The snake's way of locomotion. Snakes crawl due to an uneven coefficient of friction and a constant redistribution of weight. Can a snake crawl backwards

There is no doubt that the fantasy of nature significantly exceeds the human one: amazing shapes, bright colors, all kinds of sizes of living and extinct representatives of flora and fauna often simply do not fit into the framework of our perception. But, unlike the characters of science fiction books and films, in real organisms each of these expressive features is necessary to perform a particular function. This is especially true for the way you travel.

Smooth fish scales covered with a thin layer of mucus; strong and at the same time light bird feathers; thin leathery membranes of flying lizards; cat claws; protruding thumb in primates; numerous "finds" for upright walking, which people are so proud of; six or even more pairs of legs in arthropods. But each of these limbs must be controlled, and even balanced by the rest of the body, so that it does not have to be lifted again.

In this regard, snakes, worms and legless amphibians made the right choice - if you are already on the surface, then you, in fact, have nowhere to fall. But the mechanics of their movement turned out to be much more complicated than it seemed. David Hu of New York University and colleagues

proved that the characteristic crawl is provided by an uneven distribution of the friction force over the surface of the body in contact with the ground and a constant redistribution of weight.

In this they are fundamentally different from their "brothers" in misfortune - worms and legless amphibians. The latter synthesize an abundant amount of mucus, the worms push themselves forward, clinging to small hairs. But in the case of snakes, until recently, it remained only to rely on hypotheses.

According to one of them, the friction force in the longitudinal direction was much less than that in the transverse direction. If you add the ability to squirm here, then the loops will provide the necessary stability, while the movement will continue forward. A demonstration of this approach is wheeled snake robots, whose body moves forward easily and does not move sideways at all. However, they also need fulcrum from which to build. In the case of sand or bare stone, this approach will not work.

The authors publications in the Proceedings of the National Academy of Sciences have significantly expanded the existing ideas about the movement of these reptiles. Their wards were 10 young milk snakes (Campbell's king snake or Lampropeltis triangulum campbelli). These snakes, native to North America, are known for being very similar in appearance to poisonous coral asps, although they themselves are much less dangerous.

To begin with, the experimenters euthanized the reptiles and measured the force of friction in all directions.

As expected, when moving to the side, it turned out to be almost twice as large, and backward - one and a half, than when moving forward.

But this is only if the surface is rough. If something supersmooth acted as a substrate, then the friction force in all directions tended to zero. However, they didn’t expect a miracle from snakes - it would be strange to believe that the scales cling to something that, in principle, is impossible to cling to in different ways.

The resulting model also explains the ability of snakes to move along an inclined surface and gives calculated speeds that are almost close to real ones.

Dynamic load distribution in lateral bends. Top photo - Snake crawling on the mirror. This picture shows the "wave" used to redistribute the weight. Although this photo was taken more for demonstration (the surface is smooth, so the reptile hardly moves), the same phenomenon was observed when moving on rough surfaces. Below is the calculated driving force on a model with uniform (middle row) and uneven (bottom row) weight distribution. The red dot marks the center of mass, the black dots mark the places of greatest pressure on the surface //David L.Hu et al., PNAS

The scientists explain the missing “kilometers per hour” as a kind of wave that the snake sends through its body. She managed to register when video recording movement on a mirror surface. At the same time, reptiles do not completely tear off their body, but only reduce the load on certain areas, constantly moving the center of mass.

The authors even expect to find a practical application for their find - such robots in some cases are significantly superior to wheeled and even "six-fingered" ones. Wheels will be absolutely useless if the height of the obstacle is more than half the diameter of the wheel, and the limbs require much more room to maneuver than a thin, flexible body. So when parsing rubble or in reconnaissance, such robotic snakes can bring a lot of benefits. It remains only to learn how to make scales similar to a snake.

