How mice navigate. Bats have a developed speech apparatus

Bats usually live in huge flocks in caves, in which they can navigate perfectly in complete darkness. Flying in and out of the cave, each mouse makes sounds inaudible to us. Thousands of mice make these sounds at the same time, but this does not prevent them from perfectly orienting themselves in space in complete darkness and flying without colliding with each other. Why the bats can they fly confidently in complete darkness without bumping into obstacles? The amazing property of these nocturnal animals - the ability to navigate in space without the help of vision - is associated with their ability to emit and capture ultrasonic waves.

It turned out that during flight the mouse emits short signals at a frequency of about 80 kHz, and then receives reflected echo signals that come to it from nearby obstacles and from insects flying nearby.

In order for a signal to be reflected by an obstacle, the smallest linear size of this obstacle must be no less than the wavelength of the sent sound. The use of ultrasound can detect smaller objects than could be detected using lower sound frequencies. In addition, the use of ultrasonic signals is due to the fact that as the wavelength decreases, the directionality of the radiation is more easily realized, and this is very important for echolocation.

The mouse begins to react to a particular object at a distance of about 1 meter, while the duration of the ultrasonic signals sent by the mouse decreases by about 10 times, and their repetition rate increases to 100–200 pulses (clicks) per second. That is, upon noticing an object, the mouse begins to click more often, and the clicks themselves become shorter. The smallest distance a mouse can detect in this way is approximately 5 cm.

While approaching the object of hunting, the bat seems to estimate the angle between the direction of its speed and the direction towards the source of the reflected signal and changes the direction of flight so that this angle becomes smaller and smaller.

Can a bat, sending a signal with a frequency of 80 kHz, detect a 1 mm midge? The speed of sound in air is taken to be 320 m/s. Explain your answer.

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Beginning of the form

For ultrasonic echolocation, mice use waves with a frequency

1) less than 20 Hz

2) 20 Hz to 20 kHz

3) more than 20 kHz

4) any frequency

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Beginning of the form

The ability to perfectly navigate in space is associated with bats with their ability to emit and receive

1) only infrasonic waves

2) only sound waves

3) only ultrasonic waves

4) sound and ultrasonic waves

Sound recording

The ability to record sounds and then play them back was discovered in 1877 by the American inventor T.A. Edison. Thanks to the ability to record and play back sounds, sound cinema appeared. Recording pieces of music, stories, and even entire plays on gramophone or gramophone records became a popular form of sound recording.

Figure 1 shows a simplified diagram of a mechanical sound recording device. Sound waves from a source (singer, orchestra, etc.) enter horn 1, in which a thin elastic plate 2, called a membrane, is fixed. Under the influence of a sound wave, the membrane vibrates. The vibrations of the membrane are transmitted to the cutter 3 associated with it, the tip of which draws a sound groove on the rotating disk 4. The sound groove twists in a spiral from the edge of the disk to its center. The figure shows the appearance of sound grooves on a record viewed through a magnifying glass.

The disc on which the sound is recorded is made of a special soft wax material. A copper copy (cliché) is removed from this wax disk using a galvanoplastic method. This involves the deposition of pure copper on an electrode when an electric current passes through a solution of its salts. The copper copy is then imprinted onto plastic disks. This is how gramophone records are made.

When playing sound, a gramophone record is placed under a needle connected to the gramophone membrane, and the record is rotated. Moving along the wavy groove of the record, the end of the needle vibrates, and the membrane vibrates along with it, and these vibrations quite accurately reproduce the recorded sound.

When recording sound mechanically, a tuning fork is used. By increasing the playing time of the tuning fork by 2 times

1) the length of the sound groove will increase by 2 times

2) the length of the sound groove will decrease by 2 times

3) the depth of the sound groove will increase by 2 times

4) the depth of the sound groove will decrease by 2 times

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2. Molecular physics

Surface tension

There is a force at work in the world of everyday phenomena around us that is usually not paid attention to. This force is relatively small, its action does not cause powerful effects. However, we cannot pour water into a glass, we cannot do anything at all with this or that liquid without bringing into action forces called surface tension forces. These forces play a significant role in nature and in our lives. Without them, we could not write with a fountain pen; all the ink would immediately pour out of it. It would be impossible to soap your hands because foam would not be able to form. A light rain would have soaked us through. Would be violated water regime soil, which would be disastrous for plants. Important functions of our body would be affected.

The easiest way to grasp the nature of surface tension forces is from a poorly closed or faulty water tap. The drop grows gradually, over time a narrowing is formed - a neck, and the drop breaks off.

The water appears to be enclosed in an elastic bag, and this bag breaks when the force of gravity exceeds its strength. In reality, of course, there is nothing but water in the drop, but the surface layer of water itself behaves like a stretched elastic film.

The same impression is produced by the film of a soap bubble. It looks like the thin stretched rubber of a children's ball. If you carefully place the needle on the surface of the water, the surface film will bend and prevent the needle from sinking. For the same reason, water striders can glide along the surface of the water without falling into it.

