Who has the best eyesight in the world. Which animal has the best vision Animal vision

Not only chameleons, but also seahorses can look in two directions at once. Animals often see much better than humans.

Even those who are considered the closest genetic relatives of man - monkeys - see three times better than him. And not only them, of course. The eagle, for example, also has three times as sharp a vision as a man.

Deep-sea fish, as you know, can see in pitch darkness, and all because the density of placement of rods in their retina reaches 25 million / sq. mm, which is 100 times more than in humans.

Cats also see perfectly in the dark, because their pupils can expand up to 14 millimeters. Yes, and dogs in the dark see three times better than we do.

In dogs, visibility is on average 240-250 degrees, which is 60-70 units higher than similar capabilities inherent in humans.

The dove has a 340-degree field of view. In a horse with a raised head, vision also approaches spherical. However, as soon as the horse lowers its head, it loses half of its vision. The record holder in panoramic vision is the woodcock bird, whose vision is almost circular!

In a fly, the image change rate is 300 frames per second, i.e. it exceeds the similar ability of a person by 5-6 times.

White butterflies (colias) can distinguish image elements as small as 30 microns, more than three times faster than humans.

The vulture distinguishes small rodents from a distance of up to 5 kilometers.

The falcon is able to see a target of 10 cm from a distance of 1.5 km, and even at high speed it retains the clarity of the image of objects.

The cockroach notices a movement of 0.0002 mm. So when you stand in the kitchen and try to pounce on a cockroach to kill it with a slipper, you have almost no chance.

four-eyed

These fish live in Mexico and Central America. They are very small, up to 32 cm in length, they feed on insects, so they spend most of their time near the very surface of the water. Despite their name, these fish only have 2 eyes. However, these eyes are separated by a vein, and each half has its own pupil. This strange adaptation allows the four-eyed bird to see well both above and below water.

stalk-eyed flies

These small but unusual creatures live in the jungles of Southeast Asia and Africa. They got their name because of the long protrusions on both sides of the head with eyes and antennae at the end. Males have longer stems. Females have been observed to prefer males with longer stems.

Tarsier

It is a small nocturnal primate that lives in the rainforests of southeast Asia. This is the only predatory primate in the world, it feeds on lizards, insects and even birds. But its most interesting feature is its huge eyes, disproportionately large in relation to the whole body. If these proportions are applied to a person, then his eyes should be the size of a grapefruit. The tarsier has very sharp eyesight. It has even been suggested that they can see ultraviolet light. On the other hand, tarsiers have poor color discrimination, like many other nocturnal predators.

Chameleon

Chameleons are known for their color-changing ability, which helps them communicate and express their intentions or moods (only a few chameleon species use color change as camouflage). These lizards also have very unusual eyes. The eyelids are fully connected, there is only a small gap for the pupil. Each eye moves independently of the other, allowing the chameleon to keep an eye on prey and possible threat at the same time.

Dragonfly

The dragonfly's eyes are so large that they cover almost the entire head, making it look like a helmet and giving it a 360-degree field of view. These eyes are made up of 30,000 parts, each containing a lens and several light-sensitive cells. Dragonflies have excellent eyesight. They can detect colors and polarized light, and dragonflies are especially sensitive to movement.

leaf tail gecko

The leaf-tailed gecko has very unusual eyes. He has vertical pupils that have several "holes" in them. These openings widen at night allowing these lizards to see better. Gecko eyes contain many more photosensitive cells than human eyes, enabling the animal to detect objects and even distinguish colors at night. While cats and sharks see 6 and 10 times better than humans, geckos see 350 times better.

colossal squid

It is the largest invertebrate known to science. This squid also has the largest eyes in the animal kingdom. Each eye can be up to 30 cm wide. Such large eyes allow the squid to see in the semi-darkness, which is very useful for an animal that spends almost all of its time hunting at a depth of 2000 m underwater.

