Fish react to sounds: a clap of thunder, a shot, the sound of a boat's oar on the surface of the water causes a certain reaction in the fish, sometimes the fish even jumps out of the water at the same time. Some sounds attract fish, which fishermen use in their methods, for example, fishermen in Indonesia and Senegal lure fish using rattles made from coconut shells, imitating the natural crackling sound of a coconut in nature, which is pleasant for fish.
Fish make sounds themselves. The following organs are involved in this process: the swim bladder, the rays of the pectoral fins in combination with the bones of the shoulder girdle, jaw and pharyngeal teeth and other organs. The sounds made by fish resemble blows, clicking, whistling, grunting, squeaking, croaking, growling, crackling, ringing, wheezing, beeping, bird calls and chirping insects.
Sound frequencies perceived by fish are from 5 to 25 Hz by the lateral line organs, and from 16 to 13,000 Hz by the labyrinth. In fish, hearing is less developed than in higher vertebrates, and its acuity varies among different types: ide perceives vibrations whose wavelength is 25...5524 Hz, silver crucian carp - 25…3840 Hz, eel - 36…650 Hz. Sharks pick up vibrations made by other fish at a distance of 500 m.
They record fish and sounds coming from the atmosphere. Plays a major role in recording sounds swim bladder, connected to the labyrinth and serving as a resonator.
The hearing organs are very important in the life of fish. This includes the search for a sexual partner (in fish farms, traffic is prohibited near ponds during the spawning period), school affiliation, and information about finding food, territory control, and protection of juveniles. Deep-sea fish, which have weakened or absent vision, orient themselves in space and also communicate with their relatives using hearing, along with the lateral line and smell, especially considering the fact that sound conductivity at depth is very high. 
Like all vertebrates, the hearing organ of fish is paired, but if we take into account that elements related to hearing were found in the lateral line, then we can talk about panoramic auditory perception in fish.
Anatomically, the organ of hearing is also one with the organ of balance. There is no doubt that physiologically these two are completely different organs feelings that fulfill various functions, having a different structure and working on the basis of various physical phenomena: electromagnetic oscillations and gravity. In this regard, I will talk about them as two independent organs, which, of course, are connected to each other, as well as to other receptors.
The hearing organs of fish and animals living on land differ significantly. The dense environment in which fish live conducts sound 4 times faster and over longer distances than the atmosphere. Pisces do not need ears or eardrums.
The hearing organ has especially great importance for fish living in muddy water.
Experts say that the auditory function in fish is carried out, in addition to the hearing organ, by at least the lateral line, the swim bladder, as well as various nerve endings.
In the cells of the lateral line, elements equivalent to the organ of hearing were found - mechanoreceptive organs of the lateral line (neuromasts), which include a group of sensitive hair cells similar to the sensitive cells of the organ of hearing and vestibular apparatus. These formations record acoustic and other vibrations of water.
There are different opinions regarding the perception of sounds of different frequency spectrum by fish. Some researchers believe that fish, like people, perceive sounds with a frequency of 16 to 16,000 Hz; according to other data, the upper limit of frequencies is limited to 12,000–13,000 Hz. Sounds of these frequencies are perceived by the main organ of hearing.
It is assumed that the lateral line perceives low sound waves with a frequency, according to various sources, from 5 to 600 Hz.
There is also a statement that fish are capable of perceiving the entire range of sound vibrations - from infra- to ultrasonic. It has been established that fish are able to detect 10 times less changes in frequencies than humans, while the “musical” hearing of fish is 10 times worse.
The swim bladder of fish is believed to act as a resonator and transducer of sound waves, increasing hearing acuity. It also performs a sound-producing function.
The paired organs of the lateral line of fish stereophonically (more precisely, panoramicly) perceive sound vibrations; this gives the fish the opportunity to clearly establish the direction and location of the source of vibration.
Fish distinguish near and far zones of the acoustic field. In the near field, they clearly locate the source of the vibrations, but it is not yet clear to researchers whether they can locate the source in the far field.
Pisces also have an amazing “device” that a person can only dream of - a signal analyzer. With its help, from all the chaos of surrounding sounds and vibrational manifestations, they are able to isolate the signals that are necessary and important for their life, even those weak ones that are on the verge of arising or fading. Pisces are able to enhance them and then perceive them with analyzing formations.
It has been reliably established that fish widely use sound signaling. They are able not only to perceive, but also to produce sounds in a wide range of frequencies.
In light of the problem under consideration, I would like to especially draw the reader’s attention to the perception of infrasonic vibrations by fish, which, in my opinion, is of great practical importance for fishermen.