Scientists have figured out why snakes crawl quickly

MOSCOW, 18 February. Science for a long time could not find the answer to the question of why snakes are able to move so quickly, because crawling is a rather complicated way of moving. It was believed that during the bends, the body of the snake is repelled by bumps in the ground and from various plants, which gives it the ability to crawl faster, writes Science.YoRead.ru.

Scientists have conducted a number of studies and refuted this opinion. They found out that the secret of the snake's rapid movement lies in the structure of its scales. The scales on the skin of the snake's belly are located in such a way that they do not allow it to move towards the tail and sideways, thereby determining the forward direction as preferable. A similar mode of movement is used in skiing and skating. Such uneven friction in different directions of motion is commonly called frictional anisotropy.

To prove their theory, the researchers built a mathematical model of the snake's movement, where they took the speed at which the snake's center of mass moves as a function of the size and speed of the frictions that appear when the snake's body is bent.

The study of the constructed mathematical model proved the correctness of the scientists and showed that the scales help to create non-uniform friction of the snake's body on various surfaces, which helps the snake move quickly even on slippery surfaces.

Earlier it was reported that a snake with one clawed paw in the middle of the body, similar to the limb of a lizard or a frog, was found in China. A strange mutant "appeared" at midnight in the bedroom of a 66-year-old resident of the city of Suining, southwestern Sichuan. The snake, 40.5 cm long and as thick as a little finger, climbed a vertical surface, deftly clinging to it with the claws of a single leg. The Chinese woman says that she was very frightened, but nevertheless she had the “courage” to beat the creature to death with a slipper. Moreover, making sure that the snake is dead, the woman also placed it in a bottle of alcohol. Thanks to her almost professional actions, the Chinese scientists got hold of the mutant reptile, and are already doing the necessary research. One of them, a specialist in snakes, admitted to the newspaper that what he saw shocked even him. He hopes to find out the cause of the mutation only by the results of the autopsy.

The most common mutation among snakes today is "two-headed". It is formed according to the same principle as the doubling of body parts in Siamese twins. Such individuals have little chance of surviving in the wild, if only because both heads continually strive to attack each other.

It should be noted that snakes rarely develop really impressive speed. Most species move no faster than eight kilometers per hour, but the black mamba, for example, can crawl at speeds of sixteen to nineteen kilometers per hour.

One of the main ways of movement is the accordion movement. The snake first collects its entire body into folds, then, fixing the tip of the tail in one place, it pushes itself forward. After that, she pulls up the back of the body, again gathering into folds.

The second way to move is the movement of the caterpillar. Thus, the snakes move in a straight line and overcome some bottlenecks. With this method, the snake uses large scales located on its belly. She plunges them into the ground like small spatulas. When the scale is in, the snake moves it towards the tail with its muscles. As a result, the scales in turn are repelled from the ground, which allows the snake to move. This method is similar to rowing, which people use to get around in boats. The movement of the scales is similar to movements.

Amazing spectacle

The characteristic wriggling movement is used by snakes to move on fairly hard ground. To propel itself forward, the snake rests on roots, stones, sticks and other hard objects, bending the body to the side. With this method of movement, the snake contracts the lateral muscles alternately, which allows it to crawl forward.

Such undulating movements are the basis of snake crawling. From the outside, this sight is mesmerizing. The reptile seems to lie motionless, but at the same time it flows forward for the eye. This feeling of lightness and invisibility of movement is deceptive. Snakes are surprisingly strong creatures, their smooth movements are provided by the synchronous and measured work of the muscles.

The fourth type of movement is called lateral movement or twisting. It is characteristic mainly of snakes that live in the desert. With the help of this type of movement, they are on loose sand, and they do it surprisingly quickly. The lateral move is so called because first the snake's head moves diagonally forward and to the side, and only then it pulls up the body. First, it rests on the back of the body, then on the front. This type of movement leaves strange parallel marks on the sand with characteristic hooks at the ends of the segments.

