Shark fish description for children. Types of sharks. Terrifying Sand Shark

The oldest predators of the seas and oceans are sharks; there are about 400 of their species in the world out of the 8 orders represented. Originating in the Jurassic period, fish have a perfect body, ideally adapted for life and hunting. All types of sharks differ in size, habitat, and only some pose a danger to humans.

There are about 400 species of sharks in the world from the 8 groups represented

Characteristics and features of sharks

As large as the World Ocean is, so great is the diversity of fish in it; each individual is unique in its own way and has characteristic differences. This also applies to sharks; there are representatives 15-20 cm long and 15-20 meters long, whose weight reaches 30 tons. But not all predators are as scary as people see them; some of them are dangerous only for small fish or shellfish.

The body structure, behavior, and manner of hunting of sharks of all species are similar; the common features are as follows:

A special feature is the absence of chewing teeth, i.e. when meeting prey, the shark tears it into pieces and swallows the pieces without chewing. When hunting, the predator develops a speed of 20-30 km/h, warm-blooded animals up to 50 km/h, the usual speed of movement is 5-8 km/h.

The average life expectancy is 30 years, but there are also long-livers whose life span exceeds 100 years, mainly whales, polar sharks or sand katrans.

Sharks live up to 30 years on average, but there are also centenarians who live up to 100 years

Types and differences

The classification of the superorder of sharks is represented by 8 orders and includes 34 families, representatives of which differ from each other in body shape, size and even hunting style, some of them are absolutely safe for humans, but there are species with which it is better not to joke.

List of shark squads:

1. Carchariformes.
2. Varieties.
3. Polybranchiformes.
4. Lamniformes.
5. Wobbegong-shaped.
6. Sawtooth.
7. Katraniformes.
8. Flat-bodied.

In total, oceanologists know about 400−420 different species of sharks, including ancient and endangered ones. There are about 300 species of the most popular and frequently encountered.

Carchariformes or Carcharidae

This order is the largest of all, it consists of three hundred species and eight families. The place of residence of these individuals is the coastal zones of the seas of the tropical and temperate zones, the highest concentration is in the waters of the World Ocean, as well as the Mediterranean and Caribbean Seas. Some individuals have been spotted in fresh waters and deep waters.

Carcharid representatives are dangerous to humans. The most popular types:

Most individuals of the carcharid species are quite large in size and have good hunting abilities.

Heterothed, bovine or horned

The species combines 9 families, but quite recently there were more of them, this is due to the extinction of some of the most ancient subspecies. Representatives with different teeth are united by an unusual appearance: a large head with formations in the eye area, an oval mouth, the presence of a spine on the dorsal fin and 5 gills. A characteristic feature that distinguishes them from other families is that their teeth are different in shape and size; in front they are sharp, capturing prey, and in the depths of the mouth they are grinding.

Different-toothed specimens are not as scary as people imagine them to be, the basis of their diet is small marine inhabitants.

Different-toothed animals do not attack people, but there was a recorded case when a shark bit an annoying scuba diver, but there were not even marks left on the skin. The species reproduces by laying eggs at the bottom of coastal areas.

Polybranched representatives

The species contains 5-6 families of fish that have one fin and 6-7 gill slits; they lack blinking in the eyes and a spine on the dorsal fin. The size and shape of the body differs depending on the variety.

The most famous representative of polygill sharks is the sevengill shark.

The most famous representative is the ash sevengill shark - a voracious and very active resident of the warm waters of the coasts of China, Australia, Japan, Indonesia, southern Brazil, North Carolina and Cuba. It can be found at the bottom of the continental plume at depths of up to 720 meters. The sevengill feeds on bony fish, crustaceans, scalefish, serpentine mackerel or sabrefish. The predator is very active; once caught in a net, a specimen can behave quite aggressively towards the fisherman.

The family also includes the frilled shark, which is more similar to a conger eel. Its body is elongated, its muzzle is short, its anal fin is larger than its dorsal fin. The genus also includes several extinct species.

