Sharks description and lifestyle. Types of sharks. Description, names and features of sharks. What does a shark eat?

The shark is one of the most ancient representatives of the fauna of the planet. In addition, these inhabitants of the deep waters are little studied and have always been considered mysterious creatures. People have come up with many myths about such insidious, daring and unpredictable predators, which have also given rise to quite a lot of prejudices.

A huge number of stories, frightening with cruel details, have been spread about sharks across all continents at all times. And such stories about bloody attacks on people and other living beings are not at all without foundation.

But despite all their terrible properties, these creatures of nature, classified by scientists as the phylum Chordata and the order Selachia, are extremely curious in structure and behavior, and have many interesting features.

These are not aquatic mammals, as some believe, they belong to the class of cartilaginous fish, although this is sometimes difficult to believe. Most of them live in salty bodies of water. But there are, although rarely, freshwater inhabitants.

For sharks, zoologists have assigned a whole suborder of the same name as these creatures. It is distinguished by the huge diversity of its representatives. How many types of sharks found in nature? The figure is impressive, because there are neither less nor many of them, but about 500 varieties or even more. And they all stand out with their individual and wonderful features.

Whale shark

The variety of features of the shark tribe is primarily emphasized by the size of these creatures. They vary in a most impressive way. The average representatives of this suborder of aquatic predators are comparable in size to a dolphin. There are also extremely small deep-sea shark species, whose length is only no more than 17 cm. But giants also stand out.

Whale shark

The latter include the whale shark, the largest representative of this tribe. Some multi-ton specimens reach 20 meters in size. Such giants, almost unstudied until the 19th century and only occasionally encountered by sea vessels in tropical waters, gave the impression of monsters with their fantastic size. But fears of these creatures were highly exaggerated.

As it turned out later, such sedentary giants cannot pose a danger to people. And although they have several thousand teeth in their mouths, their structure is not at all similar to the fangs of predators.

These devices are something like a dense lattice, reliable locks for small plankton, which these creatures feed exclusively on. With such teeth it holds its prey in its mouth. And she catches every ocean trifle by filtering it out of the water with a special apparatus located between the gill arches - cartilaginous plates.

The coloring of the whale shark is very interesting. The general background is dark gray with a bluish or brown tint, and is complemented by a pattern of rows of large white spots on the back and sides, as well as smaller dots on the pectoral fins and head.

Giant shark

Other representatives of the tribe we are interested in also have the type of nutrition just described ( types of sharks in the photo allow us to examine their external features). These include largemouth and basking sharks.

Giant shark

The last of them is second in size among its relatives. Its length in the largest specimens reaches 15 m. And the mass of such impressively sized predatory fish in some cases reaches 4 tons, although this weight for giant sharks is considered a record.

Unlike the previous variety, this aquatic creature, while obtaining food for itself, does not absorb water and its contents at all. A giant shark simply opens its mouth wide and plows through the elements, catching and filtering what gets into its mouth. But the diet of such creatures is still the same - small plankton.

The coloring of these creatures is modest - brown-gray, marked with a light pattern. They live alone and in schools mainly in temperate waters. If we talk about danger, then man, through his crafts, caused such sharks much more harm than they did - essentially harmless creatures caused him trouble.

Largemouth shark

These curious creatures were discovered quite recently, less than half a century ago. They are found in warm ocean waters, in some cases swimming into temperate areas. The color tone of their body is brown-black above, much lighter below. The largemouth shark is not a small creature, but still not as large as the previous two specimens, and the length of these representatives of the aquatic fauna is less than 5 m.

Largemouth shark

The muzzle of these creatures is very impressive, rounded and wide, with a huge, almost one and a half meter long mouth standing out on it. However, the teeth in the mouth are small, and the type of nutrition is very similar to that of a giant shark, with the only interesting feature that the large-mouthed representative of the predatory tribe has special glands that tend to secrete phosphorites. They glow around the mouths of these creatures, attracting jellyfish and small fish. This is how a large-mouthed predator lures prey in order to get enough.

White shark

However, as you might guess, not all specimens from the suborder of sharks are so harmless. It’s not for nothing that these aquatic predators have inspired terror in humans since ancient times. Therefore it is necessary to especially mention dangerous shark species. A striking example of the bloodthirstiness of this tribe is the white shark, also called the “white death” or in another way: a man-eating shark, which only confirms its terrible properties.

The biological lifespan of such creatures is no less than that of humans. The largest specimens of such predators are over 6 m long and weigh almost two tons. The shape of the body of the described creatures resembles a torpedo, the color on top is brown, gray or even green, which serves as a good camouflage during attacks.

White shark

The belly is much lighter in tone than the back, which is why the shark got its nickname. The predator, suddenly appearing in front of the prey from the ocean depths, previously invisible above the water due to the background of the upper body, only in the very last seconds demonstrates the whiteness of the lower body. With its surprise, this shocks the enemy.

The predator has, without exaggeration, a brutal sense of smell and other highly developed sense organs, and her head is endowed with the ability to detect electrical impulses. Its huge, toothy mouth inspires panic in fur seals, seals, and even whales. She also brought fear to the human race. And you can meet such talented in hunting, but bloodthirsty creatures in all the oceans of the world, with the exception of the waters of the North.

Tiger shark

Tiger sharks prefer warm tropical climates, found in equatorial waters around the world. They stay close to the shore and like to roam from place to place. Scientists claim that since ancient times these representatives of the aquatic fauna have not undergone fundamental changes.

The length of such creatures is about 4 m. Only young individuals stand out with tiger stripes against a greenish background. More mature sharks are usually just gray. Such creatures have a large head, a huge mouth, and their teeth are razor-sharp. The speed of movement in water of such predators is ensured by a streamlined body. And the dorsal fin helps to write complex pirouettes.

Tiger shark

These creatures pose an extreme danger to humans, and their jagged teeth can instantly tear human bodies to pieces. It is curious that in the stomachs of such creatures objects are often found that cannot be called tasty and edible at all.

This could be bottles, cans, shoes, other debris, even car tires and explosives. From which it becomes clear that such sharks have the habit of swallowing anything.

It is extremely interesting that nature has endowed them with the ability to get rid of otherworldly objects in the womb. They have the opportunity to rinse its contents through the mouth by simply turning the stomach.

Bull shark

Listing names of shark species, who do not disdain human flesh, the bull shark should also be mentioned. The horror of meeting such a carnivorous creature can be experienced in any of the oceans in the world, with the only pleasant exception being the Arctic Ocean.

Bull shark

In addition, there is a possibility that these predators will stop by to stay in fresh waters, because such an element is quite suitable for their life. There are cases where bull sharks were found and even lived permanently in the rivers of Illinois, in the Amazon, in the Ganges, in the Zambezi or in Lake Michigan.

The length of predators is usually about 3 m or slightly more. They attack their victims quickly, leaving them little chance of salvation. Such sharks are also called blunt-nosed sharks. And this is a very apt nickname. And when attacking, they may well inflict a severe blow on the victim with their blunt muzzle.

And if you add sharp, jagged teeth, the portrait of an aggressive predator will be completed with the most terrible details. The body of such creatures has the shape of a spindle, the body is stocky, the eyes are round and small.

Katran

The waters of the Black Sea are not particularly attractive for the habitat of bloodthirsty sharks. The reasons are the isolation and densely populated coasts, the saturation of the water area with various types of maritime transport. However, there is nothing particularly sad about this for humans, given the extreme danger of such creatures.

Katran shark

But this does not mean that representatives of the described tribe are not found in such areas at all. Listing types of sharks in the Black Sea, first of all, it should be called katran. These creatures are approximately only a meter in size, but in some cases they can boast a size of two meters. They live for about 20 years.

These sharks are also called spiny spotted sharks. The first of the epithets is awarded to them for the rather sharp spines located on the dorsal fins, and the second - for the light spots on the sides. The main background of the back of such creatures is gray-brown, the belly is white.

Their bizarre shape looks more like an elongated fish than a shark. Katrans mainly feed on small-sized aquatic inhabitants, but with a large concentration of their own kind, they may well decide to attack dolphins and even humans.

cat shark

The cat shark is found in the coastal waters of the Atlantic and the Mediterranean Sea. These predators are found in the Black Sea waters, but rarely. Their sizes are quite small, about 70 cm. They do not tolerate the vastness of the ocean elements, but mostly hang around the coast and at shallow depths.

cat shark

The color of such creatures is interesting and impressive. The back and sides have a dark sandy hue, mottled with dark small spots. And the skin of such creatures is amazing, feeling like sandpaper. These sharks deserve their name for their flexible, graceful and long body.

The habits of such creatures also resemble cats. Their movements are graceful, they doze during the day, and walk at night and are well oriented in the dark. Their diet usually consists of fish and other small aquatic inhabitants. For humans, such sharks are completely harmless. However, people eat, sometimes even with great pleasure, this type of shark, like katran meat.

Cladoselachia

Scientists believe that sharks lived on Earth about four million centuries ago, these creatures are so ancient. Therefore, when describing such predators, their ancestors should also be mentioned. Unfortunately, it is now impossible to find out clearly what they looked like.

And their appearance is judged only by the fossilized remains and other traces of the life activity of such prehistoric living creatures. Among such finds, one of the most remarkable is the perfectly preserved imprint of the body of a representative extinct species of shark, left on the shale hills. Such ancient progenitors of present-day forms of life were called cladoselachians.

Extinct species of Cladoselachia shark

The creature that left the imprint, as can be judged by the size of the footprint and other features, turned out to be not particularly large, only 2 m long. Its torpedo-shaped, streamlined shape helped it move quickly in the water element. However, such a fossil creature was obviously still inferior to modern varieties in the speed of movement.

It had two dorsal fins equipped with spines, and a tail in many ways similar to the current generation of sharks. The eyes of the ancient creatures were large and keen. It seems that they ate only small aquatic items. And larger creatures were considered among their worst enemies and rivals.

Dwarf shark

Baby sharks were discovered in the waters of the Caribbean Sea only in the second half of the last century. And only two decades after the discovery of this type of shark, they received their name: Ethmopterus perry. A similar name was given to dwarf creatures in honor of the famous biologist who studied them.

