Oddly enough, but the small eyes of spiders are arranged in much the same way as our eyes. There is a retina, there is a lens.

But spiders see at a very short distance - from 3 to 20 centimeters. Therefore, they cannot follow our gaze.

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The vision of spiders is imperfect, especially in the tenet forms. Stray spiders see better, especially active during the day. The eye is usually four pairs. The front medial eyes, called the main ones, are dark; the rest, secondary eyes, usually shiny due to the inner shell (mirror) reflecting light. The size and mutual position of the eyes are different in different systematic groups spiders. More often they form two transverse rows, but they are arranged differently. Sometimes individual pairs of eyes are enlarged, for example, four anterior eyes in jumping spiders, medial posterior eyes in Dinops (family Dinopidae). In some cases, the number of eyes is reduced to six, four or two. Among the cave spiders there are blind ones. The eyes of web spiders are located so that they cover a large field of view, but they mainly distinguish the strength and direction of light, capturing the movement of large objects. Many spiders sitting on nets notice an approaching person and fall on a web of thread. With a sharp change in the usual lighting of surrounding objects, mink spiders lose their orientation and cannot immediately find their lair. Sidewalk spiders (family Thomisidae), lying in wait for prey on flowers, notice a cabbage butterfly at a distance of 20 cm, and a fly only at a distance of 3 cm. do not recognize its shape.

A kind of exception is represented by small jumping spiders (family Salticidae). Their long-focus main eyes produce a large image on the retina with a small field of view (as in a camera with a telephoto lens). Unlike other eyes, the visual elements of the retina are densely located here, due to which the vision is objective: at a distance of 8 cm, the spider sees the fly in detail. The small field of view of these eyes is compensated by a remarkable feature: they can move with the help of special muscles. The spider follows its prey with its eyes - a rare example among terrestrial arthropods. Side eyes do not distinguish the shape of objects, but are located in such a way that the spider notices any movement in front, behind itself and above itself. The anterior lateral eyes have a total binocular field of view of about 40°, due to which the spider perceives the volume of objects and the distance to them. The eyes of horses act as a single visual apparatus. If a fly approaches the spider from behind, it notices its movement with its rear eyes at a distance of 20-25 cm and turns towards it so that it enters the field of view of the front eyes. Now it is perceived more clearly and in space. Then the spider catches it with its main eyes, perceives close-up and begins to follow her eyes. At a distance of 8 cm, the object is recognized as prey, from 4 cm the spider begins to creep up and from 1.5 cm jumps at the fly with lightning speed with such accuracy that it rarely misses. Good vision of horses helps them to move in the grass, deftly jumping from leaf to leaf. With the help of the eyes, the male detects the female, and being blinded, does not recognize her and does not perform his characteristic mating dances. Placed in front of a mirror, the male racer reacts to his image as a rival, assumes a pose of threat or rushes at him.

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"The eyes of spiders of different families are very different. Spiders that hunt without a trapping net, like wolf spiders (Lycosidae), lynx spiders (Oxyopidae) and jumping spiders (Salticidae), have very well developed vision. Jumping spiders can see almost as good as humans. Experiments have shown that they can even distinguish colors. Cave spiders that live in the dark have no or very poor vision. They are completely dependent on sounds and sensations.
Orb-web spiders, such as Araneus diadematus, have very small eyes. They don't need much vision to catch prey."

"The tenet forms see the worst. Wandering spiders have the best eyesight among spiders. There are even blind cave spiders.
The eyes of web spiders cover a large field of view, but they only detect the movement of large objects and distinguish the direction and brightness of light."

"But, as you know, there are exceptions to all rules. These exceptions are jumping spiders (Salticidae). Their main eyes have a very small field of view, but they give a fairly large image on the retina, due to the long focus, like in a telephoto camera. Except In addition, due to the dense arrangement of the visual elements of the retina, the vision of these spiders is objective, so at a distance of 8 cm the spider can see the fly in detail.

"Experimentally, it has been proven that horses, as well as some other spiders, distinguish colors."

"Horse spiders do not weave trapping webs, they track down prey and jump on it from a distance of several centimeters. Obviously, this method of hunting requires good eyesight, and this is true: studies have shown that horses have some of the sharpest eyes among spiders; they also see colors, but jumping requires accurate distance calculation, and how spiders do this is not entirely clear.As for other animals that face a similar problem, the most common solution here is binocular vision with overlapping fields of view of both eyes "In this case, the brain determines the distance to the object by comparing information from one and the other eye. Some animals can get by with one eye - for example, a chameleon: it simply changes the focal length of the lens. For the same purpose, insects turn their heads from side to side .
Horse spiders have four eyes on the front (“front”) of the head, two central ones are larger, two extreme ones are smaller. Studies have shown that the extreme (small - see photo) eyes do not affect the accuracy of the jump. On the other hand, the visual fields of the central eyes in spiders do not overlap. They also cannot change the focal length in any other way. It turned out that spiders, surprisingly, rely on color vision to determine the distance to jump.
In 1981, Japanese scientists from Osaka University found that the retina of horses is arranged in an unusually complex way: it is formed from four layers of light-sensitive cells. One of them consists entirely of receptors Green colour. But at the same time, the green of the spiders is never in focus, so any image is blurry.
As researchers write in the journal Science, spiders determine the distance to the prey due to the contrast between the blurry image on the “green” layer and the focused image on other layers of the retina. If spiders saw everything in perfect focus, then with non-overlapping fields of view, they would not be able to accurately estimate the distance to an object. In the experiment, the horses began to miss their prey if the green spectrum was removed from the lighting.
Thus, in order to accurately aim, the spiders need to keep the target defocused. Although only horses of the Hasarius adansoni species participated in the experiment, scientists have no doubt that the vision of all other spiders of this vast group is similar.
These are the only animals that use this kind of engineering solution to obtain a three-dimensional image, and the only animals with such a peculiar retinal device. Yes, there are microscopes that determine the depth of the image according to the same scheme, but the patent here clearly belongs to the spiders.