Lamniformes and Wobbegongiformes

The real torpedoes of the underwater world are represented in the lamniformes family. Sharks have 2 dorsal fins, one lower fin and five pairs of gills; there is no nictitating membrane on the eyes. Some individuals feed on smaller fish, even relatives and mammals, so you should avoid them and not swim in the neighborhood.

Most famous families: Sand, False Sand, Herring, Goblin shark, etc., are represented by the following species:

The largest sharks include the Wobbegong genus; their body length ranges from 70 cm to 20 meters. Specimens live more at the bottom and prefer to feed on cuttlefish, crabs, crayfish, squid and other mollusks. These include: saddle sharks, spotted saddle sharks, Asian cats, Persian cats, zebra sharks and others.

These are just isolated examples of what kind of sharks there are in each species, but in fact there are many more of them and it is simply impossible to list them all. Oceanologists cannot definitively answer the question of how many species of sharks exist, because all of them have not yet been fully studied and the evolution of the oldest animal in the world occurs every day.

Which sharks should you be afraid of? Eminent ichthyologists and famous scientists argue that one should be wary of all, without exception, individuals of the “toothed family” whose length is more than 1 meter.

However, among the many existing species of sharks, one can single out the most aggressive and bloodthirsty representatives, a meeting with which definitely does not bode well, often ending in death for a person.

So, the 10 most dangerous sharks that have gained worldwide fame for their ferocious temperament; 10 cold-blooded killers, contacts with whom should be avoided by all those who value their own lives.

Watch video: 10 most dangerous sharks - BBC

10. Aggressive Lemon Shark

Blending in with the color of light brown sand, it poses a huge danger to swimmers, lying motionless on the shallows for hours, letting water pass through its gills and being ready to strike back with a swift response to any, even the most insignificant, provocation.

Lemon sharks are extremely sensitive to sudden movements, they are inquisitive, vindictive and have excellent memory. This sharp-toothed, short-winged creature lives primarily in the warm Caribbean Sea, near the Bahamas and the Gulf of Mexico, but can sometimes be found in the waters of the Atlantic.

Thanks to its adaptability to significant changes in salt concentrations, the lemon shark can even swim into fresh waters.

9. Blue shark - fatal beauty

In penultimate, ninth place is another shark with an unusual color, this time blue. The blue one has an indigo-colored back, the sides are painted in blue tones, and the belly is perfect white.

This colorful predator, with a spindle-shaped shape and long pectoral fins, can be found in tropical, subtropical and temperate latitudes of the Pacific Ocean.

Nature has deprived these fish of the ability to distinguish colors, rewarding them with excellent orientation and sensitive recognition of subtle contrasts.

The length of the blue shark is on average 3-4 meters, and opinions about its aggressiveness are often contradictory, but most researchers agree that these fish are extremely warlike and are ready to attack the enemy at any moment.

Photo: Blue Shark

8. Dangerous shark with a formidable tool

The eighth place in the “hit parade” belongs to the shark, which has a brownish or dark olive color on its back and the most unusual, hammer-shaped head. The habitat, which cannot be confused with any other species, is tropical and subtropical, and sometimes temperate latitudes.

You can meet her not only on the open sea, but also in shallow water, where attacks most often occur. On average, its size is 4-5 meters, but the length of some individuals reaches 7 meters or more.

This ancient fish, which has a terrifying appearance and long saw-shaped teeth, is distinguished by its maneuverability, high speed and mercilessness towards the enemy.

It has rightfully earned its reputation as one of the most dangerous sharks - many cases of attacks on people by representatives of this species have been documented.

It is especially risky to meet her during breeding, for which, ironically, she chooses popular and crowded places on the beaches of Hawaii, Florida and California.

Photo of a hammerhead shark

7. Terrifying Sand Shark

In seventh place of the “hot ten” is , whose length can reach 4.5 meters.

A gray-brown back, rounded dark yellow spots on the sides and a dirty white belly - these are the external characteristics of this deadly fish that lives in the subtropical and tropical latitudes of the Pacific and Atlantic oceans, as well as in the waters of the Mediterranean Sea.

Its mouth is equipped with a huge number of thin, long, sharp teeth that curve inward, which, coupled with the serious size of this shark, leaves almost no chance for the enemy to succeed in a fight.

