Description: War Thunder is a next generation military MMO game dedicated to...
I fit after death in the minds of a hundred sparrows and it was fun and strange when they scared them away
"The eyes of spiders of different families are very different. Spiders that hunt without trapping net, like wolf spiders (Lycosidae), lynx spiders (Oxyopidae) and jumping spiders (Salticidae), very well developed vision. Jumping spiders can see almost as well as humans. Experiments have shown that they can even distinguish colors. Cave spiders that live in the dark do not see at all or see very poorly. 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."
"Spiders-jumps 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 to jump, you need to accurately calculate the distance, and how spiders manage to 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 victim 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 structure. 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.
Banned on Google?
Ecology
The eight-eyed jumping spider has a field of view of nearly 360 degrees, according to new research. Scientists have found that these "all-seeing spiders" can perfectly see a person, and can also watch videos with nature.
This study tried to describe how each of the spider's 8 eyes work. During the experiments, the researchers also found that spiders can sometimes focus on videos or people.
"Many spiders, such as the black widow or brown recluse, try to avoid humans, and jumping spiders often look completely fearless., says the researcher Elizabeth Jacob.“I doubt they can confuse large objects like people and prey, but they definitely show interest in knowing if you are a threat.”
"If you start pulling the thread near a spider, it is more likely to lunge at it, as is the case with cats that attack a moving rope.", added Jacob, a professor at the University of Massachusetts and a researcher in organismic and evolutionary biology.
She said that there is a lot of misinformation on the net that the bite of these spiders is supposedly quite dangerous for humans. These creatures rarely bite a person, but even if they do, you will get off with a slight fright and a small red spot on the skin, which will quickly pass.
During the experiment, Jacob and her colleagues showed jumping spiders (lat. Salticidae) video clips and conducted a series of tests to better understand how the visual system of these creatures works. Some spiders have only 2 eyes, but jumping spiders have as many as 4 pairs of eyes!
The two main eyes look straight ahead. "If you look at the spider from the front, you will see two large main eyes that will look directly at you, Jacob said. - These eyes have a very unusual structure. They have large fixed lenses and a tiny boomerang-shaped retina that provides high resolution images and allows the spider to see both color and ultraviolet images."
The retina of each of the main eyes is located on reverse side a long moving tube inside the spider's head. The spider can move these tubes in order to scan everything around. One of the researchers said that it looks like a spider is looking at the surroundings with a flashlight.
The other three pairs of eyes are called secondary or secondary eyes. They also see very well and can distinguish movements well. Of these, one pair is directed forward and to the sides. Another pair is very tiny and also looks away. The last pair is located on the sides and at the back of the spider's head.
Jumping spiders not only have excellent eyesight, they prefer to stay in groups and seem extremely curious about a person, and everything that surrounds them.
"If a spider is staring at you, it's safe to say it will be a jumping spider", Jacob said. These spiders react to their reflection in the mirror and can even watch videos of insects.
If the spiders are shown a video with a moving cricket, it will attack the screen. AT wild nature spiders chase prey in much the same way as cats do, if they notice a moving mouse, they will carefully follow it, waiting for the right moment to attack.
Jakob and her colleagues plan to create a special device in the future - i-tracker, which allows you to follow the movement of the main pair of spider eyes as they explore objects. This will help scientists look at the world through the eyes of spiders and look into their brains, which could not be done before.
Guys, we put our soul into the site. Thanks for that
for discovering this beauty. Thanks for the inspiration and goosebumps.
Join us at Facebook and In contact with
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, a 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.
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.
More:
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 between 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. Side-walker 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 it in close-up and begins to follow it with its 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.