Opisthoproct

Opisthoproct is a deep-sea fish with one of the strangest eye structures. A characteristic feature of the opisthoproct are the eyes of a cylindrical shape, directed upwards.

mantis shrimp

These crayfish are known for their aggressiveness and peculiar weapons (they have a very sharp and powerful claw that can easily cut a human finger in two and break glass in an aquarium). Mantis shrimp have the most complex eye in the animal kingdom. They distinguish between 12 primary colors - four times more than humans, as well as various types of light polarization, that is, the direction of vibration of a light wave. Light-sensitive cells of the eye rotate relative to the plane of polarization of light, perceiving almost the entire visible spectrum - from the ultraviolet to the infrared. Now we can only guess what the world looks like for this crustacean.

Ogre spider

Spiders are known to have many eyes. The ogre spider has 6, but it looks like it has 2, as the middle pair of eyes is very enlarged. All this serves to improve night vision. Ogre spiders have excellent night vision, not only because of the size of their eyes, but also because of the large number of light-sensitive lenses that cover them. This membrane is so sensitive that it breaks down every morning and grows back at night.

We see the world around us and it seems to us that it is exactly like that. It's hard to even imagine that someone sees it differently, in black and white, or without blue and red. It is hard to believe that for someone our familiar world is completely different.

But that's just the way it is.

Let's look at the world around us through the eyes of animals, let's figure out how animals see, in what colors they perceive the world.

So, to begin with, we will analyze what vision is and what functional abilities it includes.

What is vision?

Vision is the process of processing images of objects in the surrounding world.

• carried out by the visual system
• allows you to get an idea of ​​the size, shape and color of objects, their relative position and distance between them

The visual process includes:

• penetration of the light flux through the refractive media of the eye
• focusing light on the retina
• transformation of light energy into a nerve impulse
• transmission of nerve impulses from the retina to the brain
• information processing with the formation of the seen image

visual functions:

• light perception
• perception of moving objects
• field of view
• visual acuity
• color perception

Light perception - the ability of the eye to perceive light and determine the various degrees of its brightness.

The process of adapting the eye to different lighting conditions is called adaptation. There are two types of adaptation:

• to dark - when the light level decreases
• and towards the light - with an increase in the level of illumination

Light perception is the basis of all forms of visual sensation and perception, especially in the dark. The light perception of the eye is also affected by factors such as:

• distribution of rods and cones (in animals, the central area of ​​the retina at 25 ° consists mainly of rods, which improves night perception)
• the concentration of light-sensitive visual substances in rods (in dogs, the sensitivity to light of rods is 500-510nm, in humans 400nm)
• the presence of a tapetum (tapetum lucidum) - a special layer of the choroid of the eye (the tapetum sends back the photons that have passed to the retina, forcing them to once again act on the receptor cells, increasing the light sensitivity of the eye, which in low light conditions is very valuable) in cats, the eye reflects 130 times more light than a human (Paul E. Miller, DVM, and Christopher J. Murphy DVM, PhD)
• pupil shape - the shape, size and position of the pupil in various animals (the pupil is round, slit-like, rectangular, vertical, horizontal)
• the shape of the pupil can tell whether the animal belongs to predators or prey (in predators, the pupil narrows into a vertical strip, in victims into a horizontal one - scientists discovered this pattern by comparing the shapes of pupils in 214 species of animals)

So, what are the forms of pupils:

• Slit-shaped pupil - (in predatory animals such as domestic cats, crocodiles, gecko lizards, snakes, sharks) allows you to more accurately adjust the eye to the amount of light around, so that you can see in the dark and not go blind in the midday sun

• Round pupil - (in wolves, dogs, big cats - lions, tigers, cheetahs, leopards, jaguars; birds) because. they are spared the need to see well in the dark

• The horizontal pupil (herbivores) allows the eye to see well what is happening near the ground and covers a fairly wide panorama of the eye is protected from direct sunlight from above, which could blind the animal

How do animals perceive moving objects?

The perception of movement is vital because moving objects are signals of either danger or potential food and require prompt appropriate action, while stationary objects can be ignored.

For example, dogs can recognize moving objects (thanks to a large number of rods) at a distance of 810 to 900 m, and stationary objects only at a distance of 585 m.