It is believed that frequencies of 4–6 Hz have a detrimental effect on living organisms: these vibrations resonate with the vibrations of the body and individual organs.
The sources of oscillations of these frequencies can be completely different phenomena: lightning, auroras, volcanic eruptions, landslides, sea surf, storm microseisms (oscillations in the earth’s crust excited by sea and ocean storms - “voice of the sea”), vortex formation at wave crests, nearby weak earthquakes, swaying trees, operation of industrial facilities, machines, etc.
It is possible that fish react to the approach of inclement weather due to the perception of low-frequency acoustic vibrations emanating from zones of increased convection and frontal sections located near the center of the cyclone. On this basis, it can be assumed that fish have the ability to “predict”, or rather, sense weather changes long before they occur. They record these changes by the difference in sound strength. Fish may also be able to “judge” impending weather changes by the level of interference for the passage of individual wave bands.
It is also necessary to mention such a phenomenon as echolocation, although, in my opinion, it cannot be carried out using the hearing organ of fish; there is an independent organ for it. The fact is that echolocation in the inhabitants underwater world discovered and quite well studied, today there is no doubt. Some researchers only doubt whether fish have echolocation.
In the meantime, echolocation is classified as the second type of hearing. Doubting scientists believe that if evidence is obtained that fish are capable of perceiving ultrasonic vibrations, then there will be no doubt about their ability to echolocation. But now such evidence has already been obtained.
Researchers have confirmed the idea that fish are capable of perceiving the entire range of vibrations, including ultrasonic ones. Thus, the question of echolocation in fish seems to be resolved. And we can talk about one more sense organ in fish - the location organ.
Any sound source located on the substrate, in addition to emitting classical sound waves propagating in water or air, dissipates part of the energy in the form various kinds vibrations propagating in the substrate and along its surface.
Under auditory system we understand a receptor system capable of perceiving one or another component of sound study, localizing and assessing the nature of the source, creating the prerequisites for the formation of specific behavioral reactions of the body.
The auditory function in fish is carried out, in addition to the main organ of hearing, by the lateral line, the swim bladder, and also specific nerve endings.
The hearing organs of fish developed in an aquatic environment, which conducts sound 4 times faster and at long distances than the atmosphere. The range of sound perception in fish is much wider than in many land animals and people.
Hearing plays a very important role in the life of fish, especially fish that live in muddy water. In the lateral line of the fish, formations were discovered that record acoustic and other water vibrations.
Hearing analyzer a person perceives vibrations with a frequency from 16 to 20,000 Hz. Sounds with a frequency below Hz are referred to as infrasounds, and sounds above 20,000 Hz are referred to as ultrasounds. The best perception of sound vibrations is observed in the range from 1000 to 4000 Hz. The spectrum of sound frequencies perceived by fish is significantly reduced compared to humans. So, for example, crucian carp perceives sounds in range 4 (31-21760 Hz, dwarf catfish -60-1600 Hz, shark 500-2500 Hz.
The hearing organs of fish have the ability to adapt to factors environment in particular, the fish quickly gets used to constant or monotonous and frequently repeated noise, for example the operation of a dredge, and is not afraid of the noise. Also, the noise of a passing steamship, train, and even people swimming fairly close to the fishing site does not scare away the fish. The fish's fear is very short-lived. The impact of the spinner on the water, if it is made without much noise, not only does not frighten the predator, but perhaps alerts it in anticipation of the appearance of something edible for it. Fish can perceive individual sounds if they cause vibrations in the aquatic environment. Due to the density of water, sound waves are well transmitted through the bones of the skull and are perceived by the hearing organs of the fish. Pisces can hear the footsteps of a person walking along the shore, the ringing of a bell, or a gunshot.
Anatomically, like all vertebrates, the main organ of hearing - the ear - is a paired organ and forms a single whole with the organ of balance. The only difference is that fish do not ears and eardrums, since they live in a different environment. The organ of hearing and the labyrinth in fish is at the same time an organ of balance; it is located in the back of the skull, inside the cartilaginous or bone chamber, and consists of upper and lower sacs in which otoliths (pebbles) are located.
The hearing organ of fish is represented only by the inner ear and consists of a labyrinth. The inner ear is a paired acoustic organ. In cartilaginous fish, it consists of a membranous labyrinth enclosed in a cartilaginous auditory capsule - a lateral extension of the cartilaginous skull behind the orbit. The labyrinth is represented by three membranous semicircular canals and three otolithic organs - the utriculus, sacculus and lagena (Fig. 91,92,93). The labyrinth is divided into two parts: the upper part, which includes the semicircular canals and utriculus, and the lower part, the sacculus and lagena. The three curved tubes of the semicircular canals lie in three mutually perpendicular planes and their ends open into the vestibule or membranous sac. It is divided into two parts - the upper oval sac and the larger lower - round sac, from which a small outgrowth extends - the lagena.
