Probably, many people are familiar with the outwardly unusual flattened flounder fish, which, in addition to its originality, is also famous for its excellent taste. Of course, by its flat appearance, one can guess that it lives precisely at the bottom, but few people know about its vital activity in the water depths. Let's characterize the external features of this unique fish, describe its habits and character, find out the permanent places of flounder dislocation.
Origin of the species and description
The flounder family is a class of ray-finned fish belonging to the flounder order. These fish are called right-handed flounders, because. their eyes are located on the right side of the head. Some fish varieties are characterized by a right-sided (reverse) arrangement of eyes. The fins located on both sides of the flounder's belly are completely symmetrical, they have a narrow base. The flounder family consists of 60 species of fish united in 23 genera.
Despite the fact that each view has its own characteristics, there are still common features, common to all flounders, they have:
- a strongly flattened body;
- close-set eyes that have a convex shape. Their movements can be multidirectional and completely independent of each other;
- an unusual asymmetrical head;
- a lateral line located between the eyes;
- a skewed mouth and very sharp teeth ;
- elongated fins equipped with many rays;
- light blind side, which is covered with rough and dense skin;
- short caudal peduncle.
Flounder eggs do not have a fat drop, so they move freely in the water column (float), sometimes developing in the upper layer. Only five species from the entire flounder family spawn at bottom.
Interesting fact: Flounders have a special talent for camouflage, which manifests itself in changing the color of the skin to match the bottom surface, in this case, when it comes to mimicry, they rival even chameleons.
It is worth noting that fish of different sexes have a number of differences between themselves. Males are smaller than females, have a longer distance between the eyes, their first rays of dorsal and pectoral fins are also longer than females.
Appearance and features
We have already found out that representatives of the flounder family are distinguished by a flattened body, which can be shaped like a rhombus or oval, all this excessive compression and flattening is associated with bottom life. It is customary to divide all flounders into river flounders, which prefer fresh waters, and marine flounders, which have chosen salty water spaces.
The river flounder is represented by three varieties:
- star-shaped flounder, which has a left-sided arrangement of eyes. The color of this fish can be dark green or brownish, wide stripes of black are visible on the fins. The eye side is characterized by the presence of studded stellate plates. On average, the length of the body of the fish reaches half a meter and a little more, and the mass does not exceed three to four kilograms;
- polar flounder, characterized by cold resistance, an elongated oval body and a solid brown color, the fins have a red-brick tint;
- the Black Sea Kalkan, which has eye sockets on the left side of the round body, covered with numerous tuberous spikes on the eye part of the body. The color is dominated by a brownish-olive tone. The dimensions of the fish are very large, exceeding the limits of one meter in length, and the mass can reach 20 kg.
Sea flounders are very diverse in size, color, shape and location of the eyes.
Among them are:
- sea common flounder, which is characterized by a greenish-brown color scheme with orange or red spots. The greatest length of the fish can reach up to a meter, and the weight is 6 – 7 kilograms. Mimicry among this variety is highly developed;
- a yellow-finned flounder that loves a cold climate, has a rounded body, which is bordered by yellowish-golden fins. The length of the body of the fish does not exceed half a meter, and the mass is about a kilogram. This species is distinguished by the presence of scales with small spines;
- white-bellied northern and southern flounder, belonging to the bottom variety and reaching half a meter in size. From the side of the eyes, the fish is colored milky, and a brownish or brownish tint appears in the area of the eyes. This flounder is distinguished by a bifurcated arcuate lateral line;
- halibut, which has five varieties. The largest ones reach 4.5 meters in length and weigh about 350 kg. The smallest is considered the sterlet-toothed halibut, whose mass does not exceed 8 kg, and the length varies from 70 to 80 cm.
Many have heard of the Far Eastern flounder, but it is not a variety, but a collective name that about ten different species.
Interesting fact: Halibuts are considered the largest representatives of flounders. These giants live in the Atlantic and Pacific Oceans and are long-lived, able to survive half a century in the water depths
Where does the flounder live?
Various types of flounder inhabit all kinds of water areas, let's try to figure out where exactly this or that species lives. The star flounder occupied the northern waters of the Pacific Ocean, settling in the Bering, Okhotsk, Chukchi and Japan seas. Fish of this species, which prefer fresh water, live in the lower reaches of the river, lagoons and bays. The Black Sea Kalkan has chosen the north of the Atlantic Ocean and the waters of the Black, Mediterranean and Baltic Seas. In addition to the sea areas, the Kalkan can be found in the Dnieper, Dniester, in the lower reaches of the Southern Bug, at the mouth of the Don.