How do animals react to flickering light (for example, on TV)?

The reaction to flickering light gives an idea of ​​the function of rods and cones.

The human eye is able to pick up oscillations of 55 hertz, while the dog's eye picks up oscillations at a frequency of 75 hertz. Therefore, unlike us, dogs, most likely, see only a flicker and most of them do not pay attention to the image on the TV. Images of objects in both eyes are projected onto the retina and transmitted to the cerebral cortex, where they merge into one image.

What are the visual fields of animals?

The field of view is the space perceived by the eye when the gaze is fixed. There are two main types of vision:

• binocular vision - perception of surrounding objects with two eyes
• monocular vision - the perception of surrounding objects with one eye

Binocular vision is not available in all animal species and depends on the structure and relative position of the eyes on the head. Binocular vision allows you to make fine coordinated movements of the forelimbs, jumps, and move easily.

Predators binocular perception of hunting objects helps to correctly assess the distance to the intended prey and choose the optimal trajectory of the attack. In dogs, wolves, coyotes, foxes, jackals, the angle of the binocular field is 60-75°, in bears 80-85°. Cats have 140° (the visual axes of both eyes are nearly parallel).

Monocular vision with a large field allows potential victims (marmots, ground squirrels, hares, ungulates, etc.) to notice the danger in time. reaches 360° in rodents, 300-350° in ungulates, and more than 300° in birds. Chameleons and seahorses are able to look in two directions at once, because. their eyes move independently of each other.

Visual acuity

• the ability of the eye to perceive two points located at a minimum distance from each other as separate
• the minimum distance at which two points will be seen separately depends on the anatomical and physiological properties of the retina

What does visual acuity depend on?

• on the size of the cones, the refraction of the eye, the width of the pupil, the transparency of the cornea, the lens and the vitreous body (they make up the light-refracting apparatus), the state of the retina and optic nerve, age
• cone diameter determines the magnitude of maximum visual acuity (the smaller the diameter of the cones, the greater the visual acuity)

The visual angle is the universal basis for expressing visual acuity. The limit of sensitivity of the eye of most people is normally equal to 1. In humans, to determine visual acuity, the Golovin-Sivtsev table containing letters, numbers or signs of various sizes is used. In animals, visual acuity is determined using (Ofri ., 2012):

• behavioral test
• electroretinography

The visual acuity of dogs is estimated at 20-40% of the visual acuity of humans, i.e. a dog recognizes an object from 6 meters, while a person recognizes it from 27 meters.

Why can't dogs have human visual acuity?

Dogs, like all other mammals except monkeys and humans, lack the fovea fovea (the area of ​​maximum visual acuity). Most dogs are slightly farsighted (hypermetropia: +0.5 D), i.e. they can distinguish small objects or their details at a distance of no closer than 50-33 cm; all objects that are closer seem blurry, in circles of dispersion. Cats are nearsighted, meaning they don't see distant objects as well. The ability to see well up close is more suitable for hunting prey. The horse has low visual acuity and is relatively nearsighted. Ferrets are nearsighted, which is no doubt a reaction to their adaptation to a burrowing lifestyle and the search for prey by smell. The myopic vision of ferrets is as sharp as ours and maybe even a little sharper.

Thus, the eagle has the sharpest vision, then in descending order: falcon, man, horse, dove, dog, cat, rabbit, cow, elephant, mouse.

color vision

Color vision is the perception of the color diversity of the surrounding world. The entire light part of electromagnetic waves creates a color spectrum with a gradual transition from red to purple (color spectrum). Color vision is done with cones. There are three types of cones in the human retina:

• first perceives long wavelength colors - red and orange
• the second type perceives better medium-wave colors - yellow and green
• the third type of cones is responsible for short-wavelength colors - blue and violet

Trichromasia - perception of all three colors
Dichromasia - the perception of only two colors
Monochromatic - the perception of only one color

How do animals perceive color?

