Surprisingly, but true: in terms of sensitivity to sounds lying in the range from 500 to 1000 Hz, the hearing of fish is in no way inferior to the hearing of animals. And some representatives of freshwater fish have unique ability pick up electromagnetic waves and use their electroreceptor cells and organs to communicate and exchange information.
As for some freshwater inhabitants of the Dnieper, they are able to determine the quality of food by touching the food object with the gill cover, fins and even the caudal fin.
Pacific salmon and American eel have a keen sense of smell. These fish 
capable of detecting levels of a substance whose concentration is one part per billion parts of water. Thus, the eel living in the Great Lakes is able to detect an alcohol level of one teaspoon in the entire lake.
Many fish have an extremely sensitive sense of smell. They perceive bloodworm extract in a ratio of 1: 1,000,000,000. The presence of the so-called alarm pheromone, released from the skin of wounded fish in a concentration of 10-7 mg/l, also causes anxiety in the peaceful inhabitants of the river depths, which can provoke their departure from dangerous place.
And crucian carp and carp even react to water in which predatory fish were kept.
Features of the nervous system
According to scientists, bony fish, which includes the majority of inhabitants of fresh water bodies, have memory - the ability for imaginative and emotional “psycho-nervous” activity (albeit in a rudimentary form). So, for example, a perch, once caught on a hook, avoids feasting on the worm on the hook, but willingly grabs the worm on the thread offered to it.
Fish that once got caught in a trawl or net, but managed to escape, are more careful and fearful, which allows them to avoid such dangerous fishing gear in the future.
Many aquarium fish They eat food from the hands of their owner, but never from the hands of other people.
There is no doubt that throughout their lives, fish learn, gaining very useful experience, they develop conditioned reflexes. It has been established, for example, that when experimentally catching ruffe, chub and bream with a fishing rod, these freshwater fish develop a conditioned defensive reflex as a result of 1–3 observations of catching fellow members of the school. Having seen how a spotted fellow “soars” to the surface of the water, a seasoned bream will remember how to act in such a situation - to run away as best you can!
Fish quickly develop defensive reflexes to hooking gear, to the swing of a rod, to the angler walking along the shore or in a boat, to fishing line or bait. Predatory fish They accurately recognize many types of spinners and have “learned by heart” their vibrations.
The larger and older the fish, the more experienced and smarter it is, the more it has accumulated conditioned reflexes. And accordingly, the more difficult it is to catch it with old gear. To outwit such fish, you will have to learn new techniques fishing, and it doesn’t hurt to update the gear.
The thickness of the World Ocean truly hides mysterious creatures unusual colors and sizes, from very tiny to gigantic, with amazing abilities and impressive age. It was in water that the first life arose many millions of years ago, but even today you can find specimens of the most ancient representatives of fish. The ranking contains the most Interesting Facts about fish, records and historical data.
In the waters of the seas and oceans, even today you can find specimens of the most ancient representatives of fish. Rating of unusual fish
Among a huge amount There are individuals of fish that stand out for their bizarre and sometimes frightening appearance. Representatives of this category are not always dangerous, but use their exotic appearance to scare away predators or hunt.
Dimensional record holders
Evolution and climate change lead to complete or partial modification of individuals, this also applies to sea inhabitants. Once huge and majestic primitive species became smaller or became extinct, some changed in appearance, learned to breathe on land, or stopped swimming altogether and adapted to walk on fins.
The list shows interesting facts about giant and dwarf fish:
Due to the demand for seafood, large quantities of fish are caught from the seas and oceans every day, which leads to a reduction in their population and leads to the extinction of species.
The reservoirs of Europe are becoming poorer, and the title of the busiest river goes to the Amazon, which has more than a million plants and inhabitants in its waters. According to scientists, the river is only 30% studied and hides many interesting facts about fish and river populations.
Exotic outfits
Divers will confirm that the ocean is beautiful. The unusual, bright and original colors of the inhabitants create a breathtaking picture that is simply impossible to forget. The appearance of some species of sea inhabitants is fascinating and sometimes frightening.
The list of such representatives includes:
A mutant embryo can cause horror bull shark. Once every 50-100 years, scientists come across such specimens; by nature they are albinos with one eye, which are unable to survive in natural environment, so they die immediately after birth.
Amazing abilities and skills
In addition to external data, sea creatures there are many other talents and skills lurking. Some of the individuals can be trained, others see ultraviolet rays and cannot blink or swim. There are many more interesting facts about fish for children. that even adults don’t know.
