Animal sense organs. General characteristics of animal sense organs

If we humans have any superiority over animals, then this certainly does not extend to the senses...

1. Catfish - a giant floating tongue

The average person has 10,000 lingual papillae. And they are all concentrated in one place - in the language. According to the statements of one neurophysiologist and part-time fish specialist, a catfish 15 centimeters long has at least 250,000 taste buds. And they are located throughout its body. That is, no matter where you touch him, he will always feel what you taste like. Unless it's fried, of course.

2. Bats “see” our circulatory system

Bats (a species called "vampires") are the only mammals that feed on blood. This gastronomic addiction is associated with an unusual subtle development feelings, thanks to which, by the way, bats received their extremely unaesthetic nose from Mother Nature. This sense allows animals to “see” the blood running through your veins.

The nose of the “vampires” is equipped with a kind of infrared detector that responds to changes in body temperature – at a distance. This is already surprising because other mammals, including you and me, need to touch an object to tell whether it is warm or cold. But the most amazing thing is that they can determine which vein is of greatest interest to them.

Their “heat sensors” are so advanced that they don’t have to waste time repeatedly sinking their teeth into the flesh of their prey. "Vampires" hit the vein, and always on the first try.

3. Narwhal Tusk – A Giant Sensitive Organ

For a long time, scientists wondered why the narwhal needed this strange tusk protruding from its head. And finally we found out. First of all, the tusk turned out to be not even a tusk at all, but a tooth. One (occasionally two) long, spiral-shaped tooth covered with ten million nerve endings.

Studies have shown, for example, that a narwhal can determine the degree of salinity of water with its teeth. Why do they need this? Salt content affects the freezing of water. And if you live among floating ice floes and breathe air, then it is very important for you to know that at any moment you can rise to the surface.

So the tusk-tooth is a device that can predict the formation of ice. And not only. It can detect temperature, water pressure, and if lifted into the air, barometric pressure.

4. The ghost fish hunts and observes at the same time using mirror vision

Ghost fish (opisthoproctaceae family) is one of the most unusual inhabitants depths of the sea. She was associated with a nightmare thanks to her eyes - two large orange spheres.

In order not to get caught in the teeth of a predator, this fish must be constantly on alert - even when hunting itself. That is, she needs an all-round view. And she has one.

The ghost fish's eyes are divided into two parts, allowing it to look forward and backward at the same time. It's like having an extra pair of eyes in the back of your head.

Only in the case of our fish this is not a separate pair of eyes, but a complex system with built-in curved plates resembling a mirror, which allow you to capture the finest glow half a kilometer below the surface of the water. That is, these are more likely not even eyes on the back of the head, but a pair of special glasses with built-in mirrors that allow you to see what is happening behind.

When the ghost fish goes hunting, the little black eyes you see on the sides are looking for future food. And what looks like big orange eyes from above is back side a mirror surface that captures biological luminescence and warns of the appearance of predators.

5. Clam with stone eyes

The shell mollusk or chiton does not look anything interesting - it looks like a wood lice. But he also has something truly amazing - stone eyes. We don't mean to say that this creature has eyes that look like stone. They consist of aragonite - a form of limestone, the same one that is part of mollusk shells.

And there can be several hundred such stone eyes on a mollusk shell.

Mollusks somehow manage to achieve optical qualities from the material from which we build houses, and “make” an optical lens out of it... Scientists have yet to figure out how. And although chitons’ vision is not very good, with their stone eyes they are quite capable of distinguishing light from shadow and even distinguishing the shape of an object.

Any living organism is an ideal system, and if the circulatory, nervous and others allow us to exist, then the sense organs are exactly what the body uses to know and perceive external environment. Moreover, each class of animal organisms has its own characteristics.

Sense organs of fish

Representatives of this class of animals have fairly developed eyes, which consist of a retina, lens and cornea. Fundamental difference of these organs is that when perceiving an image, the lens does not change curvature, like in other vertebrates - it simply moves relative to the cornea, thereby focusing the gaze.