Kind of animal	Short wavelength, nm	Average wavelength, nm	Source
Dog	454	561	Loop et al. (1987) Guenther & Zrenner (1993)
Cat	429-435	555	Neitz et al. (1989); Jacobs et al. (1993)
Horse	428	539	Carroll et al. (2001); Timney & Macuda (2001)
Pig	439	556	Neitz & Jacobs (1989) Cow 451 555 Jacobsetal. (1998)

Dog color vision:

Color vision of cats:

Horse color vision:

Have you ever wondered what you look like in your dog's eyes? Or even how a bee sees the world? The vision of each animal species on Earth is unique, and some can see what is not available to us.

Dogs

Dogs have poor eyesight; their eyes are insensitive to most colors, and they see the world in a somewhat faded way. On the other hand, they see very well at night. They have a well-developed sense of perspective and depth, and their eyes are more sensitive to movement.

Fish

Your normal aquarium fish can see in the ultraviolet and everything in its immediate vicinity is magnified. This is probably why so many fish look surprised all the time.

Birds

Our feathered friends have sharp eyesight. Nocturnal birds see very well when there is no light, and during the day they can see shades of colors that humans cannot see, as well as ultraviolet rays.

snakes

Snakes usually have poor eyesight, but they can see heat at night ten times better than any modern infrared equipment. During the day, however, they only react to movement - if their prey doesn't move, they won't catch it.

Mice and rats

Each of the mouse's eyes moves independently, so they see two separate pictures. The world for them is blurry, slow and blue-green.

cows

For cows, their pastures are not green, but orange and red. They see everything a little bigger.

Horses

The horse's eyes are located on the sides of the head. This helps alert them to any danger. But it also has its drawbacks: these animals never see what is right in front of their noses.

bees

Bees comprehend the world three times faster than humans. They also see ultraviolet rays, which we cannot.

flies

Flies have thousands of tiny eyes that create a single image. They can see ultraviolet rays, and the world moves somewhat slower for them than humans.

sharks

Underwater predators such as sharks do not see any colors, but their underwater vision is much sharper than ours.

Chameleons

Chameleons are interesting creatures not only because of their appearance, but also because their eyes can move independently of each other. This gives them a 360? view.

night geckos

These lizards have real night vision. They can see 350 times better than humans.

butterflies

Butterflies are amazing insects. Their eyesight is not very sharp, but they can see many more colors and shades than humans, including ultraviolet light.

How do our four-legged friends see?

Until now, we, the owners of our four-legged pets, know practically nothing about their vision. Do our cats and dogs see colors? How do they see the world around them? Are dogs really nearsighted and cats, on the contrary, farsighted? Is it true that animals can see farther than humans? All these interesting and entertaining questions are answered by the Head of the Center for Veterinary Ophthalmology Associate Professor Shilkin Aleksey Germanovich and his colleagues.

I want to say right away that humans and animals see the world around them in completely different ways and have a different structure of the eye. A person receives more than 90% of information about the world around him through vision. It is not only the most important, but also dominant among the other senses. Our vision has excellent sharpness far and near, the widest color gamut, and this is due to the fact that in the human eye there is a functional center of the retina - a yellow spot. The human eye through the refractive system: the cornea, pupil and lens directs the entire flow of light into the eye to the yellow spot.

The human visual system.

The human optical system focuses the visual image into the macula - the central part of the eye, where the largest amount of light perceiving cone receptors is located. This forms the macular - the central vision of a person.

Here are located photoreceptors - cones, with the highest visual activity. The denser their concentration, the higher the visual acuity. Moreover, each cone through the fibers of the optic nerve has its own representation in the central nervous system. It looks like a high resolution matrix.

In our optic nerve, there is simply a huge number of nerve fibers - more than 1 million 200 thousand. All information from the eye passes into the visual area of ​​the cerebral cortex, where there are unusually developed higher cortical centers. By the way, the old Russian proverb about what we see not with the eyes, but with the back of the head in the light of modern knowledge is not without meaning.

human eye fundus

1. The optic disc, consisting of 1 million 120 thousand nerve fibers, provides high visual resolution.
2. Macula( maculae), is the functional center of the human retina, due to the large number of nerve fibers, provides high visual acuity and full color perception.
3. The vessels of the retina are arteries and veins.
4. The periphery of the retina is represented by rods not tightly adjacent to each other. Due to this, a person's vision in the dark is weak.