And right up to this day from existing shark species Smaller living creatures have not been found in the world. The length of these babies does not exceed 17 cm, and females are even smaller. They belong to the family of deep-sea sharks, and the size of such creatures never exceeds 90 cm.

Dwarf shark

Ethmopterus perry, living at great depths of sea waters, has been studied very little for the same reason. They are known to be ovoviviparous. Their body is elongated, their outfit is dark brown, marked with stripes on the belly and back. The eyes of the babies have the property of emitting a greenish light on the seabed.

Freshwater shark

Describing different types of sharks, it would be nice not to ignore the freshwater inhabitants of this suborder. It was already mentioned earlier that these aquatic predators, even living permanently in the oceans and seas, often visit lakes, bays and rivers, swimming there only for a while, spending the main part of their life in a salty environment. A striking example of this was the bull shark.

But science also knows species that are born, constantly live and die in fresh waters. Although this is rare. There is only one place on the American continent where such sharks live. This is a large lake in Nicaragua, located in the state of the same name, very close to the Pacific waters.

Freshwater shark

The mentioned predators are very dangerous. They grow up to 3 m and attack dogs and people. Some time ago, the local population, the Indians, had a custom of burying their fellow tribesmen in the waters of the lake, thereby giving the dead to food for carnivorous predators.

Freshwater sharks are also found in Australia and some areas of Asia. They are distinguished by a wide head, stocky body and short snout. Their upper background is gray-blue; the bottom, like most of its relatives, is much lighter.

Blacknose shark

The gray shark family is the most widespread and numerous of the entire shark tribe. It has a dozen genera, including a huge number of species. Representatives of this family are also called sawtooths, which in itself indicates their danger as predators. These include the blacknose shark.

This creature is small in size (formed individuals reach about a meter in length), but it is for this reason that they are incredibly mobile. Blacknose sharks are inhabitants of the salty element that prey on cephalopods, but primarily on bony fish.

Blacknose shark

Their prey is anchovies, sea bass and other fish of this type, as well as squid and octopus. These sharks are so agile that they can easily steal lunch from even their larger relatives. However, they themselves may well become their victims.

The body of the creatures described, like most members of their family, is streamlined. Their snout is rounded and elongated. Their developed teeth are serrated, which helps blacknose sharks cut down prey.

These sharp devices in the mouth have the shape of an oblique triangle. Placoid scales of a special structure, more typical of fossil specimens, cover the body of these representatives of the ocean fauna.

Their color can be judged from the name of the family. Sometimes their color is not pure gray, but has a brown or greenish-yellow tint. The reason for the name of the species of these creatures was a characteristic detail - a black spot on the tip of the snout. But this mark usually adorns the appearance of only young sharks.

Such predators are found off the coast of the American continent, usually living in the salty waters washing its eastern part. The gray shark family has earned a reputation as man-eaters, but this particular species does not usually attack humans. However, experts still advise behaving more carefully with such dangerous animals. If you show aggression, you can easily run into trouble.

Whitetip shark

Such creatures also represent the family of gray sharks, but dominate over its other species. The whitetip shark is a powerful predator that will be more dangerous than its blacknose relatives. It is extremely aggressive, and in the competition for prey it usually wins over its family members.

In size, representatives of this species can reach three meters in length, so small sharks can easily become victims of whitetip bullies if they are not careful.

Whitetip shark

The described creatures inhabit the waters of the Atlantic Ocean, but are also found in the Pacific and Indian. Their color, according to the name of the family, is gray, but with a blue shimmering bronze; the belly of this variety is white.

It is not safe for a person to encounter such creatures. It is not uncommon for these daring creatures to chase divers. And although no deaths have been recorded, aggressive predators are quite capable of tearing off a leg or arm of a representative of the human race.

However, man himself causes whitetip sharks no less, and even much more, trouble. And people’s interest in them is explained simply: it’s all about the tasty meat of these fauna representatives.

In addition, the skin, fins and other parts of their body are valued, because all this is used in industrial production. Predatory fishing has caused an alarming decline in the number of such sharks in the waters of the World Ocean.

Dark tip shark

This type is another specimen from the already mentioned family. Such sharks are also called Indo-Pacific sharks, which indicates their habitat. Darktip sharks prefer warm waters and often hang around reefs, channels and lagoons.

Dark tip shark

They often unite in flocks. The "hunched" posture they like to adopt is evidence of their aggressive attitude. But by nature they are curious, so they often feel not fear or a desire to attack a person, but simple interest. But when pursued by people, they are still capable of attacking. They hunt at night, and eat about the same as their relatives in the family.

The size of such creatures is about 2 m. Their snout is round, their body is shaped like a torpedo, and their eyes are quite large and round. The gray color of their back can vary from light to dark shade; the caudal fin is distinguished by a black edging.

Narrowtooth shark

When describing gray sharks, one cannot fail to mention their narrow-toothed brother. Unlike other relatives of the family, which are pampered, thermophilic and strive to live closer to the tropics, these sharks are found in waters of temperate latitudes.

The forms of such creatures are quite unique. Their body is slender, the profile is curved, the muzzle is pointed and long. The color varies from gray-olive to bronze with the addition of pink tones or a metallic tint. The belly, as usual, is noticeably whiter.

Narrowtooth shark

By nature, these creatures are active and fast. Large flocks are usually not created; they swim alone or in a small company. And despite their considerable length of three meters or more, they can often become victims of larger sharks. This species is relatively peaceful, including towards humans. Its members are viviparous, like other representatives of this family.

lemon shark

It earned its name for its yellowish-brown body color, sometimes with the addition of pink tones and, of course, gray, because despite the original coloring, the shark still belongs to the same family. These creatures are rather large and reach a length of about three and a half meters and weigh 180 kg.

They are most often found in the waters of the Caribbean Sea and the Gulf of Mexico. They prefer to be active at night, often hanging around reefs and being spotted in shallow bays. Young animals usually hide from the older generation of such sharks, uniting in schools, because if they meet, they may well run into trouble, as well as become prey for other predators.

lemon shark

These creatures consume fish and shellfish as food, but aquatic birds are also among their frequent victims. Childbearing age for representatives of the species, which also belongs to the viviparous type, occurs after 12 years. Such sharks are aggressive enough to give people reason to be very afraid of them.

Reef shark

It has a flat, wide head and a thin body, so much so that with a body length of about one and a half meters, it weighs only about 20 kg. The color of the back of these creatures can be brown or dark gray, in some cases with prominent spots on it.

This species belongs to the genus of the same name from the family of gray sharks, where it is the only species. Representatives of the genus of reef sharks, according to their name, are found in coral reefs, as well as in lagoons and sandy shallow waters. Their habitat is the waters of the Indian and Pacific oceans.

Reef shark

These creatures often form groups whose members prefer to sit out in secluded places during the daytime. They can climb into caves or huddle under natural eaves. They feed on fish that live among corals, as well as crabs, lobsters and octopuses.

Larger representatives of the shark tribe may well feast on a reef shark. They often become victims of other salt water hunters; even large predatory fish are able to feast on them. These creatures treat humans with curiosity, and with adequate behavior on his part, they usually turn out to be quite peaceful.

Yellowstripe shark

The family of bigeye sharks earned this scientific nickname because its members have large, oval-shaped eyes. This family includes about four genera. One of them is called: striped sharks, and is divided into several varieties. The first of these species to be described here is the yellowstripe shark.

Yellowstripe shark

These creatures are small in size, usually no more than 130 cm. The main background of their body is bronze or light gray, on which yellow stripes stand out. This shark chooses the waters of the eastern Atlantic for its life.

These creatures can often be observed off the coast of countries such as Namibia, Morocco, and Angola. Their diet consists mainly of cephalopods and bony fish. This species of shark is not at all dangerous to humans. Quite the contrary, it is people who eat the meat of such aquatic animals. It can be stored both salted and fresh.

Chinese striped shark

As the name itself eloquently speaks, such sharks, like the previous species, belong to the same genus of striped sharks, and also live in salty waters in close proximity to the coast of China.

Chinese striped shark

It would be nice to add to this information that these creatures are found, in addition to everything, in the Pacific Ocean off the coast of Japan and some other countries close in territorial location to China.

These sharks are quite small in size (no more than 92 cm in length, but often even smaller). In view of this, such babies cannot be dangerous for humans. However, their meat itself is edible, and therefore is often eaten by people. The snout of these sharks is elongated. The body, the main background of which is gray-brown or simply gray, resembles a spindle in shape.

Whiskered Dog Shark

Sharks of this species are the only representatives of their genus and family that bear the same original name: whiskered dog sharks. These creatures earned this nickname for their external resemblance to famous animals, impressive folds in the corners of the mouth and mustaches located on the snout.

The members of this species are even smaller in size than the previously described variety: a maximum of 82 cm and nothing more. Moreover, the body of these creatures is very short, and the entire size of the extremely slender body is achieved due to the long tail.

Whiskered Dog Shark

Such inhabitants of the salty elements prefer ocean depths of up to 75 m, and usually do not rise above a depth of ten meters. They often swim near the very bottom, preferring to live where the waters are especially muddy.

They are viviparous, giving birth to up to 7 young at a time. Due to the hunt for their meat, dog sharks are in very dire straits and may disappear forever from the oceans of the planet.

Such creatures are found, as a rule, along the African coast, and spread in the waters somewhat further north up to the Mediterranean Sea. Sharks of this type are considered excellent, fast swimmers and excellent hunters. They feed on invertebrates; in addition to the fish itself, they also eat its eggs.

Harlequin shark

Harlequin shark is the name of a genus in the family of striped catsharks. This genus includes the only species of Somali sharks. Unlike most species already described, they are considered ovoviviparous.

Their length usually does not exceed 46 cm; color spotted, brown-red; The body is stocky, the eyes are oval, the mouth is triangular. They live in the western part of the Indian Ocean.

Harlequin shark

For the first time, such a variety was described only in the second half of the last century. The reason that these creatures were hidden from human eyes for a long time is understandable. They live at considerable depths, sometimes reaching 175 m.

