Ecology
Many marine animals live in a world where form is felt through sounds. They produce clicking sounds that reverberate off objects in order to visualize a clear map of the area, as well as to track down prey.
Researchers from the state of Hawaii have recently discovered how precisely the "echolocation devices" of these creatures can be tuned. Toothed whales can focus their sound beam, highlighting the target with a stream of clicking sounds in order to study it in detail.
Laura Kloepper, student University of Hawaii, who led the research, worked with a trained little killer whale (dolphin family) named Kina, who has lived in the research institute's sheltered bay since 1993.
Past research has shown that it can distinguish between objects that vary minimally in thickness. The difference in thickness may be less than a human hair! Scientists suspected that this amazing accuracy was partly due to the ability of the whales to focus on the echolocation sound beam.
Kloepper and her team have conducted tests for the first time to accurately measure the beam as the animal changes focus if the "echolocation task" becomes more difficult.
The researchers taught Kina to recognize a cylinder of special dimensions. In case she recognizes the object, Kina swims to the surface and touches the sword with her nose. Whenever a task was completed correctly, the killer whale received a treat in the form of a fish.
Then Kina had to complete another task: to find her object among similar ones. The first cylinder was already familiar to her, the walls of the second were 1 centimeter thicker, and the walls of the third were only 0.2 millimeters thicker. All three items were the same length.
At the signal of the trainer, Kina plunged under the water and swam into a special fence to complete the task. The exit in front rose up, so she could not detect the object in front of her using echolocation. During the experiment, the researchers used underwater microphones. To measure Kina's sound beams.
"By recording sound from different positions, we were able to depict the shape (size) of this beam" Kloepper said.
The images showed that Kina changed the size of the beam depending on how difficult it was to identify the cylinder. She produced a larger sound beam when the cylinder in front of her was harder to distinguish from her target.
Scientists believe that when Kina produced this large beam, her frontal lens acted as a reactive sound lens, picking up all the sounds that bounce off the object of interest.
"In this case, she gets more sonic energy back while examining the subject, said Kloepper. This makes sense, as echolocation helps animals survive. At great depths, there is little to see, so they track and fish using sounds."
Subsequent research by a team of scientists showed that guinea pigs have the same ability to focus sound.
By tuning her echolocation beam, Kina is able to change the sensitivity of her hearing, making it super sensitive when hunting, as well as blocking it in case of potentially dangerous very loud sounds.
underwater hunters
Toothed whales and dolphins, which belong to the suborder Odontoceti, use echolocation for hunting and navigation.
Echolocation clicks travel through a fatty structure at the front of the skull called forehead lens. It is this structure that forms the visible tubercle on the head in animals. Scientists believe that it works like a tuned acoustic lens, collecting sound into a beam, the size of which can be changed.
Other sea creatures that don't use echolocation have other tricks for getting around underwater. Seals, for example, have super sensitive whiskers that can tell where the fattest fish are by feeling the trail they leave behind.
Humans have long assumed that bats fly and hunt in pitch darkness with their highly developed eyesight. Today, these animals are known to have a sensitive and precise organ that allows them to navigate through space using sound rather than light. More important than vision for bats are hearing and smell.
Basic data:
How well does a bat "see"?
A person perceives the world around him mainly with the help of vision. Therefore, it is difficult to imagine how a bat can create the same picture based on the analysis of sound signals.
As a result of many experiments, it has been proven that bats "see" very well. Bats can accurately determine the distance to an object, for example, insects, and in which direction it is moving. The only property of an object that the echolocation system does not allow to determine is its color.
Not all types of bats use echolocation. Most fruit bats have not found an echolocation mechanism. They navigate by sight. Only cave species of fruit bats produce weak noise signals. In leather animals, the mechanism of echolocation is developed to the most perfect degree. These animals are able to isolate the reflection of "their" signal from a mixture of various ultrasonic and sound waves.
Flying between wires
The accuracy of the echolocation apparatus is amazing. Bats "notice" wires with a thickness of 0.28 mm, being at a distance of more than a meter from them. If the wires are thicker than 3 mm, they "see" them for about 2-3 meters. The echolocation system of the southern horseshoe bat is even better. The beast in flight can avoid collision with wires with a thickness of 0.05 mm. The pointed-eared bat detects a wire with a diameter of 2 mm at a distance of 1.1 m.
Clarity of the "image"
As a result of numerous experiments, it was proved that North American big bats can distinguish objects located at a distance of about 10-12 mm from each other, and also distinguish a triangle with a side length of 10, 10 and 5 millimeters from a triangle with a side size of 9, 9 and 4 .5 millimeters.
Signal emission: the bat emits ultrasonic signals at regular intervals. The animal quite accurately determines the time between the signal and the echo reflected from the object.
Signal reception: the bat catches the echo of the signal with its ears, and in the brain, based on the sounds received, a picture is built - an accurate representation of the shape and size of the object.
Fixture Features
Sound formation
Only in 1938, scientists discovered that bats make a lot of sounds that are above the human hearing threshold. The frequency of ultrasound is in the range of 30-70 thousand Hz. Bats emit sounds in the form of discrete pulses, the duration of each of which is from 0.01 to 0.02 seconds. Before making a sound, the bat compresses the air in the vocal apparatus between two membranes, which, under the influence of air, begin to oscillate. The membranes are stretched by various muscles and allow the bat to produce various sounds. Before the sound exits through the mouth or nose, it is amplified and modified by passing through several chambers. All bats that send signals through their noses have complex growths on their noses.
The structure of the ears
The ears of bats are extremely sensitive. This is necessary in order to better perceive the signals that are reflected from objects. Bat ears are real radars that pick up and recognize high frequency sounds. Bats can move their ears, turning them so that they can best perceive sound signals that come from different directions. The sound waves captured by the ears enter the brain, where they are analyzed and compiled in the same way that a three-dimensional image is formed in the human brain from the information that the organs of vision transmit when observing an object. With the help of such "sound" pictures, bats absolutely accurately determine the location of prey.
VISION "SOUND IMAGE"
Bats get a picture of the world around them by analyzing the reflections of sound waves, just like a person gets it, unconsciously analyzing visual images. However, human vision of objects depends on external light sources, and bats build pictures thanks to the sounds that they themselves send. The signals of different types of bats vary greatly in their intensity. To navigate in the dark, they send out a series of short high-frequency sounds that spread like a flashlight. When such a signal encounters an object on its way, its reflection comes back and is captured by the bat. This way of orientation has many advantages.
