the World of an animal is defined by its sensations. Often prevailing role is played by any one sense organ, but also others continuously throw the owner information hailstones.
Ears of the owl silently flying over a meadow in a moonlight night, sensitively catch each rustle in a grass, and from its sharp-sighted eyes will not disappear the slightest movement. The mouse, probing shivering short moustaches road in dense raznotrave, finds on a smell food and all time listens attentively to night calm - whether the easy rustle of owl's wings will reach. The life completely depends on sense organs and mice, and owls. If will bring hearing or sight one is threatened with instant destruction, another - starvation. Anyhow, posterity it not to deduce any more. The life to new generation will be given only by those who will manage to survive, - owls and mice with the sense organs aggravated to a limit, and their posterity will inherit these qualities. So sensual perceptions of a predator and a victim are from generation to generation perfected in struggle for a survival. As a result of evolutionary process of an owl and the mouse became owners hardly probable not the most advanced sense organs in all animal kingdom.
For us there is no more important feeling, than sight, and some animals perfectly do without it, living in the dark world of smells and touches. However, the majority of live beings reacts to light in this or that form. We will tell, the earthworm does not have eyes, but all its body feels a sunlight. The worm hooked by a shovel immediately will feel that it has appeared on light, and will hasten to be earthed, far away from hungry bird's eyes and hot solar beams. At animals the light perception is concentrated mainly in groups of special photosensitive cages, i.e. In eyes. The most simple on a structure of an eye at larvae of insects, for example, at caterpillars. They feel light and moving shades of potential enemies, but anything more. Each simple eye consists of group of photosensitive cages, or a retina located behind a motionless crystalline lens which serves it as protection and focuses on it light beams.
Difficult compound eyes of an adult insect consist of set of simple eyes. So, the eye of a usual bee includes approximately 5000 fasetok, each of which covers the tiny field of vision and will transform it to the primitive image. Of these uncountable elements also there is a mosaic picture of world around.
However difficult eyes with their huge field of the review and excellent colour sensitivity nevertheless do not give the accurate image of a subject. In this sense single-chamber eyes of vertebrate animals (fishes, amphibious, reptiles, birds and mammals) and such advanced bespozvonochnyh, as squids and cuttlefishes are much more perfect.
In more advanced eye structure familiar to us "§Ёѕё=рышъ-ёх=ёр=ър" it is improved and allows to receive more accurate image. Much more widely and more variously a set of photosensitive cages and in the retina. At land animals light gets into an eye through a cornea - convex "юъю°ъю" forming a forward wall of an eye, - and a crystalline lens, the flexible lens, capable to change a refraction corner. Thanks to it focusing varies, and irrespective of distance on a retina the accurate image of a subject gets. The excellent visual acuity allowing such birds as the falcon-sapsan, to notice small extraction from height to 100 m and with sniper accuracy becomes result to amaze a victim.
The Distinctive feature of the majority of predators is also binocular sight. Two directly and close planted eyes see hardly different images of the same subject which, being combined in a brain, give sensation of depth. Ability unmistakably to define a distance to a victim has huge value for birds of prey.
But - to a pigeon - the circular review is required to their potential extraction in time to notice the enemy. Therefore his eyes are located on each side heads, expanding a point of view, but, without providing binocular vision. The same law is traced and at mammals - compare, for example, a wolf and a deer.
Colour of a light beam depends on length of a wave. The shortest light waves which the person is capable to distinguish, - violet, the long - red. At some animals, for example, dogs, colour sight is developed worse, than at us, but at others it leaves far beyond a visible spectrum. Many insects (butterflies, bees) react to the ultra-violet beams reflected by colours, and some snakes (boas, rattlesnakes, pythons) "тшф =" infra-red radiation of the warm-blooded victim, catching its special receptors in poles on a lip. With their help the rattlesnake finds extraction in a total darkness, steals up to it and strikes well-aimed blow.
If sight is a perception of light beams touch and hearing is a mechanical reaction of touch cages on external razdrazhiteli at direct contact to firm bodies, liquids or under the pressure of air. For some animals touch is pivotal of all feelings. To a walrus, digging out molluscs from a ground ground, helps to be guided with muddy water not only a gentle and sensitive skin on a muzzle, but also "ѕё№" consisting from 450 with superfluous hairs. Through a network of nervous fibres they transfer almost visible image of a sea-bottom in a brain. The same function is carried out by picturesque moustaches of other mammals and hairs at many other live beings. We will tell, insects feel nothing as a surface of the chitinous armour, but perfectly perceive surrounding subjects the thin hairs which have sprouted through kutikulu. At other animals this function is carried out by the nervous terminations located in especially sensitive sites of a skin. So, at primacies the most sensitive tactile zone are finger-tips, and at an elephant - a trunk tip. Osjazatelnye receptors of a snail are concentrated to tips flexible rozhek, and at marsh birds like kronshnepa - on a tip of a long beak.
the Lateral line
At fishes osjazatelnye receptors are collected in lateral lines on both parties of a body. The lateral line is the channel lasting under a skin from a head to a tail, supplied nearby osjazatelnyh receptors and opening outside the tiny in regular intervals located apertures. At movement of fish in water the slightest fluctuations of external pressure get into apertures of a lateral line and gidravlicheski are transferred along all channel, stimulating the nervous terminations.