In any case, such small representatives of the shark tribe, as a rule, do not rise higher to the surface than 75 m. For the first time, such a shark was caught off the coast of Somalia, for which representatives of the species received such a name.

frilled shark

These creatures, belonging to the genus and family of the same name, are remarkable in many respects. Being cartilaginous fish, like all sharks, they are considered a relic, that is, a form of life that has not changed since long ago geological eras, a kind of relic of the fauna. This is indicated by some primitive features of their structure. For example, underdevelopment of the spine.

In addition, the appearance of such creatures is very peculiar, and looking at them, you might rather decide that you see sea snakes, but not sharks. By the way, many people think exactly this way. The frilled shark especially resembles these reptiles at the moments when this predator goes hunting.

frilled shark

Its victims are usually small bony fish and cephalopods. Seeing prey and making a sharp lunge towards it, like a snake, this creature first bends its entire body.

And its mobile long jaws, equipped with slender rows of sharp and small teeth, are quite suitable for swallowing whole prey of impressive size. The brown body of such creatures is covered in front with peculiar skin folds.

Their purpose is to hide the openings of the gills. On the throat, the gill membranes, merging, take the form of a voluminous skin blade. All this is very similar to a cloak, which is why such sharks are called frilled sharks. Such animals are found in the waters of the Pacific and Atlantic Oceans, usually living at considerable depths.

Wobbegong shark

Wobbegongs are a whole family of sharks, divided into two genera, and they are also divided into 11 varieties. All their representatives also have a second name: carpet sharks. And it not only reflects the features of their structure, it should be considered extremely accurate.

The fact is that these sharks have only a distant resemblance to most of their relatives from the shark tribe, because the body of wobbegongs is incredibly flat. And it was not by chance that nature endowed them with such forms.

Wobbegong carpet shark

These predatory creatures live in the very depths of the oceans and seas, and when they go out to hunt, they become completely invisible to their prey in this form. They merge with the bottom, near which they try to stay, which is also greatly facilitated by the spotted camouflage color of these creatures.

They feed on cuttlefish, octopuses, squids and small fish. The rounded head of wobbegongs is practically one with their flattened body. Small eyes are barely visible on it.

The organs of touch for such representatives of the superorder of cartilaginous fish are fleshy antennae located at the nostrils. Funny sideburns, beard and mustache stand out on their face. The size of these bottom inhabitants depends on the species. Some are about a meter in size. Others may be much larger.

The record holder for this indicator is the spotted wobbegong, a three-meter giant. These creatures prefer to settle in the warm waters of the tropics or, at worst, somewhere nearby.

They are found mostly in two oceans: the Pacific and Indian. Cautious predators spend their lives in secluded places under corals, and they never even try to attack divers.

Brownie shark

Another proof that the world of sharks is incomprehensible in its diversity is the goblin shark, otherwise known as the goblin shark. The appearance of these creatures is so unusual that, looking at them, it is difficult to classify them as a shark tribe. However, these representatives of the ocean fauna are considered to be exactly that, belonging to the Scapanorhynchidae family.

Types of brownie shark

The size of these inhabitants of salt waters is approximately a meter or a little more. Their snout is surprisingly elongated, taking the shape of a shovel or oar. In the lower part there is a mouth, equipped with a large number of crooked teeth.

Such facial features produce an extremely unpleasant impression, but mixed with mystical sensations. That is why such a shark is awarded the names already mentioned. To this we should also add a very strange, pinkish skin that sets this creature apart from other living creatures.

It is almost transparent, so much so that blood vessels can even be seen through it. Moreover, due to this feature, this deep-sea inhabitant experiences painful transformations during sudden ascents.

And at the same time, not only her eyes literally pop out of their sockets, but also her insides come out through her mouth. The reason is the difference in pressure at the depths of the ocean familiar to such creatures and its surface.

Brownie shark

But this is not all the remarkable features of these creatures. Their already mentioned crooked teeth almost exactly copy the teeth of prehistoric sharks, especially since the sharks themselves of this species look like ghosts of bygone eras, preserved at the bottom of the oceans.

The range of these rare representatives of the earth's fauna and its boundaries remain unclear. But presumably goblin sharks are found in all oceans, perhaps excluding the waters of northern latitudes.

Mako shark

In size, such a shark is quite large and has a length of more than three meters and a mass of about 100 kg. It belongs to the herring family, therefore, like its other representatives, it is endowed by nature with the ability to maintain a certain body temperature, above the surrounding aquatic environment.

This is an aggressive predator, famous for its manner of ruffling its scales before attacking. Such creatures are sensitive to the smell of possible prey. Such insolent creatures are quite capable of attacking a person, but the human race also does not disdain the meat of such sharks. They may also well end up prey to larger saltwater predators.

Mako shark

The shape of these creatures resembles a spindle; the snout is conical and elongated. Their teeth are incredibly thin and sharp. The upper body has a grayish-blue tint, the belly is noticeably lighter.

Mako sharks live in the open ocean, in temperate and tropical latitudes, and are famous for their swiftness, as well as their ability to perform acrobatic performances. Their speed of movement in water reaches 74 km/h, and when jumping out of it, such sharks rise to a height of about 6 m above the surface.

fox shark

Sharks belonging to this family have received the nickname sea thresher for good reason. The fox shark is a creature unique in its ability to use the natural capabilities of its own tail to obtain food.

For her, this is the most reliable weapon, because it is with it that she stuns the fish on which she feeds. And it should be noted that among the shark tribe, with its own hunting style, it is the one and only.

fox shark

The tail of this creature is a very remarkable part of the body, possessing a striking external feature: the upper blade of its fin is unusually long and comparable to the size of the shark itself, and it can reach 5 m. Moreover, such creatures control their tail truly masterfully.

Fox sharks are found not only in tropical, but also in less comfortable, temperate waters. They live in the Pacific Ocean near the coast of Asia, and also often choose the coast of North America for their livelihoods.

Hammerhead shark

This is another extremely amazing creature from the diverse species of sharks. It is absolutely impossible to confuse such a specimen with any of its relatives. The reason is the unusual shape of the head. It is flattened and incredibly expanded, making the shark itself look like a hammer.

Hammerhead shark

This creature is far from harmless. It is not safe for a person to meet with her, because such predators are more than aggressive towards the species of bipeds. The family of such sharks has about 9 species. Among them, the most interesting to mention is the giant hammerhead shark, the largest specimens of which reach eight meters in length.

Interesting features of such aquatic creatures include the presence on the scalp of a large number of sensory cells that detect electrical impulses. This helps them navigate in space and find prey.

Silky shark

This creature is classified as a member of the gray shark family. The placoid scales covering its body are extremely soft, which is why the silky shark is named so. This species from the shark tribe is considered the most widespread in warm ocean waters everywhere in the world. Such creatures usually descend no more than 50 m into the depths and try to stay closer to the coastlines of the continents.

Silky shark

The length of such sharks is on average 2.5 m, the weight is also not the largest - somewhere around 300 kg. The color is bronze-gray, but the shade is rich, giving off a metallic feel. The distinctive features of such sharks are: endurance, acute hearing, curiosity and speed of movement. All this helps such predators in hunting.

Having encountered schools of fish on their way, they simply continue to move rapidly, with their mouths open. Tuna is a particularly favorite prey for them. Such sharks do not specifically attack people. But divers, in case of their provocative behavior, should be wary of the sharp teeth of these predators.

Atlantic herring

This shark can boast of numerous nicknames. The most impressive of the names is perhaps “porpoise”. Although the appearance of these creatures, belonging to the herring family, should be considered the most typical for sharks.

Their body is torpedo-shaped, elongated; fins are well developed; there is a huge mouth, equipped, as expected, with very sharp teeth; caudal fin in the shape of a crescent. The body color of such creatures is bluish-gray; large black eyes stand out on the snout. Their body length is about 3 m.

Atlantic herring shark

The way of life of such sharks is constant movement, in which they are from birth until the hour of death. This is their nature and structural features. And they die, sinking to the bottom of the ocean elements.

They live, as the name suggests, in the waters of the Atlantic Ocean, and they inhabit both the open ocean and its eastern and western coasts. The meat of such sharks has decent taste, although there is still a need for cooking it before consumption.

Bahamas sawnose shark

The species of such sharks, belonging to the sawnose family, is very rare. And the range of these aquatic creatures is ridiculously small. They are found only in the Caribbean Sea, and in a limited area, in the area between the Bahamas archpelago, Florida and Cuba.

Bahamas sawnose shark

A notable feature of such sharks, which gave rise to the name, is a flattened elongated snout, ending in a narrow and long sawtooth outgrowth, measuring a third of the entire body. The head of such creatures is stretched and slightly flattened, the body is slender, elongated, gray-brown in color.

Such creatures use their growth, as well as long antennae, when searching for food. Their diet is almost no different from most members of the shark tribe. It consists of shrimp, squid, crustaceans, and small bony fish. The size of these sharks usually does not exceed 80 cm, and they live at considerable depths.

General body shape of most sharks elongated, spindle-shaped (Fig. 51). In front there is a skull rostrum, which moves the mouth and nostrils to the lower surface of the head. On the sides behind the head there are 5-7 pairs of gill slits. Behind the eyes, a pair of the very first, underdeveloped slits opens - sprinklers. On the lower surface of the body at the root of the tail is located cloacal slit, leading to cloaca. The spine extends into the upper, large blade of the caudal fin. Male sharks have finger-like projections on the inside of their ventral fins that serve as copulatory organs.

Skeleton and spine

Veils

Veils sharks have thick and dense, covered placoid scales(Fig. 58). Scales of this type are also called dermal teeth, since shark teeth are simply large scales growing along the edges of the jaws.

The base of the tooth (scales) is immersed in the dermis (inner connective tissue layer of the skin, Fig. 58-1). The body of the tooth consists of a bone-like substance dentin(2). The part protruding outwards is covered with a layer tooth enamel(4). In the thickness of the tooth there is a chamber filled with fibrous connective tissue, blood vessels and nerve endings - pulp (3).