First, shortwave sounds are easy to distinguish, so they are good for finding the flying insects that most bats feed on. Low sounds of long waves are not reflected from small objects and do not return back. High frequency sounds are very easy to distinguish from the sounds of the surrounding world, the frequency of which is much lower. In addition, bats "see" but remain "invisible" because the sounds they make are inaudible to other animals (that is, insects cannot spot bats and avoid them).
MYSTERY SOLVED
Even on the darkest nights, bats confidently fly between tree branches and catch flying insects.
Scientists once thought that just like other nocturnal animals, bats have very well developed eyesight. However, in 1793, the Italian naturalist L. Spallanzani noticed that bats hunt even on dark nights, when no night birds that have excellent night vision, such as owls, fly. L. Spallanzani determined that bats fly just as well with their eyes closed as they do with their eyes open. In 1794, the Swiss biologist S. Zhyurin confirmed the experiments of L. Spallanzani. He found that these animals with wax-blocked ears become helpless in flight and cannot navigate in the air. Later, this version was rejected and forgotten, they returned to it after 110 years. In 1912, X. Maxim, the inventor of the easel machine gun, expressed the idea that seeing with "ears" is explained by the mechanism of echolocation. In 1938, D. Griffin, using the apparatus invented by G. Pierce, recorded the sounds that bats make. In In the early 1950s, the theory of ultrasonic echolocation became firmly established in science.
ECHOLOCATION AND ITS USE
The signals that bats send out consist of 5 sounds of the same or different frequencies. One signal can contain a whole range of frequencies. The duration of the sounding of signals can be different, from one thousandth to one tenth of a second.
By emitting sound signals of various frequencies, bats "observe" in what order sound reflections return. Sounds of different frequencies propagate at different speeds. From the received reflected sound signals, the bat makes an accurate picture of the surrounding world and registers the slightest changes in it, for example, the movements of flying insects.
Most bats have such fine hearing that they can very easily distinguish "their" signals from the sounds that other bats make. The signals that send out reconciliations are quite short, so bats distinguish sounds that go out and come back. Strength and frequency of signals varies depending on the terrain the animal is flying through. When flying near trees, the bat sends out signals of lesser strength so as not to cause a loud echo. In flight, habitual signals are heard, and when hunting, the bat uses the full power of sounds.
INTERESTING FACTS. DO YOU KNOW WHAT...
- Most of the ultrasonic signals emitted by bats cannot be heard by humans, however, some people experience their pressure and can determine that animals are nearby.
- Some types of insects can hear the signals that bats send, so they try to hide from their pursuers. Night butterflies even send out their sound signals to confuse bats that prey on them.
- The sound signals emitted by a bat have the same strength as the sound of a jet aircraft. In order not to go deaf, the animal closes its ear openings every time before “shouting” with the help of special muscles.
- The expression "blind as a bat" is not true. Almost all bats have very good eyesight. For example, fruit bats eat fruits that they find with their eyesight.
- Bats that feed on insects and nectar, as well as those that make faint sounds, are sometimes called “whisper” bats by scientists. signals.
Bats and other echo sounders in nature. Biologist Gunars Petersons tells. Video (00:33:01)
Echolocation in animals (biologist Ilya Volodin tells). Video (00:24:59)
Animals use echolocation to navigate in space and to determine the location of objects around them, mainly using high-frequency sound signals. It is most developed in bats and dolphins, it is also used by shrews, a number of species of pinnipeds (seals), birds (guajaro, salangans, etc.) ... Biologist Ilya Volodin tells.
Animal instinct. Series 8. Wildlife of planet Earth - dolphin echolocation. Video (00:02:39)
Dolphins are special, unique creatures. Their ability to understand people has always aroused genuine interest among both scientists and laymen. However, there are also features that we may not even be aware of. For example, studies conducted by American scientists in the Hawaiian Islands revealed that dolphins, like whales, track their prey using echolocation.
Interesting facts - Bats. Video (00:05:46)
Bats - Interesting Facts
Among all mammalian species, only bats are capable of flight. Moreover, their flight is quite difficult to confuse with other animals, since it is quite different from the usual sight for our eyes. This type of flight is inherent in bats because their wings are somewhat similar to a small parachute. They don't need to constantly flap their wings to fly; rather, bats push off in the air.
Indeed, there are mice that need blood. There are three such types. But there are practically no cases when a bat attacked a person in order to “taste” his blood. Bats, first of all, focus on animals that are not able to resist them. Such animals include, for example, cows. These species live in South and Central America.
There are rumors that bats are capable of carrying a serious infection, and in interaction with a person, creatures can infect him with a dangerous disease. In fact, North American bats have only infected 10 people over the past half century. Bats themselves are much more afraid of humans than we are of them. Therefore, creatures try not to meet with a person, and in case of contact they immediately fly away. If you are bitten by a bat, you should not worry too much. If you immediately go to the hospital, nothing serious will happen - a regular injection will save you from unnecessary fears. Here you should be afraid of another, if the bat drank at least a little of your blood, then the probability is very high that this particular creature will “visit” you again soon. She seems to understand that you are an affordable source of nutrition, so she chooses you. If, of course, she manages to find you, and it is quite possible for her to do this, since bats remember and distinguish a person by his breathing.
8 FACTS ABOUT BATS. Video (00:06:12)
Bats have long been considered one of the most mysterious animals. They aroused apprehension, fear and, at the same time, great interest. And this is not surprising, because they are very different from their wingless counterparts. Today we offer you to get acquainted with the most interesting facts about bats.
Echolocation. Unusual human capabilities. Video (00:03:20)
Echolocation is a very unusual ability that is found in a small number of representatives of the animal world. Over time, people have learned to use this ability. Daniel Kish is the first to intuitively master echolocation.
Sonar animals emit wave vibrations, which, meeting stones, rocks, trees or other obstacles on their way, are reflected from them and come back. The animal perceives the echo as information and creates an image. The location medium can be air or water, and the means can be waves: water, sound, ultrasonic and electromagnetic.