Thanks to it fish perfectly feels the direct environment. Too close having swum up in the dark to an obstacle, she will feel increase of pressure and will turn aside. At approach of other subject - we will tell, the enemy - its remoteness, size, a direction of movement and even the form can be defined on waves which disperse from it in the dense water environment.
The Principle of action of organs of hearing about the same, as a lateral line. Sound waves is, as a matter of fact, the same fluctuations of pressure of air or water. So, published by movement of wings komarinyj peep represents 500 fluctuations of pressure (cycles) in a second, i.e. Its frequency is equal 500 hertz. That the ear has caught these fluctuations, sound waves should get to the acoustical channel supplied with a thin membrane - an eardrum. It vibrates in a resonance with fluctuations of external pressure, and these vibrations are transferred to group of the receptors hidden in an internal ear.
At mammals acoustical nerves are located in a twisting conic tube - a snail. The narrowed end of this tube reacts to high frequencies (high notes), and wide - on low. As well as in a case with the sight, different animals perceive various ranges of sounds. The whale hears the low-frequency sound signals reaching for hundreds of kilometres in ocean waters. But the bat catches sounds frequency to 100 thousand hertz. The top limit zvukovosprijatija makes the person of all 20 thousand hertz.
The Bat in own way uses a hypersensibility to high frequencies. The majority of these small animals is guided in space on a sound, continuously publishing high-frequency poshchelkivanija and defining distance to obstacles and extraction on the reflected signal. The above frequency of impulses, the works system more effectively.
It is curious that ears of the majority of moths are set up so that sensitively catch these ultrasonic impulses. Bats - their main enemies so the before them you will hear, the better.
Some animals do not have ears as those, but they feel the vibrations transferred by firm materials. The snake is absolutely deaf from the anatomic point of view, but bones of its jaw and a skull catch the easiest concussions of soil.
We seldom realise "Sense organs" that air is full of the smallest chemical particles which for some animals are not less informative, than images or sounds. The snake hunting in a grass, continuously tries air the doubled language which submits the caught particles to a special receptor in the top sky, named Yakobson's body. Analyzing their chemical compound, the snake unmistakably tracks down a victim.
The Dog too sniffs to air (and to subjects), involving a nose soaring chemical particles. For it the smell is the main characteristic of world around, and even with the relatives it communicates with the help of smells, leaving the "тшчш=э№х ърЁ=юёъш" at each lamppost.
The Smell is capable to transmit strong sexual signals, and many females use smells for attraction of males. These chemical substances named feromonami, are often carried by a wind and caught by males on huge distances. So, the female of a silkworm develops feromon bombikol, and the male catches its receptors similar to aerials. They are set sensitively up on strictly certain substance, and, hardly having felt its presence at air, the insect directs to a smell source.
With the mechanism of sense of smell flavouring sensation - the mechanism is in many respects similar to that difference that chemical particles are dissolved in liquids and felt only in a mouth. The aggravated flavouring perception meets at the most unexpected animals, serving as reliable protection against poisonous food. So, the spider often suffices and will paralyse improper extraction, but, hardly having tried it, immediately throws out away.
We have rather foggy idea About touch systems of some animals. It is known that the shark is guided, first of all, by sharp sense of smell. But at a short distance it finds the victim captured by fear on weak electrosignals of its nervous fibres. Them catches "ср=рЁхщър" from the receptors filled with jellylike weight in a head of a shark, and at some small kinds these bodies even can generate the chaotic electric categories confusing large sharks.
To some signs, sharks use this system and for orientation at ocean, somehow becoming isolated on a magnetic field of the Earth (magnetism and an electricity - closely connected phenomena). Similar bodies, apparently, serve as navigating devices to whales and birds of passage.
The Animal not only reacts to world around. Sense organs are necessary to it and to operate own body - to keep balance, to be guided in space, to feel a pain, hunger, weariness, fear and many other things.
Many functions are carried out automatically, without the realised analysis. Out of the realised control some mechanisms of perception of an external world operate also. All of us yet do not know, how the information arriving from the outside is processed. However, judging at least on capacity of computers demanded for this purpose, it is easy to present, what extensive sites of a brain are occupied by decoding of a chaotic stream of touch signals, comparing them and connecting in a complete picture of world around - or that, than this world is represented to our sense organs.