The inner side of the jaw (Fig. 59-1) in sharks is covered with a connective tissue fold (3), under which there is an area of ​​permanent formation of teeth (2). As the body grows, new areas of the integument bearing teeth move to the edge of the jaw and come into working position.

Circulatory system

Structure shark circulatory system(Fig. 60) is fundamentally similar to the structure of the circulatory system of agnathans.

The circulatory system of each gill actually includes not one gill artery, but two - the adductor and efferent (Fig. 61). They are connected by capillary networks.

If you strictly follow the nomenclature of vessels, then it would be more correct to call the efferent artery, and with it the dorsal aorta and carotid arteries, veins (after all, the blood has already passed through one capillary network on its way from the heart!). But traditionally, all these vessels in fish are called arteries.

Rice. 61. Vessels of the gills

Respiratory system

The respiratory organs of sharks - gills - are located on five to seven pairs of gill arches. Ventilation occurs due to the movement of the gill arches, compressing and stretching the pharynx. The anterior edges of the gill slits bear a movable fold - a valve. If the pressure in the pharynx becomes less than the external pressure, the valve closes passively, and water can only enter the pharynx through the mouth. When the pharynx is compressed and the mouth is closed, the valve opens and water flows out through the gill slits. When sharks swim fast, so-called ram ventilation occurs: the incoming flow of water through the open mouth enters the pharynx, creating a stable zone of increased pressure there.

Nervous system and sensory organs

The spinal cord and spinal nerves in sharks acquire a structure typical of all other vertebrates (Fig. 63).

The shark's brain is relatively large and complex compared to the brain of agnathans. The cerebellum is well developed, allowing the coordination of much more complex movements. The midbrain is especially large compared to other parts. The telencephalon is connected to large olfactory bulbs located near the olfactory sacs. Material from the site

Sharks have 10 pairs cranial nerves. Among the sense organs, the sense of smell, lateral line and inner ear are well developed. Sharks' vision is rather poorly developed.

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Introduction

Sharks (Selachimorpha) are a superorder of cartilaginous fish (Chondrichthyes), belonging to the subclass of elasmobranchs (Elasmobranchii) and having the following distinctive features: an elongated body more or less torpedo-shaped, a large heterocercal caudal fin, usually a large number of sharp teeth on each jaw.

The word “akumla” comes from the Old Icelandic “hbkall”. The most ancient representatives existed already about 420-450 million years ago. To date, more than 450 species of sharks are known: from the deep-sea shallow Etmopterus perryi (English), only 17 centimeters long, to the whale shark (Rhincodon typus)? the largest fish (its length reaches 12 meters). Representatives of the superorder are widespread in all seas and oceans, from the surface to depths of more than 2000 meters. They mainly live in sea water, but some species can also live in fresh water. Most sharks are so-called true predators, but certain species, in particular whale, basking and largemouth sharks, are filter feeders; they feed on plankton, squid and small fish.

1. Anatomy

1.1 Skeleton

Is the skeleton of a shark noticeably different from that of bony fish? it has no bones and is formed entirely from cartilaginous tissue. The skeleton has the following sections:

The axial skeleton is a vertebral column formed by numerous cartilaginous amphicoelous vertebrae.

A skull with two sections - the braincase and the skeleton of the oral and gill apparatus.

Paired limbs with belts - pectoral and ventral fins.

Unpaired fins are usually a caudal, anal and two dorsal fins.

The chord passes through the canals of the vertebra, penetrating the entire spinal column. The skull of sharks is a solid cartilaginous box, its anterior end is extended into a rostrum that supports the snout. On the lateral surfaces there are orbits that protect the eyes; between the walls of the orbits lies the brain. The girdle of the forelimbs is formed in the form of a cartilaginous arch lying in the thickness of the muscular wall behind the branchial region, and is in no way connected with the axial skeleton. On the lateral surface of the belt there is a protrusion, which is the site of attachment of the fin skeleton. The belt of the pelvic fins looks like a cartilaginous plate that lies in the muscles of the abdominal cell in front of the cloaca. The skeleton of the pelvic fin is attached to the lateral surface, which consists of one elongated basal element with a number of radial cartilages attached to it. In males, does the basal element serve as the skeletal basis of the pterygopodium? copulatory growth. The skeleton of unpaired fins consists of radials embedded in the muscles and penetrating the base of the fin. The caudal fin is heterocercal, and the end of the vertebral column extends into its upper lobe. The fin blades are supported by elastostrichia.

1.2 Leather

Shark skin? An excellent abrasive material for preparing wasabi.

The combination of the shape, location and composition of the skin denticles plays a significant role in the streamlining of the shark’s body. For example, the pronounced raised ridges on these denticles in a white shark give the skin a hydrodynamic effect that can be compared to the aerodynamic effect of a golf ball. The presence of tiny protrusions and depressions results in a noticeable reduction in the appearance of turbulence, thereby preventing the appearance of vortices. The shape, structure and size of the denticles vary among different shark species. According to scientists, the skin of the fastest species reduces water resistance by up to 8%. In addition, the hydrodynamic properties of the cloves provide another very useful effect for the hunter - noiselessness. Unlike bony fish, whose fins generate turbulence when moving, producing sound waves, the movements of a white shark when pursuing prey remain practically inaudible for its prey almost until the very moment of the attack.

1.3 Musculature

The musculature of sharks is divided into 3 groups:

Cardiac muscles continuously working in the heart.

Visceral muscles functioning in internal organs and arteries.

Somatic muscles that move the body, which in turn are divided into:

Red muscles

White muscles

According to its functional purpose, it can be divided into the muscles of the fins, the muscles of the head with the gill and jaw apparatus, and the muscles of the digestive system and internal organs. In sharks, the entire body musculature (somatic) consists of a number of muscle segments? myomeres, which are separated from each other by myosepts. The musculature of the fins is formed by separate bundles of muscles. A feature of muscles is its relative autonomy, that is, it retains the ability to contract even when communication with the central nervous system is disrupted.

1.4 TeethAndjaws

The teeth of most sharks are shaped like sharp dentin cones, and sit on the cartilage of the upper and lower jaws. Are teeth regularly replaced as they fall out or wear out like a conveyor belt? their replacement is constantly growing from the inside. In their structure and origin, these are modified placoid scales. Depending on diet and lifestyle, teeth and jaws vary greatly between shark species. Benthic sharks, whose food is usually protected by a hard shell, have hundreds of small, smooth teeth. Pelagic species are characterized by the presence of very sharp teeth, adapted for easy penetration into the flesh of prey. Sharks like the tiger have knife-shaped teeth designed for tearing the flesh of large prey. Plankton-eating sharks have vestigial small teeth.

1.5 Tail

The tail fin of sharks is heterocercal in shape. The shape of the tail in different species has evolved in accordance with certain living conditions, and each species has its own obvious distinctive features. In fast swimmers such as the mako shark and white shark, the lower and upper lobes are almost identical, but in most other species the upper lobe is noticeably larger than the lower.

2. Physiology

2.1 BreathAndcirculation

Like other fish, sharks obtain the necessary amount of oxygen from water by passing it through their gills. The respiratory organs are gill sacs, which open into the pharynx with internal gill openings, and external ones? on the sides of the head to the surface of the body. Sharks are characterized by the presence of five to seven (up to ten) pairs of gill slits (depending on the species), located in front of the pectoral fins. The gill openings are delimited from each other by wide interbranchial septa, in the thickness of which lie cartilaginous gill arches. The gill filaments sit on the anterior and posterior walls of the gill slits, where they form the semi-gills. Respiration is characterized by countercurrent movement of blood and water mass.

When sharks inhale, the pharyngeal region expands, and water is sucked into it through the mouth opening and spray, which washes the gill filaments and passes into the outer gill cavities; water pressure from the outside presses the edges of the intergill membranes, and they close the outer gill slits. When exhaling, the gill arches of the right and left sides come closer together and thereby reduce the volume of the pharynx; the almost closed gill filaments of the adjacent hemigills impede the outflow of water into the pharynx; the pressure in the outer gill cavities increases, the valves bend and water flows out. Like all cartilaginous fish, the gill filaments are not capable of secreting the products of nitrogen metabolism and salt, so the function of the gills is limited only to gas exchange. The heart has two chambers - the atrium and the ventricle, and is located in the thoracic region of the fish, near the head. It moves blood through the gill artery into the vessels located in the gills, and from there, already enriched with oxygen, it enters other organs. Sharks have one circulation, and only venous blood in the heart. The amount of blood is 3.7-6.8% of body weight, the hemoglobin content is 3.4-6.5%, and the oxygen capacity is 4.58.7% by volume. The maximum indicators of hemoglobin content and oxygen capacity in sharks are lower than the similar average indicators of bony fish, which indicates a lower energy level of their body. The blood pressure maintained by the shark's heart is not enough to fully supply oxygen to its body. Because of this, the shark must constantly help its heart with muscle contractions (movements) that stimulate blood flow.

2.2 Buoyancy

Unlike bony fish, sharks do not have a swim bladder. Instead, a huge liver, cartilaginous skeleton and fins help them compensate for negative buoyancy. A decrease in the specific weight of the body is achieved due to the accumulation of squalene bicarbonate in the liver with a specific gravity of 0.86 g/cm3, as well as the density of cartilage is approximately half that of bone. Many sharks are also characterized by neutral buoyancy due to the hydration of the skeleton. The rest is compensated by the lifting force generated during movement. At the same time, do sand sharks (Odontaspididae) solve the problem of the lack of a swim bladder easier? they create its likeness by drawing air into the stomach. Most species of sharks are forced to constantly move in order to maintain breathing, so they cannot sleep for a long time. However, some species, such as the baleen nurse shark, are able to pump water through their gills, allowing them to rest on the bottom.

2.3 Osmoregulation

Unlike bony fish, the osmoregulation mechanism of sharks is quite simple and primitive. In terms of electrolyte composition, blood and tissue fluids of the body are almost no different from sea water, that is, they are almost completely isotonic to the external environment.

