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The fact that cats' eyes shine in the dark is no secret to anyone. To a greater extent, this is manifested if you direct a beam of light at the cat. Why is this happening? All this can be explained by simple light reflection. In addition, the eyes shine not only in cats, but also in other nocturnal animals. As for cats, it was the eyes that glow in the dark that caused them many troubles. These include various superstitions. So, for example, to this day people believe that a black cat is the cause of human troubles, and cats with glowing eyes have always been considered messengers of the dark kingdom and companions of witches. No one paid attention to the fact that the eyes of these animals do not glow by themselves.

In fact, the glowing eyes of animals have nothing to do with dark forces. They simply reflect light rays that enter them from third-party sources. If you close a cat in a dark room with no windows, then you will not see its glowing eyes. The conclusion is simple - since there is no external light source, then there is no glow of the eyes.

And yet, why do they glow?

It's all about the structure of the animal's retina, which consists of a layer of transparent cells (tepetum). It can be compared to a mirror reflecting surrounding objects. The retina absorbs light incident on it only partially. Most of it is reflected from the tepetum, transformed into a narrowly directed light beam, and emitted into the surrounding space. Due to this, the cat can see in the dark. Although, in a completely dark room, protected from third-party light sources, she does not see anything.

The color of the glow in the eyes of animals can be completely different. It depends on the pigment that is part of the tepetum. If we talk about cats, then their eyes glow, either green or yellow. But in Siamese cats, the glow of the eyes is crimson.

If you carefully observe a person, you will notice that his eyes can also glow in the dark. We just don't pay attention to it. Try to shine a flashlight in the eyes of a person, and you will be convinced of this. In photographs, the effect of glowing eyes appears when using a flash. Photographers call it the red-eye effect.

So we came to the conclusion that the reason for the glow of a cat's eyes lies in the light hitting them from third-party sources. These can be: a street lamp, a luminous moon, celestial bodies, which include stars, headlights of a car. All of this is reflected light. The eyes themselves do not take part in its production. If the darkness is absolute, then you will not see any glow.

The cat is a dexterous hunter, and her vision works excellently even at night. But such a unique feature of the cat's eyes, as the ability to glow in the dark, did not always bring only one benefit to this animal.

The Holy Inquisition, which was active in medieval Europe, declared cats to be the henchmen of the devil and the witch's offspring... The reason for this was the activity of cats in the dark, as well as the vertical pupils and eyes of these small predators burning with "hellfire in the night". In addition, cats were revered by pagans, and the early Christians tried in every possible way to destroy the roots of alien beliefs. During the Middle Ages, thousands of cats were burned alive in bonfires and drowned in sacks along with the alleged witches. These atrocities continued until the 19th century, which was marked by the beginning of the Age of Enlightenment.

However, the barbaric attitude towards cats was typical only for those European countries where the Catholic Church dominated. Among the pagans of Africa and the Eurasian continent, the cat has always been revered as a sacred animal. In Russia, since ancient times, cats were considered the keepers of the hearth, and before the advent of Christianity they were associated with the names of the deities of the Rod, Veles and Mokos. And the unique vision of these four-legged animals was explained by the need to travel between light and darkness - the worlds of the living and the dead, people and gods.

Russian Orthodox Christianity has retained this fondness for cats, despite their unusual habits. So, to this day, a cat is allowed to enter an Orthodox church and wander around it wherever it pleases. For example, a dog is forbidden to walk even on the territory next to the church.

Why do eyes shine?

In the strict sense of the word, cats' eyes themselves do not glow, but only reflect light. This effect is due to the unusual device of feline vision. The mechanics of the pupils and the photoreceptors of the bottom of the eyes in these animals are adapted to a greater extent to work in low light, because the cat is predominantly a nocturnal predator.

Behind the retina of these animals there is a special layer - the tapetum, which contains a large percentage of photoluminescent pigment.... The light falling on this layer is reflected, as if from a mirror, and is amplified several times, allowing the animal to see perfectly in the dark. For this, the faint light of the stars is sufficient. At the same time, in the dark, the pupils of cats open wide to let in as much light as possible inside the eyes.

The maximally dilated pupils occupy almost the entire area of ​​the iris, reflecting the light flux from the entire area of ​​the fundus. If at this moment a ray of more or less bright light hits the cat's eyes, a glowing effect occurs. And if the light source is bright, such as light from car headlights, a flashlight, or a flashlight, then the cat's eyes literally flare up with bright fire.

Luminescent pigment in the retina is present in almost all predators (especially nocturnal ones), and in humans too. The difference is that its amount in the retinas of cats is much higher. For example, a dog's eyes also partly reflect light in the dark, and people's eyes often “light up” during a camera flash, which is why a “red-eye effect” appears in the photo.

