The striking sparkle in your cat's eyes in the dark may seem cunning trick, which your pet performs, as if flirting with you. But, in fact, the glowing eyes of a cat are inherent in its biology. Cats have certain anatomical features eyes that people don't have.
Tapetum
Your cat's eyes have thin layer light-reflecting cells that are located after the retina, at the back of the eyeball. Many other animals, including dogs, deer and even horses, also have a tapetum in each eye, but it is most striking in cats.
Purpose of tapetum
The reason why cats' eyes glow in the dark is because they are nocturnal creatures. The tapetum helps improve night vision and gives your cat's eyes a second chance to collect extra light and send that visual signal to the brain. This makes your cat's eyes about six times more sensitive to light than human eyes, and it also explains why she can easily move around a completely dark room when you can see literally nothing.
When do cats' eyes glow?
You may notice glowing eyes a cat's in very low, dim light, but they won't glow if the room is really dark. This is because the tapetum needs at least some light to reflect it.
Differences between cats
Most cats' eyes glow green, but some may have other colors of shine. Owners Siamese cats sometimes note that their pets' eyes glow yellow, and some other Siamese cats have a certain genetic mutation eyes glow less brightly than others. In case cats' eyes have different levels pigmentation, then even two cats of the same breed may have eyes different colors glow.
Cause for concern?
Typically, cats' tapetum is well protected as it is located behind the retina, so you don't have to worry about it. However, a deficiency of taurine and some other amino acids found in meat and fish can lead to tapetum disorders. Most commercial feeds contain sufficient taurine to prevent this type of deficiency. However, if you are preparing your cat's food at home, you may want to consult with your veterinarian to ensure that your cat is receiving the correct amount of taurine to maintain its health.
On a bright day, apathy comes over the cats. They are able to lie for hours without moving under the warm rays of the sun. IN winter time they try to grab a place near the radiator or in a warm chair. But with the arrival of darkness, the behavior of animals changes. They are active, which even causes discontent among vacationing owners. At night, genes from distant ancestors are activated in cats wildlife who began to hunt at the end of the day. It is precisely for such a case that nature provides a special structure for cat’s eyes, which have the ability to capture even weak light - the radiance 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 this amazing abilities, and cats turned from mysterious creatures into harmless pets. But their eyes continue to glow in the dark with a bright and sometimes frightening light.
The cat is an adroit hunter, and its vision is excellent even at night. But such a unique feature of cat eyes as the ability to glow in the dark did not always bring this animal only benefit.
The Holy Inquisition, which began active work in medieval Europe, declared cats to be minions of the devil and witches. The basis for this was the activity of cats in dark time days, as well as the vertical pupils and burning “hellfire in the night” eyes of these small predators. In addition, pagans revered cats, and 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 supposed witches. These brutal massacres continued until the 19th century, which marked the beginning of the Age of Enlightenment.
However, the barbaric attitude towards cats was characteristic only of those European countries where catholic church. Among the pagans of Africa and the Eurasian continent, the cat has always been revered as a sacred animal. In Rus', cats have been considered since ancient times as guardians of the hearth, and before the advent of Christianity they were associated with the names of the deities Rod, Veles and Mokosh. 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 retained this favor towards cats, despite their unusual habits. So, to this day the cat is allowed to enter Orthodox church and wander around it wherever you please. For example, dogs are prohibited from walking even in the area next to the church.
Why do my eyes glow?
In the strict sense of the word, the eyes of cats themselves do not glow, but only reflect light. This effect is explained by the unusual structure of cat vision. The mechanics of the pupils and the photoreceptors of the fundus of the eyes in these animals are adapted to a greater extent to work in low light, because the cat is primarily a nocturnal predator.
Behind the retina of these animals there is a special layer - tapetum, which contains a large percentage of photoluminescent pigment. The light falling on this layer is reflected, like from a mirror, and is amplified several times, allowing the animal to see perfectly in the dark. For this, weak starlight is enough. At the same time, in the dark, cats' pupils open wide to allow as much light as possible into the eyes.
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 flash with bright fire.
Almost all predators (especially nocturnal ones) have a luminescent pigment in the retina, and humans too. The difference is that its amount in the retina of cats' eyes is much higher. For example, a dog's eyes also partly reflect light in the dark, and people's eyes are often “exposed” during a camera flash, which is why the “red-eye effect” occurs 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 is similar to mother of pearl and its color varies from yellow to green. At the same time, in the center there is more golden-green, and at the edges there is more bluish-green. The eyes of cats with this type of tapetum glow yellow, yellow-green or blue-green.
The shade of the eye glow also depends on the angle of incidence of the light rays. If the light hits a cat with a well-pigmented tapetum directly at the center of the pupils, the glow will be as bright as possible, light yellow or greenish-golden. In side light, the eyes will glow with turquoise, bluish or violet light.
The eyes of kittens up to 3 months sparkle in the dark with faint reddish reflections, because their retina is still poorly pigmented, and the reflective layer has not completely formed. As the kitten grows, the retina accumulates luminescent pigment, and the eyes begin to glow yellow or green in the dark.
But in some cats (for example, Siamese), the tapetum can remain crimson throughout its life. In the dark, the eyes of such cats glow red, since the light entering through the pupils in this case is reflected to a greater extent from blood vessels. This effect is generally seen predominantly in blue-eyed cats. And all because they got tapetum nigrum - a version of tapetum with a low content of luminous pigment.
