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The rhombotal slopes are characterized by a strongly flattened rhomboid body, the presence of peculiar outgrowths on the pelvic cartilage and traces of gill folds in the sprays. There are no tail needles (spikes). The order includes three families (Rajidae, Arhynchobatidae and Anacanthobatidae).

The family of Rhida rays or Rhombuses

The family of rhombic stingrays includes 6 genera and more than 100 species. They are characterized by a wide disk, which has a more or less rhomboid shape and is usually covered with large spikes and small spines. The pectoral fins reach the snout or merge in front of it. Dorsal fins, as a rule, two. The caudal fin is reduced to a small membranous fold, and in adults it is sometimes completely absent. Many species have vestigial electrical organs on the sides of the tail.

Extremely strong individual, age, and sexual variability is typical of rhombic stingrays. Young individuals noticeably differ from adults in body proportions, the degree of prickling, tooth structure and other features. Females are usually much larger than males and have a wider disk with more developed spines.

These stingrays are widespread in the seas and oceans. They are especially characteristic of cold-water (in the Arctic and Antarctic) and moderately warm regions, but they also occur in the tropical strip, where they usually live at considerable depths. Most of the species of this family are among the inhabitants of coastal shallow waters, but there are also deep-water forms. Seven species are known, in particular, from a depth of more than 2000 m.

Rhombus ramps do not reach particularly large sizes. The maximum length of various species is usually in the range from 35 to 180 cm. True, the largest of the European rays is smooth ramp (Raja batis) - can reach 2.5 m in length and more than 1.5 m wide with a weight of 60-74 kg.

All members of this family multiply, laying eggs enclosed in a horn capsule to the bottom. Such a capsule is painted in dark chestnut, brown or black and has a quadrangular shape and is equipped with tubular processes at the corners, which in some species are very elongated. Using these processes, the capsule is attached to the bottom. As observations in the aquarium have shown, the female usually lays eggs in pairs with an interval of 1-5 days, and the total breeding period can be very long. It sometimes continues for several months in a row. The total number of delayed capsules, apparently, varies greatly among different species, ranging from 4-5 to 50 or more. Egg incubation lasts from 4 to 14 months.

Rhombic rays belong to the number of bottom fish. Alarmed, they are usually more strongly pressed to the ground, and their color, like that of flounders, can vary depending on the color of the surface on which they lie. The favorite habitat of these fish is a smooth sandy or shell bottom. In the daytime, the slopes are usually inactive and calmly lie at the bottom, sometimes digging into the ground so that only eyes, spatter and part of the back remain on the surface. When digging, they use pectoral fins in order to throw sand on their backs.

At the same time, these rays often rise into the water column, pursuing prey, and sometimes even observed at the surface. During swimming, they wave their pectoral fins, like wings, and, if necessary, can move quite quickly. When hunting for floating prey, stingrays cannot grab it as a result of a direct attack, since their mouth opening is located on the underside of their heads. In this case, they first float on top of their prey, and then press them to the bottom and swallow.

Rhombic ramps are common in our northern waters. In the seas washing the northern coast of the Soviet Union, there are 7 species of this family, in our Far Eastern seas - about 10 species, in the Black Sea - 1 species.

Stingray encountered in the Black Sea sea ​​fox (Raja clavata) is one of the species widely distributed off the coast of Europe and North Africa (from the Canary Islands to Norway). Along the midline of his body is a row of 24-32 large spines.

In this species, females reach 125 cm in length, and males - 70-85 cm. The sea fox is usually kept at a shallow depth, but sometimes sinks quite deeply. In the Black Sea, this slope is found to a depth of 100 m. The food of this species is fish and decapods, as well as bottom mollusks. Reproduction occurs in the summer, and the female lays several dozen eggs, the development of which lasts 4.5-5.5 months. Hatched juveniles have 12-13 cm in length and 8 cm wide. The economic importance of this stingray in our waters is insignificant, but in the North Sea it makes up some bycatch in trawl fishing.

In the Barents and White Seas, it is quite common stingray (Raja radiata), belonging to the number of cold-loving species of the family. Its length reaches 100 cm, but in our waters there are no individuals larger than 60 cm. The distribution range of stellate rays covers the entire northern part of the Atlantic Ocean. It is found at depths from a few meters to 900 m and prefers sandy and silty soils and the temperature is slightly higher than 0 °. Star stingray reproduces throughout the year, but usually lays eggs in February - June. Egg capsules of this species are small (their length does not exceed 68 mm), and the tubular processes at their corners have different lengths: on the one hand there is a pair of long "horns", on the other - short outgrowths. Young slopes emerging from the capsules are about 10 in length. cm. Stingray - a predatory fish, searching for food at the bottom and in the bottom layers of the water with the help of smell. Its food consists of fish (capelin, gerbil, cod, haddock, flounder, etc.), as well as various crustaceans. This slope is mined during the trawl fishery, but in the Barents Sea it does not have significant significance as an object of fishing.