Due to the salt content, about 50% of the osmotic pressure of blood and tissues is provided. Due to the peculiarities of nitrogen metabolism in the blood of sharks, urea (a rather toxic substance) and trimethylamine oxide accumulate in significant quantities, which diffuse poorly through the membranes of kidney and gill cells, due to which the remaining increase in osmotic pressure is achieved. The result is an increased osmotic pressure of the internal environment (26 atm versus 24 atm in sea water), that is, conditions are created for the free penetration of water from the external environment into the intercellular fluid and blood, which ultimately leads to the diffusion of sodium and potassium. But since the shark’s body has homeostasis, does it also have a special mechanism for maintaining electrolyte composition? For this purpose, there is a rectal gland, which removes excess salts into the cloaca.

2.4 Thermoregulation

Most sharks are poikilothermic (cold-blooded) animals. The body temperature of sharks corresponds to the ambient temperature. However, exceptions to this rule are some species of pelagic sharks - for example, mako, white and blue sharks (about 8 species in total). They are partially warm-blooded and can have a body temperature 8-11 C higher than the ambient temperature due to the intense work of the muscular system. Many small veins intertwine large muscles, which release the generated heat into the blood. Higher body temperatures allow sharks to move faster and more efficiently.

2.5 Digestivesystem

On the skin covering the movable cartilaginous jaws, teeth, which are transformed placoid scales, are located in several rows.

The oral cavity passes into the pharynx, behind which the esophagus begins, without noticeable boundaries, turning into an easily extensible U-shaped stomach. The concentration of hydrochloric acid in gastric juice reaches 3%. The small intestine departs from the stomach, which passes into the large intestine, which in turn passes into the rectum, which opens into the cloaca. Inside the large intestine there is a spiral valve that significantly increases the absorption surface. The rectal gland, which is an organ of salt metabolism, departs from the rectum; it removes excess salts that enter the body along with food and sea water. During the breeding season, the gland secretes odorous mucus, which facilitates the meeting of individuals of different sexes.

A special place in the body of sharks is occupied by a massive three-lobed liver, the mass of which can be up to 30% of the mass of the entire body. The liver accumulates fat reserves (up to 70% of the liver mass in a basking shark), animal starch glycogen and some vitamins, serving as a storage facility for energy reserves and a hydrostatic organ to increase buoyancy.

It is reliably known that in predatory sharks the enzyme collagenase plays an important role in digestion.

After a hearty meal, sharks are able to starve for a long time, slowly and economically using up accumulated resources, and in general their need for food is relatively small. For example, a captive three-meter Australian sand shark (Carcharias taurus) weighing 150 kg ate only 80-90 kg of fish per year.

Sharks periodically perform an eversion of the stomach - they turn it out through the mouth into the aquatic environment for the purpose of cleansing. It is curious that they never damage the stomach with their numerous teeth.

3. NervoussystemAndorgansfeelings

The sensory organs of different species of sharks are developed to varying degrees depending on their habitat. The spinal cord of sharks has great functional independence. Sharks have particularly well developed photo- and chemical reception sensors, as well as an acoustic-lateral system.

3.1 Smell

Do sharks have a sense of smell? one of the main sensory systems. Experiments have shown the high sensitivity of sharks to odors. Are the olfactory organs represented by the nostrils? small bags on the muzzle that allow water to reach the olfactory receptors. The sense of smell is involved in searching for prey and breeding partners. The white shark uses 14% of its brain for smell. Do hammerhead sharks have a particularly well-developed sense of smell? spaced at a decent distance from each other on a head of a peculiar shape, they allow you to more clearly determine the direction of the source of the smell. Research has shown that sharks respond better to the odors of wounded or alarmed prey. Some scientists have suggested that sharks are able to detect odors in the air just as well as in water. The white shark has often been observed with its snout poking above the surface of the water. Sharks can smell blood diluted 1:1,000,000, roughly equivalent to one teaspoon in a medium-sized swimming pool.

3.2 Vision

The structure of a shark's eye is for the most part the same as that of all vertebrates, but with some peculiarities. Does a shark's eye have a special reflective layer? tapetum? located behind the retina. The tapetum directs the light that passes through the retina back so that it once again affects the receptors, thereby increasing the sensitivity of the eye. This significantly improves visual acuity, especially in low light conditions. Another feature of some species is the presence of a blinking eyelid, which closes the eye directly during an attack on the victim, protecting it from damage. Sharks, which do not have a blinking eyelid, roll their eyes when attacking a victim. Previously, it was believed that the shark's eye contains too few cones and is not able to distinguish colors and small details. However, modern technology has made it possible to prove the opposite. The visual acuity of some shark species is up to 10 times sharper than humans

3.3 Hearing

Sharks have a hearing organ? This is the inner ear, enclosed in a cartilaginous capsule. Sharks perceive predominantly low sounds of 100--2500 Hz. Most sharks are able to detect infrasound with frequencies below 20 Hz. The inner ear is also an organ of balance.

3.4 Lateralline

The lateral line canal runs along the lateral surface of the body in the thickness of the skin and is a seismosensory organ. It looks like a narrow and deep skin groove, branching in places. The lateral line perceives mechanical movements of water particles, and possibly infrasonic vibrations. It plays an important role in hunting, species communication and short-range orientation.

3.5 Electro-Andmagnetoreception

The electroreceptive apparatus of sharks is represented by ampullae of Lorenzini (English)? These are small connective tissue capsules immersed in the skin with tubes emanating from them that open to the surface of the skin. Sharks respond to electric fields as low as 0.01 µV/cm. Therefore, they are able to detect prey by electrical fields created by the work of the respiratory muscles and heart. There are suggestions that the shark also uses them as thermal sensors that determine the temperature of the environment with an accuracy of 0.05 °C.

The migration trajectory observed in some species in a straight line over fairly long distances has led scientists to think about the ability of sharks to navigate by the earth’s magnetic field. Studies conducted with captive blue-gray sharks (English) (Carcharhinus plumbeus) confirmed these guesses - the behavior they demonstrated allows us to confidently speak about magnetic sensing. In the perception of a magnetic field in a shark, the following may be involved: magnetically sensitive receptors, the influence of the magnetic field on chemical processes, the electroreceptive apparatus, or all of the above in combination.

4. Durationlife

Each species has a specific lifespan, and it is not easy to estimate it for all sharks. In general, sharks grow relatively slowly, and in general, most species can be said to live 20-30 years. However, the spotted spiny shark has a record life expectancy, living for more than 100 years. Whale sharks of a similar age are also known.

5. Reproduction

Sharks have the internal fertilization characteristic of cartilaginous fish, a primitive uterus and a fairly perfect placental connection. Does the fetus develop in the uterus and is born well adapted to independent life? Newborn sharks have well-developed musculoskeletal systems, digestive systems and sensory organs, which allows them to feed independently and quickly gain weight. Do sharks produce different numbers of babies? some species up to 100, others only two or three. A white shark gives birth to approximately 3-14 sharks at a time. Unlike most bony fish, which produce millions of eggs, shark procreation focuses on quality rather than quantity. The care of some species for their offspring (the baby shark is under the care of the mother for some time) allows sharks to have a high survival rate, and therefore lower fertility.

Sharks are divided into oviparous, ovoviviparous and viviparous. The copulatory organ of males is a pair of pterygopodia, each of which is a modified posterior part of the ventral fin. During reproduction, one of the pterygopodia bends forward and is inserted into the female's cloaca.

After fertilization, the egg is covered with a gelatinous protein shell, and on top of it in most oviparous species? horn-like shell, often with projections and cords. This protects the embryo from dehydration, many predators, mechanical damage and allows it to be suspended on algae. The eggs are large and contain a lot of yolk. Usually from 1-2 to 10-12 eggs are laid simultaneously, and only the polar shark (Somniosus microcephalus) lays up to 500 eggs about 8 cm long at a time. The embryonic development of sharks is slow, but the hatched baby differs from the adult only in size and capable of independent life. About 30% of species are oviparous. In ovoviviparity, fertilized eggs are retained in the uterine parts of the oviducts. In this case, the cubs hatch and remain inside the mother for some time, eventually being born well developed and adapted for independent existence. In herring sharks (Lamnidae), the young, after using their yolk sac, eat the unfertilized eggs accumulated in the uterus. In viviparous species, after using the yolk, the yolk sac grows to the wall of the uterus, forming a kind of placenta, and the embryo receives oxygen and nutrients from the mother’s bloodstream through osmosis and diffusion. In mustelids (Triakidae) up to 20 can develop simultaneously, and in hammerhead fish (Sphyrnidae) ? up to 30-40 embryos. The gestation period in ovoviviparous species is not precisely known, but it approximately ranges from several months to two years (in the spotted spiny shark), which is one of the longest periods among all vertebrates.

Internal fertilization, large eggs with significant nutrient reserves, a strong outer shell, and widespread ovoviviparity and viviparity dramatically reduce embryonic and postembryonic mortality. Are there also isolated cases of parthenogenesis? that is, the female produced offspring without any participation from the male. All of these phenomena have occurred in captive sharks. There are no known cases of asexual reproduction of sharks in the natural environment, and it is assumed that this is a last resort measure for reproduction in the absence of males.

6. Spreading

Sharks are distributed throughout all oceans and climate zones. Most of them live in sea water; the blunt-nosed shark can also live in fresh water, swimming quite far into rivers. In depth they are distributed mainly up to 2000 meters, sometimes going down to 3000 meters, and they are extremely rarely observed below. The greatest documented depth belongs to the Portuguese shark (English) ? 3700 m.

7. Imagelife

In the traditional view, the shark looks like a lone hunter, roaming the ocean in search of prey. However, this description applies only to a few species. Many sharks lead sedentary, inactive lives. But even solitary hunters are found to breed or in food-rich areas, which can force them to travel thousands of miles in a year. Perhaps shark migration is more complex than even bird migration.

Sharks can also exhibit social behavior. Sometimes more than a hundred bronze hammerhead sharks (Sphyrna lewini) gather around seamounts and islands, for example in the Gulf of California. Sharks also have an interspecific social hierarchy. For example, the whitetip shark is dominant over the silky shark of the same size when it comes to feeding.