The reputation of the most ruthless predators has been earned by sand sharks that live in the waters of South Africa, where the largest number of fatal attacks on humans have been recorded.

Photo of a sand shark

6. Deadly Guardian of the Coral Reefs

The sixth place in the list of the most dangerous sharks is occupied by the shark, armed with large triangular teeth with jagged edges and having a length of about 2 meters.

As the name suggests, the preferred habitats of this fish are rocks and coral reefs located in the Red Sea, as well as the Pacific and Indian Oceans.

The high speed and maneuverability of the gray reef shark is ensured by the torpedo-shaped body, which has a gray color with a characteristic black edging on the tail.

Cruel and merciless, she is capable of becoming furious even from minor vibrations of water and without hesitation attacking the source of irritation. Having nervously circled around the victim, it arches its back, opens its mouth and makes a swift attack - this is what an attack by a gray reef shark looks like.

Watch the video - Why are killer sharks from the TOP 10 dangerous:

5. The armor-piercing mako shark is as dangerous as a bullet.

It rightfully ranks fifth in the ranking. Being extremely aggressive and dangerous, this shark reaches 4 meters in length, and few can compete with its dynamism, power and swimming speed - no joke, the mako shark is capable of jumping over the water to a height of 6 meters!

You can meet this individual almost anywhere, with the exception of cool ocean waters.

It is not uncommon for mako sharks to attack people directly in the beach area. Aggressive and steadfast in defense, she without hesitation attacks boats on the open sea, and in pursuit of her intended prey she is even ready to jump out of the water onto the shore in a powerful jump.

Photograph of a mako shark

4. Bloody messenger of tragedy

Being in fourth place among the ten most dangerous sharks, it inspires fear with its appearance alone.

Large size, disproportionately long fins, triangular and dagger-sharp teeth, and, to top it all, not at all friendly character - a meeting with this persistent and unshakable killer, stubbornly pursuing his goal, can have sad and even tragic consequences.

Fortunately, whitetip sharks are rarely seen near the coast, but they are responsible for a huge number of victims in the open ocean, including in cases of plane crashes or shipwrecks with numerous victims in the water.

Representatives of this species live in almost all tropical and subtropical waters of the globe.

3. Sea jungle tiger - danger is imminent

The third, leading place in the list of the most aggressive and dangerous sharks for humans belongs to. It owes its name to its peculiar color - an interlacing of dark and white stripes on the back of young individuals, which fades with age.

However, the tiger coloring is not the only feature of this fish that makes it recognizable: they have a blunt and short snout with a characteristic grin, a spindle-shaped body and impressive sizes, reaching 4-5 meters in length.

The warm Caribbean Sea and the Gulf of Mexico are the favorite habitats of tiger sharks. It is not uncommon for these aggressive creatures to open the “hunting season” on the coasts, in popular beach holiday destinations. Usually slow, during an attack tiger sharks are capable of developing stunning speeds, leaving the victim no chance of escape.

Photo of a tiger shark

2. The most famous dangerous shark is the White Death

The second place is rightfully occupied by a real murderer - a ruthless and bloodthirsty woman, well known to everyone from the film "Jaws". Its mere appearance can cause shock, because the size of a white shark reaches 6 meters or more, and the weight of the monster sometimes exceeds 3 tons.

Watch video - White shark attacks:

Gluttonous and strong, it can attack a person not only in warm, but also moderately cool water, in the open sea and in shallow water, and its silent and sudden appearance has long become a kind of calling card of this monster.

High speed, huge jaws, terrifying size, persistence and aggressiveness - this is what makes this fish with a lead-gray back and dirty white belly one of the most dangerous sharks that ever existed on earth.

This predator has chosen tropical and subtropical latitudes, and in Australia, where many cases of white shark attacks have been recorded, it is called the “White Death”.

Photo: White Shark

No. 1 among dangerous predators is the bull (blunt-snout) shark

And finally, the undisputed leader of the top ten is the most dangerous, unpredictable and bloodthirsty, guilty of many unprovoked attacks on humans.