To carry out echolocation, animals need to have not only an organ that reproduces waves, but also one that perceives the echo. For this, fish have lateral lines on both sides of the body filled with small reticulate receptors. The receptors detect the reflection from an ordinary water wave, and this helps the fish not to hit sharp pitfalls when swimming, especially when the water is cloudy. Other animals use ultrasonic waves produced by themselves with the help of special organs that are located near the lips. Typical ultrasonic echolocators are bats, and among marine animals - dolphins, killer whales, whales. All of them can reproduce waves and perceive them as an echo of reflected ultrasonic vibrations. There are also animals that emit real electromagnetic waves. The technical principles of electric organs are similar to those of modern radars. Rather, radars are built on the principle of life adaptations in animals. Infrared waves are also used to orient animals.
Sounds are made by animals not only in the air, but also in the water depths. The inhabitants of the sea, for example, have been publishing them for millions of years, but researchers have only recently begun to study them systematically. It has now been established that a significant number of marine organisms (from crustaceans to whales) can produce sounds of a wider range than humans. Many fish also make sounds. Anatomically, the inner ear of a fish does not differ from the inner ear of a person, but the fish does not have an external and middle ear, so sound waves travel through its entire body to the head. Fish make sounds with their swim bladder.
Pomor fishermen are well aware of the sounds made by fish. They know how to tap on the bottom of the boat or pat the water, making the fish swim in the right direction. Fitting fish schools to the nets, Japanese fishermen put bamboo sticks into the water and hit them with a wooden mallet. In eastern countries, fishermen know how to lure fish with onomatopoeia. They put traps in the water and imitate the voices of the sea so skillfully that they attract fish exactly to the place where they are placed. In the Pacific Ocean, local fishermen attract sharks by tapping on coconut shells.
The speed of sound propagation in water is greater than in air, so sound transmission from air to water and vice versa is difficult. This is one of the reasons why the sea seems "silent". Thus, the well-known "world of silence" by Jacques-Yves Cousteau and the folk saying "mute as a fish" are simply fiction.
Approximately one percent of sound energy can cross the border between air and water. It plays the role of a reflector: air waves-sounds return back to the air, and water waves - to the water. But the roar of walruses and eared seals that have dived halfway into the water spreads through the water, the sound transmission of the body immersed in the water is high. Therefore, seals, when lying on the ice, can hear other seals in the water. Walruses, seals and fish have a whole system that receives and transmits sounds, which has a certain biological significance and its own locational features. Fish, hunting at night for insects falling into the water, find them with the help of hydroacoustics.
With the systematic study of hydroacoustics, more and more species of fish are being discovered that emit various sounds. With the help of the produced and reflected oscillatory movements of water, fish in the dark locate floating organisms, various obstacles, rapids and waterfalls that are found on the bottom, in the thickness and on the surface of the sea. Perception is carried out using the lateral line. The Soviet physiologist Frolov considers the lateral line in fish to be the main organ that perceives sounds. However, herring, for example, does not have a lateral line and perceives sound with the help of auditory organs. The strongest sounds of fish are made by three helpers of the swim bladder, in the walls of which there are special muscles. Among these fish are the sea swallow and sea rooster, hake, Mediterranean fizis, sea, many cod fish, gobies, etc. The sea rooster makes especially strong sounds. It lives on the sandy bottom near the shores, mainly in the Yellow Sea, although it is also found in the Black Sea. Underwater bettas can sing at night and during the day all year round. Their voice is similar to grunting or sounds that arise from rubbing a wet finger on a rubber balloon, sometimes it resembles clucking and clucking. The inflated swim bladder occupies half of the abdominal cavity of the fish and consists of two parts. With a uniform contraction of muscular fibers, the ratios of the volumes of the parts change and the walls of the bubble begin to vibrate, which creates low-frequency vibrations (up to 200 hertz), but it happens that they reach 2400 hertz. In young fish, the bladder is shorter than in adults, and therefore the tone of their "voices" is lower. When catching gurnards from trawls, fishermen hear chaotic sounds.
Hydroacoustic activity is also exhibited by ocienic fish. On a quiet evening or in the morning, they can be overheard. The myth about the songs of the sirens in the Odyssey is inspired, apparently, by the sounds of these fish. Once, fishermen chased an almost two-meter ocien by the sounds it made, like hunters chasing game over hills and rocks. Sea horses are characterized by mating duets. Strongly "voiced" the Yellow Sea.
There are times when fish emit electromagnetic waves. This is a live radar. One of them, mormirius, is found in the Nile River and in other water bodies of Central Africa. This fish never gets into the net and feels the approach of a person from afar. It is also called the elephant fish because of the elongated, like a trunk, front of the head. The elephant fish prefers to burrow into the mud, and since it does not see anything around, nature has provided it with a radar. An electrical organ, as it were, is mounted in the tail of the fish, which produces a current of several volts. The electromagnetic waves sent by the mormirius are reflected from surrounding objects and picked up by a receiver located at the base of the dorsal fin. Enemies do not manage to catch this fish by surprise.
Other fish are also equipped with radars, such as the North American freshwater hymnarchus and the hymnotid, which lives in dense underwater thickets. If a hymnotid is placed between electrodes connected to an oscilloscope, the electrical impulses emitted by it can be detected and recorded. This fish is guided by radar.
Analyzing the characteristic cases of echolocation in nature, we begin with its elementary manifestations in invertebrates and end with the highly specialized echolocation abilities of bats and dolphins.
There are a lot of invertebrates that make sounds in water and on land, but only a few have their own echolocation. Invertebrates produce bizarre sounds and use a wide range of sounds on the audio frequency scale. The first place among them is occupied by crustaceans: Alpheus shrimp, which can hardly hear their own sounds, since they do not have developed auditory organs. These animals, 2 to 10 cm in size, live in warm and subtropical regions of the World Ocean, but are also found in the Black Sea. They live at the bottom near the shores, but they like to move and sometimes gather in large numbers. Where there are many of them, crackling is heard around the clock, reminiscent of a knock on iron sheets, or crackling of burning pine firewood. If these sounds are caught by a microphone placed in the water, then in the air they will be reproduced as shots: it is not for nothing that the Japanese call shrimp "cannon cancer". Such sounds can drown out the sound of the sea with a two-point wave and can be heard for two kilometers. It is still impossible to talk about any location here, just the sounds made play a protective role. Small crustaceans and fish are believed to die at ultrasonic frequencies between 100,000 and 135,000 hertz.