The polar flounder, loving the cold climate, was registered in the Kara, Bering, Okhotsk, Barents, White Seas. The cold-loving fish inhabits the Ob, Karoo, Yenisei. Tuguru, where it prefers to live in silty soft ground. Common sea flounder can live both in highly saline and slightly saline water at depths of 20 to 200 meters. This species is considered commercial and lives in the eastern part of the Atlantic, in the Barents, Baltic, Mediterranean, White Seas. A typical inhabitant of the coastal regions of Primorye can be called the southern white-bellied flounder, which also chose the Japanese, Kamchatka, Okhotsk and Bering Seas.
The yellowfin flounder can be found in the waters of the Sea of Japan, the Bering and the Sea of Okhotsk, where it has settled quite extensively. A lot of this fish lives near Sakhalin and the western Kamchatka coast, where the flatfish adheres to a depth ranging from 15 to 80 meters and loves the bottom covered with sand. Halibut have chosen the Atlantic, are found in the extreme depths of the Northern Ocean, inhabit the Pacific Ocean, including the territories of the Japan, Okhotsk, Barents and Bering Seas.
An interesting fact: Biological flexibility and a large number of species of flounder allowed them to safely settle along the entire coast of Eurasia and populate inland seas.
Now you know where the flounder lives. Let's see what it eats.
What does a flounder eat?
The flounder menu is very diverse, this fish can be called a predator. These flattened fish can show feeding activity at night, at dusk, and during the day, it depends on belonging to a particular species. The fish diet is represented by animal food.
Young flounders eat:
Mature fish individuals eat:
- brittle brittle stars;
- all kinds of echinoderms;
- small fish;
It has been noticed that flounders simply adore small-sized capelin and shrimp. Due to the fact that the fish head has a lateral location, flounders have adapted to deftly gnaw out small mollusks that live on the river or sea bottom from the ground. Thick crab shells and strong core shells for flounder are not an obstacle, because it has powerful and strong jaws. The flounder is reluctant to leave its secure shelter, so there are usually enough small fish swimming next to it.
Interesting fact: Anglers have noticed that the flounder rarely leaves its shelter, therefore, in order for it to be caught on hook and turned her attention to the bait, you need to twirl it right at the nose of the fish, so it is not so easy to catch it.
It is worth noting that flounder meat is highly valued, for the most part, due to the fact that fish nutrition is balanced and contains a large amount of protein.
Peculiarities of character and lifestyle
Basically, all flounders lead a solitary bottom life. In terms of disguise, they are consummate professionals. Fully adapting to the surrounding area (the ability of mimicry). They spend the lion's share of their fish time lying down on the bottom or in the thickness of the soil, buried up to their very eyes. This helps to go unnoticed by large predators and skillfully grab fish prey from an ambush.
At first glance, the flounder may seem clumsy and slow; it slowly glides along the surface of the ground with wave-like movements. This is how the flat behaves when it does not feel any threats, but if there are reasons for that, then the fish instantly transforms into a swift swimmer, the start of which is simply lightning fast, and the speed develops quite decent in a short period of time.
When the situation requires it, the flounder, like a bullet, makes a powerful jerk of its flattened body, which instantly moves the fish a few meters in the right direction, while using the gill cover, the flounder releases a forceful stream of water towards the bottom, thereby raising turbidity from it . While it dissipates, the cunning flounder can catch its chosen prey or hide from predatory eyes, although it is very difficult to notice the fish anyway, because it merges with the landscape.
An interesting fact: Conducting an experiment, scientists covered the bottom of the aquarium, where the flounder lived, with a special substrate, painted in black and white checkered. After a short time, clearly visible spots appeared on the fish body, both dark and light colors.
Social structure and reproduction
As already noted, flounders prefer bottom solitary existence. Spawning time for each variety is individual, it depends on the level of warming of the water column and the onset of spring. The general flounder breeding season runs from February to May. There is an exception to this interval. For example, such a variety as turbot enters the mating season from April to August in the waters of the North and Baltic Seas. The polar flounder spawns in the icy Kara and Barents seas from December to January.