It seems as if nature itself made sure that the primacy went to this particular representative of the shark clan, providing it with a changing color of gray tones, allowing it to skillfully camouflage itself in shallow water, the ability to live in both salt and fresh water (rivers, lakes, estuaries), a unique maneuverability, powerful jaws, a set of impeccably sharp teeth, extraordinary gluttony and extreme belligerence towards people.

You can meet a bull shark in warm waters all over the world - the Bahamas, which are so popular among tourists, are especially dangerous in this regard.

Its impressive size (up to 4 meters) and natural aggressiveness deprive it of a sense of danger: a signature head blow, a swift throw, a fatal bite - this is the scenario for the attacks of this most dangerous shark, the ending of which, alas, is almost always tragic.

According to data, about 50 people die annually from the teeth of a bull shark, and about 100 people become crippled.

A shark is a formidable sea predator, persistently pursuing its goal to the end and rarely retreating. It is not for nothing that people who are purposeful, persistent in achieving their goals, and tenacious are also called sharks.

But today we will talk specifically about representatives of aquatic fauna.

These predators belong to the chordates, class cartilaginous, superorder “sharks”. “Shark” in the Russian interpretation dates back to the times of the Vikings, who called all fish “hakall”.

On our territory in the 18th century, dangerous marine inhabitants were called this way, and this name was pronounced “sharks”.

Most sharks are found in salt waters, but some specimens are also found in fresh waters.

Description of the shark and structural features

As a result of the diversity of species, the length of sharks varies from 20 cm (small bottom sharks) to 20 m (whale sharks) with a weight of 34 tons.

The peculiarity of the structure of the shark skeleton is that it is completely boneless and contains only cartilage. The streamlined body is covered with embossed scales with protrusions as strong as teeth, which is why it is called “skin denticles.” Pay attention to the photo of the shark.

The shark breathes through slits in the gills located in front of the pectoral fins.

The shark has low blood pressure and therefore needs to be in constant motion to support its heart, stimulating blood flow and causing constant muscle contractions.

However, there are also individuals that can calmly lie on the bottom and pump water through their gills.

Another structural feature is the absence of a swim bladder, unlike other bony fish.

The shark swims due to its huge liver, which makes up 1/3 of the mass of the predator, low cartilage density and fins.

Thanks to its elasticity, sharks' stomachs can accommodate enormous amounts of food. But the acidity of the gastric juice is not always enough to digest such a mass, as a result of which the shark has to get rid of the excess on its own, but without harming the stomach.

Sharks' vision is 10 times greater than that of humans. She hears with the help of her inner ear and is able to perceive infrasounds and low frequencies.

One can envy the shark’s sense of smell, because it smells both in the air and in the water. Predators are especially sensitive to the smell of blood; this is equivalent to a teaspoon for an entire swimming pool.

When moving, sharks reach speeds of no more than 5-8 km/h, and when chasing prey, almost 20 km/h. A white shark can reach speeds of almost 50 km/h.

The life cycle of these dangerous inhabitants is on average about 30 years, although whale sharks, polar sharks and southern dogfish sometimes live more than 100 years.

The teeth of this dangerous predator are long and sharp in the shape of a cone. The gray shark has flat, sharp teeth that are capable of tearing large prey to pieces.

The whale mainly feeds on plankton, which is why its teeth are small, about 5 mm, but their number is several thousand.

The horned species of shark consumes bottom food with the help of small teeth in front and large teeth in the back. In cases of damage or loss of teeth, they are immediately replaced with new ones that grow inside the mouth.

The size of the teeth varies for each species. So, in a white predator, the tooth is 5 cm, and in individuals that feed on plankton - 5 mm.

Habitats

There are plenty of places on earth where sharks live. They are especially common in the waters of the equator and the seas adjacent to it, in reefs and water areas off the coast.

Some types of sharks are able to live in any water, such as gray and blunt-snout sharks. A comfortable depth for them is about 2000 m, sometimes 3000 m.

Predator feeding

Each species has its own diet and preferences. But most prefer the fish assortment. Deep-sea species feed on crabs and other crustaceans.

