Flounder is the name of several types of fish that live in the seas and have a flat body. Distinctive features of the flounder are primarily in the flat, flattened shape of the body, as well as the location of the eyes, which are on one side. Flounder has fins that are located on the side facing up.
Several exotic species of flounder are known, the main "attraction" of which is the presence of an eye on the edge of the head. Flounder lives on the seabed, some can enter freshwater bodies. The meat of this fish is quite tasty, which is the reason that the flounder has become of commercial importance.
Different species prefer to "settle" at different depths and choose different soil. Sizes also vary. Flounder is capable of changing the color of its body at lightning speed. It all depends on the soil next to which this fish is located. Thus, it becomes almost invisible. Many flounder species are of commercial importance.
The flounder is characterized by a high body, very strongly compressed from the sides. It is asymmetrical. In simpler terms, what we can take for the back and belly is nothing more than a side and one more side. To answer the question of which side is on top and which is on the bottom, it is necessary to find out to which species this flounder belongs.
The "young" flounder behaves like all other fish. This is true. And this also applies to swimming, before reaching maturity, the flounder in this regard does not differ from other fish. Her body is symmetrical. The eyes are also located on either side of the head. With age, the flounder lies on one of the sides. At the same time, her eyes shift to the other side, which is also due to the uneven growth of the flounder's body.
The flounder is characterized by a bottom lifestyle. Flounders burrow into the sand in such a way that only the eyes and the upper part of the head remain on its surface. These fish are capable of burrowing into the ground very quickly. They do this in the following way: with the help of wave-like movements of the edges of their body, flounders create a small depression in the ground. They immediately plunge into it. These movements stir up the soil, which then settles on the body of the flounder, and it turns out to be buried in it.
Flounders are poor swimmers. Mostly everything. Flounders swim with the oscillating movements of their fins. If they are in danger, then flounders turn on the edge and in this form quickly swim forward. After eliminating the danger, these fish burrow into the ground again.
Flounder can change color of its body at lightning speed. Rather, the side on which the gas is located. The color of the flounder depends on the color of the bottom, as well as on its pattern. Thus, the flounder achieves that it becomes almost invisible. This ability to imitate is called mimicry. However, it should be noted that mimicry is not characteristic of all flounder individuals, but only sighted ones. If the flounder is blinded, then it cannot imitate, i.e. does not change the color of its body.
The size of flounders varies from a few centimeters to several meters. The mask of the smallest species of flounder is only a few grams. The mass of the largest species of flounder exceeds three hundred kilograms, and the size is more than four meters.
Halibut is the name of the largest flounder. They inhabit the depths of the Atlantic and Pacific oceans. These flounders can live up to fifty years of age. The largest recorded weight is 363 kilograms. In addition, halibut is a very tasty fish, which makes halibut a desirable prey for fishermen.
Halibut spawns at a depth of three to seven hundred meters. Spawning takes place in deep pits in the fjords or along the coast. Halibut predominantly spawns off the Norwegian coast, as well as in the following areas: Faroe Islands, Danish Strait, watershed of Greenland, Scotland and Iceland.
Commercial halibut fishing is difficult. Moreover, it is strictly controlled. This is due to the peculiarities of the life of halibuts. They do not form clusters, but swim alone. In addition, halibuts grow very slowly. In connection with this fact, large individuals are found in the catches of fishermen not so often. True, a way out of this situation was found. It consists, first of all, in the artificial cultivation of halibut - in special tanks the young halibut reaches a mass of about one hundred grams, after which it is sent to sea cages. Here, halibut already reaches a mass of two to five kilograms, which is marketable.
The Black Sea Kalkan is a valuable fish. This flounder is of commercial importance. Black Sea Kalkan has very tasty meat. For example, a kilogram of this fish in Turkey can be bought for no less than fifteen dollars. In the sixties of the last century, two or three tons of Black Sea kalkan were caught off the coast of the Crimea annually. However, in the seventies, the stock of this fish decreased significantly. This was the reason for the imposition of a ban on the fishing of the Black Sea Kalkan. There is currently no ban.
Fishing for the Black Sea kalkan in our time is undermining the stocks of this fish. Kalkan is caught using multi-kilometer nets. Large-mesh bottom nets block the spawning migration routes of the Black Sea kalkan - this is the traditional way of catching this flounder. Moreover, the length of the networks is hundreds of kilometers. Recently, the fishery has become unmanageable, which can lead to a significant loss of reserves of the most valuable Black Sea kalkan.