There are other ways for snakes to move. Paradise snakes, found in Indochina, Indonesia and the Philippines, live on palm trees. If they want to change their habitat, they simply fly to another tree. In fact, they, of course, jump. Before jumping, the paradise snake takes a very deep breath to create an air chamber inside the body that works like a parachute. This allows her to glide to an impressive distance of up to thirty-odd meters.

Snake locomotion

In fact, snakes are able to move on the ground in four main ways. If one method does not work, then they use another. Sometimes, especially on a very flat surface, they have to try all four ways. Crawling snakes can be quite fast, and some of them are even able to chase their prey. However, even the fastest snakes rarely reach speeds exceeding 8 km/h. The crawling speed record is 16-19 km / h and belongs to the black mamba.

1. Movement with an accordion.

First, the snake gathers the body into folds. Then, holding the tip of the tail in place, pushes the front of the body forward. And finally tightens the back of the body.

2. Caterpillar movement.

The snake can move in a straight line. She uses this movement when she needs to overcome some kind of bottleneck. At the same time, the snake moves large scales located on the belly. One by one, the scales sink into the ground like small spatulas. As soon as the scale has sunk into the ground, the muscles move it towards the tail. One after another, the scales are repelled from the ground, and due to this, the snake moves.

3. Wriggling movement.

Designed to move on hard ground. To move forward, the snake bends its body to the side, resting on stones, roots, sticks or other hard objects. With this movement, the snakes alternately contract the muscles on their sides, so that their torso bends in an S-shape: the snake wriggles and crawls.

Body undulations are the most common way for snakes to crawl.

4. Twisting or lateral running is a mode of movement used only by some species of snakes living in the desert. Using this method, they can move quickly on loose sand. In this case, the head of the snake goes sideways and forward, and then the torso is pulled up. Snakes begin to almost walk, if one can say so about completely legless creatures: leaning on the back of the body, they carry the front forward, then vice versa.

5. Digging move.

Among them, for example, are blind snakes.

Many species of blind snakes have tiny eyes that can distinguish light from darkness; some species have no eyes at all. A strong skull and large shields on the front of the head help the blind snakes to dig tunnels in the thickness of loose soil.

Often snakes escape underground from heat or cold. Others look for the minks of small animals and, climbing into them, eat their owners. For some desert snakes, sand provides excellent hiding places. Having exposed only their heads above its surface, they patiently wait for prey.

6. Woody look.

Many snakes are good at climbing the branches of trees and shrubs. But some species of snakes spend their whole lives in the crowns of trees. Such snakes are called tree snakes. While hunting lizards, the Mexican sharp-headed snake often throws its body from branch to branch. In preparation for the "flight", the snake flattens the body, greatly spreading the ribs. This allows her to glide smoothly through the air.

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Snakes do not have legs or even their rudiments, but how do they manage to “run” so fast? Interest Ask. The snakes, having lost their limbs, returned to the old way of transportation. It seems to us that the snake moves with the help of abdominal shields, catching them on the ground. But this is not true. By carefully observing the movement of the snake and having studied descanally, the methods of its movement, it was found that they move very, specifically, using the movement of the whole body. The snake bends its torso in a horizontal plane, creating waves of bends that continuously follow from front to back, creating a force that moves the snake forward.

An obstacle to the movement of the snake is a perfectly flat surface. Snakes cannot crawl on glass or . But if there is even the slightest roughness, then movement is quite possible. According to this principle, snakes "walk" on the sand. When bending the body, loose sand shifts and forms folds, which help the movement. True, the speed of movement is very slow.

When moving on a smooth surface, friction occurs between the front of the body and the soil (static friction), the snake gathers the body into an accordion and pulls its back forward - sliding friction is less than static friction. Then, leaning on the tail of the snake, he lunges forward with the front of the body and again shrinks into an accordion. This method of movement is used by large snakes with a heavy and strong body. So "go" boas, snakes and vipers.

