Ways of communication of animals, Tactile sensitivity. Touch...

Methods of animal communication

Tactile sensitivity. Touch

On the surface of the body of animals is a huge number of receptors, which are the endings of sensitive nerve fibers. According to the nature of sensitivity, the receptors are divided into painful, temperature (thermal and cold) and tactile (mechanoreceptors).

Taste is the ability of animals to perceive various external influences, carried out by the receptors of the skin and the musculoskeletal system.

Tasteful sensations can be diverse, as they arise as a result of a complex perception of various properties of the stimulus acting on the skin and subcutaneous tissues. By means of touch, the form, magnitude, temperature, the consistency of the stimulus, the position and movement of the body in space, etc. are determined. The basis of the sense of touch is the irritation of specialized receptors and the transformation of the incoming signals into the corresponding sensation (tactile, temperature, painful) in the central nervous system.

Skin Analyzer

The receptors of this analyzer are:

• free endings of nerves in the epithelium, which perceive pain and temperature sensations, pressure and serve as chemoreceptors;

• tactile cells, braided by a network of nerve fibers;

• Tactile bodies formed by groups of tactile cells enclosed in a connective tissue envelope. They are best developed on the fingers of climbing mammals, at the end of an elephant's trunk, a mole stigma, etc.

But the main receptors that perceive tactile stimuli and partly the position of the body in space are the hair in mammals, especially the special thick vibrissae The most noticeable vibrissae are the "whiskers", well noticeable in cats or rodents. Vibris responds not only to touching the surrounding objects, but also to fluctuations in air. In animals constantly living in burrows with a wide contact surface with the walls of the burrow, vibrissae, except the head, are scattered throughout the body. In climbing forms, for example, in squirrels, lemurs, they are also located on the abdominal surface and on parts of limbs that come into contact with the substrate when moving through trees.

Tactile feeling is due to irritation of the mechanoreceptors located in the skin at a certain distance from each other. Animals are able to accurately determine the location of the localization of stimuli: the crawling of insects on the skin or their bites causes a sharp motor and defensive reaction. The highest concentration of receptors in most animals is observed in the head region, respectively, the scalp, the mucous membranes of the mouth, lips and eyelids have the highest sensitivity to touch. In the first days of the life of the mammalian baby, the main tactile organ is the oral cavity. A touch to the lips causes him to suck.

Continuous exposure to mechano- and thermoreceptors leads to a decrease in their sensitivity, i.e. they quickly adapt to irritating factors. Skin sensitivity is closely related to internal organs (stomach, intestines, kidneys, etc.). So, it is enough to apply irritation to the skin in the area of ​​the stomach to get an increased acidity of the gastric juice.

With the irritation of painful receptors, the resulting excitement is transmitted to the sensitive nerves in the cerebral cortex. In this case, incoming impulses are identified as a result of pain. The feeling of pain is of great importance: pain signals violations in the body. The threshold of excitation of pain receptors is species-specific. So, in dogs it is somewhat lower than, for example, in humans. Irritation of pain receptors causes reflex changes: increased adrenaline release, increased blood pressure and other phenomena. With the action of certain substances, such as novocaine, pain receptors are turned off. This is used for local anesthesia in operations.

The irritation of skin's causes the sensation of heat and cold. Two types of thermoreceptors can be distinguished: cold and thermal. The temperature receptors are distributed unevenly in different parts of the skin. In response to the irritation of the temperature receptors, the lumen of the blood vessels narrows or widens reflexively, as a result of this the heat transfer changes, and the behavior of the animals also changes.

Although touch is somewhat limited in its ability to transmit information compared to other senses, in many respects it is the main of communication channels for almost all kinds of living matter that responds to physical contact.

Tactile sensitivity in different taxonomic groups is different.

