Vision or the ability to receive electromagnetic radiation of a certain spectrum plays an important role in their lives. The cells of the retina of the eyes of fish are similar in composition to human ones.
- of course, the eye, consisting of a spherical lens close to the flat cornea and located on the side of the head. Characteristic features of fish vision: myopia; the ability to see in several directions at the same time.
The angle of view of the fish is as follows: about 150 ° vertically and up to 170 ° horizontally.
Fish vision is monocular: each eye sees independently. In order to see something with both eyes, the fish quickly turns. With both eyes, she sees a very narrow cone-shaped area ahead.
Many fish have a lens protruding from the pupil opening, which increases the field of view. Anteriorly, the monocular vision of each eye overlaps to form 15–30° binocular vision. The main disadvantage of monocular vision is inaccurate distance estimation.
The eye of a fish has three shells: 1) sclera (outer); 2) vascular (medium); 3) retina, or retina (internal).
The outer shell of the sclera protects the eye from mechanical damage, forming a transparent flat cornea.
choroid provides blood supply to the eye. In the anterior part of the eye, the choroid passes into the iris, in which, in turn, the pupil is located, with the lens entering it.
The retina contains: 1) pigment layer (pigment cells); 2) photosensitive layer (light-sensitive cells: rods and cones); 3) two layers of nerve cells; rods and cones for the perception of light in the dark and color discrimination.
According to the number of these rods and cones (light-sensitive cells) in the retina, fish are divided into diurnal and twilight.
Another one salient feature fish vision: it is color. Scientists have found that some species of fish can distinguish up to 20 colors. Carnivores have better color vision than herbivores. Many fish perceive a range of light waves even wider than humans. Fish can also partially see ultraviolet radiation. In general, the spectrum of visible light emission in different types fish is different.
On average, the fish sees well in clear, sunlit water, but some species have adapted to see at dusk and in muddy water. These types of fish have a special structure of the eyes. However, in clear water, the maximum visibility of the fish is 10-14 meters. The most accurate visibility is within 2 meters. 
The refraction of light waves in water is a rather complex topic, and at different depths different wavelengths of the light spectrum predominate, so the fish develops susceptibility to various types spectral waves of light. But on average, the range of perception of light waves in fish is 400–750 nm.
Unlike humans, vision does not play a major role among the sense organs of fish. Damaged or missing organs of vision of a fish (for example, with) are well compensated by other organs: the lateral line, the organs of smell, and taste.
Fish living in special conditions, such as deep-sea species, often have a structure of organs of vision that is different from most fish, or they do not have them at all. Once in the air, the fish sees almost nothing.
Sense organs. Vision.
The organ of vision - the eye in its structure resembles a photographic apparatus, and the lens of the eye is similar to a lens, and the retina is a film on which an image is obtained. In land animals, the lens has a lenticular shape and is able to change its curvature, so animals can adjust their vision to distance. The lens of fish is spherical and cannot change shape. Their vision is rebuilt at different distances when the lens approaches or moves away from the retina.
The optical properties of the aquatic environment do not allow the fish to see far. Practically, the distance of 10-12 m is considered the limit of visibility for fish in clear water, and fish see clearly no further than 1.5 m. predatory fish living in clear water (trout, grayling, asp, pike). Some fish see in the dark (perch, bream, catfish, eel, burbot). They have special light-sensitive elements in the retina of the eye that can perceive weak light rays.
The angle of view of the fish is very large. Without turning the body, most fish are able to see objects with each eye in a zone of about 150° vertically and up to 170° horizontally. (Fig. 1).
Otherwise, the fish sees objects above the water. In this case, the laws of refraction of light rays come into force, and the fish can see without distortion only objects that are directly above their heads - at the zenith. Obliquely incident light rays are refracted and compressed into an angle of 97°.6 (Fig. 2).
The sharper the angle of entry of the light beam into the water and the lower the object, the more distorted the fish sees it. When a light beam falls at an angle of 5-10 °, especially if the water surface is restless, the fish stops seeing the object.
Rays coming from the eye of a fish outside the cone depicted in rice. 2, are completely reflected from the water surface, so it appears to the fish as a mirror.
On the other hand, the refraction of the rays allows the fish to see, as it were, hidden objects. Imagine a body of water with a steep shore (Fig. 3).beyond the refraction of rays by the water surface can see a person.
Fish distinguish colors and even shades.