There is another way to move the snake. It is based on the difference between static friction and sliding friction. With such crawling, the snake does not bend, and its body remains straight. Part of the shields on its belly is fixed on the soil, and the other part is pulled forward by the muscles. Movable shields are fixed, and those that were not mobile are pulled up. This “rectilinear” way of movement is used by snakes with a short body and a thick one, these are some, boas and blind snakes.

Both described methods of locomotion of snakes do not allow them to crawl quickly, although they do allow them to overcome smooth surfaces. Snakes use "lateral movement" to move quickly. The lateral way of “walking” of snakes can only be observed in them, and other animals also use other methods when moving.

When moving sideways, the snake, lying on the ground or sand, raises its head, and then the front part of the body, bends it at a right angle and puts it in a new place. The emphasis is on two points, the snake does the same with the rest of the body, so in parts it transfers its body forward and to the side in the direction of movement. In the course of such a movement, traces remain in the sand in the form of imprints of the body of a snake, they are directed obliquely to the direction of movement. This is how snakes of the species walk - horned vipers, ephs, rattlesnakes that live in the sands.

proved that the characteristic crawl is provided by an uneven distribution of the friction force over the surface of the body in contact with the ground and a constant redistribution of weight.

To begin with, the experimenters euthanized the reptiles and measured the force of friction in all directions.

As expected, when moving to the side, it turned out to be almost twice as much, and backward - one and a half, than when moving forward.

But this is only if the surface is rough. If something supersmooth acted as a substrate, then the friction force in all directions tended to zero. However, they did not expect a miracle from snakes - it would be strange to believe that the scales cling to something that, in principle, cannot be hooked on in different ways.

The resulting model also explains the ability of snakes to move along an inclined surface and gives calculated speeds that are almost close to real ones.

The authors even expect to find a practical application for their discovery - such robots in some cases significantly outperform wheeled and even "six-fingered" ones. Wheels will be absolutely useless if the height of the obstacle is more than half the diameter of the wheel, and the limbs require much more room to maneuver than a thin, flexible body. So when parsing rubble or in reconnaissance, such robotic snakes can bring a lot of benefits. It remains only to learn how to make scales similar to a snake.

Ways of transportation

It may seem that moving without legs is very difficult, but snakes do it masterfully. In fact, they are able to move on the ground in four main ways. If one method does not work, then they use another. Sometimes, especially on a very flat surface, they have to try all four ways. Crawling snakes can be quite fast, and some of them are even able to chase their prey. However, even the fastest snakes rarely reach speeds exceeding 8 km/h. The crawling speed record is 16-19 km / h and belongs to the black mamba.

1. Accordion movement
One way the snake moves is called the accordion movement. First, the snake gathers the body into folds. Then, holding the tip of the tail in place, pushes the front of the body forward. And finally tightens the back of the body.

2. Caterpillar movement
With the help of caterpillar movement, the snake can move in a straight line. She uses this movement when she needs to overcome some kind of bottleneck. At the same time, the snake moves large scales located on the belly. One by one, the scales sink into the ground like small spatulas. As soon as the scale has sunk into the ground, the muscles move it towards the tail. One after another, the scales are repelled from the ground, and due to this, the snake moves. The same method is used by people when they row while in a ship. They sink their oars into the water in the same way that snakes sink scales into the ground.

3. Wriggling movement
Designed to move on hard ground. To move forward, the snake bends its body to the side, resting on stones, roots, sticks or other hard objects. With this movement, the snakes alternately contract the muscles on their sides, so that their torso bends in an S-shape: the snake wriggles and crawls.
Body undulations are the most common way for snakes to crawl. A calmly crawling snake is an amazingly beautiful and bewitching sight. Nothing seems to be happening. Movement is almost imperceptible. The body seems to lie motionless and at the same time quickly flows. The feeling of ease of movement of the snake is deceptive. In her amazingly strong body, many muscles work synchronously and measuredly, accurately and smoothly transferring the body. Each point of the body in contact with the ground is alternately in the phase of either support, or push, or forward transfer. And so constantly: support-push-transfer, support-push-transfer ... The longer the body, the more bends and the faster the movement. Therefore, in the course of evolution, the body of snakes became longer and longer. In this regard, they are champions among vertebrates. The number of vertebrae in them can reach 435 (in humans, for comparison, only 32-33).

