is a transparent film - something like glass on a watch - protecting the eyes of snakes from bruises, injections, litter, water. And no self-respecting rabbit will succumb to the "bewitching" look and dutifully wander into the mouth of a boa constrictor: features visual system the snakes are such that they only allow her to see the outline of moving objects. Only the rattlesnake was lucky: it has three sense organs on its head that help to find prey.
The rest of the members of the creeping family have extremely poor eyesight: frozen, potential victims immediately lose sight of the huntress. By the way, most animals - and those very notorious rabbits - perfectly use this, knowing the tactics of snake hunting. From the outside - a duel of views, but in fact, the snakes have to work hard before they manage to catch someone for dinner. Is it possible to hypnotize the snakes themselves? After all, everyone knows the picture of a cobra dancing in front of the caster.
I don't want to be disappointed, but this is also a myth. The snakes are deaf and do not hear the mournful music of the pipes. But very sensitively capture the slightest fluctuations in the surface of the earth next to them. The cunning spellcaster first lightly taps the basket with the snake or stomps, and the animal immediately reacts. Then, playing a motive, he continuously moves, sways, and the snake, constantly watching him, repeats his movements so that the person is always in front of his eyes. A spectacular sight, but the hypnotist from the caster, alas, is useless.
By the way, king cobras are well versed in music. Quiet melodious sounds soothe them, and the snakes, rising, slowly sway to the beat. The abrupt, sharp sounds of jazz, especially loud, unnerve the cobra, and it uneasily inflates its "hood". Heavy and even more “metal” rock leads the “music lover” into indignation: she stands on the tail and makes quick threatening movements in the direction of the music source. Recent studies by Russian herpetologists have shown that to the classical works of Mozart, Handel and Ravel, cobras dance with obvious pleasure, closing their eyes; but pop music causes lethargy, apathy and nausea.
By the way, about snake movements: it is interesting to observe how the body of a snake moves - there are no legs, nothing pushes, does not pull, but it slides and flows, as if without bones. In fact, the fact is that snakes are simply filled with bones - in some species, up to 145 pairs of ribs can be attached to a flexible spine! The peculiarity of the snake "gait" is given by the articulated spine, to which the ribs are attached. The vertebrae are attached to each other by a kind of hinges, and each vertebra has its own pair of ribs attached, which gives a unique freedom of movement.
Some Asian snakes can fly! They can famously climb to the tops of trees and from there soar down, spreading their ribs to the sides and turning into a kind of flat ribbon. If the heavenly tree snake wants to move from one tree to another, it literally flies to it without going down. In flight they take S-shape in order to stay in the air longer and get exactly where they need to be. As strange as it may sound, the tree snake is an even better glider than flying squirrels! Some flyers can cover distances up to 100 meters in this way.
By the way, all lovers of hot rumba should be grateful to snakes. There is a curious step in the dance: the gentlemen throw their legs far to the side and, as it were, crush someone. It comes from a dance movement from not so old times, when rattlesnake in Mexican dancing was quite commonplace. The imperturbable machos, in order to impress the ladies, crushed the uninvited guests with the heel of their boots. Then this movement became the highlight of the rumba.
Do not count the beliefs about magic power snake heart, giving strength and immortality. In fact, hunters for such a treasure would have to sweat a lot in search of this very heart: after all, it can slide along the body of a snake! This miracle is bestowed by nature in order to make it easier for the snake to pass food through the gastrointestinal tract.
Despite the reverent fear of snakes, mankind, as is known, has been using their "gifts" for healing since ancient times. But there are also more curious cases of how people - and not only - use the features of these amazing creatures. For example, owls sometimes place small snakes in their nests. They deal with small insects competing with owlets for prey brought by their mother. Thanks to the amazing neighborhood, the chicks grow faster and get sick less.
In Mexico, along with kittens and puppies, local “domestic” snakes are considered the favorites of children. They are herbivores and are covered with thick, shaggy hair. Brazilians prefer royal boas: in the houses of the suburbs of Rio de Janeiro and in the cottages of the mountain resort of Petropolis, these huge reptiles enjoy great love and respect. The fact is that in the country there are a great many poisonous snakes. But not a single poisonous individual will crawl into a garden where a boa constrictor is found, even if everything around is teeming with them. Moreover, boas are tenderly attached to children. As soon as the child leaves the house, the "nanny" begins to follow his every step. The boa constrictor invariably accompanies children on walks and during games, protecting the kids from snake attacks. Unusual governesses saved thousands of lives with their devotion, especially in countryside, where it is extremely problematic to deliver the saving serum. Kids respond to their guards with warm reciprocity: boas are very neat, always have a dry, pleasant to the touch and very clear skin, and it’s worth mentioning especially about unpretentiousness in everyday life: a boa constrictor eats once every two, or even four months, being content with an annual ration of no more than five rabbits.
And on Greek island Kefalonia snakes are not tamed, not used as a rodent exterminator or secuudica. It was on this day to miraculous icon, before which the nuns were once asked for intercession, small poisonous snakes with black crosses on their heads crawl into the temple from all around. What is amazing: they are drawn to the miraculous icon, as if spellbound, not afraid of people and not trying to bite them. People just as calmly react to unusual "parishioners" who crawl over the icons and without fear get over on their hands when they are extended to them. Even kids play with snakes. But soon after the end of the festive service, the snakes crawl off the icon of the Mother of God they love and leave the church. As soon as they crawl across the road and end up in the mountains, they again become the same: it’s better not to approach them - they will immediately hiss and bite! Yes, one can talk endlessly about these amazing creatures of nature: they stand apart in the animal world so much. And yet, in vain, for the most part, we do not like snakes so much. After all, the Chinese say that a person uses snakes with everything except hissing, and in return they receive nothing but hostility. Well, is that fair?