They are found in fish and consist of three semicircular, mutually perpendicular canals. Some representatives have the so-called Weber's organ, which connects the cavity of the inner ear with the organ, which in this case works as a sound resonator. Receptors for taste and smell can be located not only in the mouth and nostrils, but also scattered throughout the body.

Another interesting organ is the lateral line, which is a collection of channels associated with nerve fibers. The lateral line is especially developed in those fish that do not have eyes - it is thanks to it that they can perceive the outside world and maintain balance.

It's no secret that some fish can react to electric fields and even generate electrical impulses using special cells and nerve fibers.

Sense organs of amphibians

The sense organs of representatives of this class are already more adapted to existence in air environment. For example, their eyes already have eyelids, as well as a nictitating membrane, which performs moisturizing and protective functions. The lens can change its size depending on the lighting.

In addition, amphibians have olfactory sacs that open outward through the nostrils. An animal can perceive odors only in the air. As for the hearing organs, amphibians are already developing a small bone called the stapes.

All mechanical receptors are located in skin tissues. In primitive aquatic amphibians, as well as in tadpoles, the lateral line is still preserved.

Sense organs of reptiles

Representatives of this class have more developed senses and are adapted to life in the air. Very important for these animals are the eyes, which are more developed than those of amphibians - there are developed muscles that are attached to the lens and can change its curvature to focus the image. In addition, reptiles develop real secretions that protect the animal’s eyes from drying out. There are also movable eyelids.

Such animals have choanae (internal nostrils), which are located closer to the throat, which greatly facilitates breathing while eating. It has been proven that reptiles are much more sensitive to odors than representatives of the amphibian class.

The taste organs are represented by specific structures - taste buds, which are located in the pharynx. And between the eyes and nose there is the so-called facial fossa, which allows you to react to temperature changes. For example, in some snakes this organ allows them to quickly find food.

The hearing organs are not very well formed and resemble the hearing aid of amphibians. Reptiles have a middle and eardrum, as well as a stapes - a small bone that transmits vibrations to the eardrum. Hearing is not particularly important in the life of these animals. For example, in snakes it is practically not developed.

As can be seen, the sense organs gradually changed during evolution, adapting to survival in certain conditions and becoming more complex and functional.

“Qualities exist only insofar as it is customary to consider sweet as sweet, bitter as bitter, hot as hot, and color as colorful. however, only atoms and emptiness really exist.” Democritus, 460-370. BC. "Tetralogies"

Night vision. The huge eyes of the slender loris help him navigate, moving in complete darkness through the night forest. Lorises are nocturnal animals and rely primarily on their sense of smell to find prey. They use scent marks and sounds to transmit information to relatives.

Scout eye. Our knowledge of the nature of light suggests that the eyes of a horsefly cannot discern fine details, but since the workings of the brain are not well understood, we cannot reproduce what this fly sees.

Animals' sense organs are not like humans'. Some animals see light that is invisible to us. Others hear sounds that our ears cannot perceive. Some animals are sensitive to magnetic field Earth and to the electric field. Dolphins reproduce a three-dimensional picture of the world around them, much more detailed than a person sees, but at the same time they use echolocators that catch reflections of the sounds they make. The picture of atoms and void that a dolphin creates by converting reflected echoes is almost certainly very different from the one we create with our eyes and brain. We will probably never be able to experience the world the way a dolphin sees it, but by studying the behavior of animals, we can find out what stimuli they react to and how their senses help them survive. Democritus would be surprised at such modest progress in the study of animal life.

Hunting by ear. This bat - the horseshoe bat - makes sounds during the hunt, which, reflected from flying insects, help it determine their location. One sound repeated 10 times per second allows the mouse to detect the insect. “When it comes to the victim,” it makes a glissando - a sequence of merging sounds, which helps to make an accurate throw.

Snake sense organs. The Gaboon viper, or cassava, “sees” in the dark by detecting changes in temperature using temperature sensors in the pits on its face. The ears perceive only low frequencies. The organ of smell is the forked tongue, with which the snake “tastes” the air.