The sound-producing apparatus is possessed by sea lobster crabs. They make sounds reminiscent of the squeaking of a mouse. In some crustaceans, only males emit sounds, while others have signal communication regardless of gender. The crooked matuta crayfish in the Indian Ocean rubs its claw against the edge of the shell, making a sound similar to the voice of a cricket, and the desert crayfish, which is found in the Caroline Islands, emits a sharp rook cry, turning into a lowing, when irritated.
Among insects, only a few species primitively use echolocation and location. The water beetle uses surface waves for orientation. Its catching organs are special villi located at the base of the antennae. They provide the beetle with unhindered movement on the surface of the water. If the nerve endings of the antennas are cut, the water-lover will begin to spin around the aquarium, holding on to the water, but hitting the walls.
It can be assumed that some insects are capable of ultrasonic orientation. Evidence of this is the ability of some nocturnal insects to locate the ultrasounds of bats with their auditory organs. Once within the range of a bat's sonar, small moths scatter in different directions, trying to avoid a dangerous locating zone. This is similar to how an aircraft spotted by an enemy searchlight tries to avoid illuminated space. Other night butterflies, irradiated with the ultrasonic wave of a bat, instantly fold their wings and fall to the ground, which saves them from danger. There are some butterflies that absorb ultrasonic waves in their hairy covering, and some that, in response to ultrasonic waves, send electrical signals to help them hide. Such signals are recorded on tape, with which insects mislead pursuers in the same way that aircraft mislead radars with the help of special metallized paper tapes and foil scattered over the hull lining.
A living locator - a bat - can detect a wire with a diameter of 0.18 mm at a distance of 90 cm, although it itself barely reaches 10 g. It detects a wire even when its diameter is much smaller than the length of the ultrasonic waves sent.
Radars are of great importance, and, undoubtedly, this is one of the significant achievements of mankind. Special radar installations can transmit to the screen in a fraction of a second a picture of an area of hundreds of square kilometers. They clearly work, despite the clouds, haze and storm. But given their size and energy expended, live bat locators remain incomparably more economical, accurate and efficient.
It should be noted that echolocation and location in nature are more common than we think. In recent decades, there has been an intensive study of the location of bats and dolphins. The ability of a person to echolocation has not yet been studied enough.
Let us give as an example a simple case of human echolocation. In thick darkness at the edge of a rocky shore, a boat with fishermen is moving through the strait. They know very well the place where they have passed more than once, they know every meander of the canal, but they do not see any landmark. The darkness, the surroundings are quiet, calm, and the sea is calm. With the help of an ordinary whistle or just a voice, one can relatively accurately determine the distance to a rock, a cliff protruding from the water, or to the coast. Fishermen who have used this method assure that they can detect a beacon 1 m in diameter in a thick haze at a distance of 200 m.
No one has learned to use echolocation in everyday life like the blind. A blind six-year-old boy rode freely on a tricycle on the sidewalk. He managed to turn in time so as not to crash into a wall or run into a person walking towards him. There are blind people who cross the street in a busy city, ride buses and trams, and no one at first glance can recognize them as blind. How do they do it? It turns out that their feet serve as an echo sounder. A sharp and frequent sound comes from the shoeing of the heels and the short tap of the cane in front of you. The sharp clicking of shoes and canes is reminiscent of the crackling sound made by dolphins. Close objects reflect the sound in the same way, and the ear of the blind must be able to differentiate the nuances of the rotating mixed echo.
The work of the human brain and ear is conscious, while in the dolphin and other animals it is considered half reflex. Careful observations of the blind show that they almost accurately guess obstacles at a distance of about 2.1 m. They assure that they feel and even see hands and outlines of faces on the screen. When the head and shoulders of the blind were tied with thick cloth, and leather gloves were put on their hands, leaving their ears free, the average distance at which they could guess objects was reduced to 1.5 m. Thus, the skin on the hands and hands helps the blind to reproduce the reflected sound waves. face. However, with complete isolation of the ears, when the face and hands were open, the blind stopped guessing the obstacles. Thus, the assumption was confirmed that the main organ that perceives the echo is still the ears. How perfect is the decoding of signals in the brain, says the following fact. During the Second World War, some experienced submarine sonar operators became so perfect at their work that the sounds in the apparatus determined where the spotted submarine was moving, when it changed speed, when it turned. Physicists know that, according to the Doppler effect, the tone of receding sounding objects is lower, while that of approaching ones, on the contrary, is higher. The sound of constant frequency emanating from the sonar towards a moving object gives a variable echo, the speed of which depends on the movement of the object. The tone of the modulated frequencies towards the moving object has characteristic shades. With prolonged training, the operator becomes a specialist who can make very accurate pickups.
The echolocation of bats and dolphins has been perfected over thousands of generations. In their brain centers such reflexes have been formed, with the help of which they are able to distinguish a fly on a fluttering leaf or quickly fix a swimming fish against the background of inanimate objects. When there is no time to make such distinctions, animals respond to certain sound nuances with precisely defined reflex actions. In one case, this is the desire to avoid a collision, turn back and return back, in the other, the need to rush forward and quickly grab the prey.
Sounds are made by amphibians and reptiles. Crocodiles roar and moo during the mating season. Darwin recalled the lowing of male Galapagos lizards during mating. The algae-eating iguanas of the Galapagos Islands hiss softly. The yellow-bellied sea snake hisses in the same way, which is found throughout the equatorial zone of the Pacific and Indian oceans.
Some snakes have a peculiar organ that captures thermal infrared waves. The animal displays a defensive reaction in the direction dictated by the thermal radiation of the victim or enemy. So, the family of American rattlesnakes is called pit vipers. These snakes have a pair of pits in front of their eyes, in which thermolocators are located, which are a double chamber, partitioned off by a thin, 0.025 mm, membrane. Thermolocators are filled with nerve cells and endings. Nerve cells pick up temperature differences up to 0.2°C and wavelengths up to 0.001 m. This sensitivity is less than the sensitivity of modern improved thermolocators, which reveal distant heated bodies and invisible stars. They perceive infrared rays and can sense cold and warm objects against warmer or colder backgrounds. So they find a moving plane in the sky and an iceberg in the water. The rattlesnake can sense objects with a temperature lower or higher than its surroundings.