Amazing skills are also given to deep-sea representatives that live on great depth where complete darkness reigns. Such individuals illuminate their path with unique organs - photophores. Black dragons, lantern-eyed fish, anglerfish, glowing anchovies, and Brazilian glowing sharks have such glands.
In addition, there are many more interesting things about fish for children.
Famous fishing records
One of the most expensive aquarium representatives is the dragon fish, which costs 80 thousand dollars, but it is surpassed by the platinum arowana with a price of 400 thousand dollars per individual.
Representative ancient world are coelacanths and coelacanths - copies of primitive prehistoric fish.
Giant mammals are considered blue whale, which is larger in size than all the animals in the world. Its size reaches 33 meters, and its weight is 150 tons, in its blood vessels A small herring or trout can swim through; the diameter of the aorta is 25 cm.
Electric stingrays are known for having the largest number of taste buds - 27 thousand, while humans have only 7 thousand.
In 1989, a record-breaking beluga with a length of 6 meters was caught in Russia. Pike caught in the Tsaritsyn ponds near Moscow are considered to be long-lived; in its gills it was found Golden ring with an engraving by Boris Godunov, this made it possible to establish its age at 200 years.
Along with invertebrates, amphibians, reptiles, birds and mammals, fish are one of the 6 main groups of animals, and are widely distributed in oceans, seas, lakes and rivers around the world. In this article, you'll discover 10 basic facts about fish, ranging from how these aquatic vertebrates breathe to their reproductive habits.
1. There are three classes of fish
Fish are divided into the following three main classes:
1) Ray-finned fish (Actinopterygii)- the most diverse class, including more than 20,000 species known to science fish;
2) Lobe-finned fish (Sarcopterygii)- class of bony fish, to which the genus of ancient fish - coelacanths - belongs;
3) Cartilaginous fish (Chondrichthyes)- a class including such widely famous fish, like sharks and rays, as well as chimeras.
2. All fish have gills
Like all animals, fish need oxygen to maintain their metabolism: the difference is that terrestrial vertebrates breathe air, while fish get oxygen from water. To this end, fish have developed specially adapted gills - complex, efficient, multi-layered organs that absorb oxygen from the water and secrete carbon dioxide. For the gills to function properly, it is necessary that oxygenated water constantly pass through them, for this reason fish most They are in motion for a long time and quickly die when they are out of water.
Some species of fish (for example, lungfish), in addition to gills, have rudimentary lungs, and are able to breathe air when circumstances require it.
3. Fish were the first vertebrates on the planet
Before the appearance of “true” vertebrates, there were small marine animals with bilateral symmetry, as well as primitive nervous system, running along the length of their body. A little over 500 million years ago, during Cambrian period, the chordate population evolved into the first true vertebrates, which became the foundation for the reptiles, birds, amphibians and mammals we all know and love.
The largest of the 6 major groups of animals, invertebrates have followed their own evolutionary path and today they make up a whopping 97 percent of all fauna species.
4. Most fish are cold-blooded
Like amphibians and reptiles, to which fish are distantly related, the vast majority of fish species are cold-blooded: they depend on temperature environment(water) to support internal metabolism. However, barracudas, tuna, mackerel and swordfish - all belonging to the suborder mackerel - have a warm-blooded metabolism, although it is quite different from that of mammals and birds. Tuna can maintain a core body temperature of 32 degrees Celsius, even when swimming in 7 degree Celsius water!
Mako sharks are also warm-blooded, which gives them extra energy when chasing prey.
5. Fish are oviparous, not viviparous.
Unlike other vertebrates, most species of fish fertilize their eggs (eggs) externally: the female lays hundreds or thousands of small, unfertilized eggs, and the male at this moment releases his sperm into the water, thereby fertilizing the eggs. Some fish are characterized by males using their penis to transfer sperm into the female.) There are exceptions: ovoviviparous fish, the fry of which emerge from eggs in the female’s body, as well as viviparous fish, for example, the lemon shark, which has an organ very similar to the placenta of mammals.
6. Most fish have a swim bladder
Fish live in stratified ecosystems: 10 meters below the water surface is very different than at a depth of 1-2 kilometers. For this reason, it is in the fish's best interest to maintain a constant depth, which most species achieve using the swim bladder, a gas-filled organ that keeps the fish buoyant and eliminates the need to swim at top speed.