Only smell and touch. U starfish there are no eyes or ears; crawling along the seabed in search of food, they rely on touch and smell.

Bone dome. The beluga whale's domed skull is part of its echolocation transmission system, serving as a lens that focuses sounds into a narrow beam.

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The world of an animal is determined by its sensations. Often one sense organ plays a predominant role, but others constantly bombard the owner with a hail of information.

The ears of an owl, silently flying over a meadow on a moonlit night, sensitively catch every rustle in the grass, and not the slightest movement can be hidden from its keen eyes. The mouse, probing its way through the thick grass with its trembling antennae, looks for food by smell and all the time listens to the silence of the night to see if the light rustle of an owl's wings can be heard. The life of both mice and owls depends entirely on the senses. If hearing or vision fails, then one faces instant death, the other - starvation. One way or another, they will no longer produce offspring. Life will be given to a new generation only by those who can survive - owls and mice with senses heightened to the limit, and their offspring will inherit these qualities. Thus, from generation to generation, the sensory perceptions of predator and prey are sharpened in the struggle for survival. As a result evolutionary process owls and mice became the owners of perhaps the most highly developed sense organs in the entire animal kingdom.

For you and me, there is no more important sense than vision, and some animals do well without it, living in a dark world of smells and touches. However, most living things react to light in one form or another. Let's say an earthworm has no eyes, but its whole body senses sunlight. A worm picked up by a shovel will immediately feel that it is in the light and will hasten to bury itself in the ground, away from the hungry bird eyes and hot sun rays. In animals, light perception is concentrated mainly in groups of special light-sensitive cells, i.e., in the eyes. The most simple eyes in structure are those of insect larvae, for example, caterpillars. They sense light and the moving shadows of potential enemies, but nothing more. Each simple eye consists of a group of light-sensitive cells, or retina, located behind a fixed lens, which protects it and focuses light rays on it.

Compound eyes

The complex compound eyes of an adult insect consist of many simple ocelli. Thus, the eye of an ordinary bee includes approximately 5,000 facets, each of which covers its own tiny field of vision and transforms it into a primitive image. From these countless elements a mosaic picture of the surrounding world is formed.

However, compound eyes, with their huge field of view and excellent color sensitivity, still do not provide a clear image of an object. In this sense, the single-chamber eyes of vertebrates (fish, amphibians, reptiles, birds and mammals) and highly developed invertebrates such as squids and cuttlefish are much more perfect.

In a more highly developed eye, the familiar lens-retina structure is improved and allows for clearer images. The set of light-sensitive cells in the retina itself is much wider and more diverse. In land animals, light enters the eye through the cornea, a convex “window” that forms the front wall of the eye, and the lens, a flexible lens that can change the angle of refraction. Thanks to this, the focus changes, and regardless of the distance, a clear image of the object appears on the retina. The result is superior visual acuity, allowing birds such as the peregrine falcon to spot small prey from heights of up to 100 m and strike prey with sniper precision.

A distinctive feature of most predators is binocular vision. Two straight and close-set eyes see slightly different images of the same object, which, when combined in the brain, give a sense of depth. The ability to accurately determine the distance to prey is of great importance for birds of prey.

But their potential prey - the pigeon - requires all-round visibility in order to notice the enemy in time. Therefore, his eyes are located on the sides of his head, expanding the angle of vision, but not providing binocular vision. The same pattern can be seen in mammals - compare, for example, a wolf and a deer.

Color perception

The color of the light beam depends on the wavelength. The shortest light waves that a person can distinguish are violet, the longest are red. Some animals, such as dogs, have less developed color vision than us, but in others it goes far beyond the visible spectrum. Many insects (butterflies, bees) react to reflected flowers ultra-violet rays, and some snakes (boas, rattlesnakes, pythons) “see” infrared radiation its warm-blooded prey, capturing it with special receptors in the pits on the lip. With their help, the rattlesnake finds prey in pitch darkness, approaches it and delivers a well-aimed blow.