When approaching too close, some sharks give off threat signals. As a rule, they consist of increasing the amplitude of swimming movements, and their intensity can indicate the level of danger.[

7.1 Speed

Sharks generally move at a cruising speed of approximately 8 km/h, but when hunting or attacking, the average shark accelerates to 19 km/h. The mako shark can accelerate to speeds of 50 km/h. The white shark is also capable of similar jerks. Such exceptions are possible due to the warm-blooded nature of these species.

7.2 Intelligence

Contrary to the popular belief that the shark is just a “hunting machine” driven by instinct alone, recent research has shown the ability of some species to solve problems, social behavior and curiosity. The ratio of brain to body mass in sharks is roughly equivalent to that of birds and mammals. In 1987, off South Africa, a group of seven white sharks worked together to drag a half-stranded whale to deeper water for a meal. Sharks can also exhibit playful behavior. For example, the Atlantic herring shark has been repeatedly observed chasing another individual with a piece of algae in its teeth.

7.3 Dream

Some sharks can rest on the bottom, pumping water through their gills, but their eyes remain open and monitor what is happening around them. When resting, the shark does not use its nostrils, but it is quite possible that it uses squirts. If a shark used its nostrils, it would suck in sand from the bottom rather than water. Therefore, many scientists believe that this is one of the cases that justify the need for a sprinkler. In the katran, the process of movement is controlled more by the spinal cord than by the brain, so it can sleep peacefully even when swimming. It is also possible that sharks sleep like dolphins, resting each hemisphere of the brain in turn, allowing them to remain conscious at all times.

7.4 Nutrition

The food preferences of sharks are very diverse, and they depend on the characteristics of each species, as well as on their habitat. The main food for sharks is fish, mammals, plankton and crustaceans. For example, lamna, mako and blue sharks feed primarily on marine fish of pelagic species, and the shape of their thin, sharp teeth is adapted to grab prey in motion. The white shark prefers seals and sea lions, but if possible, it also hunts whale mammals, since the features of its teeth allow it to snatch off large pieces of flesh. The diet of benthic sharks consists mainly of crabs and other crustaceans, and their teeth are short and adapted to breaking shells. Basking, largemouth and whale sharks feed on plankton and small marine organisms. Most species are carnivores. Some species, such as the tiger shark, are almost omnivores, swallowing almost anything that comes their way.

8. Evolution

The first shark-like creatures appeared about 450 million years ago, but the oldest evidence of the existence of sharks - fossilized teeth - is approximately 400 million years old. These were small teeth that belonged to an individual, apparently no more than 30 cm in length. Basic information and theories of the origin of sharks in general are based mainly on fossils of teeth found. This is due to the fact that cartilaginous skeletons disintegrate quite quickly after death, and the discovery of a well-preserved shark skeleton is a rather rare and successful occurrence.

The oldest such find, the perfectly preserved skeleton of Cladoselache, dates back to the Devonian period and is approximately 350 million years old. At that time, the vast territories of what is now Europe and North America were covered with warm, shallow seas, and in these extremely favorable conditions for the development of marine life, along with other fish, a great variety of sharks flourished and multiplied. At this time, sharks competed mainly with armored fish, already having an advantage over them in the form of a body structure that had better hydrodynamic characteristics and simplicity. By the beginning of the Carboniferous, the diversity of sharks had increased so much that scientists called this period the “golden age of sharks.”

In addition to fish with obvious shark characteristics, there were also more bizarre creatures. One example - Stethacanthus, with a probable size of about 3 meters, differed from all existing and extinct sharks by the presence of a “helmet” of small teeth on its head and an unusual formation on its back, reminiscent of a triangular shaving brush, located approximately in the place where it should be a dorsal fin. Or, for example, Helicoprion and Ornithoprion, which developed rounded lower jaw teeth that looked and apparently acted like a circular saw. Around the same time, sharks also developed with a “conveyor” mechanism for changing teeth, a feature that has been preserved in modern species. After Carboniferous there were two qualitative leaps in the development of teeth. One during the Eocene (56--35 million years ago), when the bulk of the modern shark fauna was formed, and the second during the Miocene (23--5 million years ago), when the oceans were inhabited by the huge white shark Carcharodon megalodon.

By the end of the Carboniferous, about 300 million years ago, the increase in shark diversity came to an end, and they survived with minor evolutionary changes until the global cataclysm after the end of the Permian period. Around 245 million years ago, widespread volcanic eruptions, coupled with climate and sea level changes, caused the extinction of approximately 96% of marine life. Many remaining species of sharks became extinct due to the disappearance of the marine inhabitants that were their food, and many joined the list of extinct ones, themselves becoming food for stronger species. But still, several species remained, which ultimately allowed sharks to occupy vacant places in the ecosystem during the next evolutionary breakthrough.

In the subsequent Triassic, Jurassic and Cretaceous periods - the era of reptiles - sharks, with their swift form, the ability to develop high speed and developed senses, were practically unrivaled. The species Palaeospinax appeared, which had similarities with modern katrans, which retained spines on the dorsal fin. At that time, species of larger sizes also developed - for example, Cretoxyrhinid, active hunters more than 6 m long. In deposits of the Cretaceous period there are teeth that are just like those of a tiger shark, as well as teeth of large herring sharks with dimensions of more than 6 meters. The appearance of the ancestors of giant, pelagic largemouth and gray sharks is also attributed to the same time. With the extinction of the giant reptiles, mammals began to populate the land, and some of them returned to the sea. The appearance of whales, dolphins, seals and sea cows became the main source of food for the ancestors of the white shark. The oldest fossils of teeth similar to those of a great white shark are approximately 65 million years old. Even then, the ancestors of white sharks were fully developed in evolutionary terms, being the most powerful marine predators.

About 50 million years ago, a huge predator appeared - Carcharodon megalodon. The structure of the megalodon is similar to the modern white shark, but much larger. Its largest tooth found measures over 15 cm from base to tip. Taking the white shark as a model, it is not unreasonable to assume that the megalodon reached a length of approximately 12-30 meters. Despite the hopes of science fiction writers, most scientists agree that megalodon did not survive to this day, having disappeared from 30 to 5 million years ago due to a decrease in the amount of food and climate change. Contrary to popular belief, sharks have not remained unchanged throughout the 300-400 million years of their existence. However, many modern families have apparently existed for 150 million years. Studying the developmental history of sharks is difficult due to the fact that mainly research has to be carried out only on their fossilized remains of teeth. One of the main weaknesses of this method is that teeth can vary significantly depending on their location in the jaw and stage of development. In the recent past, this was the reason that scientists discovered several species of extinct sharks, which in fact turned out to be one animal. After the discoveries of extinct species were revised to take into account the dental formation of modern sharks, the number of extinct species was halved.

9. SharksAndHuman

9.1 Attackssharks

Despite the relative rarity of attacks, fear of them has grown through anecdotal accounts such as the 1916 Jersey Shore attack, which killed 4 people and maimed 1, as well as literature and horror films such as the Jaws film series. " Many experts believe that the danger posed by sharks has been greatly exaggerated.

It is estimated that a person's chance of being attacked by a shark is 1 in 11.5 million, and the chance of dying from such an attack is 1 in 264.1 million. For example, the annual number of drownings in the United States is 3,306 people, and those killed by sharks 1 .

Contrary to popular belief, only a few species of sharks are dangerous to humans. Of all the species, only four have been recorded in a significant number of unprovoked fatal attacks on humans: white, tiger, tiptoe and tiptoe sharks. There have been cases of unprovoked attacks of other types, but they rarely resulted in the death of a person. These are: mako shark, hammerhead, Galapagos, dusky gray, lemon, silky and blue sharks. These sharks are large and powerful predators that can be attacked simply by being in the wrong place at the wrong time. However, they are considered less dangerous for swimmers and divers. The remaining several species also attack humans every year, causing potentially life-threatening wounds. But such cases occur either due to deliberate provocation, or due to mistaken identity by the shark due to water conditions, etc.

Sharks pose the greatest danger to swimmers closer to the surface, and there are still no effective ways to repel sharks. The shark senses the fear of the victim, and also becomes more dangerous when provoking it into defensive actions. But the attack usually does not begin immediately - first the shark studies the person, swimming around, and then it can disappear and suddenly appear.

9.2 SharksVcultureAndtraditions

In the centuries-old history of China, sharks occupy a special place mainly due to the world-famous delicacy? shark fin soup. This dish is one of the most expensive and important in Chinese cuisine, symbolizing respectable social status or a sign of respect for distinguished guests. In addition, the soup is considered as a tonic. In China, there are also widespread beliefs that cartilage from fins helps fight cancer, and dried fins can be used as an aphrodisiac. According to statistics, Hong Kong is the world center for the shark fin trade, occupying 50-80% of this market segment, and 27% of this amount is supplied there by the EU. In the culture of Polynesia, especially in the Hawaiian Islands, sharks have a special attitude. In Polynesian myths, 9 gods are associated with sharks, and they were considered guardians of the sea and protectors of the Hawaiian people. Have you also encountered stories about a werewolf? a shark man, ferocious and greedy for human flesh. In other parts of Polynesia, such as Tonga, there is a belief that sharks? it is food sent by the spirits of ancestors to support the population. Unlike modern Western culture, in which ideas about sharks are largely based on films such as Jaws, Polynesians, who have long lived by the sea in contact with these creatures, have a tendency to respect and deify sharks. In Japanese culture, sharks are represented as sea monsters that take the souls of sinners. Several references to sharks are also found in Greek mythology. In Australia, as in Tonga, the Aborigines consider sharks to be part of the natural resources intended for people. Some Aboriginal communities in north-east Arnhem Land consider the gray shark Mdna to be their ancestor.