Color vision in fish is confirmed by their ability to change color depending on the color of the ground (mimicry). It is known that perch, roach, pike, which stay on a light sandy bottom, have a light color, and darker on a black peat bottom. Mimicry is especially pronounced in various flounders, capable of adapting their coloration to the color of the ground with amazing accuracy. If a flounder is put into a glass aquarium, under the bottom of which a chessboard is placed, then cells similar to chess ones will appear on its back. Under natural conditions, a flounder lying on a pebble bottom merges with it so much that it becomes completely invisible to the human eye. At the same time, blinded fish, including flounder, do not change their color and remain dark-colored. From this it is clear that the change in color by fish is connected with their visual perception.
Experiments on feeding fish from multi-colored cups have confirmed that fish clearly perceive all spectral colors and can distinguish close shades. The latest experiments based on spectrophotometric methods have shown that many species of fish perceive individual shades as well as humans.
It has been established by food training methods that fish also perceive the shape of objects - they distinguish a triangle from a square, a cube from a pyramid.
Of known interest is the relation of fish to artificial light. Even in pre-revolutionary literature, they wrote that a fire lit on riverbank, attracts roach, burbot, catfish and improves the results of fishing. Recent studies have shown that many fish - sprat, mullet, syrt, saury - are sent to sources of underwater lighting, so electric light is currently used in commercial fishing. In particular, sprats are successfully caught in this way in the Caspian Sea, and saury near the Kuril Islands.
Attempts to use electric light in sports fishing have not yet yielded positive results. Such experiments were carried out in winter in places of accumulation of perch and roach. A hole was cut in the ice and an electric lamp with a reflector was lowered to the bottom of the reservoir. Then they were fishing with a mormyshka with replanting a bloodworm in an adjacent hole and in a hole cut down away from the light source. It turned out that the number of bites near the lamp is less than away from it. Similar experiments were made when catching zander and burbot at night; they also did not give a positive effect.
For sport fishing, it is tempting to use baits coated with luminous compounds. It has been established that fish seize luminous baits. However, the experience of Leningrad fishermen did not show their advantages; ordinary fish baits in all cases are taken more readily. The literature on this issue is also not convincing. It describes only cases of catching fish with luminous baits, and does not provide comparative data on fishing under the same conditions with ordinary baits.
Features of fish vision allow us to draw some conclusions that are useful for the angler. It can be said with certainty that a fish located near the surface of the water is not able to see a fisherman standing on the shore further than 8-10 m and sitting or wading - further 5-6 m; the transparency of the water also matters. In practice, it can be assumed that if the angler does not see the fish in the water when he looks at the well-lit water surface at an angle close to 90 °, then the fish does not see the angler either. Therefore, masking makes sense only when fishing in shallow places or on top in clear water and when casting a short distance. On the contrary, the items of the angler's equipment that are close to the fish (leash, sinker, net, float, boat) should merge with the surrounding background.
Hearing.
The presence of hearing in fish has long been denied. Facts such as the approach of fish to the feeding place on a call, the attraction of catfish by hitting the water with a special wooden mallet (“squirting” of catfish), the reaction to the whistle of the steamer, proved little. The occurrence of the reaction could be explained by irritation of other sense organs. The latest experiments have shown that fish react to sound stimuli, and these stimuli are perceived both by the auditory labyrinths in the head of the fish and by the surface of the skin, and swim bladder playing the role of a resonator.
What is the sensitivity of sound perception in fish has not been precisely established, but it has been proven that they pick up sounds worse than humans, and fish hear high tones better than low ones. The sounds that occur in the aquatic environment are heard by fish at a considerable distance, and the sounds that occur in the air are poorly heard, since sound waves are reflected from the surface and do not penetrate well into the water. Given these features, the angler should be careful not to make noise in the water, but may not be afraid to scare the fish by talking loudly. It is interesting to use sounds in sports fishing. However, the question of which sounds attract fish and which scare them away has not been studied. So far, the sound is used only when catching catfish, "squirting".
Lateral line organ.
The lateral line organ is found only in fish and amphibians that live permanently in the water. The lateral line is most often a canal that runs along the body from head to tail. Nerve endings branch out in the canal, perceiving with great sensitivity even the most insignificant water vibrations. With the help of this organ, fish determine the direction and strength of the current, feel the currents of water formed when washing underwater objects, feel the movement of a neighbor in a flock, enemies or prey, and excitement on the surface of the water. In addition, the fish also perceives vibrations that are transmitted to the water from the outside - shaking the soil, hitting the boat, a blast wave, the vibration of the ship's hull, etc.