Stingray family (Anacanthobatidae)

Representatives of this family, consisting of two genera and three species, are close to rhombic rays, but they easily differ from them in the shape of the snout, the end of which is elongated into a long thin thread. They have no spines on the body, and the dorsal fins are completely absent. These are rare and poorly studied fish that live on the Atlantic coast of America and South Africa at depths exceeding probably 300 m. Their lifestyle is completely unknown.

Mexican stingray (Springeria folirostris) is known only from the Gulf of Mexico, where at a depth of 330-460 m only about a dozen immature individuals were obtained. Largest of them had 62 cm in length. In this species, the snout in front of the filamentous extension is widened and flattened, forming a kind of leaf-like structure.

Stingrays or rhombotelic rays

Order of stingrays or rhomboids (Rajiformes) is the most numerous in the number of combined species in the order of stingrays. These cartilaginous fish live everywhere in the waters of the oceans, but the cold waters of the Arctic and Antarctic are avoided. The most diverse species representation of stingrays in temperate and temperate cold latitudes. The order is represented by five families uniting more than 200 species, which in turn are united according to similar external and anatomical characteristics into 26 genera.

Representatives of this order are characterized by a wide and highly flattened rhomboid body, a pointed, protruding snout and a long, most often whip-like tail. There are no prickly spikes and needles on the tail of the rhombus ramps. On the back of stingrays, there are often spiked denticles extending in stripes along the midline of the back. The number of dorsal fins differs in different species - there are slopes with two or one dorsal fin, there are species in which this organ is absent altogether.

Stingrays (rhombotelae) stingrays - bottom fish, almost exclusively marine - only a few species can be found in desalinated waters near river mouths. They are found both in coastal shallow waters and at great depths, far from the coast. For permanent living, sites with soft bottom soils are chosen. They are more active in the dark, preferring to rest on the ground during the day, burying themselves in sand or silt. The body color of these fish can vary greatly depending on the color and nature of the soil in the habitat. The ability to camouflage at the bottom for stingrays is a vital aspect.

The order is represented by families - uncovered slopes (Anacanthobatidae), diamond stingrays (Rajidae), rashplevy or transverse slopes (Rhinidae), dead ramps (Rhinobatidae), shark-tailed (wingless) stingrays (Rhynchobatidae) It should be noted that in different scientific sources, systematisers are not united in this division of the order of rajids by family, referring rasplevy (transverse) rajids (Rhinidae) either to the superorder of sharks, or considering them to be a transitional form from dead flyback rays to sharks.
I think that for us it is not essential. If any of the readers of the article ever becomes an ichthyologist, then, I hope, will put a bullet in the debate and contention of the taxonomists.

Rhombus ramps (Rajidae), or as they are also called - stingrays, represented by more than 100 species of bottom predators, characterized by a disk-shaped rhomboid and highly flattened body, on the upper side of which there are often spikes of various sizes. The pectoral fins are wide and merge with the body of the fish. There are two dorsal fins, the caudal fin is very small, sometimes completely absent. Eyes and sprays are located on the upper side of the head, gill slits and mouth on the lower.
In order to grab prey, the ramp often has to press it to the bottom surface, because they do not know how to throw back their jaw (as sharks do).

Rhombus ramps are found in all oceans, from northern to southern latitudes, but are most common in moderately cold-water regions. In tropical latitudes, these fish prefer to inhabit significant depths, sometimes more than 2 km. In the temperate and cold latitudes of rhombic rays, one can meet both in shallow water and in depth.
In the seas of Russia, you can meet about a dozen types of rhombic rays, most of which live in the Far Eastern and Northern seas. In the Black Sea, there is only one species - stingray fox or fox stingray (Raja clavata) Females of this species can reach a length of 125 cm, males are noticeably smaller.

Favorite habitats of rhombic stingrays are the seabed with a loose (sandy or shell) bottom. In the daytime, they rarely rise to a considerable distance from the bottom, preferring to rest on the ground, throwing sand or silt on the body with a wave of pectoral fins. It is difficult to notice the stingray disguised in this way at the bottom - sometimes only eyes and spiracles remain on the surface.
The body color of these fish corresponds to the nature of the soil, and may vary depending on the conditions of camouflage and illumination. The basis of the diet of these fish are small fish, cephalopods and conch mollusks, crustaceans.

There are no giants among the stingrays (rhombus) stingrays - the maximum length of individual species does not reach even the two-meter mark along with the tail. Only the largest representative of this family - european smooth ramp (Raja batis) can grow up to 2.5 m with a weight of up to 75 kg. In the wingspan, this large slope can reach one and a half meters.