Echolocation has recently been discovered in nocturnal guajaro birds living in Central America and on the island of Trinidad. They, the inhabitants of dark and long caves, leave them in the evening and return in the morning. Their sharp cries at 7000 hertz can be perceived by the human ear. Probably, Chinese swallows-salagans, which nest in caves and rocks, also orient themselves in the same way.
Bats and dolphins are classic examples of echolocation in mammals, although there is no relationship between them. Bats are a special group of flying animals, while dolphins are aquatic animals that breathe with their lungs. Dolphins have a highly developed brain.
The presence of echolocation in bats was discovered 150 years earlier than in dolphins. The first information about the behavior of bats was received by the Italian scientist Spalanzani, who became interested in the reasons and the possibility of movement of various animals in the dark. In 1793 he made his first experiments with owls and bats. In doing so, he discovered
that owls become completely helpless in complete darkness, and bats continue to fly, no matter how dark they are placed. This puzzled the researcher. Then he blinded the mice, set them free, and four days later he caught and opened them. The dissected specimens had stomachs full of insects, just like the sighted ones. At the same time, experiments with bats were carried out by the Swedish biologist Charles Zhurin, who argued that bats can easily do without sight, but hearing loss is fatal for them. And indeed, as soon as they were deprived of their hearing, they began to stumble upon all the obstacles they encountered. Spalanzani was a resourceful and attentive experimenter. He proved that the cause of disorientation in a bat after its ears are plugged is not mechanical irritation or damage. He invented thin miniature tubes, inserted them into the ear canals of mice and noted that they fly normally with them, but as soon as the tubes are filled with wax, the animals lose all orientation. By a whole series of experiments he proved that the disturbance of the sensitive organs of bats, with the exception of the organ of hearing, does not matter for their flight. At that time, he did not yet know about ultrasound and, naturally, could not understand how ears serve these animals? In 1800 it was still impossible to answer this question. Spalanzani's discovery was rejected, ridiculed, and experiments were banned. The indisputable authorities of that time expressed the opinion that bats have some kind of organ of touch in the wing membrane. Only in our days it has been proven that bats emit ultrasounds, which contain, however, very few components that are barely perceptible to the human ear. However, they are so weak that they are drowned out by the noise of the wings. Spalanzani did not note this. Today, this has been proven with the help of electronic devices. The voices of bats can easily be heard by children as they are more receptive to high tones. If you find a place in the evening from where bats will fly out, then with good hearing and some skill you can hear their voices. Exotic carnivorous bats make louder noises.
When a bat flies directly towards an obstacle, it emits 5-10 "ticks" per second. But these are weak "ticks" of high tones, audible only in complete silence and concentrated attention. There are two types of sounds emitted by bats: constant frequency and modular. Bats are an evolving group of animals. Their evolution is aimed at improving flight and echolocation, providing them with favorable feeding conditions.
In Bulgaria, there are 25 species of bats of three families, and in the world there are up to 1000 species, united in 2 suborders and 16 families. Of our bats, five species belong to the horseshoe family. They have a skin fold-membrane near the nose in the form of a horseshoe, which serves as a mouthpiece and amplifier for them when they make sounds. The signals of these mice are very simple, they are almost pure tones with a constant frequency from 60 to 1200,000 hertz. The duration of an individual signal is from 50 to 100 milliseconds. Compared to the signals of other bats, they are quite long.
Insectivorous bats have modular frequency signals. During the whole time (several milliseconds) they are served by a whole octave. A typical nocturnal bat orientation signal contains 50 sound waves, between which no two are identical. It starts with the highest tone, reaches the lowest and lasts 2 milliseconds. The sounds of some tropical bats can only be picked up by the most sensitive instruments. They call such animals "whisperers", they emit simple signals: a single tick and tick.
A bat weighing 7 g can catch 1 g of insects in one hour. Smaller animals, weighing 3.5 g, increase their weight by 10% in 15 minutes. They catch up to 175 mosquitoes, every 6 seconds - one mosquito. At the time of the attack, the mouse is at a distance of 60-90 cm from the insect. During a calm flight, it emits signals in series: 10-12 ticks lasting 1-2 milliseconds each. Under laboratory conditions, its signals in front of obstacles (screen, mesh, tape) increase to 250 per second at intervals of one millisecond. A stone or a rolled-up rag thrown into the air is pursued by the mouse (like prey) with quicker signals, but, having overtaken it, leaves it. This makes it possible to consider that bats pursue small flying objects purely reflexively, having no idea about the object.
Bat signals are listened to by devices in which they turn into a crackle and squeak amplified by headphones; when bats fly directly at a height of 2 m from the ground, their voices are heard as "pat-pat-pat" and are like the noise of a small motor. When the animal pursues the insect, the sound it makes becomes more frequent and stronger. This sound means that the target has been detected. The accuracy of echolocation in bats is amazing. Small bats hit the thread when its diameter exceeds 0.07 mm. Such an object does not interest them, it is artificial. If the diameter of the thread is 0.12 mm, one can observe the direction finding of the obstacle by the animal.
In 1963, R. Karen found that the sensitivity of bats to extraneous noise and echoes from other sources exceeds perfect radar by a factor of a hundred. And indeed, alarmed bats scatter in a dark cave as soon as they are scared away. However, with high saturation of signals in a small space, each bat recognizes its own echo and, guided by it in the dark, does not run into an obstacle (wall) and avoids collision with other bats. She will never be misled by another echo. The riddle is represented by bats "whisperers", which catch insects, small birds and lizards sitting motionless on the branches and leaves of plants. Their location abilities have not yet been explored. Perhaps these mice perceive mysterious biosignals of a special frequency emitted by the animals themselves.