The cavity of the membranous labyrinth is filled with endolymph, in which small crystals are suspended otoconia. The cavity of the round sac usually contains larger calcareous formations otoliths consisting of calcium compounds. Vibrations that are perceived by the auditory nerve. The endings of the auditory nerve approach individual areas of the membranous labyrinth, covered with sensory epithelium - auditory spots and auditory ridges. Sound waves are transmitted directly through vibration-sensing tissues, which are perceived by the auditory nerve.
The semicircular canals are located in three mutually perpendicular planes. Each semicircular canal flows into the utriculus at two ends, one of which expands into the ampulla. There are elevations called auditory maculae, where clusters of sensitive hair cells are located. The finest hairs of these cells are connected by a gelatinous substance, forming a cupula. The endings of the VIII pair of cranial nerves approach the hair cells.
The utriculus of bony fish contains one large otolith. Otoliths are also located in the lagena and sacculus. The sacculus otolith is used to determine the age of fish. The sacculus of cartilaginous fish communicates with external environment through a membranous outgrowth; in bony fishes, a similar outgrowth of the sacculus ends blindly.
The work of Dinkgraaf and Frisch confirmed that auditory function depends on the lower part of the labyrinth - the sacculus and lagena.
The labyrinth is connected to the swim bladder by a chain of Weberian ossicles (cyprinids, common catfishes, characins, gymnothids), and fish are able to perceive high-pitched sound tones. With the help of the swim bladder, high-frequency sounds are transformed into low-frequency vibrations (displacements), which are perceived by receptor cells. In some fish that do not have a swim bladder, this function is performed by air cavities associated with the inner ear.
Fig.93. Inner ear or labyrinth of fish:
a- hagfish; b - sharks; c - bony fish;
1 - posterior crista; 2-crista horizontal channel; 3- anterior crista;
4-endolymphatic duct; 5 - macula of the sacculus, 6 - macula of the utriculus; 7 - macula lagena; 8 - common pedicle of semicircular canals
Pisces also have an amazing “device” - a signal analyzer. Thanks to this organ, fish are able to isolate from all the chaos of sounds and vibrational manifestations around them the signals that are necessary and important for them, even those weak ones that are at the stage of emerging or on the verge of fading.
Fish are able to amplify these weak signals and then perceive them with analyzing formations.
The swim bladder is believed to act as a resonator and transducer of sound waves, which increases hearing acuity. It also performs a sound-producing function. Fish widely use sound signaling; they are capable of both perceiving and emitting sounds in a wide range of frequencies. Infrasonic vibrations are well perceived by fish. Frequencies equal to 4-6 hertz have a detrimental effect on living organisms, since these vibrations resonate with the vibrations of the body itself or individual organs and destroy them. It is possible that fish react to the approach of inclement weather by perceiving low-frequency acoustic vibrations emanating from approaching cyclones.
Pisces are able to “predict” weather changes long before they occur; fish detect these changes by the difference in the strength of sounds, and possibly by the level of interference for the passage of waves of a certain range.
12.3 The mechanism of body balance in fish. In bony fishes, the utriculus is the main receptor for body position. The otoliths are connected with the hairs of the sensitive epithelium using a gelatinous mass. When the head is positioned with the crown up, the otoliths press on the hairs; when the head is positioned down, they hang on the hairs; when the head is positioned sideways, varying degrees hair tension. With the help of otoliths, fish receive correct position the head (top up), and therefore the body (back up). To maintain correct body position, information coming from visual analyzers is also important.
Frisch found that when the upper part of the labyrinth (the utriculus and semicircular canals) is removed, the balance of the minnows is disturbed; the fish lie on their sides, bellies, or backs at the bottom of the aquarium. When swimming they also take different position bodies. Sighted fish quickly restore the correct position, but blind fish cannot restore their balance. Thus, the semicircular canals are of great importance in maintaining balance, in addition, with the help of these canals, changes in the speed of movement or rotation are perceived.
At the beginning of the movement or when it accelerates, the endolymph lags somewhat behind the movement of the head and the hairs of the sensitive cells deviate in the direction opposite to the movement. In this case, the endings of the vestibular nerve are irritated. When movement stops or slows down, the endolymph of the semicircular canals continues to move by inertia and deflects the hairs of sensitive cells along the way.