The role of the lateral line in the capture of fish prey has been studied in detail. Repeated experiments have shown that a blinded pike is well oriented and unmistakably grasps a moving fish, not paying attention to a stationary one. A blind pike with a destroyed lateral line loses the ability to orient itself, bumps into the walls of the pool, etc. being hungry, does not pay attention to the swimming fish.
Given this, the angler must be careful both on the shore and in the boat. The shaking of the soil under your feet, the wave from inaccurate movement in the boat can alert and scare away the fish for a long time. The nature of the movement of artificial lures in the water is not indifferent to the success of catching, since predators, when chasing and seizing prey, feel the water vibrations created by it. Catch, of course, will be those baits that most fully reproduce the signs of the usual prey of predators.
Organs of smell and taste.
The organs of smell and taste in fish are separated. The olfactory organ in bony fish is paired nostrils located on both sides of the head and leading to the nasal cavity lined with olfactory epithelium. Water enters one hole and exits the other. Such a device of the olfactory organs allows the fish to smell the substances dissolved or suspended in the water, and in the current the fish can smell only along the stream carrying the odorous substance, and in calm water - only in the presence of water currents.
The olfactory organ is least developed in diurnal predatory fish (pike, asp, perch), stronger in nocturnal and twilight fish (eel, catfish, carp, tench).
Taste organs are located mainly in the mouth and pharyngeal cavity; in some fish, taste buds are located in the area of the lips and whiskers (catfish, burbot), and sometimes they are located throughout the body (carp). As experiments show, fish are able to distinguish between sweet, sour, bitter and salty. Just like the sense of smell, the sense of taste is more developed in nocturnal fish.
In the literature, there are indications of the advisability of adding various odorous substances to the bait and nozzle, as if attracting fish: mint oil, camphor, anise, laurel-cherry and valerian drops, garlic and even kerosene. The repeated use of these substances in the feed did not show any noticeable improvement in the bite, and with a large amount of odorous substances, on the contrary, the fish almost completely ceased to be caught. A similar result was given by experiments performed on aquarium fish, which reluctantly ate food moistened with anise oil, valerian, etc. , attracts fish and speeds up their approach to the feeder.
The significance of certain sense organs when searching for food by various fish is shown in tab. one.
Table 1
How do fish see? Do they see us? And who are we to them? Aliens, for whom the inhabitants of the underwater world are only food, or friendly aliens who study their unknown and mysterious world. The life of underwater inhabitants is full of wonderful and amazing secrets.
The role of vision for underwater animals is extremely important. With its help, as well as with the help of other senses (smell, touch, hearing), fish receive information about the environment, and also provide contact between individuals of their species. Vision also determines the feeding activity of fish. For predators, he has one goal - to find prey and hide from a stronger inhabitant of the sea in order to avoid attack and rush again in search of less protected and weak individuals. And for defenseless herbivorous fish, there is nothing more important than to get away from a predator and hide in a secluded place.
The optical properties of water do not allow the animal to see far. The lens in fish cannot change shape and adapt vision to distance. Its sharpness depends on the transparency of the water. Well, fish can see in clear water no more than at a distance of 1.5-2 meters, but they distinguish objects within 12-15 meters.
Better see predatory fish living in running clear water (trout, grayling, asp). Since the eyes of the fish are located on the sides of the head and at some elevation above the surface of the body, their angle of view is very large and, without turning, they can see with each eye not only in front, but also on the sides - up to 1700 horizontally and about 1500 horizontally. vertical.
The hammerhead shark, due to the strange shape of its head, clearly sees in all directions: not only what is happening in front of it, but also vertically - above and below, from the side and behind.
In muddy and opaque water, the second sight allows the fish to navigate - the lateral line, a unique apparatus that performs the function of a kind of radar that allows you to capture the slightest fluctuations in the water. The eyes of fish are devoid of eyelids, and they are constantly open. Sea water washes them and cleans them from foreign impurities.
And now back to the question of whether the fish see us. It is especially often asked by amateur anglers. Not very good, but fish can see the surface world. According to the law of refraction of light rays, they relatively clearly see without distortion objects that are directly above their heads, for example, a boat or a bird flying over water.
Obliquely incident rays are refracted. And the sharper the angle and the lower the object, the more distorted it seems to the fish. For example, an angler standing on the shore is visible to the fish quite well. But if he sits down, the fish practically does not see him, especially in turbulent weather.