Interestingly, 4 species of bats are able to fish. Flying close to the surface of the water, from time to time they dip their hind legs into the water, on which there are long and curved claws, like those of a bird of prey. With them, the animals grab a small fish, usually hunting in the evening. In the presence of fog above the water or on a dark night, these mice emit signals reminiscent of the signals of other bats. Here, echolocation is complicated by the difficulties of overcoming the sound boundary between water and air. Since the sound falls at a right angle, 0.12 of the sound energy passes through the water, and when it returns, it goes back into the air, losing some more. What fraction of 0.12 remains, and what does the bat catch from it? We will assume that the swollen swim bladder of a fish swimming near the very surface of the water plays the role of a sound resonator and that the echolocation distance is very short - only a few centimeters. Mathematical calculations, by analogy with the sensitivity of the echolocation of other bats, prove that it is possible to receive a backscattered signal.
Even more interesting and complex are the echolocation abilities of dolphins and killer whales and sperm whales close to them. Dolphins adapted to the aquatic environment about 50 million years ago. The timing of the emergence of dolphins and today's great apes is nearly over. Modern forms of dolphins and whales have been around for nearly 25 million years. Early cetaceans had small brains. Animals adapted to life in water have an elongated respiratory canal with a valve for inhalation and exhalation. The main sound organ in dolphins is the breathing hole with muscles and saccular branches. With beeps, the water vibrates and the valve closes. The blowhole is wide, allowing for half a second to absorb from 10 to 12 liters of air. Some authors express the opinion that the bronchi and alveoli of these animals perform acoustic functions. The water regime has imposed on their light features that are anatomical and specific in nature. Cubs, for example, are born to dolphins not head first, but tail. At this time, the female emits a special whistle that attracts another female, and she comes to the rescue first, helping her to push the baby to the surface, and for him to take his first breath. The first two weeks, both females are near the baby. When the mother gets food, the helper stays with the cub. Dolphins love to play near ships. The waves created by the ship make it easier for them to navigate. They glide over them like children on a sled or like a cyclist who finds it easier to follow a motorcycle. But the noise of the ship also attracts dolphins.
Dolphins are intelligent, human-friendly animals. They lend themselves well to training, quickly respond to commands, whistles, gestures. These animals have three most important features: a large brain, a certain "intelligence" and a tendency to be friends with humans. From this arose three main directions in their study: echolocation, comparison of their brains with the brains of other animals, experiments on communication between dolphins and humans.
Dolphins belong to the order of cetaceans. There are 50 species of them - marine and freshwater. Freshwater are found in the Amazon, Ganges and other rivers. Many experiments are being carried out with long-winged bottlenose dolphins, common in all seas and oceans, except for the waters of the Arctic and Antarctica. Bottlenose dolphins living in the Black Sea are the largest dolphins: the length reaches 310 cm and weighs up to 120 kg. In the Black Sea, there are also white-barreled dolphins, which are smaller than bottlenose dolphins: length up to 200 cm, average weight 53 kg. In 1947, the overseer of the Maryland Dolphinarium was the first to draw attention to the ability of these animals to locate at night, in dark water. In the 1950s, many scientists became interested in the life of dolphins and, above all, in their echolocation.
In complete darkness, the dolphin can recognize the smallest objects that are at a considerable distance from it. The dolphins immediately find a piece of food secretly placed in one of the corners of the pool. Swimming on the surface of the water, they make a semi-croaking, semi-whistling sound, and under water - many other sounds, which, in particular, are also used to communicate with their own kind. A.G. Tomilin writes that an ordinary Black Sea dolphin, taken out of the water onto the deck, makes sounds resembling a buzz to a child's tune, the quacking of a duck, the mewing of a cat, the croaking of a frog, and others, lasting up to two seconds.
The characteristic signal of the bottlenose dolphin contains a series of fast creaking sounds; repeatability of signals - from 5 to 10 per second. The shortest sound of these dolphins has a duration of about 0.001 s. If these sounds are reproduced, they will be like the clicking of a blind man's cane on the pavement. This clicking sounds for about a third of a second. It starts on the lowest note (like the backward modular signal in insectivorous bats) and gradually reaches a high frequency, up to 170,000 hertz, i.e. 8 times the tone that the human ear can perceive. The interval between the signals transmitted by the dolphin and the reception of the echo indicates the distance to the object. It is assumed that the nuances of the echo reveal not only the distance to the located object, but also its shape, volume and other characteristics. Dolphins are able to make such distinctions.
When meeting their friends, dolphins emit whistling signals in the range of sounds almost audible to humans, which last from half to three seconds. If we combine creaking and clicking into signals of the same order, then creaking and whistling will be signals of a different order: the first ones are shorter, the second ones are quite long. Many scientists share the clicking and whistling of dolphins. If the click-like signals have a purely locational meaning and can be transmitted simultaneously or in a series at high speed, then the whistle expresses an emotional state and often takes on the character of a conversation. The baby and mother, when they are apart from each other, make a whistle and soon meet. Dolphins can also alternate between clicking and whistling.
Dr. Kenyed Noris spoke about experiments with a bottlenose dolphin nicknamed Alice at the University of Los Angeles (California), where he was a teacher of zoology. He and Dr. Ronald Turner taught Alice to distinguish between two steel balls. When choosing a large ball, she received a fish. Having blindfolded Alice, they gradually began to increase the size of the small ball, until the balls differed by 6 cm. In the last experiment, balls with diameters of 6.35 and 5.71 cm were used. The person could hardly catch the difference between them. The dolphin, blindfolded, made a fairly correct choice. With a difference in the diameters of the balls up to 2.5 cm, he did not make a single mistake during a hundred repetitions of the experiment. At the end, Noris reports that dolphins can also distinguish two balls of exactly the same size, but one is made of tin, the other is made of plastic.
In 1965, William Schafil and his wife Barbara Lawrence made another experiment that was supposed to answer the question of whether a dolphin could find dead fish using echolocation and at what distance. The experiments were carried out at night. Near the shore, a man was sitting in a boat and holding motionless a dead fish, several centimeters covered with water. One dolphin found a boat and got a fish. Experiments have shown that dolphins, using the echo of their sound signals, can detect such small objects as a 15-centimeter fish, and distinguish the sound of the echo from the shore, the bottom, stones, aquatic vegetation hidden in the water, from a boat sunk in the water and a net that stood in the water perpendicular to the boat. Studies by Soviet scientists have shown that dolphins, thanks to echolocation, distinguish at a distance the offered fish or caviar, which is a great delicacy for them.