Different types of flounders become sexually mature between three and seven years of age. Females of a larger number of species are very prolific, so one clutch can have from 0.5 to 2 million eggs. Basically, the incubation period does not exceed two weeks. For spawning, fish choose deep-sea places of coastal zones with a sandy bottom.
An interesting fact: Flounder fry have the usual appearance for fish, they are not born flat right away and have symmetry on both sides.
Growing up, the fish gradually transform, becoming similar to their parents. Their eye, located on the left or right, moves to the side of the second eye, this part of the fish becomes the upper, and the eyeless side refers to the belly, the skin of which becomes rough, because. used to slide along the bottom. At first, benthos and zooplankton predominate in the diet of young animals.
It should be added that some species spawn at impressive depths of fifty meters, because the eggs have an increased swimming ability, and they do not need to be attached to any hard surface. The average lifespan measured for flounders is quite long, it is about 30 years, but fish that live to this point are considered a rarity, because there are many enemies and negative factors on their way.
Natural enemies of flounder
Although flounders have an excellent camouflage talent that helps them go unnoticed, nevertheless, the fish have enemies. One of the ill-wishers are eels, who are not averse to eating flat fish. In addition, large halibut shamelessly attack their flounder relatives. Of course, inexperienced young animals are the most vulnerable, which can become a snack for any aquatic predators.
Sadly, but the enemy of the flounder is the person who exterminates this fish because of the tasty, delicious, white meat, which is very healthy. Almost everywhere, flounder is constantly caught, both by individual amateur anglers and on a large scale by fishing vessels. It is not surprising that fish rarely manage to live to the age of thirty, because a huge number of them die, caught in fishing nets.
In addition to the direct impact, people also have an indirect effect, negatively affecting the environment with their economic activities, which leads to a deterioration of the environmental situation in general. Many water sources (rivers and seas) become very polluted, so small fish disappear in them, which serve as a food base for flounders. People can be called the most important and malicious enemies of flounders, because. tons of these fish are caught every day. In addition to all the above unfavorable situations for fish, one can also mention the fact that the survival rate of its eggs is not so high, so only half of them continue to exist.
Population and species status
Situation with the size of the flounder population is ambiguous. Much here depends on a particular type of fish. Scientists have noticed that the number of flounder is subject to cyclicity, when growth surges are observed, gradually turning into a decline in the fish population.
Of course, the number of flounders is gradually decreasing, in some varieties this process is slowed down, in others it proceeds very rapidly, which is why environmental organizations are concerned. Many flounder populations are constantly under the influence of negative anthropogenic impacts, which, first of all, include the highest fishing load.
A huge number of flounders are caught daily, which naturally reduces their population. Some individual species are threatened with extinction, because there are extremely few of them left, so they need special protective measures. Do not forget that the deteriorating ecological situation and the 50% survival rate of eggs also negatively affect the number of flatfish. A person should think about his barbaric actions, moderate his appetites, otherwise some representatives of this flattened family will completely disappear from the water depths, then the situation will become incorrigible.
Protection of the flounder
As already noted, the state of the number of some populations of flounders is very deplorable, they are subject to the threat of complete destruction, which cannot but worry. For example, such varieties of flounder as the Mediterranean arnoglos (Kessler's flounder) are in danger of extinction, because they have become extremely rare. This species has been listed in the Red Book of Ukraine since 1994. The main limiting factor is the pollution of the Black Sea area, which prevents the full development of eggs. Also, fishing with nets leads this flounder to death along with another catch.
The Black Sea flounder (Kalkan) is the most valuable and expensive commercial fish. In the sixties of the last century, too active production of this fish was carried out near the Crimean territories (up to two to three thousand tons annually), which led to a sharp reduction in its livestock, and in 1986 the authorities announced a ban on catching the Kalkan, because it had almost completely disappeared on throughout the former Soviet Union. Now this ban is not respected, although the number of sea otters is still a matter of concern.
The main measures for the conservation of endangered species of flounder fish are:
- a strict ban on fishing;
- increasing fines for violating this ban;
- identifying places of permanent fish deployment and including them in the list of protected areas;
- explanatory work among the local population.
In conclusion, it remains to be added that although such flattened fish as flounder is very tasty and healthy, it is worth treating it more carefully, reducing uncontrolled and massive catches in order to avoid the deplorable negative consequences that can occur due to immoderate human appetites .