Sharks - description, types, what they eat, features, how long they live, where they live, photos and videos

Author: IdIuaM

08 July 2022 19:39

Community: Animals

Tags: sharks sea oceans

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Shark: description and photo. What does a shark look like?

There are over 500 different species of sharks. The superorder is characterized by a variety of sizes, shapes and other features. For example, the smallest deep-sea shark with a length of 17 cm is considered the smallest. One of the largest is the whale shark (up to 20 m in length). The same applies to weight - from 200 grams to several tens of tons.

Unlike bony fish, sharks have a skeleton made of cartilage tissue. At the same time, it is endowed with a sufficient level of rigidity. The skeleton includes 4 sections:

spinal column (axial skeleton);
unpaired fins;
paired limbs (pelvic and pectoral fins);
scull.

Anatomy of a shark
The maneuverability and speed of movement of a fish is ensured by several factors. The fish performs wave-like movements using its body, tail and fins. The tail fin, which includes two blades, serves as the main “engine” for the shark and also helps set the direction of movement. The fins located on the sides allow you to increase the speed of movement and perform maneuvers.

Shark tail fin

Each species of shark has certain anatomical features of its tail.
For example, a white shark moves very quickly, so its tail fin blades are almost identical. In other species, the upper lobe is larger than the lower one. Interesting fact : when a shark slows down, dives down or rises up, the paired fins along with the dorsal fins help it maintain balance. In this case, the fish is not able to swim in the opposite direction.

Dorsal fin of a shark
The body of sharks is covered with very strong placoid scales. Each scale is a diamond-shaped plate with a spike at the protruding end. Shark scales are called dermal denticles because they are similar to teeth in terms of strength and structure. The scales fit tightly to each other. Because of this, at first glance it seems that the skin is perfectly smooth and even. But if you run your hand over it in the opposite direction, from the tail to the head, a rough effect immediately becomes noticeable - the skin feels like sandpaper to the touch.

Shark skin under a microscope

The musculature of a shark is represented by several muscle groups:

cardiac;
somatic (red and white, responsible for body movement);
visceral (muscles in blood vessels and internal organs).

The body of sharks is quite simple, and the metabolism is slow. Because of this, they cannot undergo prolonged physical activity. As a result of intense activity, excessive amounts of lactic acid accumulate in the body, which can negatively affect internal processes.

Sharks breathe oxygen from the water through their gills. The role of their respiratory organs is performed by the gill slits. They are located in front of the pectoral fins. The number of slits depends on the type of shark - from 5 to 7 pairs.

Shark gill slits

Due to the work of the heart, blood in sharks is transported through the gill artery into the vessels that are located in the gills. There the blood is saturated with oxygen and sent to the organs. However, blood pressure is not enough to supply the entire body with enough oxygen. Therefore, the shark is in constant motion - muscle contraction increases blood flow.

Bony fish have a swim bladder filled with gas. Sharks do not have it, so buoyancy is provided by the huge liver, as well as the skeleton and fins. And sand sharks imitate a swim bladder, filling the stomach with air.

Most sharks are cold-blooded with the exception of about 8 species. In white, blue and other sharks, certain parts of the body have a higher temperature than the environment. This allows them to move faster in cold water. Active muscle work contributes to an increase in temperature.

The stomach of sharks is U-shaped and can easily stretch. The liver occupies about 30% of the volume of the entire body. In addition to participating in buoyancy processes, it serves as a kind of storage facility, which contains useful substances and energy reserves.

The shark spends its accumulated resources for a very long time and gradually after eating, so it is capable of starving for a long time. For example, a shark weighing 150 kg requires about 80-90 kg of fish per year. From time to time, fish have to empty their stomachs of food debris. To do this, they turn it out through the mouth without causing absolutely any damage to the teeth.

For sharks, the main sensory system is a well-developed sense of smell. They are excellent at distinguishing odors by passing water through their nostrils to the receptors.

Interesting fact : some sharks have such sensitive receptors that they recognize the smell of blood in a ratio of 1 to 1 million. That is, they are able to sense it at a great distance, dissolved in a large mass of water.

The vision of some fish species is characterized by increased acuity. In addition, they are able to distinguish small details and some colors. Perception frequency – 45 frames per second. Some species have blinking eyelids, others do not. To protect their eyes from damage, the second type of shark rolls them up during an attack.

Shark eyes and nostrils

The organ of hearing is the inner ear, located inside the cartilaginous capsule. Predatory fish are able to detect low-frequency sounds and infrasound. The ear also helps maintain balance.

Interesting fact : the white shark has the best hearing among sharks.