Kalkan's habitat is very limited. In addition to the Black and Azov Seas, Kalkan lives in the adjacent Mediterranean Sea. The Black Sea Kalkan can enter the mouths of the Dniester and Dnieper. This species of flounder inhabits silty and sandy soils at a depth not exceeding one hundred meters. The Azov Sea is inhabited by the Azov Kalkan subspecies, the size of individuals of which is somewhat smaller than the size of individuals of the Black Sea Kalkan.
Kalkan is a predatory fish. Kalkan's diet includes small crustaceans, molluscs, small fish. The juveniles of the Kalkan feed mostly on crustaceans, and the adult Kalkans feed on crabs and bottom fish (they eat at least one hundred and fifty grams of fish per day).
There are about ten species of flounder in the Red Sea. The name of the most famous of them, translated into Russian, means "Moses' flounder." This flounder is characterized by a small size - the body length is only about twenty-five centimeters. Inhabits a depth not exceeding fifteen meters. The diet of Moses' flounder includes invertebrates. Mostly spends time without moving, buried in the ground.
River flounder inhabits freshwater reservoirs. Not quite a correct statement. The river flounder can enter lakes and rivers and travel hundreds of kilometers in fresh water. However, river flounder does not even breed in fresh water bodies. In the Russian Federation, river flounder is found in the Azov and Black Seas, as well as in the White, Barents and Baltic Seas.
The river flounder belongs to the same family as the halibut. This is a family of flounders proper. However, the sizes of these two species differ significantly from each other. If the mass of halibut can reach three hundred kilograms, then the mass of river (or, as it is also called, rough) flounder does not often exceed five hundred grams.
The Baltic Sea is "rich" in river flounder. It is found everywhere there. The river flounder belongs to the massive marine fish. The river flounder is of great commercial importance. In some years, the catch of this flounder has reached thirteen percent of the total fish catch. River flounder lives at depths of at least sixteen to eighteen meters. As a rule, this type of flounder keeps on sandy soils.
The river flounder is a common inhabitant of the Gulf of Finland. Indeed, you won't surprise anyone there. The river flounder somewhat prefers the southern coast of the bay to the northern one. This is due to the fact that in the southern part the influence of the saline waters of the Baltic Sea is stronger.
During spawning, river flounder lays a huge number of eggs. In larger females of the river flounder, this number can reach two million. Spawning occurs in the spring. In the Gulf of Finland, it lasts from May to June. Interestingly, the caviar of this species of flounder is free-swimming. The female lays eggs on a rocky or sandy bottom. But caviar develops directly in the water column. The behavior of the fry of the river flounder does not differ from the fry of other species of flounder - they settle to the bottom only after metamorphosis (the body flattens, both eyes are on the same side, the fry becomes asymmetrical).
The turbot flounder is a representative of the Kalkanov family. In ancient times, fishermen called this fish "pilvina". The turbot (or large rhombus) differs markedly from the river flounder. Firstly, the size - the turbot is much larger. Secondly, the location of the eyes - in turbot, the eyes are located on the left side. Thirdly, the width of the pelvic fins is much larger in the large rhombus.
Large diamond - large fish. The length of some individuals reaches one meter. As a rule, it is about eighty centimeters. In the Gulf of Finland, smaller flounders are often found. The large rhombus has a tall body. The body height of a turbot is half its length.
Turbot is a predator flounder. Turbot has a large mouth. Both jaws are set with sharp teeth that are small in size. The diet of a large diamond includes mainly fish: cod, gerbil, and even river flounder. It also eats sea cockroaches and sometimes molluscs. In the methods of hunting and obtaining food, turbot resembles a river flounder - it also slowly creeps along the bottom, looking for a prey, or, hiding in its shelter, waits for it. Turbot hunts in the same way as river flounder. Turbot slowly creeps along the bottom in search of prey or waits for it, hiding and disguised as the color of the ground.
The larvae of the large rhombus are free-swimming. Like the river flounder. Metamorphosis in turbot larvae is completed when their body length reaches about twenty-five centimeters. Then they move on to life at the bottom.
The large rhombus prefers significant depths. The depth, as a rule, does not exceed one hundred meters. Loves sandy or muddy bottom.