Goat pupil. Why do goats and sheep have rectangular pupils? Unusual pupil shape

And fainting goats competing for attention can't distract attention from what the goats' eyes look like. Their horizontal, rectangular pupils appear alien compared to the round pupils of humans and dogs and the vertical pupils of cats. Why do goats' eyes look this way? And for that matter, why do cat eyes look the way they do?

In a new study, vision scientist Martin Banks found that the shape of an animal's pupils is a clue to its place in the food chain . Banks and his team examined the eyes of 214 various types land animals, and found a clear relationship between the shape of their pupils and their ecological role.In predatory animals that ambush their prey, as a rule, vertical section pupil, while herbivores, which are prey for other animals, have horizontal pupils.The predator-prey distinction based on pupil shape suggests that both hunters and those being hunted derive some benefit from a specific pupil type.

To find out what these benefits might be, the researchers analyzed the abilities of the two pupil shapes and how they might serve the different visual needs of predators and prey. Goats and other herbivores (eg, deer, large cattle and elk), which are hunted by predators, have a fairly simple strategy to avoid being eaten: pay attention to danger and run if they see it.

To support such a strategy, their eyes must be able to do two things. “On the one hand, these animals must have panoramic vision in order to detect predators that might approach different directions,” the researchers write. “On the other hand, they must see straight ahead clearly enough to move quickly over potentially uneven terrain.”

Horizontal pupils help here because their shape creates a sharp panoramic view that is wider and shorter than what others get by having round or vertical pupils, and such a pupil allows the animal to see almost everything around it. A long horizontal pupil also improves the quality of images of objects in front and behind the animal, and also helps the eye capture more light along the surface and less glare overhead.

Of course, these benefits don't work if the pupil remains oriented in the same way and becomes vertical when the animal lowers its head to graze. However, after observing grazing animals at the zoo, researchers discovered that their eyes rotate in such a way as to remain horizontally aligned when their heads are in an upright position.

The researchers say the long horizontal pupil seems ideal for these animals. In other words, goats strange eyes because they help them survive.

At the same time, the team found that vertical, slit-shaped pupils help small predators such as ambush and judge the distance to prey and other objects so that they know how far they should jump.

“For those species that are active both day and night (for example, domestic cats), the pupil size provides dynamic range"needed to help them see in dim light and also to prevent them from going blind in the midday sun," Martin Banks said in a statement. “However, this hypothesis does not explain why the cuts are placed vertically or horizontally. Why don't we see with diagonal cuts? This study is the first attempt to explain this."

Round pupils, like those in humans (or like those in adult cats), tend to belong to carnivores. The eyes, which are slanted to the sides like those of goats, belong to animals that graze in the pasture and are prey. Using computer models, the researchers confirmed that lateral eyes produce a much wider field of vision than eyes like ours.

Researchers say that next accent will be done by them by studying the shape of the pupil of animals that live in water. This will be much more difficult, since the lateral position of the eyes of a sea creature, such as an octopus, for example, can indicate that it is both a predator and a prey.

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Scientists have concluded that the visual system in animals began to develop approximately 540 million years ago. At first it had a simple structure, but over time it became more complex and improved for each type of vision. For example, fish see wonderfully underwater, eagles with enormous height They will easily notice a small rodent on the ground, and cats are excellent at navigating in the dark.

Take a look at a selection of the most unusual eyes animals and see the uniqueness and wisdom of Mother Nature!

1. Mountain goat.
We are accustomed to the fact that the human pupil has round shape. But in most ungulates, in particular the mountain goat, it has rectangular shape.

2. This pupil shape and horizontally oriented vision are the best for survival in mountain conditions. So, without turning its head, the goat sees around itself at 320-340 degrees. For comparison, a person sees only 160-200 degrees. Animals with this eye structure have excellent vision at night.

3. Trilobite.
Long before the advent of dinosaurs, the entire Earth was inhabited by marine trilobite arthropods. Paleontologists have counted about 10,000 species of these animals. At this time, this class is extinct.

4. Some of the representatives of this class were eyeless, but the majority had eyes unique in their structure. Eye lens theirs consisted of calcite. This is a transparent mineral that is the basis of chalk and lime.
The shell of the eyes of modern invertebrates consists of chitin, a hard, translucent substance. Unusual composition eyes gave these arthropods the ability to simultaneously keep objects in focus in the near and long distance. The vision of trilobites had a horizontal or vertical orientation. But regardless of this, the animal could only see at a distance of approximately equal to length own body.