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Like most other arachnids, the primary sense of many spiders is touch. These "many" are mainly those spiders that build trapping webs. The spider with extraordinary sensitivity perceives the slightest changes in the tension of the web threads and the almost imperceptible vibration of the network. By the way the web shakes, the spider is able to determine very precisely which animal it has caught, and acts accordingly. As a result, it is quite difficult to deceive a spider and lure it out of its hiding place. Sometimes your touch will be successful and the spider will jump out, but very often you will be exhausted, pulling the signal threads this way and that, and a twig, and a hair, and the spider will only get deeper into the gap.
The spider perceives air vibrations not only through the web. On his body there are thin hairs that are attached to the shell movably, as if on a hinge, and react to the slightest fluctuation of air. These hairs are scattered all over the body, so that the spider hears both with its legs, and with its back, and with its stomach. Spiders are beautiful
but they hear the buzzing of a fly, the soft flapping of a butterfly's wings, the singing of birds, and the sounds musical instruments. Spiders appearing from hiding places at the sound of a violin are not beautiful fairy tale but a boring scientific fact. By the way, there are quite a few spiders that sing themselves. Spiders from the teridiid family, for example, have spines on the posterior edge of the cephalothorax, and on leading edge abdomen - bristles. The spider turns its “head”, the spines pull the bristles and a song is heard that enchants the representatives of the opposite sex. Unfortunately, the human ear does not perceive this song.
Spiders distinguish smells quite well; in many orb-weavers, for example, males distinguish the network of a mature female from the network of a young girl by smell. The organs of smell are most strongly developed on the legs, but they are also scattered over the entire surface of the body, so that the spider can sniff both with its stomach and back. Spiders and taste are distinguished, although this sense is not very subtle in them.
The vision of different spiders is different. Most species have eight eyes, but there are spiders with six eyes, four eyes, and even two eyes. Some see very vaguely, as if through tissue paper, others - very decently. Large moving objects distinguish all spiders; a cross, for example, when a person appears in the field of view, jumps off the net or runs along the web to a shelter. Spider-spiders generally have two eyes out of eight in terms of complexity and perfection that are not inferior to ours, and they see the world clearly, in
the smallest details. Another thing is that the range is short, the horse sees the fly in all details only from 15 cm, but given that he himself is 7 mm long, the distance is quite decent. Horses in addition, and many other spiders, see the world in color, unlike many mammals.
The nerve centers of spiders are collected in the cephalothorax in a kind of brain. And although compared to the mammalian brain, this cluster of nerve cells is like a baby carriage next to a Rolls-Royce, the spider uses this baby carriage with great success. In particular, conditioned reflexes a spider develops very quickly, and spiders learn no worse than many reptiles and mammals, not to mention fish and frogs. It was thanks to the ingenuity of spiders that we managed to learn a lot about their sense organs. For example, if you offer a spider a fly under blue and red light, but under blue light “punish” it for attacking with a weak electric shock, then very quickly the spider learns to catch flies only under red light. Thus, it was possible to find out that the spider distinguishes colors.

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We are not able to see the world through the eyes of animals (but we would like to), but thanks to science we can imagine how things familiar to us look like in the eyes of our smaller brothers.

website collected 10 vivid examples of a different perception of the world.

10. How sharks see the underwater world

Until recently, there was an opinion that sharks did not see well. However, studies and experiments of scientists have refuted this assertion. sharks see the world in faintly gray or green light, and objects - clear and contrasting.

9. How snakes see the world

Special snake organs designed for perception of heat sources, help to find prey in the dark and protect against large predators. This ability to see heat sources is not found in other animal species.

8. How dogs see the world

Dogs don't know red from green, both of these colors - from yellow and orange. Many people do not even suspect that, looking at a traffic light, four-legged friend does not distinguish what kind of light is on there. The dog is guided by how the brightness of the eyes of the traffic light changes, and by the actions of the people around it.

7. How bees see the world

Bees see a wider color spectrum, including ultraviolet light. This allows them to easily find pollen on flowers.

6. How cuttlefish see the underwater world

Despite the incredible ability to change the color of their body, cuttlefish vision leaves much to be desired. The pupil has W-shaped form and only one photoreceptor, which allows them to see only shades of gray.

5. How sparrows see the world

Our little friends we meet everywhere see the world through rose colored glasses.For some reason, sparrows do not like the color blue, and are also afraid of shiny, sparkling stripes.

4. How eagles see the world

The eagle is able to see prey from a distance. several kilometers, if the bird at the same time helps itself with a movement of the head, then this distance can double. An eagle can scan an area of ​​an area with great care. 13 km².

3. How owls see the world

At night, owls can see 3 times better than humans. They have No eyeballs . The organs of vision of owls should rather be called "eye tubes", but they more than compensate for the lack of binocular vision with excellent night vision and farsightedness, which makes owls ferocious nocturnal predators.