4. Twisting or lateral running- this is a method of movement that is used only by some species of snakes living in the desert. Using this method, they can move quickly on loose sand, and they move so lightning fast that it is difficult to keep track of them. In this case, the head of the snake goes sideways and forward, and then the torso is pulled up. Snakes begin to almost walk, if one can say so about completely legless creatures: leaning on the back of the body, they carry the front forward, then vice versa.
At the same time, very strange marks appear in the form of oblique parallel stripes with hooks at the end. You won’t immediately guess that such a trace could be left by a living creature! It is in this way that the sand efa moves - a very dangerous snake that lives with us in Central Asia.

In addition to these methods, there are still some very unusual movement techniques. For example, in Indonesia, Indochina, and the Philippines, snakes from the genus Chrysopelea, a subfamily of false snakes, live. They are called heavenly for their elegance and beauty. The paradise snake lives on palm trees, where it feeds on lizards. And if she wants to change her place of residence, she flies to another palm tree. When flying, its body acquires an S-shape, and the tail serves as a rudder. Before the jump, the snake takes a deep breath, forming an air chamber inside the body, serving as a kind of parachute and allowing it to glide to a distance of up to 35 meters.

Some snakes are even able to jump forward, first collecting the body into rings, like a spring, and then sharply straightening it.

The muscular system of reptiles is represented by chewing, cervical muscles, abdominal muscles, as well as flexor and extensor muscles. There are intercostal muscles characteristic of higher vertebrates, which play an important role in the act of breathing. The subcutaneous musculature allows you to change the position of the horny scales.

Muscles of the head.

Due to the fact that snakes do not chew their prey, but swallow it whole, their chewing muscles do not reach strong development and serve to open, close their jaws and hold prey with the help of numerous small teeth. The facial muscles are underdeveloped, so the lips and top of the nose of snakes are practically motionless and have a strong connective tissue base.

Muscles of the spinal column.

This muscle group is highly developed and well differentiated. Snakes have the following groups of multi-segment muscles:

The longissimus muscles of the trunk and tail (m. longissimus trunci et coccygey) - These muscles provide extension of the spinal column and lateral movements of the trunk.

Interspinous muscles (m. interspinales) - They contribute to the extension of the spinal column.

Short transverse muscles (m. intertransversarii) - provide lateral movements of the torso of snakes.

Rib lifters m. levatori costarum) - These muscles are most developed in cobras in the cervical region and provide expansion of the neck with the formation of a "hood".

snake suborder poisonous skeleton

Rib retractors m. retractors costarum) - begin at the proximal end of the rib, end at the arch of the posterior vertebra.

Rib lowerers (m. depressores costarum) - begin on the ventral surface of the proximal end of the rib, end on the ventral surface of the vertebral body.

Intercostal muscles (m. intercostals) - located between the ribs, highly developed.

Flexors of the spinal column (m. flexores) - highly developed, especially in boas and pythons, located on the ventral surface of the vertebral bodies, throwing over several segments - these are the long muscles of the trunk and tail.

The strong development and elasticity of the described muscle groups provides a serpentine type of movement, that is, movement with the help of body bends and ribs that are not closed ventrally. In other words, snakes, wriggling, "walk on the ribs." When the snake makes a bend, the longissimus and transverse muscles of the side of the bend are tense, and on the side opposite to the bend, they are relaxed. During a forward lunge, these muscles are in the opposite functional state.