9.3 AssumptionsOcounteractioncancerousdiseases

Despite the fairly widespread belief that shark cartilage is a cure for cancer, there is not a single scientific confirmation of this. In addition, the organisms of humans and sharks have significant differences, and the immune system of these fish has not yet been fully studied. It is also widely believed that sharks do not get cancer. Studies have shown that this is not the case. In several species of sharks, tumors of almost all organs and systems of the body were identified, and more than half of them turned out to be malignant. Moreover, both individuals kept in captivity and those living in coastal zones and the open sea were examined. However, the sale of drugs based on shark cartilage as anti-cancer agents still continues today. Scientists do not deny that substances isolated from shark cartilage and liver could potentially be beneficial in the fight against cancer, but it is too early to talk about this until the end of the research. And if, nevertheless, claims about anti-cancer properties are confirmed, then it will always be possible to artificially synthesize the necessary substance instead of killing sharks to extract it. This misconception also increases the popularity of shark fin extract, used in alternative medicine to treat patients in the hope that, like sharks, they will never get cancer. Without any scientific basis, such treatment is more expensive than effective.

9.4 ContentVcaptivity

Currently, relatively few species are kept in captivity. And there are reasons for this. One of the main ones is that the most famous (and therefore the most interesting to the public) species are quite difficult to catch and transport without harming the fish. After all, for the most part these are large and aggressive fish, which, while fishing with bait, are in a state of hunting for prey? that is, in increased excitement. In addition, when removed from the water, some species can simply crush their internal organs with their own weight, and this must be taken into account when moving a shark from the ocean to an artificial tank. Further difficulties arise upon the arrival of sharks in the aquarium, which must have the necessary capacity for the normal life of these fish, and also take into account their increased sensitivity to electromagnetic waves.

9.5 FishingAndhunting

Along with other fish, sharks have been the subject of fishing for many years (more than 100 species). The fishing industry is interested in sharks:

Meat used as food by many cultures (although observations have shown that sharks are predisposed to accumulate mercury, the content of which in meat has increased significantly due to environmental pollution).

Fins, which in Asia are the main ingredient for a delicious soup, are also used in oriental medicine.

Cartilage, around which there is still controversy about its medicinal properties against cancerous tumors.

Leather that is used in haberdashery and as an abrasive material.

The main fishery is carried out in the Atlantic Ocean, where 26 species are commercial, about a third of sharks are caught in the Indian Ocean, and another one and a half times fewer sharks are caught in the Pacific. Every year, approximately 100 million sharks are caught worldwide. Despite the gradual introduction of restrictions and bans, shark catches have been constantly increasing since the middle of the last century. Shark fishing can be divided into three areas:

Fishing for the purpose of using their meat, liver, cartilage, skin and fins? that is, the full use of fish.

So-called bycatch? when the shark is incidental prey when catching other fish.

Fishing for the purpose of obtaining fins only. This is the most irrational (the weight of fins is up to 4% of the entire body) and inhumane way of catching sharks, which in English is called finning? when the only target is the fins, and the rest of the carcass is thrown out to rot on the shore or back into the sea.

In addition to fishing for industrial purposes, there are also reasons for hunting sharks in the world such as ensuring the safety of beaches, reducing the natural threat of industrial fish species, and simply extreme hunting and fishing.

10. EcologyAndsecurity

Salmon shark

Most sharks are at or near the top of the food chain. Therefore, they play a huge role in regulating the number of species that are hunted. But, like all inhabitants of the sea, the anthropogenic factor has not spared sharks. They are also affected by increasing fishing for their natural food, environmental pollution and direct hunting of the sharks themselves, in particular their fins. For humans, they are potentially useful in medicine and are used as food. Historically, shark fishing was carried out on a relatively small scale and did not pose problems for the recovery of their numbers. However, increased fishing since the 1980s has threatened many species. One of the reasons for the growing popularity of sharks as a fishing target? these are their fins. Shark fin soup is considered a delicacy, and fin is more expensive than shark meat. This has led to an inhumane method of hunting for fins, which are obtained by cutting them off live fish, and throwing the shark itself back into the sea. Currently, in some countries this type of fishing is already prohibited.

At the same time, is it not only the targeted fishing of sharks that poses a threat to them? about half are caught unintentionally with other fish. Unlike industrial fishing, such shark harvesting is much more difficult to control and regulate for the fishing industry. Generally, fishing in large quantities is regulated by the authorities. However, historically, records of incidentally caught sharks have not generally been kept due to their relatively small numbers. Significant damage to their population is caused as a result of the so-called. bycatch in longline fishing. In these pelagic game fisheries, sharks make up a significant portion of the catch. For example, in Australia, when fishing for tuna and billfish using this method, the bycatch of sharks is more than 25%, and in the Hawaii region when catching swordfish? 32%. Are blue sharks the largest proportion of prey species? from 47% to 92% of bycatch during research. About 6 million blue sharks are caught in nets every year as incidental prey. The size of shark bycatch depends on the type of fishing gear and fishing grounds. More sharks are caught near the surface of the sea than in the depths.

The IUCN shark specialist group estimates that 24% of the species are threatened. The shark population is constantly declining. For example, off the coast of the United States over the last 15 years of the last century, the number of hammerhead sharks has decreased by 89%, fox sharks by 80%, and white sharks by about 79%. The numbers of whitetip shark, tiger shark, blue shark and mako shark decreased by 70%, 65%, 60% and 40% respectively. According to Canadian researchers, the whitetip shark population has decreased by 99%, and in some places has disappeared altogether. Marine debris plays a significant role in reducing shark populations. Many species are very curious by nature, and some do not think much at all before swallowing something, and this often becomes the reason for their death. One of the reasons for the high vulnerability of the shark population? these are late periods of puberty and low fertility. For example, the lemon shark reaches sexual maturity at 13-15 years. Modern literature, cinema and the media have created and successfully used the image of the shark as a bloodthirsty, ruthless beast, forgetting to convey the information that the shark is primarily a marine predator, playing a huge role in the entire marine ecosystem. Therefore, many organizations involved in the protection and conservation of sharks set themselves the main goal of conveying to society more complete information about sharks and their place in nature.

11. Commonmisconceptionsaboutsharks

shark fishstructure

A shark must constantly swim to stay alive. In fact, many species are able to rest by lying on the bottom and pumping water through their gills. Moreover, they prefer this method of breathing instead of movement.

Most sharks attack and kill humans. Only a few species of sharks regularly commit unprovoked attacks on humans, and this is mostly due to misidentification of prey.

Sharks swim at high speed. In fact, sharks' cruising speed is quite slow, as they need to conserve energy. However, this does not prevent them from developing a high so-called “throwing” speed immediately before attacking the victim.

Sharks love human blood. Sharks do not have a preference for any blood. On the contrary, having grabbed a piece of flesh from a person, they usually spit it back, because this meat is not the high-fat food that they need to replenish their energy reserves. Sharks are omnivores. Most species prefer to wait until they can get their regular food instead of eating everything.

Sharks are not susceptible to cancer. This belief, which existed for a long time, caused the death of a huge number of sharks caught by humans for the sake of “anti-cancer” cartilage. However, observations of sharks in captivity, as well as in their natural habitat, have shown the presence of individuals with organs affected by cancerous tumors. The number of cancer cases turned out to be higher where the water is more polluted (including from human activity).

12. Classification

1. Hammerhead shark (Carchariformes)

2. Helmeted bull shark with egg (Radiotoothidae)

3. Frilled shark (Polybranchids)

4. White shark (lamniformes)

5. Spotted saddle shark (Wobbegongs)

6. Japanese sawnose (Sawnose)

7. Black spiny shark (Catraniformes)

8. Angelfish (Squatinidae)

9. Class: Chondrichthyes -- Cartilaginous fish

10. Subclass: Elasmobranchii -- Elasmobranch fishes

11. Superorder: Selachimorpha -- Sharks

More than 450 species of existing sharks are grouped into 8 orders and 30 families:

Carchariformes. This is the order with the greatest diversity of species among sharks. Appeared during the Jurassic period, representatives are found from the intertidal zone to the ocean depths almost everywhere. External distinctive features vary greatly, but all share five gill slits, two dorsal fins (except the single-fin cat shark), and an anal fin. Reproduction methods are also very diverse - there are oviparous, ovoviviparous and viviparous species. Some people have oophagia. (English)

Heterodontoids. They appeared in the Triassic period, and represent a group of bottom-dwelling sharks that lead a nocturnal lifestyle. Their external features are a dense body, two dorsal fins with spines and an anal fin. Distributed from the intertidal zone to the continental shelf. All species are oviparous.

Polybranchioformes. The detachment is the oldest among existing sharks - it was formed during the Permian period. It consists of two families that differ in body shape - eel-shaped in frilled sharks and the “traditional” torpedo-shaped in polybranch sharks. Both families are characterized by six or seven gill slits, one dorsal fin, and the presence of an anal fin. Mostly distributed in the cool depths of the tropics, ovoviviparous.

Lamniformes. Appeared in the Jurassic period. Large pelagic species predominate in this order. They are torpedo-shaped, have five gill slits, two dorsal fins and an anal fin. Distributed from the intertidal zone to deep ocean waters, ovoviviparous.

Wobbegong-shaped. Appeared in the Jurassic period. Distributed in warm and tropical seas from the intertidal zone to deep waters. With the exception of the whale shark, all species are bottom dwellers. They have five gill slits, two dorsal fins and an anal fin. The species include oviparous, ovoviviparous and viviparous. Some also have oophagy.

Sawtooth. Perhaps the most easily identified unit. It appeared in the Jurassic period. Sharks of this order are distinguished by a specific long sawtooth snout studded with teeth, as well as the absence of an anal fin, two dorsal fins and large spiracles. They live on the bottom, are ovoviviparous.

Katraniformes. Appeared in the Jurassic period. This order is widespread and is found throughout the world, including - the only shark - in latitudes close to the poles. They live at great depths. Representatives of the order have a torpedo-shaped body, five gill slits, two dorsal fins, and no anal fin. Ovoviviparous.

Squatinoides. Appeared in the Triassic period. Habitat typically consists of mud or sand of the continental shelf and intertidal zone in cool temperatures, as well as deeper locations in tropical waters. Sharks of this order are distinguished by a wide flattened body, a short snout, five gill slits, large pectoral and ventral fins, and the absence of an anal fin. Outwardly, they resemble stingrays, but the difference is that the gills open on the sides of the body, and not from the bottom, and wide pectoral fins, clearly separated from the head, are clearly visible. All species are ovoviviparous.