Touch

If vision is the perception of light rays, then touch and hearing are the mechanical reaction of sensory cells to external stimuli in direct contact with solids, liquids or air pressure. For some animals, touch is the most important of all senses. Helps a walrus digging out shellfish from the bottom soil muddy water not only the delicate and sensitive skin on the face, but also the “whiskers”, consisting of more than 450 hairs. Through a network of nerve fibers, they transmit an almost visible image of the seabed to the brain. The same function is performed by the picturesque whiskers of other mammals and hairs in many other living creatures. For example, insects do not feel anything with the surface of their chitinous shell, but they perfectly sense the surrounding objects with thin hairs growing through the cuticle. In other animals, this function is performed by nerve endings located in particularly sensitive areas of the skin. Thus, in primates the most sensitive tactile zone is the fingertips, and in the elephant - tip of the trunk. The snail's tactile receptors are concentrated on the tips of its flexible horns, while in wading birds like the curlew they are concentrated on the tip of its long beak.

Side line

In fish, tactile receptors are collected in the lateral lines on both sides of the body. The lateral line is a canal that runs under the skin from head to tail, equipped with a number of tactile receptors and opening outward into tiny, evenly spaced holes. When a fish moves in water, the slightest fluctuations in external pressure penetrate the holes in the lateral line and are hydraulically transmitted along the entire channel, stimulating the nerve endings.

Thanks to this, the fish has a great sense of its immediate surroundings. Swimming too close to an obstacle in the dark, she will feel an increase in pressure and turn to the side. When another object approaches - say, an enemy - its distance, size, direction of movement and even shape can be determined by the waves that diverge from it in a dense water environment.

Hearing

The principle of operation of the hearing organs is approximately the same as that of the lateral line. Sound waves are essentially the same fluctuations in air or water pressure. Thus, a mosquito squeak emitted by the movement of its wings represents 500 pressure fluctuations (cycles) per second, i.e. its frequency is 500 hertz. In order for the ear to catch these vibrations, sound waves must enter the auditory canal, which is equipped with a thin membrane - the eardrum. It vibrates in resonance with fluctuations in external pressure, and these vibrations are transmitted to a group of receptors hidden in the inner ear.

In mammals, the auditory nerves are located in a winding conical tube called the cochlea. The tapered end of this tube responds to high frequencies (high notes), and the wide end responds to low notes. As with vision, different animals perceive different ranges of sounds. Keith hears low frequencies sound signals, reaching hundreds of kilometers away ocean waters. But the bat picks up sounds with a frequency of up to 100 thousand hertz. The upper limit of human sound perception is only 20 thousand hertz.

Echolocation

The bat uses its increased sensitivity to high frequencies. Most of these animals navigate in space by sound, continuously emitting high-frequency clicking sounds and determining the distance to obstacles and prey by the reflected signal. The higher the pulse frequency, the more efficiently the system operates.

It is curious that the ears of most moths are tuned in such a way that they sensitively detect these ultrasonic impulses. Bats are their main enemies, so the sooner you hear them, the better.

Some animals do not have ears as such, but they sense vibrations transmitted by solid materials. The snake is completely deaf anatomical point vision, but the bones of her jaw and skull detect the slightest tremors of the ground.

Chemical feelings

We rarely realize that the air is full of tiny chemical particles that, for some animals, are as informative as sights or sounds. A snake hunting in the grass continuously tastes the air with its forked tongue, which delivers the caught particles to a special receptor in the upper palate called Jacobson's organ. Analyzing them chemical composition, the snake unerringly tracks its prey.

The dog also sniffs the air (and objects), drawing in floating chemical particles with its nose. For her the smell is main characteristic the surrounding world, and even with her relatives she communicates through smells, leaving her " Business Cards"at every lamppost.