Depending on their habitat, the eyes of trilobites were located either on elongated eyelids or were covered with an eye lid that protected them from the bright sun. Paleontologists have studied trilobite vision in great detail, as calcite fossils are well preserved.

5. Tarsier.
Tarsiers are primates only 9-16 cm tall and weighing only 80-150 grams that live on the islands Southeast Asia. Small size does not at all prevent the animal from being a predator. Moreover, tarsiers are the only primates in the world that eat only food of animal origin. They deftly catch lizards, insects and can even catch a bird during its flight. But their most important feature is their large eyes glowing in the darkness. Their diameter can reach 16 mm. In relation to body size, these are the largest eyes of any known mammal.

6. Local residents are still convinced that the tarsier is a messenger of evil spirits. And European tourists, seeing such a baby for the first time, shudder and then remember this meeting for a long time. Imagine you are huge too glowing eyes on a small round head. A second, and you are already looking at the back of the animal’s head. He simply turned his head...almost 360 degrees. Isn't that impressive?

In addition, tarsiers have excellent night vision. Based on this, scientists conclude that the animals recognize ultraviolet light.

7. Chameleon.
Many people know that a chameleon can change color. This is how he disguises himself and shows his mood and demands to other lizards. The vision of these animals is also unusual - tightly fused eyelids cover everything. eyeball, leaving only a small hole for the pupil.

The eyes of these lizards seem to fall out of their sockets and can rotate independently of each other through 360 degrees.

8. A chameleon's eyes look in one direction only when its gaze is fixed on its prey. The lizard feeds on insects and small rodents. The chameleon notices its prey at a distance of several meters. Like the tarsier, it is able to see ultraviolet light.

9. Dragonfly.
The dragonfly's visual organs are also unique and unusual. They occupy almost the entire head of the insect and are able to cover the space 360 ​​degrees.

Each dragonfly eye consists of 30,000 tiny photosensitive cells. In addition to two huge eyes, she has 3 more small eyes. This special vision makes the insect a dangerous aerial predator, capable of reacting to any movement literally in a split second.

10. There are also dragonflies that successfully hunt in twilight conditions. Under these same conditions, a person is unable to see much.

11. Leaf-tailed gecko.
The tropics of Madagascar are home to some very unusual geckos. It is very difficult to notice them, as the shape and color of this animal is very reminiscent of a dry leaf of a plant. Because of their large red eyes, these reptiles have received names such as “satanic” and “fantasy” geckos. These lizards have vision high sensitivity. Geckos are nocturnal animals. Even in complete darkness they can easily distinguish all objects and colors.

12. For comparison, cats can see six times in dim light better than man. Under the same conditions, geckos see 350 times better.

These reptiles owe such remarkable vision to the special structure of the pupil.

13. Colossal squid - a mystery of the ocean.
This is the largest invertebrate animal known to scientists. He is also the owner of the most big eyes among all representatives of the animal world. The diameter of its eye can reach 30 cm, and the pupil is the size of a large apple. Squids have 100 percent vision even in dim light. This is very important for him, because these animals live at a depth of at least 2000 meters.

14. But besides this, the eyes of these squids have a built-in “spotlight” that turns on in the dark and gives required quantity light for a successful hunt

15. Four-eyed fish.
This is a small fish up to 30 cm long, living in the waters of Mexico and South America. Its main food is insects, so it can often be seen on the water surface.

16. Despite the name, the fish only has two eyes. But they are divided by the flesh into four parts. Each part has its own lens.
The upper part of the eyes is adapted for vision in the air, the lower part for underwater observation.

17. Stem-eyed fly.
Another unusual representative of the animal world. It got its name because of the thin, long, stem-like growths on the sides of its head. There are eyes at the ends of the stems.
Males and females have eyestalks of different lengths and thicknesses. Females choose males with the longest stalks.

18. During the mating season, males compare their stems. To win, they even use a trick - they inflate their eyes and stalks with air, which increases their size and, of course, the chances of finding the female they like.

19. Dolichopteryx longipes.
This is a small deep-sea fish up to 18 cm long.

20. Only Dolichopteryx has unique mirror vision. Its organs of vision work on the principle of a lens, and allow the little predator to see both above-water and underwater space at the same time.

21. Spiders are ogres.
These are six-eyed spiders. But their middle pair of eyes is much larger than the others, so it seems that the spiders have two eyes.
Ogres are nocturnal predators. The spider's eyes are covered with a membrane of hypersensitive cells, providing excellent night vision.

22. Scientists believe that these spiders navigate in the dark at least a hundred times better than humans.

23. Crayfish are mantises.
These are the most dangerous representatives of arthropods in tropical waters. With their sharp claws, they can easily leave a person without fingers. They are the owners of the most unique eyes in the world.