Sharks have a sensitive organ - the lateral line, which runs inside the skin along the side of the body. It reacts to water fluctuations and allows fish to navigate in space, hunt and perform other vital functions.

Shark lateral line

General characteristics of sharks

Sharks are conventionally 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.

How many teeth does a shark have?

The shape, size and number of teeth depend on what kind of life the shark leads and what it eats. Teeth are the main weapon of these predators and their growth continues throughout the entire life cycle of the fish. This is nothing more than modified placoid scales covering the skin.

Interesting: Why don't fish blink? Description, photo and video

Most sharks have teeth growing in several rows - from 3 to 20 on both jaws. Each row contains about 30 teeth. Thus, an adult can have 200-15,000 teeth. However, they do not have roots, so teeth change quite often and unnoticed by the predator itself.

White shark teeth

Diet primarily affects the size and shape of teeth. Most predator sharks have sharp, cone-shaped teeth (about 5 cm long). If fish feed on hard-shelled food, they need flat, crushing teeth. Sharks that hunt large prey have wide and serrated teeth. Fish that feed on plankton have small teeth - only 3-5 mm.

Number of teeth in different types of sharks:

white and brindle - 5-6 rows, up to 300;
mustachioed - 5-7 rows, up to 500;
hammerhead shark – 15-17 rows, up to 700;
sand tiger - 42-28 rows, up to 1300;
giant – 6-10 rows, up to 2000;
whale - 18-20 rows, up to 15,000.

Whale shark mouth

Sharks and man

People are afraid of sharks and this is not at all surprising, since they are predatory fish of enormous size. In addition, there are enough cases of shark attacks on humans that sharks have acquired such a negative image for themselves. On the other hand, people hunt sharks not to reduce the incidence of attacks to zero, but because of the pursuit of profit.

Shark fishing

More than 100 species of sharks are listed as commercial fisheries. They are also hunted by those who practice extreme types of fishing. In addition, it is believed that sharks are to blame for the decrease in annual fish catches. Therefore, they believe that sharks should be destroyed.

Every year, up to 100 million individuals are caught in the world's oceans, and production volumes do not fall, despite significant restrictions and prohibitions. Most of the individuals are caught in the Atlantic Ocean, about 30 percent are found in the Indian Ocean and a little less in the Pacific Ocean.

Shark fishing is done based on several factors. For example:

Purposeful fishing, when all parts of the body are used for their intended purpose.
Accidental bycatch occurs when sharks are caught in nets while fishing for other fish species.
Finning is a hunt for shark fins.

Important point! “Finning” is considered the most barbaric method of killing sharks, since the fins of a caught shark are cut off, after which the shark is left on the shore or thrown into the sea.

These days, Hong Kong is considered the world center for this type of trade, accounting for almost 80 percent. The rest belongs to the EU countries.

Shark attack on a person

According to experts, sharks pose a minimal threat, although this problem has been greatly exaggerated by the media. Statistics show that the chances of becoming the target of an attack by these predators are minimized. For example, in the United States at least 3 thousand citizens drown every year and only one death is associated with a shark attack. And if we consider that only a few species are capable of such a step, then we can safely say that the fear of sharks is not just exaggerated, but significantly exaggerated.

Species of sharks such as long-nosed, blunt-nosed, white and tiger sharks can decide to become aggressive towards humans. Sometimes other species do this, such as hammerhead, mako, Galapagos, blue, silk, lemon and dark gray, although encounters with these species do not end tragically for humans.

Keeping sharks in captivity

Often in large aquariums you can also see sharks, which swim importantly among the many underwater inhabitants. Unfortunately, not all species of sharks can be transferred from the world's oceans to an artificial environment without any problems. Sharks, especially large and aggressive ones, can create a number of problems, both during catching and during transportation. Firstly, when pulling such predators out of the water, you can easily harm them, especially since it is at this moment that the shark is the most aggressive. Secondly, a shark can crush its internal organs with its weight.

The size of the aquarium also plays an important role, given the size of the shark and how sensitive it is to electromagnetic fields. In other words, it is necessary to create extremely comfortable conditions for the shark, and this is not so easy, since even the pool may turn out to be too small.

Sharks in culture

If you familiarize yourself with ancient Greek myths, you will definitely find mention of sharks. Not so long ago, the Japanese considered these predators to be sea demons who took the souls of sinners into the sea. Australian aborigines inhabiting the northeast of the country generally believed that the “Maka” shark was the ancestor of their tribes. Polynesians living on the Hawaiian Islands have a completely different attitude towards sharks. According to their ancestors, the nine sharks represent the gods who protect both the ocean and the entire Hawaiian people.