Rhombic slopes reproduce by egg laying, laying fertilized eggs on the ground, like birds and reptiles. The eggs are a quadrangular horn capsule, painted in gray-black-brown shades and having special outgrowths in the corners for attachment to the substrate. The number of eggs laid by females in different types of rhombus rays can vary greatly - from a few to a few dozen. The duration of incubation is also different - from 4 months to a year or even more.

The meat in rhombic stingrays is edible, and properly cooked is very tasty. The fleshy wings (pectoral fin area) of these fish, which can be smoked or cooked in another way, are especially appreciated.

Another well-known family of stingrays is dead or guitar stingrays (Rhinobatidae) There are 7 genera in the family, uniting about 40 species of bottom cartilaginous predators. Rukhlevy slopes prefer to settle in warm-water areas of the seas and oceans, occurring mainly in tropical latitudes, along the coast, and sometimes in desalinated areas of river mouths. They are sedentary fish, most of the time they slowly ply at the bottom surface or lie on the ground, slightly burrowing into the ground. Like all stingrays, they feed on bottom inhabitants - medium-sized fish, mollusks, and crustaceans.

The body shape of the loose mantle strangely resembles a musical instrument - a guitar or violin. For this reason, representatives of this family in different countries are called “fish-guitar”, “fish-violin”, “fish-banjo”, etc. According to the anatomical structure of the body, guitar stingrays are very close to shark-tailed stingrays, differing from them the absence of a characteristic two-bladed caudal fin and dorsal fins shifted to the caudal part of the body.
A typical representative of jagged (guitar) stingrays - spotted guitar stingray (Rhinobatos lengitinosus), which lives on the Atlantic coast of America, at shallow depths. This fish reaches a length of about 75 cm.

Guitar (dead) ramps propagate by oviparous propagation.

Roe rays are not an object of directed fishing; most often they are present in fishing gear in the form of by-catch. The meat in most species of these fish is very tasty, and is even considered delicious in some countries.

Representatives of another family of stingrays - sharktail (Rhynchobatidae) - are a kind of transitional form between two superorders of cartilaginous (plate-gill) fish - between sharks and rays. The shape of their body at the same time resembles both the first and second. Shark-tailed ramps have a flattened trunk, an elongated snout and a caudal fin with two lobes and pointed tips, resembling the shape of a shark's tail fin. The tail of the body in shark-tails is a continuation of the body and is not separated from the body, as in other skates. The anterior dorsal fin is located opposite the pelvic fins, and the pectoral fins are more separated from the body than other types of rays. In general, the body shape of these stingrays is very reminiscent of the classic shark, but more flattened.

The family is small - only two genera and several species; its representatives are relatively rare in nature.
The characteristic representative of the family is common sharktail (Rhynchobatus djiddensis), which lives in the subtropical and tropical latitudes of the Indian and western Pacific Ocean - from the southern coast of Africa to the southern regions of the Sea of ​​Japan. This is a large fish, reaching a three-meter length and weight of 225 kg.
Like all slopes, shark-tailed are bottom predators, preferring to stay in a layer of bottom waters. The main food - bottom animals - fish, invertebrates. The structure of the dental apparatus allows you to easily deal with soft-bodied food (cephalopods, fish, larvae, worms) and protected by a natural shell - crustaceans, mollusks, etc.
Shark-tailed stingrays reproduce by oviposition. In some countries, they are a favorite object of artisanal fishing, since meat has a high commercial value due to its taste.

Family uncovered slopes (Anacanthobatidae) is represented by two genera, combining only three species of these fish. These are rather rare and poorly studied stingrays that live in the Atlantic - off the coast of America and along the southern coast of Africa at considerable depths (more than 300 m). They differ from rhombic ramps in the shape of the tip of the snout, which is elongated into a long and thin thread (hence the name of the family).In addition, non-spawning rays are not dorsal fins and spines on the body.
One member of the family is Mexican stingray (Spingeria folirostris) lives in the Gulf of Mexico. It is curious that sexually mature individuals of these fish have never been in the hands of scientists - the largest of the caught "teenagers" barely exceeded 60 cm in length.

FAMILY SKAT, OR RHOMBO, SKATS (RAJ> The family of rhombic stingrays consists of 8 genera and more than 100 species. They are characterized by a wide disk with a more or less rhomboid shape and usually covered with large spikes and small spines. The pectoral fins reach the snout or merge in front of it There are usually two dorsal fins. The caudal fin is reduced to a small membranous fold, while in adults it is sometimes completely absent. Many species have vestigial electrical organs on the sides of the tail.

Extremely strong individual age-related and sexual variation is typical for rhombic stingrays. Young individuals noticeably differ from adults in body proportions, the degree of prickling, tooth structure and other features. Females are usually much larger than males and have a wider disk with more developed spines.