Invertebrates

Tactile communication proves to be dominant in the social interactions of many invertebrates, for example in blind workers in some termite colonies that never leave their underground tunnels, or in earthworms that creep out of the burrows at night. Tactile signals are also found in a number of aquatic coelenterates: jellyfish, anemones, hydra. Tactile communication is of great importance for colonial coelenterates. So, when you touch a separate section of the colony of the hydroid polyps, the animals immediately contract into tiny lumps. Immediately after this all the other individuals of the colony are compressed.

Tactile communication by its nature is possible only at a very close distance. Long antennae of cockroaches and crayfish act as "scouts", which allow them to explore the world within a radius of one body length, but this is almost the limit for touch. In invertebrates, the touch is closely related to chemical sensitivity, because specialized tactile organs, such as antennas or palms of insects, are often also provided with chemoreceptors. Public insects, through a combination of tactile and chemical signals, transmit a large amount of diverse information to members of their colonies (Figure 4.1).

Tactile communication of ants

Fig. 4.1. Tactile communication of ants

In a colony of social insects, individuals constantly enter into direct physical contact with each other. Constant licking and sniffing each other's ants testifies to the importance of touching as one of the means that organize these insects into a colony. Similarly, by touching the antennas of the abdomen of their cows - aphids, ants inform them that they should allocate a droplet of "milk".

In colonies of some species of wasps, where females are united in a hierarchy system, a wasp standing at a lower hierarchy level, when meeting with the dominant, regurgitates before it the food that the dominating wasp immediately eats.

Higher Vertebrates

Tactile communication retains its significance in many vertebrates, particularly in birds and mammals. Tactile contacts are especially important for public species, whose representatives spend a considerable part of their time in physical contact with each other. In their relationship, a special place is taken by the so-called grooming, which consists in mutual cleaning, licking or simply fingering feathers or wool. Grooming, carried out by the female in the process of rearing the offspring, and mutual grooming of the young in the litter plays an important role for their physical and emotional development. It has been shown experimentally that cubs grown in isolation and devoid of mother grooming noticeably lag behind in their physical and mental development.

The physical contact between individuals in public species serves as a necessary link in regulating the relationship between members of the community. So, one of the most effective ways, which are usually resorted to by small songbirds - amadins, in order to pacify an aggressive neighbor, is the "demonstration of an invitation to purge the pen". With the possible aggression of one of the birds directed to the other, the target of attack attacks the head high and at the same time the tail plumage of the throat or occiput. As a result, instead of attacking a neighbor, the aggressor begins submissively tapping the feathered plumage of his throat or occiput with his beak (Figure 4.2).

A similar demonstration takes place in some rodents. When two animals meet, occupying different stages of the hierarchical ladder, the subordinate animal allows the dominant to lick its fur. By allowing the high-ranking individual to touch himself, the low-ranking one shows his submission and translates the potential aggressiveness of the dominant into another channel.

Friendly tactile communication in birds

Fig. 4.2. Friendly tactile communication in birds

Friendly bodily contacts are also widespread among highly organized animals. Touching

and other tactile signals during communication are often used by monkeys. Langurs, baboons, gibbons and chimpanzees hug each other friendly, the baboon can lightly touch, push, pinch, bite, sniff or even kiss another baboon as a sign of genuine sympathy. When two chimpanzees are first encountered, they can gently touch the head, shoulder or thigh of a stranger.

Monkeys constantly sort through wool - they clean each other, which serves as a manifestation of true intimacy, intimacy (Figure 4.3).

Mutual Grooming in Monkeys

Fig. 4.3. Mutual grooming in monkeys

Grooming is especially important in those primate groups where social dominance is maintained, for example in rhesus monkeys, baboons and gorillas. In such groups, the subordinate often reports, loudly smacking his lips, that she wants to clean the other, occupying a higher position in the social hierarchy. In monkeys, grooming is a typical example of sociosexual contact. Although this kind of relationship often unites animals of the same sex, nevertheless, such contacts are more often observed between females and males, the former playing an active role, licking and combing males, while the latter are limited to exposing the partner to those or other parts of his body. This behavior is not directly related to sexual relationships.

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