7. It's possible that fish can feel pain.
Even people who advocate more humane treatment of "higher" vertebrates such as cows and chickens are tight-lipped when it comes to fish. But there are some controversial studies suggesting that fish can feel pain, even though they lack the brain structure associated with pain like mammals. In England, the Royal Society for the Protection of Animals passed a resolution against ill-treatment with fish, which presumably relates more to injuries from fish hooks than to industrial fish farms.
8. Pisces are unable to blink
One of the anatomical features that makes the fish a little strange is the lack of eyelids, and therefore their inability to blink: the mackerel's gaze will remain the same glassy, regardless of the relaxed or anxious state of the fish. In this regard, the logical question arises, does the fish sleep? Despite constantly open eyes, there is some evidence that fish do sleep, or at least tend to sleep. restorative behavior similar to human sleep: some fish slow down their swimming pace, and also hide under stones, in corals and algae.
Even when the fish are completely motionless, underwater currents still supply the gills with vital oxygen.
9. The lateral line replaces hearing and smell in fish
Many fish have excellent eyesight, but their hearing and sense of smell leave much to be desired. However, these marine animals have a sensory organ, the lateral line, which is absent in terrestrial vertebrates. The lateral line is located along the entire length of the body and detects water vibrations, and in some species, even electrical impulses. This organ is especially important for maintaining space in the food chain: Predators use the lateral line to track prey, and the prey in turn uses the lateral line to avoid predators.
Fish also use their lateral lines to form schools and choose the right direction during migration.
10. Commercial fish stocks are declining at a catastrophic rate.
The world's oceans are so vast and teeming with life that people could be forgiven for counting tuna, salmon and other species commercial fish an inexhaustible source of food. In fact, overfishing can easily lead to the extinction of many fish populations as people consume more seafood than they can replenish.
Unfortunately, despite the real risk of loss valuable species, commercial fishing for some fish species continues. If trends continue, some of our favorite fish could disappear from the world's oceans within 50 years.
Interesting facts about fish.
Fish were on Earth more than 450 million years ago. They appeared before dinosaurs.
There are about 40 species of flying fish. The fish accelerates underwater and jumps up actively waving its tail. The large lateral fins of flying fish allow them to fly over water up to 400 meters. Flying fish use this skill to escape from predators. Diet flying fish consists mainly of small crustaceans and plankton. 
Some fish swim backwards.
Stingrays scour the bottom in search of food. Special electrical sensors help them with this. When a fish swims, it emits small electrical impulses as its muscles move. With the help of this sense, stingrays can catch fish that bury themselves in the sand.
IN present time about 25,000 fish have been classified. Scientists estimate that approximately 15,000 remain to be studied. The variety of fish species is amazing. For example, if you take all the species of mammals, reptiles, birds and amphibians together, there will still be fewer of them than the number of fish species.
The most big fish- whale shark, with maximum size 20 meters long and weighing 34 tons, this giant feeds on krill and plankton. Just like all sharks, skeleton whale shark consists entirely of cartilage.
How does a fish hang motionless in water? For this purpose, fish have an air bladder. By adjusting the amount of air in it, the fish can create zero buoyancy and hang in the water column. But not all fish have an air bladder. For example, in order to stay afloat, sharks must constantly swim or lie down to rest on the bottom. Read on and find out new interesting facts on the site
Some fish have a skeleton made entirely of cartilage, such as sharks.
Pisces feel pain, just like people, animals and birds.
The largest fish with a bony skeleton is the sunfish. This the only fish height at the withers, which exceeds its length. From the end of the upper fin to the lower one, the size is 4.26 meters, and the weight is 2 tons, 235 kilograms. The female moon fish is the most fertile and can produce up to 300 million (!) eggs at a time.
The fastest fish in the world is the swordfish. It is capable of reaching speeds of up to 130, and there is evidence that it can reach speeds of up to 140 km/h. It is noteworthy that scientists, having studied the structure and streamlining of the fish, came to the conclusion that it cannot reach such speed. If we take into account its structure, then for such a speed the fish must have a force of 1700-2000 horsepower. It turns out to be a paradox: according to the laws, she cannot swim so fast, but she swims.
Swordfish are also known for their tendency to attack ships and submersibles. There are facts that ships sank as a result of attacks by these fish. A swordfish can pierce a two-centimeter steel plating of a ship and create a hole with a diameter of 25 centimeters. At the present time Insurance companies the contract specifies a clause that takes into account damage to the ship as a result of swordfish attacks.
Scary deep sea fish that have never seen the light of day. The brightest specimens are those living at depths from 1000 to 6500 meters - the most deep point world ocean. The photo shows a fish with a light beacon, which it uses to attract food.
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