Studying functional value various departments labyrinth for the perception of sound vibrations was carried out using a study of fish behavior based on the development of conditioned reflexes, as well as using electrophysiological methods.
In 1910, Pieper discovered the appearance of action currents during irritation lower parts labyrinth - sacculus of freshly killed fish and the absence of such in case of irritation of the utriculus and semicircular canals.
Later, Frolov experimentally confirmed the perception of sound vibrations by fish, conducting experiments on cod, using a conditioned reflex technique. Frisch developed conditioned reflexes to whistling in dwarf catfish. Stettee. in catfish, minnows and loaches, he developed conditioned reflexes to certain sounds, reinforcing them with meat crumbs, and also caused inhibition of the food reaction to other sounds by hitting the fish with a glass rod.
Local sensitivity organs of fish. The ability of fish to echolocation is carried out not by the hearing organs, but by an independent organ - the location sense organ. Echolocation is the second type of hearing. In the lateral line of fish there is a radar and sonar - components of the location organ.
Fish use electrolocation, echolocation, and even thermolocation for their life activities. Electrolocation is often called the sixth sense organ of fish. Electrolocation is well developed in dolphins and bats. These animals use ultrasonic pulses with a frequency of 60,000-100,000 hertz, the duration of the signal sent is 0.0001 seconds, the interval between pulses is 0.02 seconds. This time is required for the brain to analyze the information received and form a specific response from the body. For fish this time is slightly shorter. During electrolocation, where the speed of the sent signal is 300,000 km/s, the animal does not have time to analyze the reflected signal; the sent signal will be reflected and perceived at almost the same time.
Freshwater fish cannot use ultrasound for location. To do this, fish must constantly move, and fish need to rest for a significant period of time. Dolphins are on the move around the clock; their left and right half of their brain rests alternately. Fish use wide-range low-frequency waves for location. It is believed that these waves serve fish for communication purposes.
Hydroacoustic studies have shown that fish are too “chatty” for an unreasonable creature; they produce too many sounds, and “conversations” are conducted at frequencies that are beyond the normal range of perception by their primary organ of hearing, i.e. their signals are more appropriate as location signals sent by fish radars. Low-frequency waves are poorly reflected from small objects, are less absorbed by water, are heard over long distances, propagate evenly in all directions from the sound source, their use for location gives fish the opportunity to panoramic “seeing and hearing” the surrounding space.
12.5 CHEMORECEPTION The relationship of fish with the external environment is combined into two groups of factors: abiotic and biotic. Physical and Chemical properties waters that affect fish are called abiotic factors.
Animal perception chemical substances with the help of receptors - one of the forms of reaction of organisms to the influence of the external environment. In aquatic animals, specialized receptors come into contact with substances in a dissolved state, therefore, the clear division characteristic of terrestrial animals into olfactory receptors, which perceive volatile substances, and taste receptors, which perceive substances in a solid and liquid state, does not appear in aquatic animals. However, morphologically and functionally, the olfactory organs in fish are quite well separated. Based on the lack of specificity in the functioning, localization and connection with nerve centers, it is customary to combine taste and the general chemical sense with the concept of “chemical analyzer”, or “non-olfactory chemoreception”.
OLFACTORY ORGAN belongs to the group of chemical receptors. The olfactory organs of fish are located in the nostrils located in front of each eye, the shape and size of which varies depending on the environment. They are simple pits with a mucous membrane, penetrated by branching nerves leading to a blind sac with sensitive cells coming from the olfactory lobe of the brain.
In most fish, each of the nostrils is divided by a septum into autonomous anterior and posterior nasal openings. In some cases, the nasal openings are single. In ontogenesis, the nasal openings of all fish are initially single, i.e. are not divided by a septum into the anterior and posterior nostrils, which are separated only by more late stages development.
The location of the nostrils various types fish depends on their lifestyle and the development of other senses. In fish with well-developed vision, the nasal openings are located on the upper side of the head between the eye and the end of the snout. In Selakhshe, the nostrils are located on the lower side and close to the mouth opening.
The relative size of the nostrils is closely related to the speed of movement of the fish. In fish that swim slowly, the nostrils are comparatively larger, and the septum between the anterior and posterior nasal openings looks like a vertical shield that directs water to the olfactory capsule. In fast fish, the nasal openings are extremely small, since at high speeds of the oncoming flowing skate, the water in the nasal capsule is washed off quite quickly through the relatively small openings of the anterior nostrils. In benthic fish, in which the role of smell is in common system reception is very significant, the anterior nasal openings stretch out in the form of tubes and approach the oral slit or even hang from upper jaw to the bottom, this occurs in Typhleotris, Anguilla, Mnreana, etc.