Movement

When the snake moves, each abdominal shield, with the help of the corresponding muscles, takes a position at right angles to the skin. With a shield in this position, the animal rests on the ground. One movement of the muscles - the shield is pressed against the skin, and the next one takes its place. During the movement of the snake, shield after shield becomes an instant point of support and repulsion, and only thanks to them is forward movement possible. The scutes serve the snake like hundreds of tiny legs.

The movements of the vertebrae, ribs, muscles and scutes are strictly coordinated; they occur in the horizontal plane. The raised head of the snake is lowered to the ground, then the loop of the front third of the body is pulled up; with a lot, the snake again moves its head forward in order to lean on the ground again, make another forward movement and pull the whole body along with it. As long as the snake does not get a foothold, it is not able to move. The snake will not be able to move on the smooth surface of the glass, since the cross plates will only slide on it.

If you follow a snake while it is being scanned with X-rays, you can see how complex the coordinated movements of its skeleton are. The spine easily bends in any direction, and thanks to this, the snake's body can either curl up into a ring, or rise almost a third of its length above the ground, or rush forward with incredible speed.

Snake locomotion

1. Movement with an accordion.

First, the snake gathers the body into folds. Then, holding the tip of the tail in place, pushes the front of the body forward. And finally tightens the back of the body.

2. Caterpillar movement.

3. Wriggling movement.

Body undulations are the most common way for snakes to crawl.

5. Digging move.

Among them, for example, are blind snakes.

6. Woody look.

The movement of snakes is full of charming originality. The sight of a silently sliding meandering tape makes an indelible impression on the viewer and delivers aesthetic pleasure. However, typical, so-called "serpentine" movement is by no means the only way that snakes use. In different habitats, on different substrates, various snakes have developed a number of special types of movement. With the “serpentine” type of movement, the body bends in waves and the resulting waves seem to run along the body from head to tail. The arching section of the body, set obliquely to the direction of movement, rests on the substrate and creates a pushing force. It is directed at an angle to the movement, but can be decomposed into two components - perpendicular and parallel to the line of movement. The first component is extinguished by the resistance of the support, and the second one pushes the body forward.

Thus, the more bends, the greater the total driving force. Therefore, snakes using this method of movement usually have a long, flexible and slender body. Such, for example, are snakes and snakes - active snakes that track and catch up with their prey. Note, however, that the speed developed by the Snake, even with the fastest gliding, does not, as a rule, exceed 6-8 km per hour, and in many species it does not even reach 5 km per hour. Therefore, a person can easily catch up with any snake if the competition takes place in an open space. Many readers are probably also interested in the opposite result: it can be safely guaranteed that a snake cannot overtake a person, even if it really wants to do it. However, this option is only of theoretical interest, since snakes never pursue a person.

Since the support on the substrate is used in the serpentine type of movement, the efficiency of movement depends on the roughness of the support. So, a snake cannot move on smooth glass: the body wriggles, but the animal remains in place. In addition to a smooth substrate, a loose substrate is also a poor support for the body - moving desert sands not fixed by vegetation. Under these conditions, some species of snakes (sand efa, tailed viper, horned rattlesnake) have developed a special type of movement - the “lateral move”. Indeed, looking at a moving efu, you are convinced that it is not crawling forward, but, as it were, sideways. Pulling forward the rear part of the body, she throws it forward without touching the substrate and then, leaning on the entire side of the body, pulls up the front part. The trail with such a movement is not continuous, but consisting of separate parallel strips with hooked ends, located at an angle to the line of motion. The support with this method of movement is more solid, and the snake literally “steps over” from one track to another.

This type of movement is asymmetrical, so the load on the muscles is uneven. In order to equalize it, the snake has to periodically change the “working side” of the body - crawl either with its left or right side forward. Some species of snakes do not pursue prey, but guard it, lying motionless in ambush. Such snakes are inactive, and their body is usually thick and short. They are incapable of graceful serpentine movements, and they have to abandon this method, moving to a rectilinear or caterpillar type of movement. It is especially pronounced in large and short-haired African vipers (cassava, noisy viper).