These stingrays are widespread in the seas and oceans. They are especially characteristic of cold-water (in the Arctic and Antarctic) and moderately warm regions, but they also occur in the tropical strip, where they usually live at a considerable depth. Most of the species of this family are among the inhabitants of coastal shallow waters, but there are also deep-water forms, especially characteristic of the genera Bagthyraja and Rreviraja. Seven species are known, in particular, from a depth of more than 2000 m.

Rhombus ramps do not reach particularly large sizes. The maximum length of various species is, as a rule, in the range from 35 to 180 cm. True, the largest of the European rays is smooth ramp (Rajabatis) - can reach a length of 2.5 m and a width of more than 1.5 m with a weight of 60-74 kg.

All representatives of this family multiply, laying eggs enclosed in a horn capsule to the bottom. Such a capsule is painted in dark chestnut, brown or black, has a quadrangular shape and is equipped with tubular processes at the corners, which in some species are very elongated. Using these processes, the capsule is attached to the bottom. As observations in the aquarium have shown, the female usually lays eggs in pairs with an interval of 1-5 days, and the total breeding period can be very long. It sometimes continues for several months in a row. The total number of delayed capsules, apparently, varies greatly among different species, ranging from 40 to 50 or more. Egg incubation lasts from 4 to 14 months.

Rhombic rays belong to the number of bottom fish. Alarmed, they are usually more strongly pressed to the ground, and their color, like that of flounders, can vary depending on the color of the surface on which they lie. The favorite habitat of these fish is a smooth sandy or shell bottom. In the daytime, the slopes are usually inactive and calmly lie at the bottom, sometimes digging into the ground so that only eyes, spatter and part of the back remain on the surface. When digging, they use pectoral fins in order to throw sand on their backs.

At the same time, these rays often rise into the water column, pursuing prey, and sometimes even observed at the surface. During swimming, they wave their pectoral fins, like wings, and, if necessary, can move quite quickly.

When hunting for floating prey, stingrays cannot grab it as a result of a direct attack, since their mouth opening is located on the underside of their heads. In this case, they first float on top of their prey, and then press them to the bottom and swallow.

Rhombic ramps are common in our northern waters. In the seas washing the northern coast of the Soviet Union, there are 7 species of this family, in our Far Eastern seas - about 10 species, in the Black Sea - 1 species.

Stingray encountered in the Black Sea sea ​​fox (Raja clavata) is one of the species widely distributed off the coast of Europe and North Africa (from the Canary Islands to Norway). Along the midline of his body is a row of 24-32 large spines. In this species, females reach a length of 125 cm, and males - 70-85 cm. Sea fox usually keeps at a shallow depth, but sometimes lowers quite deep. In the Black Sea, this slope is found to a depth of 100 m. The food of this species is fish and decapods, as well as bottom mollusks. Reproduction occurs in the summer, and the female lays several dozen eggs, the development of which lasts 4.5-5.5 months. Hatched juveniles have a length of 12-13 cm and a width of up to 8 cm. The economic importance of rhombic rays in our waters is insignificant, but in the North Sea it makes up some bycatch in trawl fishing.

In the Barents and White Seas, it is quite common stingray (Raja radiata), belonging to the number of cold-loving species of the family. Its length reaches 100 cm, but individuals larger than 60 cm are not found in our waters. The distribution range of stellate rays covers the entire northern part of the Atlantic Ocean. It occurs at a depth of several meters to 900 m and prefers sandy or silty soils and the temperature is slightly higher than 0C. Star stingray reproduces throughout the year, but usually lays eggs in February - June. The facial capsules of this species are small (their length does not exceed 68 mm), and the tubular processes at their corners have different lengths: on the one hand there is a pair of long horns, on the other - short outgrowths. Young slopes that emerged from the capsules have a length of about 10 cm. Star-shaped slope is a predatory fish that searches for food at the bottom and in the bottom layers of water with the help of olfaction. Its food consists of fish (capelin, gerbil, cod, haddock, flounder, etc.), as well as various crustaceans. This stingray is mined in the trawl fishery, but in the Barents Sea it does not have significant significance as an object of fishing.

FAMILY NON-GRAY RAYS (A NACA NTHOBAT I DAE)

Representatives of this family, consisting of two genera and three species, are close to rhombic rays, but they easily differ from them in the shape of the snout, the end of which is elongated into a long thin thread. They have no spines on the body, and the dorsal fins are completely absent. These are rare and poorly studied fish that live on the Atlantic coast of America and South Africa at depths exceeding probably 300 m. Their lifestyle is completely unknown.

Mexican stingray (Springeria folirostris) is known only from the Gulf of Mexico, where at a depth of 330-460 m only about a dozen immature individuals were obtained. The largest of them had a length of 62 cm. In this species, the snout in front of the filamentous extension is widened and flattened, forming a kind of leaf-like structure.

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