Odorous substances dissolved in water enter the mucous membrane of the olfactory area, irritate the endings of the olfactory nerves, from here the signals enter the brain.
Through the sense of smell, fish receive information about changes in the external environment, distinguish food, find their school, partners during spawning, detect predators, and calculate prey. On the skin of some species of fish there are cells that, when the skin is wounded, release a “fear substance” into the water, which is a signal of danger to other fish. Pisces actively use chemical information to give alarm signals, warn of danger, and attract individuals of the opposite sex. This organ is especially important for fish living in turbid water, where, along with tactile and sound information, fish actively use the olfactory system. The sense of smell has a great influence on the functioning of many organs and systems of the body, toning or inhibiting them. There are known groups of substances that have a positive (attractant) or negative (repellent) effect on fish. The sense of smell is closely connected with other senses: taste, vision and balance.
At different times of the year, the olfactory sensations of fish are not the same; they become more intense in spring and summer, especially in warm weather.
Nocturnal fish (eel, burbot, catfish) have a highly developed sense of smell. The olfactory cells of these fish are capable of reacting to hundredths of concentrations of attractants and repellents.
Fish are able to sense a dilution of bloodworm extract in a ratio of one to a billion; crucian carp sense a similar concentration of nitrobenzene; higher concentrations are less attractive to fish. Amino acids serve as stimulants for the olfactory epithelium; some of them or their mixtures have a signaling value for fish. For example, an eel finds a mollusk by the complex it secretes, consisting of 7 amino acids. Vertebrates rely on a mixture of basic odors: musky, camphor, minty, ethereal, floral, pungent and rotten.
Olfactory receptors in fish, like other vertebrates, are paired and located on the front of the head. Only in cyclostomes are unpaired. Olfactory receptors are located on the blind recess - the nostril, the bottom of which is lined with olfactory epithelium located on the surface of the folds. The folds, diverging radially from the center, form an olfactory rosette.
U different fish olfactory cells are located on the folds in different ways: in a continuous layer, sparsely, on ridges or in a recess. Current of water carrying molecules odorous substances, enters the receptor through the anterior opening, often separated from the posterior exit opening only by a fold of skin. However, in some fish the entrance and exit holes are noticeably separated and are far apart. The anterior (entrance) openings of a number of fish (eel, burbot) are located close to the end of the snout and are equipped with skin tubes . It is believed that this sign indicates the significant role of smell in the search for food objects. The movement of water in the olfactory fossa can be created either by the movement of cilia on the surface of the lining, or by contraction and relaxation of the walls of special cavities - ampoules, or as a result of the movement of the fish itself.
Olfactory receptor cells, which have a bipolar shape, belong to the category of primary receptors, i.e., they themselves regenerate impulses containing information about the stimulus and transmit them along processes to the nerve centers. The peripheral process of the olfactory cells is directed to the surface of the receptor layer and ends in an extension - a club, at the apical end of which there is a tuft of hairs or microvilli. The hairs penetrate the mucus layer on the surface of the epithelium and are capable of movement.
Olfactory cells are surrounded by supporting cells, which contain oval nuclei and numerous granules different sizes. Basal cells that do not contain secretory granules are also located here. The central processes of receptor cells, which do not have a myelin sheath, having passed the basement membrane of the epithelium, form bundles of up to several hundred fibers, surrounded by the Schwann cell mesaxon, and the body of one cell can cover many bundles. The bundles merge into trunks, forming the olfactory nerve, which connects to the olfactory bulb.
The structure of the olfactory lining is similar in all vertebrates (Fig. 95), which indicates a similarity in the mechanism of contact reception. However, this mechanism itself is not yet entirely clear. One of them connects the ability to recognize odors, i.e., molecules of odorous substances, with the selective specificity of individual odor receptors. This is Eimour's stereochemical hypothesis. according to which, there are seven types of active sites on the olfactory cells, and the molecules of substances with similar odors have the same shape of active parts that fit active points receptor is like a “key” to a lock. Other hypotheses link the ability to distinguish odors with differences in the distribution of substances adsorbed by the mucus of the olfactory lining over its surface. A number of researchers believe that odor recognition is provided by these two mechanisms, complementing each other.
The leading role in olfactory reception belongs to the hairs and club of the olfactory cell, which ensure the specific interaction of odorant molecules with the cell membrane and the translation of the interaction effect into form electric potential. As already mentioned, the axons of the olfactory receptor cells form the olfactory nerve, which enters the olfactory bulb, which is the primary center of the olfactory receptor.