In its desire to contract, the surface film would give the liquid a spherical shape, if not for the gravity. The smaller the droplet, the greater the role played by surface tension forces compared to gravity. Therefore, small droplets are close in shape to a ball. In free fall, a state of weightlessness occurs, and therefore raindrops are almost strictly spherical. Due to refraction sun rays a rainbow appears in these drops.

The cause of surface tension is intermolecular interaction. Liquid molecules interact with each other more strongly than liquid molecules and air molecules, so the molecules of the surface layer of the liquid tend to get closer to each other and dive deeper into the liquid. This allows the liquid to take a shape in which the number of molecules on the surface would be minimal, and a sphere has the minimal surface area for a given volume. The surface of the liquid contracts and this results in surface tension.

Bat

A bat can fly around a dark barn at midnight without hitting any pillars, rafters, or sleeping cows. The eyes of a bat do not have special night vision devices. If a bat relied on its eyes in its movements around the barn at night, it would count no fewer pillars and rafters with its forehead than you and I.

How do bats navigate in the dark?

Bats have developed a different way of orienting themselves in the dark: they listen to dark space. They fly out to hunt after sunset. During the day, they hang upside down in their homes - caves, in hollow trees or in the entryways of village houses, clinging to the beams on the ceiling with their paws. Most During the day, bats get themselves in order, preparing for nightly adventures: they comb their fur with their claws and carefully lick their wings.

Interesting fact: Just like submarines, bats use sonar, or sound waves, to navigate in the dark.

Why do bats hunt at night?

In between these activities, bats doze. When night falls, bats leave their homes and fly out to hunt. Some species of bats prefer fruits, while others, especially tropical species, are blood-sucking; they attack birds, cows and other animals. But most bats eat bugs and other insects. Bats hunt at night because the darkness protects the bats from animals that might eat them. In addition, during night flights, their wide, non-hairy wings do not dry out from the hot rays of the sun.

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How do bats see?

To navigate in the dark, these animals use sound. In this way, they are similar to submarines, which also use sound waves to navigate the murky depths of the ocean. Bats send packs of sound waves into space; they emit waves through their mouth or nose. The waves are reflected from surrounding objects, outlining their contours, and mice catch them with their ears and perceive the sound (acoustic) picture of the environment, and they orient themselves in this picture. The process of such orientation by reflected sound is called echolocation. The bat's large, fancy ears help it navigate the sound picture of the world in the dark.

Interesting fact: When a bat targets prey, it emits a sound at a frequency of 200 beats per second.

A bat that finds itself in your bedroom at three in the morning knows exactly where to fly. It sends out packets of sound waves and picks up their reflections. The waves are reflected from chairs, a sofa, and a TV screen. The waves will not be reflected from the open window - which means the path is clear, so the bat has found a way out of the trap. The sound that a bat makes is also reflected from small objects. If prey - a tasty fly - is buzzing in the room, the bat will find it. When searching for an insect, the bat makes a sound with a frequency of 10 beats (pulses) per second. Having caught the reflected signal, it increases the frequency to 25 beats per second, at this frequency the bat can more accurately determine where the fly is so that the attack is successful.

Echolocation allows bats to navigate in space even in the dark. Animals emit signals at ultrasonic frequencies.

When the ultrasonic wave hits objects, it reflects off them and returns to the mouse. Based on the time elapsed from emission to return of the signal, it is able to determine the distance to the object.

Bats use two different signal production mechanisms. Some chiropterans produce them using the larynx, and some use their tongue (the mice seem to click with it).

Authors new job studied 26 bats that belonged to 11 groups that evolved independently of each other. As a result, scientists were able to detect clear anatomical differences between mice using two signal production mechanisms.

According to the researchers, the new data will help in studying the question of the evolution of the ability to echolocation.

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Instructions

Almost all species of bats are night look life, which means they must have sense organs adapted to darkness. Indeed, although bats have eyes that can see during the day, 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.

Bats make 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.

Job source: Solution 4255. OGE 2017 Physics, E.E. Kamzeeva. 30 options.

Task 20. The ability to perfectly navigate in space in bats is associated with their ability to emit and receive

1) only infrasonic waves

2) only sound waves

3) only ultrasonic waves

4) sound and ultrasonic waves

Solution.

Bats usually live in huge flocks in caves, in which they can navigate perfectly in complete darkness. Flying in and out of the cave, each mouse makes sounds inaudible to us. Thousands of mice make these sounds at the same time, but this does not prevent them from perfectly orienting themselves in space in complete darkness and flying without colliding with each other. Why can bats fly confidently in complete darkness without bumping into obstacles? The amazing property of these nocturnal animals - the ability to navigate in space without the help of vision - is associated with their ability to emit and capture ultrasonic waves.

In order for a signal to be reflected by an obstacle, the smallest linear size of this obstacle must be no less than the wavelength of the sent sound. The use of ultrasound can detect objects smaller than could be detected using other sound frequencies. In addition, the use of ultrasonic signals is due to the fact that as the wavelength decreases, the directionality of the radiation is more easily realized, and this is very important for echolocation.