Pheromones

Scent can convey strong sexual signals, and many females use scents to attract males. These chemical substances, called pheromones, are often carried by the wind and are picked up by males over vast distances. Yes, female silkworm produces the pheromone bombycol, and the male picks it up with antenna-like receptors. They are sensitively tuned to a strictly defined substance, and, barely sensing its presence in the air, the insect rushes to the source of the smell.

The mechanism of taste is in many ways similar to the mechanism of smell - with the difference that chemical particles are dissolved in liquids and are felt only in the mouth. Heightened taste perception is found in the most unexpected animals, serving as a reliable defense against poisonous food. Thus, the spider often grabs and paralyzes unsuitable prey, but, having barely tasted it, immediately throws it away.

Electromagnetic senses

We have a very vague idea of ​​the sensory systems of some animals. It is known that the shark is guided primarily by its acute sense of smell. But at a close distance, she finds a victim gripped by fear by weak electrical signals from her nerve fibers. They are captured by a “battery” of gelatinous receptors in the shark’s head, and in some small species these organs can even generate random electrical discharges that confuse large sharks.

According to some signs, sharks also use this system for orientation in the ocean, somehow closing in on the Earth’s magnetic field (magnetism and electricity are closely related phenomena). Similar organs apparently serve as navigation devices for whales and migratory birds.

Inner feelings

The animal not only reacts to the world. He also needs sense organs in order to control his own body - maintain balance, navigate in space, feel pain, hunger, fatigue, fear and much more.

Many functions are performed automatically, without conscious analysis. Some mechanisms of perception of the external world also operate outside of conscious control. We still don't know how information coming from outside is processed. However, judging at least by the power of the computers required for this, it is not difficult to imagine what vast areas of the brain are busy deciphering the chaotic flow of sensory signals, comparing them and connecting them into a coherent picture of the world around us - or how this world appears to our senses.

The only way to understand the world is through our senses. Consequently, the senses are the basis for understanding what is happening around us. It is commonly believed that we have five senses, but in reality there are at least nine, and maybe more, depending on what we understand by the word “sense”...

But, be that as it may, the animal world in this regard is ready to put any of us to shame. Some animals have abilities that are also inherent in humans, but in animals they are much more developed, and therefore we perceive the reality around us completely differently.

Electronic beak

At first, the description of the platypus, a mammal with a duck's beak that hatches eggs, was perceived as a practical joke. Well, what's the point of a ridiculous duck beak?

The platypus feeds on small invertebrates that live at the bottom of rivers and lakes. When he dives, his eyes, nostrils and ears are completely closed to prevent water from entering. The beak of the platypus is literally stuffed with sensitive sensors that can detect even the weakest electric fields that arise during the movement of living organisms.

Along with detecting electric fields, the platypus's beak is also very sensitive to disturbances that occur in the water column. These two senses, electroreception and mechanoreception, allow the platypus to determine the location of its prey with amazing accuracy.

Echolocation

Bats are traditionally considered blind compared to ordinary animals. If the eyes bat much smaller than other predators, and not nearly as sharp-sighted, this is only because these mammals have developed the ability to hunt using sound.

Echolocation bats lies in the ability to use high-frequency sound pulses and the ability to capture the reflected signal, by which they estimate the distance and direction to the objects around them. At the same time, when calculating the speed of insects, they evaluate their prey not only by the time spent passing the impulse back and forth, but also take into account the Doppler effect.

Being nocturnal animals and hunting mainly small insects, the bat needs abilities that are not dependent on light. Humans have a weak, rudimentary form of this sense (we can tell which direction a sound is coming from), but some individuals develop this ability into true echolocation.

Infrared vision

When police are chasing criminals at night, or rescuers are searching for people under rubble, they often resort to using infrared imaging devices. A significant part of the thermal radiation of objects when room temperature displayed in the infrared spectrum, which can be used to assess surrounding objects based on their temperature.

Some species of snakes that hunt warm-blooded animals have special indentations on their heads that allow them to capture infrared radiation. Even after being blinded, the snake can continue to hunt unerringly using its infrared vision. It is noteworthy that at the molecular level, the snake's infrared vision is completely unrelated to ordinary vision in the visible spectrum, and must develop separately.