Green, yellow, red - cats' eyes glow differently

The reflective layer of the retina (tapetum) is of two types - tapetum lucidum and tapetum nigrum. Most cats have the first type, which is highly saturated with luminescent pigment. It looks like mother-of-pearl and ranges in color from yellow to green. At the same time, there is more golden-green in the center, and bluish-green at the edges. The eyes of cats with this type of tapetum glow yellow, yellow-green or blue-green light.

The shade of the glow of the eyes also depends on the angle of incidence of the light rays. If the light hits a cat with a well-pigmented tapetum directly in the center of the pupils, the glow will be as bright as possible, light yellow or greenish-golden. With side light, the eyes will glow with turquoise, bluish, or purple light.

The eyes of kittens up to 3 months of age sparkle in the dark with faint reddish reflections, because their retina is still weakly pigmented, and a non-bottom reflective layer is formed. As the kitten grows up, the retina accumulates luminescent pigment, and the eyes begin to glow yellow or green in the dark.

But in some cats (for example, the Siamese), the tapetum can remain crimson throughout its life. In the dark, the eyes of such cats gleam red, since the light entering through the pupils in this case is reflected to a greater extent from the blood vessels. This effect is generally observed predominantly in blue-eyed cats. And all because they got the tapetum nigrum - a variant of the tapetum with a low content of luminous pigment.

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Video "The eyes of cats glow in the dark"

On a bright day, apathy finds cats. They are able to lie for hours without moving under the warm rays of the sun. In winter, they try to grab a place near the battery or in a warm chair. But with the advent of darkness, the behavior of animals changes. They are active, which even displeases the resting owners. At night, the genes of distant ancestors of wild nature, which began to hunt at the end of the day, are activated in cats. It is for such a case that nature has provided for a special structure of cat's eyes, which have the ability to capture even weak light - the glow of the moon, star rays and even the glare of a flame. Let's try to figure out why a cat's eyes glow in the dark, at night.

Why is it possible that a cat's eyes glow in the dark?

Naturally, today scientists have long found an explanation for such amazing abilities, and cats from mysterious creatures have turned into harmless pets. But their eyes continue to glow in the dark with a bright and sometimes frightening light.

In the light of day, apathy attacks cats. They can spend hours, without moving, basking in the summer sun. In winter, sloths can spend the whole day in a comfortable soft armchair, close to the radiator. But with the onset of dusk, their behavior changes. Purr forgets that only recently he was too lazy to even open his eyes, and begins to show activity, which does not always please sleeping family members. In cats, with the onset of night, the genes of their wild ancestors wake up, going out to hunt at sunset. It was for effective night hunting that Mother Nature provided for the special structure of the eyes of the entire cat tribe, capable of capturing the faintest light: moonlight, rays of stars or a reflection of a distant flame.

Source of fiction and superstition

When you see the brightly glowing cat's eyes in the darkness, all sorts of superstitions and fictions involuntarily come to mind, with which this amazing feline feature has grown over the centuries. How often people, not understanding the true nature of phenomena, come up with the most incredible explanations.

And the ability of the purr to scare passers-by in an impenetrable night with his flashlight eyes did not escape this fate. For many centuries, people considered this amazing natural phenomenon to be a demonstration of a connection with evil spirits. Due to their nocturnal lifestyle and burning eyes, cats have been credited with many witchcraft abilities. In the Middle Ages, it was believed that their strength depends on the color of the coat and eyes. Animals were considered faithful companions and helpers of witches and sorcerers.

Of course, nowadays scientists have long found an explanation for these supernatural abilities, and cats from creatures frightening with their mystical talents have turned into harmless pets. But the eyes of animals in the dark continue to glow all the same brightly and sometimes frighteningly.

Why do cat eyes burn in the dark?

To witness such a phenomenon, you need the cat itself, the onset of night and a weak source of light. In absolute, pitch darkness, you will not be able to see not only the cat itself, but also its burning eyes. And all because the eyes of these nocturnal predators are so arranged.

The muscles of the iris are able to control the flow of light to the retina and, if the light is too intense, they signal the pupil to narrow down to a thin slit. That is why in the daytime we do not notice the reflected glow that the cat's eyes emit. But in the dark, the pupil opens completely and the streams of light reflected by the "mirror" of the fundus are noticeable from afar.