In 1965, in the Bahamas, where sea noise is significant, when performing complex technical tasks, the echolocation abilities of two previously trained dolphins, Dolly and Dina, were used. At one underwater research center in California, a trained dolphin dived to a depth of 60 m, carried mail, food, and also rescued divers who had lost their way when they heard their signals over a coil of nylon rope.
Dr. Bastiani from the University of Deifis (California) taught two dolphins - Baz and Doris - to press two valves under water by light signals. A short signal made the dolphin press the left valve, and a long one the right valve. Baz did it first, Doris after him. During the third experiment, a barrier was placed between the dolphins. Doris saw the light command when the headlights were turned on, and without thinking, she made a series of sounds. Focusing on her, Baz found a diarrhea without waiting for his command, while Doris brought her diarrhea only after him, for which both dolphins received a fish.
A tiger shark was released into the bottlenose dolphin pool. When she approached the dolphins, they made a sound reminiscent of barking. Soon several dolphins rushed to the shark - and she died. Surrounding her, the animals beat the shark with their sharp snouts. It should be noted that from the swordfish, which is much larger and more dangerous than the shark, dolphins can only escape by flight.
With the help of echolocation, dolphins distinguish not only small and large, live and dead fish, but also various materials: metal and plastic balls, brass and aluminum. This extraordinary ability to differentiate in dolphins is one of nature's mysteries.
Jacques-Yves Cousteau, who worked with dolphins and wrote a book about them, notes that once a dolphin with opaque eyecups discovered and jumped a rope stretched at a height of 3 m above the water. It is difficult to decide how he managed to do this, because the ultrasounds changed and deviated twice for each medium with different densities. We have already spoken about the weak capacity of the boundary line between water and air. The presence of ultrasound direction-finding techniques in dolphins is not much more powerful than those in bats, but their focusing of objects is much more accurate. Some scientists claim that the fat tissue on the front of the dolphin's head serves as a lens for concentrating returned ultrasounds into the beam. A mirror in physics, an exact focus on a given object, means an accurate determination of the distance to it. How, then, did the dolphin fundamentally correctly calculate the height of the rope and give a certain impetus to its body, while still in the water, in order to jump over it? How did he detect and simultaneously track the reflected ultrasound? After all, the rope was stretched quite high. A common dolphin trick is hoop jumping over water. At the same time, the dolphin uses its ability to navigate equally well both in water and in the air, correcting the distances and strength of its jumps with great accuracy.
Another of the mysteries associated with echolocation in dolphins is their slipping out of dense nets. How do animals jump over them, or how do they find large holes in them? How do they find these holes? Why do networks with a large mesh not jump over, but get entangled in them? And, finally, the most inexplicable mystery of the behavior of dolphins is that they never attack people, even if they are forced to die. But these animals have every opportunity to get away from humans. The muscular tail is able to throw a hundred-kilogram body of an animal vertically up 3 m above the water. One light blow with the tail would be fatal to a human. A New Zealand female dolphin named Opo is used to playing with bathing children. If any child became rude to her, she only swam aside and beat the water with her tail in displeasure. E. Champi told the story of how once a hunter caught a small dolphin. The hunter was immediately surrounded by disturbed dolphins, but they did not try to attack. The hunter calmly reached the boat and sailed away with the captive dolphin. The desperate mother followed the boat. Rising above the water, she looked at the dolphin, but did nothing to save him.
The pages of the literature also told about an experiment in which electrodes were introduced into the brain of 29 dolphins. Animals steadfastly endured pain, and none of the dolphins showed aggression towards humans.
An international convention strictly prohibits killing dolphins in the Black Sea for the purpose of extracting blubber meat.
According to new information and experiences, predatory cetaceans - killer whales - just like dolphins, are easily tamed and amenable to training. Some researchers even talk about their superiority over dolphins. The female killer whale Shamu turned out to be a capable student. She allowed herself to be put on a belt that was tightened around her body and held by a person. Then the killer whale and the man dived together and performed a jump in the air. The trainer could even put his head between the terrible jaws of Shamu, and when diving, he held on to the folds of her lips. In 1963, experiments were carried out on the coast of California to search for sunken objects with the help of killer whales at a depth of up to 350 m.
According to some reports, it became known that killer whales can dive to a depth of 1000 m. The practical meaning of these experiments is indisputable. Trained dolphins and other cetaceans, having exceptional echolocation abilities, a highly developed brain and physical capabilities, can be indispensable helpers of a person.
Echolocation of dolphins is a complex and perfect adaptation of them, which cannot be compared with the echolocation capabilities of more primitive animals, including the echolocation of bats. Echolocation of dolphins has been brought to the level of a new cognitive tool, improved over millions of years in the conditions of the water regime thanks to the highly developed brain of these animals.
1) What systems regulate the activity of the animal body? 2) What is the role of the nervous system? 3) What is the structure of the nervous system? 4) What isreflex? What are reflexes? 5) What animals have a reticulated nervous system? 6) How is the nervous system of an earthworm arranged? 7) Tell us about the structure of the nervous system of vertebrates. 8) What departments are distinguished in the brain of vertebrates? 9) What parts of the brain are most well developed in mammals and why? 10) What is the cerebral cortex? What is its significance? 11) What are hormones? 12) What glands that secrete hormones do you know in animals? 13) What are growth substances and how do they affect the plant? SAY PLEASE)
1) What is the role of the nervous system? 2) What is the structure of the nervous system? 3) What is a reflex? What are reflexes? 4)What animals have a reticulated nervous system?
5) How is the nervous system of the earthworm arranged?
6) Tell us about the structure of the nervous system of vertebrates?
7) What departments are distinguished in the brain of vertebrates?
8) What parts of the brain are most well developed in mammals and why?
9) What is the cerebral cortex? What is its meaning?
10) What are hormones?
11) What glands that secrete hormones do you know in animals?
12) What are growth substances and how do they affect the plant?
1-what is an organ? give examples. What are the reproductive organs in plants and animals? 3-what is photosynthesis?4-What is an artery?
What animals are called cold-blooded?
6-what types of breathing are characteristic of these animals: insects; frog; fish? 7-what role does the external skeleton play? Give examples of living organisms.
8-What is fertilization?
9-list the ways of asexual reproduction. Give examples.