Interesting to know! Not all of Polynesia is so kind to sharks. Some tribes take a more realistic view of life and believe that sharks are just a source of food intended for the livelihoods of the tribes. In some parts she is called a werewolf who is able to feast on human flesh.

Nowadays, you hear and see a lot about sharks. After such ambiguous information, every person will definitely believe in the stories that the shark is nothing more than a bloodthirsty predator, which is busy tracking how to find a person in the ocean and easily deal with him. At the same time, people forget that sharks, like all living creatures, are an integral part of the ecosystem of the World Ocean.

Fish or mammal?

The term "mammal" refers to feeding its young with milk. Sharks do not do this, so they are clearly classified as fish. In addition, they breathe using gills.

Many sharks are comparable in size to large marine mammals, such as some species of whales. However, this does not give reason to classify them in this category.

Comparison of the sizes of whales and white sharks

The appearance of some shark species can also be misleading. For example, the frilled shark looks like an eel, the carpet shark lives on the bottom, and the hammerhead shark is easily recognizable by its characteristic head shape.

Interesting fact : an unusual representative of sharks, the carpet shark, has an extraordinary appearance, swims poorly and most of the time lies on the bottom waiting for fish to swim by.

lemon shark

This species of shark typically lives in shallow bays - parts of the seas separated from open waters by rocks that protect them from wind and waves. The length of adult individuals is about 3 meters, and the weight reaches 180 kilograms. Typically, these sharks hunt only at night, and primarily feed on fish and shellfish.

Due to their large size, they are considered potentially life-threatening to humans. However, no fatal attacks have yet been recorded in history. There is a known case when a lemon shark attacked a diver with a GoPro camera - fortunately, the person was not injured, which cannot be said about the recording equipment.

Behavior and lifestyle

It is believed that sharks prefer to lead a solitary lifestyle and not form schools. However, from time to time they can be seen in groups, and quite large ones at that. Most often these are places with abundant food. Sharks also live in groups during reproduction.

Certain species of sharks prefer not to change their usual habitat. Others migrate, covering distances of thousands of kilometers. The migration system of fish is much more complex than that of birds. There is also a hierarchical system among sharks, according to which some species are subordinate to others. For example, despite the same size, the silky shark is subordinate to the white shark.

Sharks do not always attack immediately as soon as they see an enemy. They communicate through movements. If an unwanted object approaches, the predator can give a threatening signal by moving its fins more intensely.

School of hammerhead sharks

The average speed of sharks is about 8 km/h. If necessary, this figure can increase to 19 km/h. Some species (white shark, etc.) make high-speed bursts of about 50 km/h. This ability is inherent in them due to the previously mentioned temperature difference.

According to new research, sharks are capable of displaying playfulness, curiosity, intelligence and other signs of intelligence. They often overcome difficulties as part of a group.

How do sharks sleep?

For a long time it was believed that sharks cannot sleep because they need to constantly move to obtain oxygen. However, experts say that at least some species of sharks (demersal) can remain dormant for some time.

Interesting fact : only some sharks can remain stationary for a long time (during sleep), for example, the whiskered nurse shark. At the same time, they pump water through their gills and receive oxygen.

Whiskered nurse shark resting on the bottom

When sleeping on the bottom, sharks do not close their eyes or use their nostrils. However, they may involve squirters. Some species can sleep while moving because their spinal cord is responsible for movement. Another theory is the ability to turn off the hemispheres of the brain in turn.

Sharks can also “take a break” in underwater caves, where there is a fairly strong current. Interestingly, in one of these caves, scuba divers discovered Caribbean reef sharks. They appeared to be sleeping, despite the fact that this species is an active swimmer.

How and what do sharks drink?

Strictly speaking, sharks do not need to regularly drink water in the strictest sense of the word. Being in salt water, they absorb it constantly, and through the walls of the stomach the fresh component is absorbed into the blood and spread throughout the body.

At the same time, the fluid in the shark's body contains less salts than the water in the environment. A physical process called osmotic pressure occurs - a liquid with a lower concentration of salts rushes towards a liquid with a higher concentration. They contact through the skin of the fish. Thus, the sharks’ body gets rid of excess salt.

Interesting fact : sharks, which are able to live in both salt and fresh water (or only fresh), have the unique ability to adapt their body to life in a certain environment. For example, a blunt-nosed shark.

Briefly about ancient shark species

From the point of view of evolution, the superorder of sharks is one of its most successful projects. Judge for yourself - over several time periods spanning hundreds of millions of years, sharks were not only able to survive, but also developed significantly.