To be fair, snakes are not as blind as is commonly believed. Their vision varies greatly. For example, tree snakes have fairly sharp eyesight, and those leading an underground lifestyle are only able to distinguish light from darkness. But for the most part, they are really blind. And during the molting period, they can generally miss during the hunt. This is due to the fact that the surface of the snake's eye is covered with a transparent cornea and at the time of molting it also separates, and the eyes become cloudy.

What they lack in vigilance, however, snakes make up for with a thermal sensing organ that allows them to track the heat radiated by prey. And some representatives of reptiles are even able to track the direction of the heat source. This organ was called a thermolocator. In fact, it allows the snake to "see" prey in the infrared spectrum and successfully hunt even at night.

snake hearing

With regard to hearing, the statement that snakes are deaf is true. They lack the outer and middle ear, and only the inner ear is almost completely developed.

Instead of an organ of hearing, nature gave snakes a high vibrational sensitivity. Since they are in contact with the ground with their whole body, they very keenly feel the slightest vibrations. However, snake sounds are still perceived, but in a very low frequency range.

Smell of a snake

The main sense organ of snakes is their surprisingly subtle sense of smell. An interesting nuance: when immersed in water or when buried in sand, both nostrils close tightly. And what is even more interesting - in the process of smelling, a long tongue forked at the end takes a direct part.

With a closed mouth, it protrudes out through a semicircular notch in the upper jaw, and during swallowing it hides in a special muscular vagina. With frequent vibrations of the tongue, the snake captures microscopic particles of odorous substances, as if taking a sample, and sends them into the mouth. There she presses her tongue against two pits in the upper palate - Jacobson's organ, which consists of chemically active cells. It is this organ that provides the snake with chemical information about what is happening around, helping it find prey or notice a predator in time.

It should be noted that in snakes living in water, the tongue works just as effectively underwater.

Thus, snakes do not use their tongue to determine taste in the truest sense. It is used by them as an addition to the body to determine the smell.

Sense organs in snakes

In order to successfully detect, overtake and kill animals, snakes have at their disposal a rich arsenal of various devices that allow them to hunt, depending on the prevailing circumstances.

One of the first places in importance for snakes is the sense of smell. Snakes have a surprisingly delicate sense of smell, capable of detecting the smell of the most insignificant traces of certain substances. The snake's sense of smell involves a forked movable tongue. The flickering tongue of a snake is as familiar a touch to the portrait as the absence of limbs. Through the fluttering touches of the tongue, the snake "touches" - touches. If the animal is nervous or is in an unusual environment, then the frequency of tongue flickering increases. With quick movements "out - into the mouth", she, as it were, takes a sample of the air, receiving detailed chemical information about the environment. The forked tip of the tongue, curving, is pressed against two small pits in the palate - Jacobson's organ, consisting of chemically sensitive cells, or chemoreceptors. Vibrating its tongue, the snake captures microscopic particles of odorous substances and brings them for analysis to this peculiar organ of taste and smell.

Snakes do not have auditory openings and eardrums, which makes them deaf in the usual sense. Snakes do not perceive sounds that are transmitted through the air, but they subtly pick up vibrations going through the soil. These vibrations are perceived by the abdominal surface. So the snake is absolutely indifferent to screams, but it can be frightened by stomping.

Vision in snakes is also quite weak and does not matter much to them. There is an opinion that snakes have some kind of special hypnotic snake look and can hypnotize their prey. In fact, there is nothing like that, just unlike many other animals, snakes do not have eyelids, and their eyes are covered with transparent skin, so the snake does not blink, and its gaze seems to be intent. And the shields located above the eyes give the snake a gloomy, evil expression.

Three groups of snakes - boas, pythons and pit vipers - have a unique additional body feelings that no other animal has.
This is a thermolocation organ, presented in the form of thermolocation pits on the snout of a snake. Each fossa is deep and covered with a sensitive membrane, which perceives temperature fluctuations. With its help, snakes can detect the location of a warm-blooded animal, i.e. their main prey, even in complete darkness. Moreover, by comparing the signals received from the pits on opposite sides of the head, i.e. using the stereoscopic effect, they can accurately determine the distance to their prey and then strike. Boas and pythons have a whole series of such pits located in the labial shields, bordering the upper and lower jaws. Pit vipers have only one pit on each side of their head.