3.8. Vision If you are in good psychological shape, then your vision becomes so much better, so much clearer that everything turns out natural and simple. Ayrton Senna, three-time world champion in Formula 1 racing. We already talked above about how important it is to watch

Unlike many animals that are nocturnal, bats hunt almost blindly. Contrary to the popular myth about their excellent night vision, they do not see well in the dark and must navigate in space using their mouth and ears.
It sounds strange, but it’s true - they make sounds, the waves of which are reflected from surrounding objects and caught by their ears. This method of orientation in space is called echolocation and, thanks to it, nocturnal predators can detect their victims.

Depending on the species, bats can feed on the blood of other animals and all kinds of vegetation, but most prefer insects. It is known that in an hour of hunting one individual can eat about 200 mosquitoes. However, they cannot get enough of mosquitoes alone, so they try to find and eat more nutritious bugs and caterpillars. Finding them sometimes turns into a real challenge, because these insects are perfectly camouflaged in the leaves of plants.

Insect camouflage

Scientists were convinced of this by conducting an experiment in which they exposed sound waves to the leaves of plants with and without insects from 541 different angles. During this process, they captured the reflected waves and assessed at what angle the insects were best detected. It was found that to successfully hunt, bats must fly to the leaves at an angle of 42 to 78 degrees.

The most cunning animals

Instructions

Almost all species of bats are nocturnal, which means they must have sensory organs adapted to the dark. And indeed, despite the fact that bats have eyes with which they are able to see daytime, they rely primarily on echolocation.

The first researchers trying to understand the abilities of bats covered their eyes and covered their bodies and wings with a composition that was supposed to make the skin insensitive, but the bats had no problem avoiding all obstacles. Only in the middle of the 20th century did scientists manage to figure out how mice navigate in space. During the flight, bats emit sound waves, and then catch their reflections from surrounding objects and thus create a picture of the world.

The bats They produce sounds in the ultrasonic range, so we cannot hear them. But the mice themselves understand each other very well. They have their own special language with at least 15 syllables. Mice don't just make sounds, they sing songs that not only help them navigate in space, but also make it possible to communicate. With their songs, mice recognize each other, attract females, and decide controversial issues about territory, they teach the cubs. Some scientists put the language of bats in second place in terms of development after humans.

Bats make strong sounds, so their ears are closed with special partitions while singing; if nature had not provided such a mechanism, mice would very quickly lose their hearing from constant overload.

No, they are not blind at all.

Of the more than 1,100 species of bats on our planet, not a single one is blind - moreover, many see very well. The idea that bats don't need eyes because they navigate solely by echolocation, or "sonar," is complete nonsense.

For example, fruit bats (also called "giant bats") They don’t use echolocation at all. The eyes of fruit bats are large, good for navigation and for searching for food, which, expectedly, consists of fruits. Echolocation- a thing that is practically useless for searching for food that does not move from place to place. Instead, to find fruit, fruit bats have a well-developed sense of smell.

The common vampire bat (Desmodus rotundus) is the only bat that feeds on the blood of mammals. She is just so blind that she is able to see a cow 120 meters away in the dead of night, in pitch darkness.

Even bats themselves (Micrichiroptera, English microbats) - those that feed on insects, include all bats in Britain and actually use sonar for hunting - use vision (their eyes are small) to avoid obstacles, recognize landmarks and calculate altitude of your flight. Bats have good night vision. Being nocturnal, they perceive everything in black and white, while fruit bats see everything in color, since their activity occurs during the daytime.

There are several species of fish-eating bats in the Americas. Thus, a large fisherman, or flying bulldog (Noctilio leporinus), with keen eyesight and clawed paws, snatches fish from the water. Flying bulldogs are very easy to recognize not only by their 66-centimeter wingspan, but also by the disgusting smell in their roosting areas.

Few people find bats edible, but for special occasions (such as weddings), the Chamorro people living on the Pacific island of Guam boil giant fruit bats or “flying foxes” in coconut milk and eat them whole, wings included. , wool, etc. This may explain why a rare and very unpleasant neurological disease, the ALS*-parkinsonism-dementia complex, is so common among Chamorros. The fact is that Guam bats feed on poisonous plants - cycads, the dangerous neurotoxins of which are transferred (lightly flavored with coconut) to the unlucky feasters.

* ALS (eng. ALS) - amyotrophic lateral sclerosis (also known as motor neuron disease, Charcot's disease or Lou Gehrig's disease, named after the legendary American baseball player who died from this disease), a terrible incurable degenerative disease of the nervous system still unknown etiology. According to statistics, every year 1-2 people out of 100,000 develop ALS. On early stages the disease manifests itself in the form of twitching, convulsions, muscle numbness, weakness in the limbs, and difficulty speaking. Then muscle weakness gradually covers everything more parts body, and sooner or later the patient loses the ability to move independently. The disease does not affect mental capacity, but leads to severe depression in anticipation of a slow death.

Great night bat

Lesser brown bat

Spectacled leaf-nosed bat

The closest relatives of bats in the order Chiroptera are fruit bats (flying dogs, flying foxes, etc.) - they simply see perfectly, sometimes even better than people. But Microchiroptera themselves, even those that actively use echolocation, are quite sighted. Bat vision won't hurt at all. Firstly, the animal must at least minimally distinguish the daylight hours from the dark (when it is necessary to start hunting). Secondly, echolocation performed by chiropterans has a very limited range of action (50 m maximum), and if there is a certain level of lighting, it is more convenient for a mouse to navigate in space using more “long-range” vision. Thirdly, as it recently became known, European bats react to the polarized rays of the setting and rising sun and, analyzing the angle of their incidence, calculate the directions. It turns out to be a kind of compass, but not magnetic, but light.

It was originally thought that the bat's retina had only rods and no cones. Let us remember that cones are different types and react accordingly to rays from different lengths waves (that is, different colors). The rods react only to changes in brightness and thus produce a monochrome image, something like what we see on night vision devices. So, it turned out that at least some bats can see a color picture, and their retinas have both rods and cones. Moreover, the eye, for example, of such a bat as is common in South America Spectacled leaf-nosed insect is sensitive to the rays of the ultraviolet part of the spectrum - the eyes of some insects have the same ability.

Sometimes the question is about which sense organ - the eye or the ear - to make one's way in space for individual species bats is not easy to solve. During experiments conducted by the University of Western Ontario (Canada), strange behavior of bats of the species of the little brown bat was noted. The researchers placed obstacles made of opaque, transparent and reflective materials at the exit of an abandoned mine where these animals live and changed the illumination in the area of ​​​​the obstacle. It turned out that even in bright light, when the mouse’s vision becomes least acute, for some reason the little brown bats prefer to use their vision and... as a result, they often stumble upon a transparent obstacle. If they had switched to echolocation, the transparent obstacle would have been easily detected.