White sharks even prefer seals, fur seals and cetaceans, while tiger sharks consume everything indiscriminately. They feed on plankton and small things: largemouth, whale, giant.

Species of sharks

Modern catalogs of the varieties of these dangerous creatures number almost 450 species, these are 8 orders:

• Carcharine sharks. This order includes 48 genera and 260 species. These include: hammerhead shark, silky shark, tiger shark, blunt-nosed shark, etc.;
• Sharks are heterogeneous. These include: zebra bull shark, helmeted bull shark, Mozambican bull shark;
• Polygill sharks: frilled shark, sevengill shark, etc.;
• Lamniform sharks: giant, fox, herring, false sand, sand, etc.;
• Wobbegong sharks: there are 32 species. The most famous of them is the whale one;
• Sawtooth sharks, includes one species: sawtooth sharks.;
• Catraniform sharks include 112 species. The most famous of them are: southern katran, nogotitsa;
• Sharks are flat-bodied. Looks like a stingray.

Features of reproduction

The sexual maturity of sharks is a rather long process. Many females reach it at 10 years of age, and whales reach it at 30-40 years of age.

Sharks are characterized by internal fertilization: some lay eggs, others are characterized by ovoviviparity, and others by viviparity. The incubation period lasts from several months to 2 years, depending on the species.

One clutch contains 2-12 eggs. Fertilized eggs are covered in white, which is topped with a horn-like film to protect them from predators.

The baby that is born immediately begins an independent life. Sharks in captivity are capable of fertilization without males.

In ovoviviparous sharks, the cubs that hatch in the womb remain in the oviducts for some time and eat unfertilized eggs, and then, as they grow up, their fellows. Therefore, one cub is subsequently born. The length of a newborn white shark is 155 cm, and that of a tiger shark is no more than 76 cm.

Danger to people

According to statistics, the countries with the highest number of dangerous attacks on people are: USA, Australia, Brazil, South Africa and New Zealand.

But according to unconfirmed data: African countries, regions of Mozambique, Tanzania and Ghana. It is worth noting that this most often occurs in ocean waters.

From time immemorial, people have associated the character of sharks with cruel killers and universal evil. There are many legends about the atrocities of killer sharks.

Of course, all this is too exaggerated, thanks to wild imagination. Sharks do not like human meat at all, and will most likely spit it back out. This diet is not for them.

Shark photo

Currently, more than 450 species of sharks are known: from the deep-sea shallow Etmopterus perryi, only 17 cm long, to the whale shark, whose length reaches 12 meters.

Sharks 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.

Skeleton

The skeleton of a shark is noticeably different from the skeleton of bony fish - it has no bones, and is formed entirely from cartilaginous tissue.

Leather

Sharks are covered with placoid scales, the scales of which are rhombic plates ending in a spine protruding outward from the skin. In structure and strength, the scales are close to bones, which gives reason to call them dermal denticles. These teeth have a wide base, a flattened shape and a very relief-defined crown. In most cases, the crowns are very sharp and fit tightly together, so the skin may appear relatively smooth if you run your hand from head to tail, and vice versa - rough, like sandpaper, if you move in the opposite direction.

Teeth and jaws

The teeth of most sharks are shaped like sharp dentin cones and sit on the cartilage of the upper and lower jaws. Teeth are regularly replaced as they fall out or wear out according to the conveyor belt principle - their replacement is constantly growing from the inside. In their structure and origin, these are modified placoid scales.

Depending on their 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 such as tiger sharks have knife-shaped teeth designed for tearing the flesh of large prey. Plankton-eating sharks have vestigial small teeth.

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.

Most species of sharks need to constantly move in order to maintain their breathing, so they cannot sleep for long periods of time. However, some species, such as the whiskered nurse shark, are able to pump water through their gills, allowing them to rest on the bottom.

Digestive system

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 three-meter Australian sand shark weighing 150 kg kept in captivity ate only 80-90 kg of fish per year.

Sharks periodically perform stomach eversion - 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.

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? The uniquely shaped nostrils, spaced at a decent distance from each other on the head, make it possible 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.