The olfactory bulb, according to A. A. Zavarzin, belongs to the screen structures. It is characterized by the arrangement of elements in the form of successive layers, and the nerve elements are interconnected not only within the layer, but also between the layers. There are usually three such layers: a layer of olfactory glomeruli with interglomerular cells, a layer of secondary neurons with mitral and brush cells, and a granular layer.
Information is transmitted to the higher olfactory centers in fish by secondary neurons and cells of the granular layer. The outer part of the olfactory bulb consists of fibers of the olfactory nerve, the contact of which with the dendrites of secondary neurons occurs in the olfactory glomeruli, where branching of both endings is observed. Several hundred fibers of the olfactory nerve converge in one olfactory glomerulus. The layers of the olfactory bulb are usually located concentrically, but in some fish species (pike), they lie successively in a rostrocaudal direction.
The olfactory bulbs of fish are anatomically well separated and are of two types: sessile, adjacent to the forebrain; stalked, located immediately behind the receptors (very short olfactory nerves).
In codfish, the olfactory bulbs are connected to the forebrain by long olfactory tracts, which are represented by the medial and lateral bundles, ending in the forebrain nuclei.
The sense of smell as a way of obtaining information about the surrounding world is very significant for fish. According to the degree of development of the sense of smell, fish, like other animals, are usually divided into macrosmatics and microsmatics. This division is associated with a different breadth of the spectrum of perceived odors.
U makresmatik The olfactory organs are capable of perceiving a large number of different odors, i.e. they use the sense of smell in more diverse situations.
Micromatics They usually perceive a small number of odors - mainly from individuals of their own species and sexual partners. A typical representative of macrosmatics is the common eel, while microsmatics are pike and three-spined stickleback. To perceive a smell, sometimes, apparently, it is enough for a few molecules of a substance to hit the olfactory receptor.
The sense of smell can play a guiding role in the search for food, especially in nocturnal and crepuscular predators such as eels. With the help of smell, fish can perceive school partners and find individuals of the opposite sex during the breeding season. For example, a minnow can distinguish a partner among individuals of its own species. Fish of one species are able to perceive chemical compounds released by the skin of other fish when wounded.
A study of the migrations of anadromous salmon has shown that at the stage of entering spawning rivers, they look for exactly the river where they themselves hatched, guided by the smell of water imprinted in memory at the juvenile stage (Fig. 96). The sources of the smell appear to be fish species that permanently inhabit the river. This ability has been used to direct migrating breeders to a specific site. Juvenile coho salmon were kept in a morpholine solution with a concentration of 0~5 M, and then, after they returned to their native river during the spawning period, they were attracted by the same solution to a certain place in the reservoir.
Rice. 96. Biocurrents of the olfactory brain of salmon during irrigation of the olfactory pits; 1, 2 - distilled water; 3 - water from the native river; 4, 5, 6 - water from foreign lakes.
Fish have a sense of smell, which is more developed in non-predatory fish. Pike, for example, do not use their sense of smell when searching for food. When it quickly rushes for prey, smell cannot play a significant role. Another predator - perch, when moving in search of food, usually swims quietly, picking up all kinds of larvae from the bottom; it uses its sense of smell to in this case uses it as a food-guiding organ.
Organ of taste Almost all fish have a taste sensation that is transmitted to most of them through the lips and mouth. Therefore, the fish does not always swallow the captured food, especially if it is not to its taste.
Taste is a sensation that occurs when food and some non-food substances act on the taste organ. The organ of taste is closely related to the organ of smell and belongs to the group of chemical receptors. Taste sensations in fish appear when sensitive, tactile cells are irritated - taste buds or so-called taste buds, bulbs located in oral cavity in the form of microscopic taste cells, on the antennae, over the entire surface of the body, especially on skin outgrowths. (Fig.97)
The main perceptions of taste are four components: sour, sweet, salty and bitter. The remaining types of taste are combinations of these four sensations, and taste sensations in fish can only be caused by substances dissolved in water.
Minimum perceptible difference in the concentration of substance solutions difference threshold- gradually worsens when moving from weak to stronger concentrations. For example, a one percent sugar solution has an almost maximally sweet taste, and a further increase in its concentration does not change the taste sensation.
The appearance of taste sensations can be caused by the action of inadequate stimuli on the receptor, for example, direct electric current. With prolonged contact of any substance with the organ of taste, its perception gradually becomes dulled; in the end, this substance will seem completely tasteless to the fish; adaptation occurs.