Their eyes consist of 10,000 hypersensitive cells. Each cell performs a strictly defined function. For example, some are responsible for determining light, others - color. This type Crayfish catch shades of colors 4 times better than humans.

They are the only ones with ultraviolet, infrared and polar vision at the same time. In addition, their eyes can rotate 70 degrees. It is also surprising that the information received in these crayfish is processed not by the brain, but by the eyes.

24. But that's not all. These crayfish have “trinocular vision.” Cancer's eye is divided into three parts, and he can see everything that happens from 3 different points of the same eye.
This is the most unique structure of the visual system. Scientists are still unable to fully explain it, much less recreate it. We can only marvel at the wisdom and uniqueness of nature.

Answered by veterinary ophthalmologist, microsurgeon, Ph.D. Konstantin Perepechaev

The pupil is essentially a diaphragm, which, by contracting or expanding, regulates the flow of light onto the retina of the eye. In addition, its size and shape affect the field of view and the quality of the image obtained on the retina. Different animals - depending on the ecological niches they occupy, location in the food chain, lifestyle and type of nutrition - these characteristics differ from each other.

Herbivorous ungulates (goats, sheep, cows, antelopes, horses, etc.) in the food chain are always victims of any predators. In accordance with this their visual analyzer forms visual information, and the brain processes it from the point of view of the “prey mentality”. Any fast-moving object, even if it is not clearly visible, may well be an attacking predator, so any unexpected movement immediately causes the herbivore to protective reflex: defense and/or flight.

All herbivores have large, slightly bulging eyes, located almost on the sides of the head. This provides the widest field of view. For example, overall width A horse's field of vision is approximately 350º. Thus, the horse does not see only a narrow sector directly behind the poll. (In the article “My Planet” you can read and even observe how a horse, bee, cat, etc. see the world.)

IN daytime in strong light, the eyes of goats and sheep look like narrow slits; in the dark, the pupil dilates, taking on the appearance of rectangles or even squares. The long horizontal pupil enhances the image quality of objects in front and behind the animal, making it easier to move quickly over uneven or mountainous terrain

The rectangular, or rather, horizontal-oval pupil of herbivores just helps them see the widest possible panoramic picture around them. Due to the stretched shape of the pupil, a goat, for example, has a viewing angle of almost 340°, that is, when grazing, it calmly observes what is happening around it, without even raising its head. In the daytime, in strong light, the eyes of goats and sheep look like a narrow slit; in the dark, the pupil dilates, taking on the appearance of rectangles or even squares. This mechanism contributes to the same thing - better review in the dark. A goat, like other animals with such pupils, is able to notice a moving predator almost behind itself at night. When a predator appears in the field of view of at least one of the goats, the entire herd will have time to escape.

According to latest research The long horizontal pupil also enhances the image quality of objects in front and behind the animal, making it easier to move quickly over uneven or mountainous terrain, and also helps the eye capture more light along the surface and less glare overhead. Additionally, by observing zoo animals grazing, researchers discovered that the animals' eyes rotated so that the line of the pupils always remained horizontally aligned, even when the animals' heads were tilted vertically downward.

The shape of the pupils of animals is predominantly round, but there are plenty of exceptions. One of these representatives is found among the artiodactyls - the goat (goat). She has rectangular pupils, turned horizontally. In bright light they narrow to the point of forming a line, and in the dark they expand to their maximum. The latter determines the origin of the expression “bug-eyed goat.”

U large number Ungulate pupils are rectangular in shape. We exclude the giraffe.

Who else has

Let us list other animals endowed by nature with rectangular pupils:

• cow, horse, llama, hippopotamus, mongoose, octopus;
• a sheep (ram) is a relative of a goat, which determines the shape of the pupils in question;
• shark, stingray - looks like a rectangle with vertical arrangement. Occurs in some species;
• gecko - less reminiscent of a regular rectangle, but its shape is elongated, which allows it to be included in the list. Not all members of this family of lizards have such pupils;
• amphibian (aka frog) - depending on the type of amphibian, the pupils are located horizontally or vertically.

Why are the pupils rectangular?

The explanation here is simple. Let's take a goat for example. She needs to constantly receive food - she grazes. Previously, goats were wild and were hunted by other animals. In this regard, there was a need to survey the surroundings without lifting the head from the ground. This led to the dilation of the pupils horizontally. The viewing angle began to reach 340 degrees without turning the head.

The same explanation applies to other representatives of the animal world with rectangular pupils.