When catching mullet with a lifting plant, a fish that has fallen into a net trap perfectly sees the wall that blocked its path, and tends to leave, trying to jump over it. Sometimes large mullets make an initial reconnaissance by jumping slightly out of the water, estimating the height of the wall, and only then make a powerful jump.
Being not in their environment, on the shore, the fish do not lose the ability to navigate. For example, an eel quietly crawls from one reservoir to another. Yes, and try to throw away a live, just caught big fish to the shore: she will do everything to be in her native element. Fish can not only see, but also remember what they see.
An amazing incident occurred off the coast of Puerto Rico. A large mako shark was shot with a hunting harpoon gun. Making a dash towards the sea and freeing herself from the arrow, she rushed to the shore. To the amazement of those present, she tried to grab the unlucky hunter, who was standing on the shore, not paying attention to the people who were nearby.
And in some fish, the eyes are specially adapted for observing not only in water, but also in the air. Anableps fish is a four-eyed fish that lives in the Amazon. Her eyes are divided into upper and lower chambers, equipped with special optics. Top part the eye is adapted for observation in the air, the lower one - in the water. This fish perfectly sees both a mosquito in the air and a small crustacean in the water.
Predatory fish see much better than herbivores. They need keen eyesight when tracking down and chasing prey. The peculiarity of the visual apparatus of some fish allows them to divide the movement of an elusive prey into separate phases and guess its direction and speed, which allows them to catch a fast and agile prey with a lightning-fast throw. Small schooling fish see much worse.
Studies have confirmed that fish even distinguish the shape of an object, a square is distinguished from a triangle, and a cube from a pyramid, which even some land animals cannot.
Fish see color. Especially living in the surface layers of water, where the sun's rays penetrate well. This has long been proven by numerous experiments and is confirmed by their rich body coloration with various color shades, especially during the spawning period. And fish brides are more favorable to a male with a bright and variegated color - they still accept them according to their clothes.
But who knows what else fish females are guided by when choosing a partner for procreation. Many species of fish know the “face” of the “husbands” chosen by them for life together and do not allow a stranger to invade their lives and break family happiness.
Color vision allows fish to adapt to their environment to protect themselves from predators. For example, fish that live on a light pound are light in color, while those living among algae have striped camouflage clothing.
Well, some fish, such as flounder, literally change color on the go, depending on the color of the ground and merge with it so that the predator, swimming over the hidden fish, does not notice it. However, blinded fish, including flounder, do not change their color depending on the change in the color of the ground, and visual perception in this case remains fundamental.
Zorchie other diurnal fish-predators. These include pike, trout, grayling. By night - pike perch, bream, catfish. They have light-sensitive elements in the retina of the eye that perceive very weak light rays, which allow them to distinguish between dark time days of the shadow of the victim.
Fish have adapted to navigate in constant darkness - in the deep part of the ocean. The eyes, as a rule, are large, having a telescopic structure, allowing them to capture the slightest glimpses of light, usually emanating from the deep-sea inhabitants themselves.
Many of them have a kind of light organs - "flashlights" built for convenience in any part of the body, for example, in the mouth. A hungry fish opens its mouth wide and the light comes on automatically. Small fish, attracted by the light, swim into the mouth, and the cunning predator immediately closes it. In some deep-sea fish, elongated processes emanating from the head “burn” like antennas that perceive the voices of other underwater inhabitants - “ours” or “strangers”.
And others shine entirely, like Christmas decorations, in the light of burning multi-colored garlands. The researchers, who descended in the bathyscaphe to a great depth, into the pitch-black realm of darkness, were amazed at the wonderful colorful world that opened before them. Glittering ghosts floated before them, shimmering with many colors.
What beauty hides from the human gaze in the endless depths of the ocean! I would like a man to be only a peace-loving alien studying this mysterious world for underwater inhabitants.
Vladimir KORKOSH, ichthyologist, journalist (Kerch).
- Read: Variety of fish: shape, size, color
Sense organs: vision of fish
- Read more: Sense organs of fish
organs of vision. Fish vision.
The eyes of most fish are located on the sides of the head. Vision in fish is monocular, i.e. each eye sees independently (horizontal field of view 160–170°, vertically about 150°). In many fish, the lens protrudes from the pupillary opening, which increases the field of view. In front, the monocular vision of each eye overlaps, and binocular vision is formed (only 15–30 °). The main disadvantage of monocular vision is inaccurate distance estimation.
Many freshwater fish the pupil is motionless, some species can narrow and expand it (eel, flounder, stargazer, cartilaginous). The eyes of most fish do not have eyelids, some sharks have nictitating membranes, and mullets and some herrings develop fatty eyelids.