On the inner surface of the eye, there is a special layer of photoreceptors (tapetum) capable of capturing and reflecting even a negligible amount of rays that pass through the cornea and lens and reach the fundus. This reflected light comes back out, helping the cat to see in the dark. In order for the purr to orientate itself perfectly and even hunt, just the illumination provided by the stars and the moon is enough. But if the animal finds itself in an absolutely dark room, then amazing vision will no longer help it to find a way out of it. We'll have to make do with only hearing and scent, which, however, are also excellently developed in this extraordinary animal.

It is surprising that the coating on the fundus of different animals differs not only in size, but also in the concentration of the dye. Usually it has a yellow-green hue, sometimes other colors (for example, crimson - in Siamese cats). In albino individuals, the reflective layer is completely devoid of pigment, and therefore the glow of the eyes of such an animal in the dark will have an eerie red tint. For an unprepared person, such a phenomenon can thoroughly scare, especially considering that cats appear absolutely silently and therefore always unexpectedly.

The fauna is diverse. Even pets living side by side with people for thousands of years sometimes make you wonder and ask questions. For example, why do cats have eyes that glow in the dark? Perhaps you have already noticed the sparkling eyes of your pet, watching you from a height. So why don't a person's eyes glow the same way?

Historical background: cat's eyes and superstitions

Cats' eyes glow from reflection.

Cats and cats in Europe, starting from the XIV century (the beginning of the Catholic Inquisition), were considered messengers of the devil and helpers of witches. The origins of these superstitions were supposedly glowing in the dark cat eyes, their vertical pupils and natural feline independence. They especially disliked black cats, apparently for their fantastic ability to dissolve in the dark. Angry fanatics burned beautiful girls and their cats, thereby for a long time impoverishing the gene pool of both those and those in the nearby European regions.

Interesting fact: In ancient times, cats were considered protectors, hunters, sometimes even idolized. Since ancient times, cats have been considered special animals; the pagans believed that cats are the messengers of the god Rod, the so-called "prelagatai", observing what is happening on earth and transmitting the collected information to the gods. In the legends that have come down to us, it is said that Makosh, the ancient Slavic goddess of water, asked the clan for an observer to look after people. Rod thought and created a fluffy domestic creature that walks between the boundaries of reality and will warn people about the approach of trouble. He distributed one to all the gods and sent several to the earth, so that they reproduce and protect the hearth of each family.

Why cats' eyes really shine

But biology does not agree with superstitious people. Moreover, cat's eyes do not shine in the literal sense of the word: they only reflect light.

Cats see better in the dark than humans.

To simplify, the process of obtaining an image by the brain can be described as follows: light reflected from objects passes through the pupil into the lens, through it - it is imprinted on the retina, which catches the light and rewrites it into an electrical signal (neural impulse) that enters the occipital lobe of the cortex cerebral hemispheres. At the stage of light hitting the retina, the so-called "glow" of the cat's eyes appears.

Behind the retina is a layer of reflective cells- tapetum, a special layer of the choroid. It is divided into two types - tapetum lucidum and tapetum nigrum. In all species of animals, it is expressed in different ways, and even within a species, depending on the breed, the ratio of one and the other type of tapetum, its location can change. Tapetum L. in cats is located in the form of a diamond or triangle and occupies a large area. Light striking the retina passes through it, reflects off the tapetum and hits the retina again, amplifying the signal and providing a better image. That is why the faint light of the stars and the moon is enough for cats - they have a built-in amplifier in their eyeballs, allowing them to see at night. And seeing eyes sparkling in the dark, we observe just the reflections of the reflected light.

Interesting fact: This night vision enhancement system is another remarkable evolutionary invention. Not only cats can boast of eyes sparkling in the dark: all nocturnal predators, to one degree or another, have similar abilities. Owls, for example, see in the dark 10 times better than cats, and are able to detect the movement of a mouse 300 meters away; but during the day they are practically helpless, as their eyes are too sensitive for bright daylight. The marsupial loris, a resident of Australia, has huge eyes and ears, as it hunts insects at night, and has adapted to hear and see even a praying mantis crawling past.

Green and red

The color of the reflected light is also explained by the properties of the tapetum. Tapetum L. gives a predominantly yellow, green, bluish glow. Tapetum N. practically does not change the reflected light, so we see a red glow - from the blood vessels of the choroid. Depending on the angle of incidence of the light and the location of the tapetum, we can see how the eyes glow green - when reflected from Tapetum L., or a dull reddish glow - these are reflections from Tapetum N. Interestingly, the eyes glow red even in humans - remember these reflections on polaroid photos, red eye? It is also a reflection of the flash in our eyes. Humans do not have such a powerful tool for enhancing night vision as cats, so our tapetum is practically invisible - unless you direct the flashlight directly into the eye, of course.