The yellow spot is inherent only to humans and a number of higher primates. Other animals don't have it. A few years ago, American scientists compared the vision of humans and monkeys. Studies have shown that monkeys see better. Then similar experiments were carried out between a dog and a wolf. Wolves, as it turned out, see better than our pets. This is probably some kind of retribution for all the benefits of civilization.

How is the eye of animals arranged?

Our four-legged pets perceive things a little differently. For dogs and cats, vision is not decisive in the perception of the world around them. They have other well-developed sense organs: hearing, smell, touch, and use them well. The visual system of animals has some interesting features. Dogs and cats see equally well both in the light and in the dark. It should be said that the size of the eye of animals practically does not correlate with the size of the body. The size of the eye depends on whether the animal is diurnal or nocturnal. In nocturnal animals, the eye is larger and convex, unlike diurnal ones.

The size of the eyes of an animal does not depend on the size of the body. All nocturnal birds have huge bulging eyes that help them navigate perfectly in the dark.

So, for example, the eyes of an elephant are only 2.5 times larger than those of a cat. Animals do not have a yellow spot - the functional center of vision. What does it give them? If a person sees mainly with a yellow spot and has a central type of vision, then dogs and cats see equally with the entire retina and have a panoramic type of vision.

The visual system of the eye of animals.

The optical system of animals evenly directs the visual image over the entire surface of the retina, thereby creating panoramic vision. Thus, the entire retina of animals sees the same way.

The retina of dogs and cats is divided into 2 parts. The upper "tapetal" part shines like mother-of-pearl and is designed for vision in the dark. Its color varies from green to orange and directly depends on the color of the iris. When in the dark we see the brilliant green eyes of a cat, we are just observing the green reflex of the fundus. And the eyes of wolves glowing at night with an ominous red color are nothing more than a colored tapetal part of the retina.

The fundus of the dog.

1. The optic disc consists of 170 thousand nerve fibers. Due to this, animals have a lower resolution of visual images.
2. The lower part of the retina is pigmented. The pigment protects the retina from being burned by ultraviolet radiation (spectrum) of daylight.
3. retinal vessels.
4. Animals have a reflective shiny membrane (tapetum lucidum). Due to its presence, animals (especially those leading a nocturnal lifestyle) see much better in the dark.

The lower part of the retina is pigmented. It is brown in color and adapted for vision in the light. The pigment protects the retina from damage by the ultraviolet part of the solar spectrum. The large convex eye and the division of the retina into two halves creates all the conditions for life in a wide range of illumination. A panoramic type of vision helps animals to better hunt and outrun prey.

What is the visual acuity of animals?

Winning in panoramic vision and the ability to adapt in a wide range of the spectrum, animals are inferior to humans in visual acuity. According to the literature, dogs see 30%, and cats 10% of human visual acuity. If dogs could read, at the doctor's appointment they would read the third line from the top (on the table that you all saw), and cats only the first. A person with normal 100% vision reads the tenth line. This is due to the lack of a yellow spot in dogs and cats. In addition, light-perceiving photoreceptors are located at a great distance from each other, and the number of nerve fibers in the optic nerve of animals is 160-170 thousand, which is six times less than in humans. The visual image seen by animals is perceived by them less clearly and with low detailed resolutions.

Are dogs really nearsighted and cats farsighted?

This is a widespread misconception, even among veterinarians. We have conducted special studies in 40 animals to measure myopia and hyperopia. To do this, dogs and cats were seated at the device with an autorefractometer (as at a reception with a human oculist) and the refraction of the eye was automatically measured by it. We have found that dogs and cats do not suffer from myopia and hyperopia, unlike humans.

Why do dogs and cats play with moving objects?