In fish, the eye includes three shells: 1) sclera (outer); 2) vascular (medium); 3) retina, or retina (internal).
The sclera protects the eye from mechanical damage; in the anterior part of the eye it forms a transparent flattened cornea. The choroid provides blood supply to the eye. In the area where the optic nerve enters the eye, there is a vascular gland characteristic of fish. In front of the eye, the choroid passes into the iris, which has a hole - the pupil into which the lens protrudes.
The retina includes: 1) pigment layer (pigment cells); 2) photosensitive layer (light-sensitive cells: rods and cones); 3) two layers of nerve cells.
Most fish have rods and cones in their retinas. Rods function in the dark and are insensitive to color, cones perceive colors.
The lens in the upper part is supported by a ligament, and in the lower part, with the help of a special muscle (Haller's bell), it is attached to the falciform process at the bottom of the eyeball, which is found in most bony fish. The lens of fish is spherical and does not change its shape. Accommodation (focusing) is carried out not by changing the curvature of the lens, but with the help of a muscle (Haller's bell), which pulls or removes the lens from the retina. The lens has the same density as water, as a result of which light passing through it is not refracted and a clear image is obtained on the retina.
Depending on the presence of photosensitive cells (rods, cones), fish are divided into: 1) twilight (there is little melanin in the pigment layer, only rods are present in the retina); 2) daytime (there is a lot of melanin in the pigment layer, there are few rods in the retina, large cones).
Fish perceive light waves at 400–750 nm. Almost all fish (except twilight and most cartilaginous) have color vision and some of them can change body color. Fish have different visual acuity. Usually they see objects at a distance of no more than 10-15 m. cartilaginous fish are the most farsighted, as they are able to narrow and expand the pupil of the eye. With a decrease in illumination, in some species, the size of the eyes increases, and they are able to capture weak light (deep-sea fish - sea bass, luminous anchovies), in others, the size of the eyes decreases (burbot, river eel). A number of deep-sea and cave fish have no eyes.
In the air, fish almost do not see with their eyes; some of them have special devices in their eyes for this purpose. In a four-eyed fish, each eye is divided by a horizontal partition into two parts. In the upper part of the eye, the lens is simplified, and the cornea is convex, which allows you to see in the air.
N. V. ILMAST. INTRODUCTION TO ICHTHYOLOGY. Petrozavodsk, 2005
Changes in the color of the body of fish are due to the fact that the fish adapt to the conditions in which they live, the color of their body becomes similar to the color of the soil, or acquire a kind of “camouflage” color if they live among aquatic plants. Compared to animals living on land, fish see the surface world in a slightly different way. If you look vertically up, then the fish see everything without distortion, and if at an angle to the side, then due to the refraction of the line of sight and two media - air and water, the picture is distorted.
Vision in fish. In fish, the maximum visibility in clear water does not exceed 10 - 12 meters, this is all because the optical properties of water do not allow you to see far. The visibility distance may also be reduced, the reason for this may be: the color of the water, the turbidity of the water, the illumination, etc. At a distance of no more than 2 meters, fish see objects most clearly. Predators see best of all, preferring the day, living in clear water - trout, grayling, pike, asp. Some fish that feed on plankton and bottom organisms (catfish, bream, eel, burbot, pike perch, etc.) have photosensitive elements in the retina that are capable of perceiving weak light rays. Thanks to these elements, these fish see quite well in the dark.
The angle of view of the fish is arranged in such a way: They can see objects in an area around 150° vertically and up to 170° horizontally. From the water in the air, the fish sees objects as if through a round “window”, limited by an angle of view of about 97 °. Accordingly, if the fish swims closer to the surface, then the “window” will become smaller and smaller.
Does the fish see the angler
Near the shore, the fish is a very good angler, but does not see it. This is just due to the refraction of the line of sight described above. Therefore, in the visibility zone, masking makes sense. Therefore, you should not wear clothes with bright colors for fishing, but on the contrary, as a disguise, choose a more protective color that will blend into the general background.
In shallow water, the likelihood that the fish will notice the angler is much less than when fishing in deeper places, close to the shore. From all this it can be concluded: that sitting is always better than standing and there is less chance of getting into the fish's field of view. That is why it is also recommended for a spinning player who hunts from a boat to fish (cast the bait and fish out the predator) while sitting, not only in order to comply with safety regulations, but also try not to be noticed by the fish.