Sharks can smell blood diluted 1:1,000,000, roughly equivalent to one teaspoon in a medium-sized swimming pool.

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.

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.

Electro- and magnetoreception

Are the electroreceptive apparatus of sharks represented by ampullae of Lorenzini? 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.

Lifespan

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 it can be said that most species 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.

Reproduction

Sharks have the internal fertilization characteristic of cartilaginous fish, a primitive uterus and a fairly perfect placental connection. The fetus develops 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 pups 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.

Lifestyle

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.

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. 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.

The ratio of brain to body mass in sharks is roughly equivalent to that of birds and mammals.

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.

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 are 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 omnivorous and swallow almost anything that comes their way.

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.

Fishing and hunting

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.

Liver contains fat rich in vitamin A and B vitamins, and is used as a raw material for the manufacture of medicines.

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.

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.

Common Misconceptions About Sharks

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.

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).

Sharks have a bad reputation due to misinformation. However, you will come to appreciate these fish once you learn the basic facts about shark life.

Approximately 465 known shark species live in the oceans today

It is difficult to estimate the population size of each shark species individually because each species' range covers such a large geographic area. But the total number of sharks in the wild is constantly declining.

While many of us are afraid of sharks, we need to know that Man is the largest predator on the planet. People are scarier than sharks. In fact, humans kill more than 73 million sharks every year.

On average, 30 to 50 shark attacks are reported annually, only 5 to 10 of these attacks are fatal to humans. The chances of dying from a shark attack are much lower than the chances of dying from a hornet, wasp, bee or dog attack. You may think of sharks as terrifying, man-eating predators, but in reality, only 3% of sharks—a small minority—are dangerous to humans.

Sharks are the predecessors of dinosaurs. They are 200 million years older than dinosaurs. Moreover, over 450 million years (the geological age of sharks), these ancient representatives of the fauna have not changed at all.

Sharks are the top of the food chain - they are the top predators of the sea and regulate the populations of all species.

Recent studies have shown that there is a massive depletion of sharks. This has cascading consequences for changes in the entire ocean ecosystem.

Sharks are fish

Sharks belong to the family of cartilaginous fish. The difference between cartilaginous fish and bony fish is that the cartilage skeleton is lighter and more flexible.

Sharks breathe through a series of gill slits, with 5-7 gill slits located on either side of their body.

All sharks have several rows of teeth. They lose teeth on a regular basis, but new teeth continue to grow and replace the lost ones.

When a shark dies, the salt of the seawater completely dissolves its skeleton, leaving only its teeth.

"Shark Skin" consists of a series of scales that act as an outer frame for easy movement in the water. The top side of the shark is usually dark to blend in with the water and is not visible from above. And their lower part is white, in harmony with the lighter surface of the sea below. This helps sharks camouflage themselves.

Sharks have a very keen sense of smell, capable of detecting blood in the water from several miles away.

Sharks' eyes have a surprisingly wide field of view, covering almost 360 degrees. Their panoramic view of the underwater world is hindered only by two blind spots, one in front of the snout and the other directly behind the head.

Sharks are adapted to life in a wide range of different aquatic temperatures.

Some species live in shallow, coastal areas, other species live in deep waters on the ocean floor, and others live on the surface in the open ocean.

The goblin shark lives along outer continental shelves and underwater ridges. Their dwellings are too deep for people, so we know almost nothing about them.

Some species, such as the bull shark, are able to live in both salt and fresh water.

Most sharks are active in the evening and at night - this is their hunting time.

Sharks are capable of migrating long distances—on a scale that can cross entire ocean basins.

There are solitary species of sharks, and there are social ones - preferring to live in groups.

How do sharks feed and what do they eat?

• Some shark species, such as the great white shark, attack from below. As a rule, their prey is seals and sea lions.
• Species of sharks that live on the ocean floor have developed the ability to collect bottom food.
• There are species of sharks that attack schooling fish.
• Large and basking sharks feed like whales, filtering ocean water through their wide-open mouths. During filtration, large quantities of plankton and krill are ingested.

