Sole fish

A sole fish is a fish that belongs to several different families of fish. Sole fish are members of the flatfish family. Outside of Europe, the flatfish name is also applied to several other similar sole fishes, especially other members of the flatfish suborder and members of the Soleidae family of flatfish. In European cuisine, there are several types that can be considered royal soles, but the common or Dover sole or sea sole fish that is Solea solea, often referred to simply as sole, is the most respected and widely used. Common sole, Dover sole, or black sole is a type of river sole fish. It lives on the sandy or muddy bottoms of the North Atlantic and the Mediterranean and often dives into the substrate. The upper part is grayish brown, and the lower part is white. It grows to a maximum length of about 70 centimeters. This species is considered to be an edible fish, which is mainly caught by trawling on the seabed. 

Fish 

Fish are aquatic animals with heads and gills without fingers or limbs. They form sister groups with tunicates and form a sense of smell together. The definition includes live mixed fish, lampreys, cartilaginous fish, and bony fish, as well as several related groups that have become extinct. About 99% of live fish species are finfish, belonging to the Actinopterygii class, and more than 95% belong to the teleost subgroup. The first creatures that can be classified as fish are the mollusk chordates that first appeared in the Cambrian period. Although they do not have a true spine, they do have a notochord, which makes them more agile than invertebrates. Fish will continue to evolve in the Paleozoic Era and diversify in various ways. Many fish from the Paleozoic era developed outer armor to protect them from predators. The first jawed fish appeared during the Silurian period, after which many fish became powerful marine predators, not just arthropod prey. Most fish change temperature and their body temperature changes with changes in ambient temperature, although some active large swimmers such as white sharks and tuna can maintain a higher core temperature. Fish can communicate with each other through sound, most commonly when they eat, attack, or court. Fish abound in most waters. They can be found in almost all aquatic environments, from mountain streams to the deepest oceans and even in the deep sea. Fish is an important resource for humans throughout the world, especially as food. Commercial and subsistence fishers fish in wild fisheries or culture them in net cages in ponds or oceans. They are also caught by recreational fishermen, kept as pets, kept by fish farmers, and displayed in public aquariums. For centuries, fish have played a role in culture, as gods, religious symbols, and themes of art, books, and movies. Tetrapods appear in leaf-finned fish, so they are also fish. However, traditionally, fish have become paraphyletic groups by excluding tetrapods (ie, amphibians, reptiles, birds, and mammals all come from the same ancestor).

Soleidae 

The majority of the sole fish in English or flatfishes are from the family of Soleidae. It includes brackish and saltwater species in the eastern Atlantic, the Indian Ocean, and the western and central Pacific oceans. They are known as river sole fishes. Freshwater species are distributed in Africa, South Asia, New Guinea, and Australia. In the past, American suns or American sole fishes were included in this family, but they have been separated into their own family Achiridae. True plantar or true sole fish are bottom-dwelling fish that feed on small crustaceans and other invertebrates. This family contains 30 genera and a total of about 180 species. The sole fishes begin their lives in the form of bilateral symmetrical larvae, with one eye on each side of the head, but during development, the left eye moves to the right side of the head. The adult aole fishes are on the left side that is the blind side of the seabed and are often covered in mud, which added to their dark color makes them difficult to detect. 

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Figure: Sole fish

Description of River Sole Fish

The small eyes are together on the right side of the body of the sole fish in English. This makes it possible for fish to hide in the sand to pass prey. The common flounder or sole fish, like all other flounders, grows into a normal fish with one eye on each side of the body. When the juveniles grow to about one centimeter, they metamorphose into flounders. The upper part is taupe and the lower part is white. The maximum length of ordinary shoe soles is close to 70 centimeters. In the United Kingdom, small soles are commercially called slips. 

Life Cycle of Sole Fishes

Dover soles or sole fish in English mature at 3-5 years of age. This is the point in their lives where they can begin to reproduce. Spawning generally occurs between February and May, but in warmer regions, it can also occur in early winter. It usually occurs in shallow coastal waters between 10-20 degrees Celsius. After fertilization of the ovum, the incubation period lasts approximately 5 days. Juveniles become juveniles after about 35 days. The maximum age recorded is 26 years. An ectoparasite of common shoe soles is Hemibdella soleae. The larvae settle on the upper surface of the fish, which is the only part that is not buried by sediment. After further development, they migrate to the bottom, where they attach to the fish with suction cups and feed on the fish's blood. 

American Flounder or American Sole Fish

The American flounder is a sole fish, which lives in the marine and freshwater environment of the Americas. This family includes about 35 species in seven genera. They are closely related to the soles (Soleidae) and are classified as a subfamily of them, but the acidic ones have many different characteristics. The eye is on the right side and the lower lip on the side of the eye has a distinct fleshy rim. The dorsal and anal fins are usually separated from the caudal fin. The pectoral fins are small or absent. They are small. Only Achirus achirus is more than 30 centimeters in length.  