The taste analyzer can also influence some reactions of the body, activity internal organs. It has been established that fish react to almost all tasteful substances and at the same time have an amazingly subtle taste. Positive or negative reactions of fish are determined by their lifestyle and, above all, the nature of their diet. Positive reactions for sugar are characteristic of animals eating plant and mixed foods. The feeling of bitterness causes a negative reaction in most living beings, but not in those that eat insects.
Fig.97. The location of taste buds on the body of the catfish is shown by dots. Each dot represents 100 taste buds
The mechanism of taste perception. The four basic taste sensations - sweet, bitter, sour and salty - are perceived through the interaction of flavor molecules with four protein molecules. Combinations of these types create specific taste sensations. In most fish, taste plays the role of contact reception, since taste sensitivity thresholds are relatively high. But in some fish, taste can acquire the functions of a distant receptor. Thus, freshwater catfish, with the help of taste buds, are able to localize food at a distance of about 30 body lengths. When taste buds are turned off, this ability disappears. With the help of general chemical sensitivity, fish are able to detect changes in salinity up to 0.3% of the concentration of individual salts, changes in the concentration of solutions of organic acids (citric) up to 0.0025 M (0.3 g/l), changes in pH of the order of 0.05-0, 07 carbon dioxide concentrations up to 0.6 g/l.
Non-olfactory chemoreception in fish is carried out by taste buds and the free endings of the vagus, trigeminal and some spinal nerves. The structure of taste buds is similar in all classes of vertebrates. In fish, they are usually oval in shape and consist of 30-50 elongated cells, the apical ends of which form a canal. The nerve endings approach the base of the cells. These are typical secondary receptors. They are located in the oral cavity, on the lips, gills, in the pharynx, on the scalp and body, on the antennae and fins. Their number varies from 50 to hundreds of thousands and depends, like their location, more on the ecology than on the species. The size, number and distribution of taste buds characterize the degree of development of taste perception of a particular fish species. The taste buds of the anterior part of the mouth and skin are innervated by fibers of the recurrent branch facial nerve, and the mucous membrane of the mouth and gills - by fibers of the glossopharyngeal and vagus nerve. The trigeminal and mixed nerves are also involved in the innervation of taste buds.
To the question Do fish hear? Do they have hearing organs? given by the author ViTal the best answer is that the organ of hearing in fish is represented only by the inner ear and consists of a labyrinth that includes the vestibule and three semicircular canals located in three perpendicular planes. In the fluid located inside the membranous labyrinth there are auditory pebbles (otoliths), the vibrations of which are perceived by the auditory nerve. Neither the external ear nor eardrum fish do not. Sound waves are transmitted directly through tissue. The labyrinth of fish also serves as an organ of balance. The lateral line allows the fish to navigate, feel the flow of water or the approach of various objects in the dark. The lateral line organs are located in a canal immersed in the skin, which communicates with the external environment through holes in the scales. The canal contains nerve endings. The hearing organs of fish also perceive vibrations in the aquatic environment, but only higher frequency, harmonic or sound ones. They are structured more simply than other animals. Fish have neither an outer nor a middle ear: they do without them due to the higher permeability of water to sound. There is only a membranous labyrinth, or inner ear, enclosed in the bony wall of the skull. Fish hear, and excellently at that, so the fisherman must maintain complete silence while fishing. By the way, this became known only recently. Some 35-40 years ago they thought that fish were deaf. In terms of sensitivity, hearing and the lateral line come to the fore in winter. It should be noted here that external sound vibrations and noise penetrate through the ice and snow cover to a much lesser extent into the fish habitat. There is almost absolute silence in the water under the ice. And in such conditions, the fish relies more on its hearing. The organ of hearing and the lateral line help the fish to determine the places where bloodworms accumulate in the bottom soil by the vibrations of these larvae. If we also take into account that sound vibrations attenuate in water 3.5 thousand times slower than in air, it becomes clear that fish are able to detect the movements of bloodworms in the bottom soil at a considerable distance. Burrowing into a layer of silt, the larvae strengthen the walls of the passages with hardening secretions salivary glands and make wave-like oscillatory movements with their bodies in them (Fig.), blowing and cleaning their home. From this, acoustic waves are emitted into the surrounding space, and they are perceived by the lateral line and hearing of the fish. Thus, the more bloodworms there are in the bottom soil, the more acoustic waves emanate from it and the easier it is for fish to detect the larvae themselves.