1) What are vitamins? How do they enter the body? What are their roles in the body?2) What is avitaminosis? What avitaminosis do you know, what are their signs? How can they be avoided?
3) Why do people need food of animal and plant origin? How should food be prepared so that it retains the maximum amount of vitamins?
4)
sugar, salt, soda, acetic acid, and many others) consist of something: objects are made of certain details, these details are made of substances, and substances, in turn, are made of the smallest particles – molecules and atoms. Atoms and molecules, interacting with each other, form new, more complex substances. The smallest particles, interacting with each other, form a system. Interacting parts of the system are called elements of this system. The more interacting elements make up the system, the more complex it is. Remember at least different constructors. The more details they have, the more difficult and time-consuming their assembly will be. Details of various devices and mechanisms, parts of organisms interact with each other. As a result of this interaction, the devices work normally, and vital processes take place in the body. Both the device and the body are systems that work due to the interaction of parts or organs. But the device is a non-living system, and the organism is alive. Since we are studying biology, we will be interested in living systems, i.e. organisms. An example of a not the most complex system in the body is the human hand. It is made up of bones, muscles, ligaments. Deprived of at least one of the constituent elements, the hand will not be able to work. The hand is a subsystem (element) of a more complex system "the human body". Eyes and ears, brain and heart, bones and muscles are the elements of the “man” system. Together, they work surprisingly well, forming an organism, although each of the organs has its own structural features. Only by interacting, individual organs form a full-fledged organism and ensure its long and well-coordinated work. It is important to understand one more thought: the properties of any system differ from the properties of those elements that make up the system. So, for example, a leaf separated from a plant is not able to create organic substances, since water from the roots does not enter it. A cell without a nucleus is unable to reproduce. Many similar examples can be cited to prove that the system acquires new properties that the elements that make up this system did not have. Using the content of the text "What is a system?" and knowledge of the school biology course, answer the questions and complete the task. 1) What is the main condition for the emergence of the system? 2) What is the difference between the “hand” system and the “muscle” system from the standpoint of anatomy? 3) Using the example of the structure of a flower, prove that this is a system. HELP TOMORROW GIA
And dolphins emit ultrasound. Why is this needed and how does it work? Let's look at what echolocation is and how it helps animals and even people.
What is echolocation
Echolocation, also called biosonar, is a biological sonar used by several animal species. Echolocating animals radiate signals into the environment and listen to the echoes of those calls that are returned from various objects near them. They use these echoes to find and identify objects. Echolocation is used for navigation and for fodder (or hunting) in various conditions.
Principle of operation
Echolocation is the same as active sonar, which uses sounds produced by the animal itself. Ranging is done by measuring the time delay between the animal's own sound emission and any echoes returning from the environment.
Unlike some human-made sonar, which rely on extremely narrow beams and multiple receivers to locate a target, animal echolocation is based on one transmitter and two receivers (ears). The echoes returning to the two ears arrive at different times and at different volume levels, depending on the position of the object generating them. Differences in time and volume are used by animals to perceive distance and direction. With echolocation, a bat or other animal can see not only the distance to an object, but also its size, what kind of animal it is, and other features.
The bats
Bats use echolocation for navigation and foraging, often in total darkness. They usually emerge from their roosts in caves, attics, or trees at dusk and hunt for insects. Thanks to echolocation, bats are in a very advantageous position: they hunt at night when there are many insects, there is less competition for food, and there are fewer species that can prey on the bats themselves.
Bats generate ultrasound through their larynx and emit sound through their open mouth or, much less commonly, their nose. They emit sound ranging from 14,000 to over 100,000 Hz, mostly outside the human ear (typical human hearing range is 20 Hz to 20,000 Hz). Bats can estimate the movement of targets by interpreting patterns caused by reflections of echoes from a special flap of skin in the outer ear.
Individual species of bats use echolocation in specific frequency bands that are appropriate for their living conditions and prey types. This has sometimes been used by researchers to identify the species of bats that inhabit the area. They simply recorded their signals with ultrasonic recorders known as bat detectors. In recent years, researchers in several countries have developed bat call libraries that contain records of native species.
Sea creatures
Biosonar is valuable to the suborder of toothed whales, which includes dolphins, killer whales and sperm whales. They live in an underwater habitat that has favorable acoustic characteristics and where vision is extremely limited due to the turbidity of the water.
The most significant early results in describing dolphin echolocation were achieved by William Shevill and his wife Barbara Lawrence-Shevill. They were engaged in feeding dolphins and once noticed that they unmistakably find pieces of fish that silently fell into the water. This discovery was followed by a number of other experiments. So far, dolphins have been found to use frequencies ranging from 150 to 150,000 Hz.
The echolocation of blue whales has been much less studied. So far, only assumptions have been made that the “songs” of whales are a way of navigating and communicating with relatives. This knowledge is used to count the population and to track the migrations of these marine animals.
rodents
It is clear what echolocation is in marine animals and bats, and why they need it. But why do rodents need it? The only terrestrial mammals capable of echolocation are two genera of shrews, teireks from Madagascar, rats, and slit-tooths. They emit a series of ultrasonic squeaks. They do not contain echolocation responses with reverberations and appear to be used for simple spatial orientation at close range. Unlike bats, shrews only use echolocation to study prey habitats and not to hunt. With the exception of large and thus highly reflective objects (such as a large rock or tree trunk), they are probably not capable of unraveling echo scenes.
The most talented sonar
In addition to these animals, there are others that can engage in echolocation. These are some species of birds and seals, but the most sophisticated echo sounders are fish and lampreys. Previously, scientists considered bats to be the most capable, but in recent decades it has become clear that this is not the case. The air environment is not conducive to echolocation - unlike water, in which sound diverges five times faster. The sonar of fish is the organ of the lateral line, which perceives the vibrations of the environment. Used for both navigation and hunting. Some species also have electroreceptors that pick up electrical vibrations. What is fish echolocation? It is often synonymous with survival. She explains how blinded fish could live to a respectable age - they did not need sight.
Echolocation in animals has helped explain similar abilities in visually impaired and blind people. They navigate in space with the help of clicking sounds they make. Scientists say that such short sounds emit waves that can be compared to the light of a flashlight. At the moment, there is too little data to develop this direction, since capable sonar among people is a rarity.