The Evolution of Fish 

As a vertebrate, the fish developed into the brother of Tunisia. As tetrapods appear in the depths of fish schools, as siblings of lungfish, tetrapods usually have the characteristics of fish, including having vertebrae and skulls. It is an animal with a large mouth, long tail, very small dorsal fin, and pectoral fin attached to the lower part of the body, resembling lizard legs in size and development. The earliest fish in the fossil record is represented by a group of small armored jawless fish called ostracods. Most of the lineages of jawless fish have become extinct. As an existing clade, lampreys can use their jaws to approximate ancient fish. The earliest jaw bone was found in the Placodermi fossil. They did not have obvious teeth but modified the oral surface of the jaw plate to meet the various uses of the teeth. The diversity of jawed vertebrates may indicate the evolutionary advantage of jaws. It is not clear whether the advantages of articulated jaws are increased bite force, better breathing, or a combination of multiple factors. Fish may have evolved from a coral-like sea squirt-like organism, and its larvae are similar to primitive fish in important respects. It is possible that the earliest fish ancestors maintained their larval form until adulthood. 

Fish's Muscular System 

Most of the fishes move by alternately contracting pairs of muscles on both sides of the spine. These contractions form an S-shaped curve that moves downward. When each curve reaches the rear fin, it applies a backward force to the water and moves the fish forward with the fin. The fin of a fish works like the fin of an airplane. The fins also increase the surface of the tail and increase the speed. The streamlined body of the fish reduces the amount of friction in the water. Since the density of body tissue is greater than that of water, fish must make up for the difference or they will sink. Many bony fishes have an internal organ called a swim bladder, which regulates buoyancy by manipulating gas. 

Tongue Fish 

Tongue fish is a flatfish of the Soleidae family. The difference between them is that there is a long hook protruding from the mouth on the nose, and there is no pectoral fin. Both eyes are on the left side of its body, and it does not have pelvic fins. There are 3 genera and more than 140 species in the undergraduate. The largest can reach 66 centimeters, although most species can only reach half or smaller. They are found in tropical and subtropical oceans, mainly in shallow waters and estuaries, although some species are found on the deep seabed, even some in rivers. Symphurus thermophilus lives by gathering around sulfur pools of hydrothermal vents on the seafloor. No other flounder comes from hydrothermal vents. Scientists are unsure of the mechanism that allows fish to survive or even thrive in such a harsh environment. 

The Immune System of Fish 

Immune organs vary according to the type of fish. Jawless fish such as lampreys and witches have no real lymphatic organs. These fish depend on areas of lymphatic tissue in other organs to produce immune cells. For example, red blood cells, macrophages, and plasma cells are produced in the pro-kidney and in certain areas of the intestine. They are similar to the original bone marrow of the hagfish. Cartilaginous fish such as sharks and rays have a more advanced immune system. They have three specialized organs unique to cartilaginous fish that are the upper horn organ around the gonads, the organ of Leydig in the esophageal wall, and the spiral valve in the intestine. These organs contain typical immune cells that are granulocytes, lymphocytes, and plasma cells. They also have a recognizable thymus and a well-developed spleen in which various lymphocytes, plasma cells, and macrophages develop and store. Cartilaginous fish such as sturgeon, white sturgeon, and beech fish, have an important place where granulocytes are produced in the groups associated with the meninges. These are the membranes that surround the central nervous system. Their hearts are often covered by tissues that contain lymphocytes, reticulocytes, and a small number of macrophages. The fatty cartilage kidney is an important hematopoietic organ, where red blood cells, granulocytes, lymphocytes, and macrophages develop. Like cartilaginous fish, the main immune tissue of bony fish or bony fish includes the kidney, which is home to many different immune cells. In addition, teleosts have scattered thymus, spleen, and immune areas within mucosal tissues. Like the mammalian immune system, it is believed that hard bone red blood cells, neutrophils, and granulocytes are located in the spleen, while lymphocytes are the main cell type found in the thymus. In 2006, a mammal-like lymphatic system was described in a bony fish, the zebrafish. Although it has not been confirmed, it is speculated that this system will be where naive T cells gather while waiting to find antigens. 4,444 immunoglobulin-carrying B and T lymphocytes and T cell receptors were found in all jawed fish. In fact, the adaptive immune system as a whole evolved from the ancestors of all jawed vertebrates.  

Circulatory System

Fish have a closed-loop circulatory system. The heart pumps blood in a single circuit throughout the body. The heart of most fish consists of four parts, including two chambers and an inlet, and an outlet. The first part is the venous sinus, which is a thin-walled sac that collects blood from fish veins and then allows it to flow to the second part, the atrium, which is a large muscular compartment. The atrium acts as a single anterior chamber, transporting blood to the third part, the ventricle. The ventricle is another thick-walled muscular chamber that pumps blood to the fourth part, the arterial bulb, a large tube, and then drains from the heart. The arterial bulb is connected to the aorta and blood flows through the aorta to the gills for oxygenation. 

Digestion 

The jaw allows fish to eat a variety of foods, including plants and other organisms. Fish ingest food by mouth and break it down in the esophagus. In the stomach, food is further digested and many fish foods are processed into a finger-like pouch called the pyloric cecum, which secretes digestive enzymes and absorbs nutrients. As food passes through the digestive tract, organs such as the liver and pancreas add enzymes and various chemicals. The intestine completes the process of digestion and absorption of nutrients.