Answer from Alexander Vodyanik[newbie]
with their skin... they hear with their skin... I had a friend in Latvia... he also said: I feel with my skin! "
Answer from User deleted[guru]
Koreans fish for pollock in the Sea of Japan. They catch this fish with hooks, without any bait, but they always hang trinkets (metal plates, nails, etc.) above the hooks. A fisherman, sitting in a boat, tugs on such a tackle, and the pollocks flock to the trinkets. Catching fish without trinkets does not bring good luck.
Screaming, knocking, shots above the water disturb fish, but it is more fair to explain this not so much by perceptions hearing aid, how much is the fish’s ability to perceive the oscillatory movements of water using the lateral line, although the method of catching catfish “by shred”, by the sound produced by a special (hollowed out) blade and reminiscent of the croaking of a frog, many are inclined to consider as evidence of hearing in fish. Catfish approach this sound and take the fisherman’s hook.
In L.P. Sabaneev’s classic book “Fishes of Russia,” unsurpassed in its fascination, bright pages are devoted to the method of catching catfish by sound. The author does not explain why this sound attracts catfish, but cites the opinion of fishermen that it is similar to the voice of catfish, which seem to cluck at dawn, calling for males, or to the croaking of frogs, which catfish love to feast on. In any case, there is reason to assume that the catfish hears.
In the Amur there is a commercial fish, silver carp, famous for that lives in a herd and jumps out of the water when it makes noise. You will go out on a boat to the places where the silver carp are found, hit the water or the side of the boat with an oar, and the silver carp will not be slow to respond: several fish will immediately jump out of the river noisily, rising 1–2 meters above its surface. Hit it again, and the silver carp will jump out of the water again. They say that there are cases when silver carp jumping out of the water sink the small boats of the Nanai. Once on our boat, a silver carp jumped out of the water and broke the window. This is the effect of sound on silver carp, apparently a very restless (nervous) fish. This fish, almost a meter long, can be caught without a trap.
What kind of hearing do fish have? and How does the hearing organ work in fish?
While fishing, the fish may not see us, but its hearing is excellent, and it will hear the slightest sound that we make. Hearing organs in fish: inner ear and lateral line.
Carp hearing aid
Water is good guide sound vibrations, and a clumsy fisherman can easily spook the fish. For example, a clap when closing a car door, through aquatic environment extends over many hundreds of meters. Having made quite a splash, there is no reason to be surprised why the bite is weak, and maybe even absent altogether. Be especially careful big fish, which accordingly is the main purpose of fishing.
Freshwater fish can be divided into two groups:
Fish with excellent hearing (cyprinid, roach, tench)
Fish with average hearing (pike, perch)
How do fish hear?
Excellent hearing is achieved due to the fact that the inner ear is connected to the swim bladder. In this case, external vibrations are amplified by the bubble, which plays the role of a resonator. And from it they go to the inner ear.
The average person hears a range of sounds from 20 Hz to 20 kHz. And fish, for example carp, with the help of their hearing organs, are able to hear sound from 5 Hz to 2 kHz. That is, fish’s hearing is better tuned to low vibrations, but high vibrations are perceived worse. Any careless step on the shore, a blow, a rustle, is perfectly heard by carp or roach.
Hearing apparatus of carp In carnivorous freshwater carnivores, the hearing organs are built differently; in such fish there is no connection between the inner ear and the swim bladder.
Fish such as pike, perch, and pike perch rely more on vision than hearing, and do not hear sound above 500 hertz.
Even the noise of boat engines greatly affects the behavior of fish. Especially those who have excellent hearing. Excessive noise can cause fish to stop feeding and even interrupt spawning. We fish already have a good memory, and they remember sounds well and associate them with events.
The study showed that when the carp stopped feeding due to noise, the pike continued to hunt, not paying any attention to what was happening.
Fish hearing aid
Hearing organs in fish.
Behind the skull of the fish there are a pair of ears, which, like the inner ear in humans, in addition to the function of hearing, are also responsible for balance. But unlike us, fish have an ear that does not have an outlet.
The lateral line picks up low frequency sound and water movement near the fish. Fatty sensors located under the lateral line clearly transmit the external vibration of water to the neurons, and then the information goes to the brain.
Having two lateral lines and two inner ears, the organ of hearing in fish perfectly determines the direction of sound. A slight delay in the readings of these organs is processed by the brain, and it determines from which side the vibration is coming.
Of course, on modern rivers, lakes and stakes there is enough noise. And over time, the fish’s hearing gets used to many noises. But regularly repeated sounds, even if it is the noise of a train, are one thing, and unfamiliar vibrations are another thing. So for normal fishing it will be necessary to maintain silence and understand how hearing works in fish.
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