Shark Facts You Should Know

Sharks mature slowly, reaching reproductive age at 12 to 15 years. And a whale shark can reproduce its first offspring only after reaching the age of 30 years. This, combined with the fact that many species only give birth to one or two young, means that sharks have great difficulty recovering. That's why their population has declined so much.

The gestation period of a shark lasts from 5 months to 2 years, depending on the type of shark. Some female sharks use sperm from multiple males to create a single litter.

Soon after birth, the baby sharks, while still puppies, swim away from their mother. They are able to stand up for themselves from birth. Baby sharks are born with a full set of teeth and are able to feed and live independently.

All sharks are characterized by cannibalism. At the same time, not only adults are cannibals; prenatal cannibalism is exhibited by baby sharks, feeding on the eggs of fellow sharks, which the female produces during pregnancy. That’s why out of a litter of 80 eggs, only 1-2 baby sharks are born.

Sharks that eat the eggs of their siblings in the womb are not vicious. They are simply looking for nutrients to support themselves as they grow.

A baby shark is a miniature copy of its parents. The photo shows tiger sharks.

The largest known extinct shark species, Megalodon, reached a maximum length of 20 meters (67 ft).

Of the living creatures, the largest is the gigantic whale shark. It can reach a body length of 15 meters.

TOP smallest sharks:

1. Dwarf spiny shark (Squaliolus laticaudus) - the usual body length is 15-20 cm, and the maximum is 24 cm.
2. The dwarf glow shark (Euprotomicrus bispinatus) is a fish 20-25 cm long.
3. Longnose shark (Heteroscymnoides marleyi) is a small fish, 12.5-30 cm long.
4. Lighttail shark (Euprotomicroides zantedexchia) - maximum length 20 cm.
5. Cuban marten shark (Triakidae barbouri) - maximum 35-40 cm.

Glowing shark - record holder of minimalism

Some known shark species drown if they stop moving. They do not have a swim bladder, so they must swim all the time - they expend a lot of energy in movement. Compare. A great white shark needs 11 tons of food every year! And a human being eats half a ton of food a year.

The great white shark (Carcharodon carcharias), Mako (blacktip, mackerel, blue-gray) shark and Salmon sharks (Lamna ditropis) of the herring family - do not have muscles, they pump water through the mouth and gills. They keep their mouths open the entire time they swim, this keeps them alive.

Sharks have large livers. Shark livers contain a lot of oil. This makes the liver a relatively buoyant organ, helping sharks maintain balance in the water.

Poking a shark in the nose or eyes to fend off their attack does not help. It’s better to hit them in the gills (these are large slits along the snout) - this tactic works much more effectively against sharks. Most sharks swim away when their target is difficult to reach for their food. You are more likely to die from drowning than from a shark attack. This is true.

Tiger sharks, great white sharks and bull sharks (blunt-nosed bull sharks) generally attack people from behind. Their prey is anything that is human-sized. They are strong enough to attack and deliver a fatal bite.

In the extremely rare event that a shark bites you, it most likely will not attempt a second bite. When attacking people, sharks usually hold them for a few seconds and then release them once they realize that what they have tasted is not a sea creature.

20-30 percent of sharks are critically endangered. The main culprit is industrial fishing, where sharks are accidentally caught on hooks and nets. And due to the excessive popularity of shark fins (commercial demand), the populations of some shark species have declined by approximately 90%.

The blue shark (Prionace glauca) is considered the rarest shark species.

Another rare species is the frilled shark Chlamydoselachus anguineus. They are often called living fossil sharks. They live at great ocean depths of 1000-1500 meters.

Shark eggs are very different in appearance from those eggs laid by birds, lizards or crocodiles. They are often protected by capsules or leathery pouches. In the case of the horn shark, they are called "mermaid purses."

Contrary to popular belief, sharks are not colorblind; they are good at distinguishing colors. Divers claim that sharks are attracted to certain colors - yellow, the color of some wetsuits, is a "yummy" color for them. While shark color preferences have not been proven, scientists do know that sharks living in a well-lit aquarium exhibit color discrimination, which humans use as cues.

Angel sharks, also known as sand devils (Squatina), burrow into piles of sand. From there they lie in wait, waiting for unsuspecting fish.