Ultraviolet

Many people would agree that plants are beautiful. However, while plants are just decoration for us, they are vital not only to themselves, but also to the insects that feed on them. Flowers that are pollinated by insects have an "interest" in attracting those insects and helping them find the right way. For bees appearance a flower can mean much more than the human eye can see.

So, if you look at a flower in the ultraviolet spectrum, you can see hidden patterns, designed to point the bees in the right direction.

Bees see the world completely differently from us. Unlike us, they distinguish several spectra visible light(blue and green), and have special groups of cells for capturing ultraviolet radiation. A botany professor once said, “Plants use colors like whores use lipstick when they want to attract a client.”

Magnetism

Bees also have a second sensual trick hidden up their furry little sleeves. For a bee, finding the hive at the end of a day of continuous flight is a matter of life and death. For the hive, in turn, it is very important that the bee remembers where the food source is and can find its way to it. But despite the fact that bees can do a lot, they can hardly be called incredibly gifted mental abilities.

They must use a lot of volume to navigate various information, including sources hidden in its own abdominal cavity. The smallest ring of magnetic particles, magnetic iron granules, hidden in a bee’s belly, allow it to navigate in the Earth’s magnetic field and determine its location.

Polarization

When light waves oscillate in one direction, it is called polarization. Humans cannot detect the polarization of light without the help of special equipment because the light-sensitive cells in our eyes are arranged randomly (unevenly). In an octopus, these cells are ordered. And the more evenly the cells are located, the brighter the polarized light.

How does this allow the octopus to hunt? One of the best forms of camouflage is to be transparent, and a huge amount sea ​​creatures practically invisible. However, polarization of light occurs under the water column, and some octopuses take advantage of this. When such light passes through the body of a transparent animal, its polarization changes, the octopus notices this - and grabs the prey.

Sensitive shell

Humans have the ability to feel through their skin because there are sensory cells all over its surface. If you wear a protective suit, you will lose most of your sensation. This may cause a lot of inconvenience for you, but for a hunting spider it would be a real disaster.

Pacu, like other arthropods, have a strong exoskeleton that protects their body. But how, in this case, do they feel what they touch, how do they move without feeling the surface with their feet? The fact is that their exoskeleton has tiny holes, the deformation of which makes it possible to determine the force and pressure exerted on the shell. This gives spiders the opportunity to sense the world around them as strongly as possible.

Taste sensations

In most communities, it is customary to keep your mouth shut. Unfortunately, this is not possible for catfish, because its entire body, in fact, is a solid tongue covered with taste sensory cells. More than 175 thousand of these cells allow you to feel the entire spectrum of flavors passing through them.

The ability to capture the subtlest taste nuances gives these fish the opportunity not only to sense the presence of prey at a considerable distance, but also to accurately determine its location, and this all happens in very muddy water - the typical habitat of catfish.

blind light

Many organisms that have evolved in dark environments have only rudimentary, vestigial vision, or even no eyes at all. In any pitch-black cave, being able to see is of no use.

The cave fish “Astyanax mexicanus” has completely lost its eyes, but in return nature has given it the ability to detect even the faintest changes in light that can be found under the rocky layer. This ability allows the fish to hide from predators, since a special pineal gland detects light (and at the same time is responsible for the sense of day and night).

These fish have a translucent body, allowing light to pass directly through the pineal gland without obstruction, which helps them find shelter.

Point Matrix Vision

In living nature we can find a stunning variety of shapes and types of eyes. Most consist of lenses that focus light onto light-sensitive cells (the retina) that project images of the world around us. To focus an image correctly, lenses can change shape like a human's, move back and forth like an octopus's, and a myriad of other ways.

For example, a representative of the crustacean species “Copilia quadrata” uses an unusual method to display the surrounding world. This crustacean uses two fixed lenses and a movable sensitive light spot. By moving the sensitive detector, Copilia builds perceives the image as a series of numbered dots, each of which is located in its place depending on the intensity of the light.