We humans see motionless objects better and owe this to cones. Dogs and cats have predominantly rod-type vision, and rods perceive moving objects better than stationary ones. So, if animals see a moving object from a distance of 900 meters, then they see the same object in a stationary state only from a distance of 600 meters and closer. As soon as a bow on a string or a ball starts to move, the hunt has begun!

Can our pets see colors?

A person perfectly distinguishes colors due to cones, which have the highest density in the zone of the yellow spot. Until recently, it was believed that if animals do not have a yellow spot, then they see the world in black and white. Discussions about the ability of animals to distinguish colors have been going on for more than a century. All sorts of experiments refuting each other were put up. The researchers shone flashlights of different colors into the eyes and tried to understand by the degree of pupil constriction to which of the colors there was a greater reaction.

An end to these disputes was put in the late 80s by American researchers. The results of their experiments showed that dogs distinguish colors, but unlike humans, their color palette is much poorer.

Animal eyes contain significantly fewer cones than humans. The color palette of a person is formed from three types of cones: the first perceives long-wavelength colors - red and orange. The second type perceives better mid-wave colors - yellow and green. The third type of cone is responsible for the short wavelength colors blue and violet. Dogs do not have cones responsible for the color red. Thus, dogs generally perceive well the blue-violet and yellow-green range of colors. But animals see up to 40 shades of gray, which gives them undeniable advantages when hunting.

How do animals navigate in the dark?

Dogs are 4 times and cats are 6 times better at seeing in the dark than humans. This is due to two reasons.

Animals have more rods than humans. They are located along the optical axis of the eye, and have high light sensitivity and are better than human rods adapted for vision in the dark.

In addition, animals, unlike humans, have a highly active reflective membrane tapetum lucidum. It greatly improves the visual abilities of animals at a distance in the dark. Its role can be compared to the silver coating of a mirror or the reflections of a car headlight. The reflective membrane in dogs is represented by guanine crystals located in the upper part behind the retina.

Reflective dog membrane (tapetum lucidum).

Reflective membrane works as follows. In the dark in dogs, each quantum of light passing through the transparent retina reaches the reflective membrane and is reflected from it again onto the retina. Thus, a much larger light flux enters the retina, and the surrounding objects become more distinguishable with a lack of light.

A gang of cats with glow-in-the-dark eyes. The eyes of cats glow green due to the presence of a reflective membrane. In wolves, it has a red color, and therefore, in the dark, the eyes of wolves glow with an "ominous red color."

In cats, reflective crystals also increase the contrast of the image by changing the wavelength of the reflected color to the optimal one for photoreceptors.

The width of the fields of view of humans and animals

Another important characteristic is the width of the fields of view. In humans, the axes of the eyes are parallel, so it is best to see straight ahead.

This is how a person sees the image.

The dog's eyes are positioned so that their optical axes diverge by about 20 degrees.

The human eye has a circle-shaped field of view, while the dog's field of view is "stretched" to the sides. Due to the divergence of the axes of the eyes and "horizontal stretching", the total field of view of the dog increases to 240-250 degrees, which is 60-70 degrees more than in humans.

Dogs have a much wider field of vision than humans.

But these are average figures, the width of the fields of view is different in different breeds of dogs. The structure of the skull, the location of the eyes, the shape and size of the nose have an influence. In broad-nosed dogs with a short nose (Pekingese, pug, English bulldog), the eyes diverge at a relatively small angle. Therefore, they have limited peripheral vision. In narrow-muzzled dogs with an elongated nose (greyhounds and other hunting breeds), the axes of the eyes diverge at a large angle. This gives the dog a very wide field of vision. It is clear that this quality is very important for a successful hunt.

The field of view of a horse is much superior not only to a human, but also to a dog.

Thus, our pets see the world in a very different way. Dogs and cats see much better than us in the dark, have a wider field of vision, better perceive moving objects. All this allows our pets to perfectly hunt and evade persecution, to see not only in front of them, but also on the sides. At the same time, they lose to us in visual acuity, the ability to subtly distinguish colors. But animals do not need this, they do not read books until ... What will happen next - let's see.