Photos
Video "Cats' eyes glow in the dark"
As you know, cats have always been considered minions evil spirits, as well as active assistants to witches and sorcerers. The eyes of these animals played a significant role in this. Not only do they have a vertical and narrow pupil, unlike other animals, but cats' eyes glow in the dark!
Agree, something like this could scare anyone in the Middle Ages, because people sacredly believed in gods, evil spirits and otherworldly forces. Today, no one can be surprised by such an effect of cat’s eyes, because people have become more educated, but many are still perplexed: why do a cat’s eyes glow in the dark? Let's figure this out together unusual phenomenon, and let’s find out why this amazing glow occurs.
So why do the eyes glow?
The cat is a domestic predator, a descendant of true hunters, whose lives directly depended on whether they could catch their prey. Powerful paws, a movable spine for instant acceleration, sharp claws - all this was created by evolution to improve the hunting abilities of big cats.
However, these properties were supplemented by one more - thanks to the specific structure of the eye, cats see perfectly in the dark, and can hunt even after sunset. This is undeniable competitive advantage, which was passed on to our pets.
What is the reason for this acute vision? It's all about the structure of the eye - all the light passing through the pupil hits the retina, but only a small part of it causes an impulse in the sensitive cells. That is, if there is special system, allowing one to collect all the remaining light and direct it to light-sensitive cells, vision would be many times sharper. And cats have such a system.
This is the tapetum - or the mirror fundus of the eye, which reflects the transmitted light back. Thus, the light is used twice, significantly increasing visual acuity.
It is this mirror coating that reflects light, creating the illusion of glowing eyes. In domestic cats, it has a different shade - from green to yellow, and thanks to this, the reflection also changes its color.
Simply put, we see light reflected from the fundus of the eye, and the less light there is, the weaker it will be. this effect. And therefore, when they say that cats’ eyes glow in the dark, this is not entirely true, because... there must be at least some source of light. In complete darkness cat eyes, of course, will not glow: they simply will have nothing to reflect.
That’s the whole secret of such an interesting phenomenon as glowing eyes in cats. Our pets are full of surprises, and if we want to learn to understand them well, we need to be interested similar phenomena and study your charges.
The fauna is diverse. Even pets that have lived side by side with people for thousands of years sometimes make us wonder and ask questions. For example, why do cats' eyes glow in the dark? Perhaps you have already noticed the eyes of your pet sparkling in the semi-darkness, watching you from above. So why don't human eyes glow the same way?
Historical background: cat's eyes and superstitions
Cats' eyes glow due to reflection.
Cats in Europe, starting from the 14th century (the beginning of the Catholic Inquisition), were considered messengers of the devil and assistants of witches. The origins of these superstitions were supposedly glowing in the dark cat eyes, their vertical pupils and natural cat independence. Black cats were especially disliked, apparently for their fantastic ability to dissolve in the dark. Embittered fanatics burned beautiful girls and their cats, thereby permanently impoverishing the gene pool of both in nearby European areas.
Interesting fact: In ancient times, cats were considered protectors, hunters, and sometimes even idolized. Since ancient times, cats have been considered special animals; pagans believed that cats were messengers of the god Rod, the so-called “prelagatai”, observing what was happening on earth and transmitting the collected information to the gods. The legends that have come down to us say that Makosh, the ancient Slavic goddess of water, asked the clan for an observer to look after the people. Rod thought and created a furry domestic creature that walks between the boundaries of reality and will warn people about approaching trouble. He distributed one to all the gods and sent several to earth so that they would multiply and protect the home of each family.
Why do cats' eyes actually glow?
But biology does not agree with superstitious people. Moreover, cat's eyes do not glow 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 captures the light and rewrites it into an electrical signal (neural impulse) entering the occipital lobe of the cortex cerebral hemispheres. At the stage when light hits the retina, the so-called “glow” of a cat’s eyes appears.
Behind the retina is a layer of reflective cells– tapetum, special layer choroid. It is divided into two types - tapetum lucidum and tapetum nigrum. In all species of animals it is expressed differently, and even within a species, depending on the breed, the ratio of one and another type of tapetum, its location may change. Tapetum L. in cats is located in the form of a diamond or triangle and occupies a large area. Light hitting the retina passes through it, is reflected from the tapetum and falls back on the retina, strengthening the signal and providing a better image. That is why cats only need the weak light of the stars and the moon - they have eyeballs a built-in amplifier that allows them to see at night. And seeing eyes sparkling in the dark, we are observing just reflections of reflected light.
Interesting fact: This system for improving night vision is another remarkable invention of evolution. Not only cats can boast of eyes sparkling in the darkness: all nocturnal predators, to one degree or another, have similar abilities. Owls, for example, see 10 times better in the dark than cats, and are able to detect the movement of a mouse 300 meters away; but during the day they are practically helpless, since their eyes are too sensitive for bright daylight. The marsupial loris, a resident of Australia, has with huge eyes and ears, since 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. produces a predominantly yellow, green, and 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 light and the location of the tapetum, we can see how the eyes glow green - when reflected from Tapetum L., or a reddish dim glow - these are reflections from Tapetum N. Interestingly, the eyes glow red even in humans - remember these reflections on Polaroid photos, red eye effect? 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 do, so our tapetum is practically invisible - unless you point a flashlight directly at the eye, of course.