The body of a crawling viper does not bend at all, and when viewed from above, it seems that it is simply floating on the surface. From the side, it is clearly visible how a series of contractions and stretching runs along the ventral side, moving the snake forward. The zigzag pattern on the sides of the body seems to come to life, its angles either decrease or increase, and it seems that the viper “walks” on a dozen pairs of short legs. In the movement of snakes, especially with the latter method, an important role is played by expanded abdominal scutes. They can fit snugly against each other, forming a smooth surface, or by contraction of the abdominal muscles, their rear edge drops, and a good support is created. By maneuvering the ventral scutes, the snake can create cohesion, or vice versa; provide gliding on different parts of the body. The significance of the abdominal shields is confirmed by the fact that sea snakes, living all their lives in the aquatic environment, have lost them. Their belly is covered with the same small scales as the back. And so, if such a snake is pulled onto land, it wriggles, but almost cannot move on a solid substrate. Burrowing, swimming and tree snakes have special specific adaptations for locomotion, which will be discussed in the description of these species.

Snakes feed on a wide variety of animals, from worms, mollusks and insects to fish, birds, rodents and small ungulates. All snakes are carnivorous, and the vast majority hunt for live prey. Only a few species sometimes show a predilection for carrion (Persian viper, water muzzle). All snakes swallow their prey whole, without tearing or chewing it. The diet depends on the size of the snake; large species feed on correspondingly larger prey. The composition of feed changes greatly with age: juveniles of most snakes feed on small invertebrates, while adults usually switch to feeding on vertebrates.

Only small species of snakes (blind snakes, contia, etc.) feed on insects, worms, etc. all their lives. Many snakes are limited to certain foods, and sometimes specialization goes so far as to cause drastic changes in the structure of the skeleton of the dental system. For example, in an African egg snake that feeds only on bird eggs, the number of teeth has decreased and they have become small and blunt, and the processes of the vertebrae, piercing the esophagus, form a sharp "egg saw" that serves to cut the egg shell. Due to the extensibility of the mouth and integuments of the body, snakes can swallow prey, which is 2-3 times thicker than themselves. However, these abilities also have their limits, and even a 10-meter boa constrictor or python cannot swallow an adult horse or cow, as "eyewitnesses" often report on returning from distant wanderings.

The largest animals ever swallowed by boas reached the size of a pig or roe deer. The seized prey of the snake is swallowed alive if it is small and does not offer strong resistance. For large and strong prey, various methods of killing are used, primarily strangulation with body rings. This technique is used by boas and most already-shaped snakes. It is important to note that when strangling, the boa constrictor does not crush the ribs of its victim at all, as is often described. It squeezes the victim only enough to paralyze its respiratory movements. A broken rib in the prey's body would be fatal to the snake itself, as it would easily pierce the snake's highly stretched skin when swallowed. Therefore, the victim enters the stomach not only whole, but also intact.

A special and very effective way of killing prey was developed by poisonous snakes. There are poisonous species in the family of already similar ones, but their poisonous teeth are located in the depths of the mouth and reach the body of the victim only when it is strongly captured by the snake's mouth. Therefore, such species are forced to hold the seized prey. Sea snakes, asps, vipers and pit vipers have poisonous teeth in front, so that these snakes, after inflicting a quick bite and introducing a portion of the poison into the body of the victim, can release the victim and wait for the poison to have its disastrous effect. The emergence of a poisonous apparatus, no doubt, is associated with the most important feature of snakes - the swallowing of large prey as a whole. Such prey must first be immobilized, and the poison performs this task in the most perfect way. In addition, the introduction of poison into the body of the victim accelerates its digestion several times, since the poison destroys the tissues of the victim's body from the inside, preparing them for absorption.