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Mammals are the highest class of vertebrates and the entire animal kingdom. Structure: skeleton; muscular, nervous, circulatory, respiratory, excretory, digestive systems; Body temperature; reproduction. Origin and development of the class of mammals.

The shark is the most dangerous marine inhabitant that can harm human life. The predator lives in sea waters and oceans. You can meet representatives of vertebrates in almost all the salty waters of the World Ocean, but there are so many varieties of fish that it doesn’t hurt to get acquainted with the brightest representatives of this family.

General characteristics of sharks

Sharks are roughly divided into eight orders. In total, today there are 450 species of predators, but researchers claim that there are also other representatives of this family that are still unknown to humans.

The diversity of sharks is so great that the smallest fish grow up to 20 cm, while the largest ones can reach 20 meters. However, all vertebrates have a number of similar features: sharks do not have a swim bladder, they breathe oxygen, which enters the gill slits, marine animals have an excellent sense of smell, which allows them to sense the blood of a prey at a distance of several kilometers. Also, all fish have a unique skeleton consisting of cartilaginous tissue.

Shark squads

Unfortunately, many species of sharks have become extinct, and information about them is hopelessly lost. Today there are 8 main orders of predators:

• carchariformes;
• heterodentate or bovine (horned);
• polybranchiformes;
• laminated;
• wobbegong-shaped;
• sawtooth;
• katran-shaped or spiny;
• representatives of flat bodies.

Of the large number of fish, not all are predators. Three species of sharks feed on plankton. There are also representatives of vertebrates that live in fresh waters.

Main types of sharks

You can meet dangerous predators in the Atlantic, Pacific, and Indian Oceans, as well as in the Mediterranean, Red and Caribbean Seas. The most unusual marine animals are:

Tiger shark

The tiger or leopard shark is one of the most greedy predators; the maximum length of the fish is 5.5 m. A distinctive feature of the sea inhabitant is the tiger pattern located throughout the body.

Hammerhead shark

The hammerhead shark is a unique shark that has a “hammerhead” on the front. The predator creates the appearance of a massive and unusual fish. Adults grow up to 6.1 m. Fish love to feast on seahorses, stingrays and stingrays.

Silky shark

Silky or Florida shark - has an unusual grayish-blue color with a metallic tint. The maximum body length of the predator is 3.5 m.

Snout shark

The blunt-nosed shark is one of the most aggressive fish. In some sources, the predator is called a bull shark. The marine inhabitant lives in India and Africa. A special feature of the fish is its ability to adapt to fresh water.

Blue shark

The blue shark is considered the closest fish to humans, as it often swims to the shore. The predator has a blue coloration and a rather slender body and generally grows up to 3.8 m.

Zebra shark

Zebra shark - distinguished by its unusual color in the form of brownish stripes on a light body. The fish species is not considered dangerous to humans. The shark lives near China, Japan and Australia.

Helmet shark

The helmeted shark is one of the rare species of predators. The surface of the fish's body is covered with denticles, the color is represented by dark spots on a light background. Adults grow up to 1 meter long.

Mozambique shark

The Mozambique shark is a red-brown fish with white spots on its body. The marine inhabitant lives in Mozambique, Somalia and Yemen, grows up to 60 cm.

Sevengill shark

The sevengill or straightnose shark is distinguished by its aggressive character and ashen color. The fish has a narrow head and grows up to 120 cm.

frilled shark

The frilled or frilled shark is a unique marine inhabitant that can bend its body like a snake. The predator has an elongated gray-brown body, reaching 2 m, and numerous leather pouches.

fox shark

Fox shark - characterized by high speed of movement and a long upper blade of the caudal fin. The latter successfully stuns the prey. The length of the fish reaches 4 m.

sand shark

Sand shark - has an upturned nose and a massive body. Prefers tropical and cool seas. The average length of an individual is 3.7 m.

Blacktip shark

The mako or blacknose shark is a predator that is one of the most effective deadly weapons. The average length of the fish is 4 m, the speed of movement is phenomenal.

Goblin Shark

Goblin shark or brownie (rhinoceros) - this type of fish is called aliens. Sharks have an unusual snout, similar to platypuses. These deep-sea individuals grow up to one meter.

Whale shark

The whale shark is a true sea giant with stunning color and grace. The maximum length of a marine inhabitant is 20 m. Fish of this species do not like cold water and do not pose a threat to humans, although they are frightening due to their mass. The main food of sharks are crayfish and mollusks.

Carpal wobbegong

The carpal wobbegong is a unique species of shark, unlike its “brothers”. The fish is perfectly camouflaged due to the flat shape of the body and the many rags with which it is covered. It is very difficult to recognize the eyes and fins of an animal by appearance.

Short-nosed sawnose

Shortnose sawfish - the fish has a gray-blue body with a light belly. A distinctive feature of the animal is its saw-tooth outgrowth, which makes up a third of the total body length. Using a unique weapon, the shark injures its victims.

Sawtooth gnome

The gnome sawnose is one of the smallest fish of this species, the length of which is no more than 60 cm.

Southern siltworm - has a pointed head, light brown body. The marine inhabitant does not pose a threat to humans.

The heavy silt swallower has a massive body. This type of fish prefers to be at great depths.

Squatins

Flat-bodied sharks or squatins - this type of fish is very similar to stingrays in shape and lifestyle. The marine inhabitant prefers to hunt at night and burrows into the mud during the day. Some people call sharks sand devils.

There are many types of sharks. The variety of fish is influenced by its habitat and lifestyle.

Other shark species

In addition to the main, well-studied species of sharks, there are also lesser-known predators, including: lemon, granule, longtip, reef, cats, mustel, soup, herring, largemouth, carpet and arctic sharks. Also in sea waters there is a species of predator called the “nurse shark”.

And, of course, a white shark

Sharks are a superorder of cartilaginous fish, including eight orders, twenty families and about 350 species. Representatives of the superorder are widespread in all seas and oceans; freshwater sharks are also found. Most species belong to the so-called true predators; some species, in particular whale, basking and largemouth sharks, feed on plankton. Sharks are a superorder of cartilaginous fish, including eight orders, twenty families and about 350 species. Representatives of the superorder are widespread in all seas and oceans; freshwater sharks are also found. Most species belong to the so-called true predators; some species, in particular whale, basking and largemouth sharks, feed on plankton.

Sharks include fish with an elongated torpedo-shaped body and a length from 20 cm to 20 m. Sharks include fish with an elongated torpedo-shaped body and a length from 20 cm to 20 m. The skin of sharks is rough, covered with scales, numerous denticles, teeth. The scales have the form of rhombic plates with a sharp, back-curved spine. The skin of sharks is rough, covered with scales, numerous denticles and teeth. The scales have the appearance of rhombic plates with a sharp spine curved at the top

The paired pectoral and pelvic fins are located horizontally and allow the fish to move up and down. The upper lobe of the caudal fin is usually longer than the lower one. Forward movement and turns are carried out by bending the caudal fin to the left or right. The paired pectoral and pelvic fins are located horizontally and allow the fish to move up and down. The upper lobe of the caudal fin is usually longer than the lower one. Forward movement and turns are carried out by bending the caudal fin to the left or right.

There are underdeveloped eyes on the head that can only see in black and white. There are underdeveloped eyes on the head that can only see in black and white. Sharks breathe using gills. Their gill arches are studded with gill filaments with a richly branched circulatory system. Sharks breathe using gills. Their gill arches are studded with gill filaments with a richly branched circulatory system.

Most sharks are poikilothermic (cold-blooded) animals. The body temperature of sharks corresponds to the ambient temperature. However, exceptions to this rule are some species of pelagic sharks such as mako, great white and blue sharks (about 8 species in total). They are partially warm-blooded and can have a body temperature 811 °C higher than the ambient temperature due to the intense work of the muscular system. Many small veins intertwine large muscles, which release the generated heat into the blood. Most sharks are poikilothermic (cold-blooded) animals. The body temperature of sharks corresponds to the ambient temperature. However, exceptions to this rule are some species of pelagic sharks such as mako, great white and blue sharks (about 8 species in total). They are partially warm-blooded and can have a body temperature 811 °C higher than the ambient temperature due to the intense work of the muscular system. Many small veins intertwine large muscles, which release the generated heat into the blood.

Sharks periodically perform an eversion of the stomach, turning it out through the mouth into the aquatic environment for the purpose of cleansing. It is curious that they never damage the stomach with their numerous teeth. Sharks periodically perform an eversion of the stomach, turning it out through the mouth into the aquatic environment for the purpose of cleansing. It is curious that they never damage the stomach with their numerous teeth.

Sharks have an extremely acute sense of smell. The front part of the brain, which is responsible for the sense of smell, is much more developed in sharks than in other fish. Blinded sharks unmistakably approach the place where pieces of fish, squid or other food were dropped into the water. Sharks have an extremely acute sense of smell. The front part of the brain, which is responsible for the sense of smell, is much more developed in sharks than in other fish. Blinded sharks unmistakably approach the place where pieces of fish, squid or other food were dropped into the water. Sharks are sensitive to Hz vibrations. In this case, high frequencies are perceived by the sensory cells of the inner ear, and low-frequency vibrations by the lateral line sensors on the surface of the head and torso. The lateral line is a very sensitive organ: the shark detects the movement of fish at a distance of up to 300 meters. Sharks are sensitive to Hz vibrations. In this case, high frequencies are perceived by the sensory cells of the inner ear, and low-frequency vibrations by the lateral line sensors on the surface of the head and torso. The lateral line is a very sensitive organ: the shark detects the movement of fish at a distance of up to 300 meters.

About 100 million sharks are killed around the world every year. There is still a method of removing fins from living sharks, which are used for cooking. After the fins are cut off, the sharks are thrown back into the water, usually still alive. Without fins, a shark cannot swim; it sinks to the bottom and dies. About 100 million sharks are killed around the world every year. There is still a method of removing fins from living sharks, which are used for cooking. After the fins are cut off, the sharks are thrown back into the water, usually still alive. Without fins, a shark cannot swim; it sinks to the bottom and dies.