Together with stingrays, they formed an independent branch among sea creatures - cartilaginous fish (Chondrichthyes).

Today, 550 species of sharks are known and documented, and this list is far from complete, because it is not possible to detect and discover all types of sharks due to the lack of knowledge and vastness of the World Ocean.

Man cannot freely explore the ocean depths - researchers still do not have the necessary deep-sea vehicles with powerful and efficient equipment.

Unlike us, sharks move freely through the ocean without needing air or suffering from pressure at great depths.

Some species of modern sharks exist only in photographs, they were caught by accident and only once - no one has ever seen them again.

For example, Scymnodalatias sherwoodi or dog shark - this species is described from a single specimen caught more than a hundred years ago off the New Zealand coast.

Scientists suggest that this rare species of small shark spends its life at great depths (about 3 kilometers) and therefore practically nothing is known about it - deep-sea descent and research using portholes, searchlights and bathyscaphe manipulators are extremely ineffective.

Ancient sharks from the age of dinosaurs

Sharks are the recognized leaders of the evolutionary race. If you compare the results of the evolution of sharks and dinosaurs, the latter lose.

That’s right - in the Jurassic period, traditionally considered the era of dinosaurs, there were about 800 species of dinosaurs, while there were about 2-3 thousand species of sharks!

The first sharks actively explored the World Ocean 200 million years before the appearance of dinosaurs. These shark species are known from imprints found in sedimentary rocks and ancient fossilized teeth.

Perfect marine predators suffered several global catastrophes that killed thousands of other species - each global cataclysm made sharks stronger, and evolution gradually took them to a new qualitative level.

Sharks are not primitive - they are different, unique. Think about it: how many living creatures are there on the planet today, whose development period spans hundreds of millions of years?

Scientists consider the Carboniferous period (360-286 million years ago) to be the first stage in the development of modern sharks - during this period, powerful cataclysms greatly reduced the number of armored fish (placoderms), which had long reigned in the seas.

The sharks did not hesitate and hastened to capture new territories, changing and forming new species of the most bizarre forms.

For example, the species of Stethacanthus sharks (lat. Stethacanthus) - on top of the males of these half-meter sharks, behind the snake-like head, there was a strange flat fin ending with many small teeth like a grater. This design of the fin “with teeth” gave rise to many theories about its purpose: it could be a suction cup for hitchhiking, a means of protection from enemies and attack in battles for females.

Photo of an ancient shark Stethacanthus

How long do sharks live?

The average lifespan of most sharks is about 30 years. However, there are also long-lived species. These include whale sharks, spotted spiny sharks, and Greenland polar sharks, which can live up to 100 years. It is the Greenland polar shark that is considered the record holder in terms of longevity. For example, the age of one of them would be estimated by scientists at 392 years with an error of 100 years. On average, the species lives up to 272 years.

Interesting fact : in 2022, scientists discovered the oldest and at the same time the largest shark, a representative of the Greenland polar species. Estimated age is about 500 years. The fact is that over the course of a year, sharks of this species grow 1 cm in length. And the length of this individual was 5.4 m.

Greenland shark

Longevity is directly related to a shark's teeth, because if a predator loses its main weapon, it will not be able to feed.

Polygill sharks

The order has existed for hundreds of millions of years. An unusual number of gill slits and a special shape of teeth distinguish the patriarchs of the shark tribe. They live in deep water.

Sevengill (straightnose) shark

Slender body of ash color with a narrow head. The fish is small in size, up to 100-120 cm in length. It exhibits an aggressive character. After catching it, it tries to bite the offender.

Frilled shark

The length of the flexible elongated body is approximately 1.5-2 m. The ability to bend resembles a snake. Color grey-brown. The membranes of the gills form leather bags similar to a cloak. A dangerous predator with roots from the Cretaceous period. The shark is called a living fossil for its lack of signs of evolution. The second name was received for the numerous folds on the skin.

Where do sharks live?

Sharks are common in the waters of the world's oceans. Thus, they live in all oceans and seas. Cartilaginous fish prefer coastal waters, reef zones, equatorial and near-equatorial waters.

Some species of sharks feel equally comfortable in both salt and fresh water. Therefore, they can swim into rivers. These species include the blunt-nosed shark, the common gray shark and others. On average, predators prefer a depth of about 2000 m, sometimes swimming 3000 m deep.

Interesting: Sharks and humans

Habitat of the white shark

Sharks of the Black Sea

Due to the high content of hydrogen sulfide in the waters of the Black Sea, the diversity of sharks that cannot tolerate it is small here. There are 2 species - the katran and the cat shark. These are small-sized individuals that do not pose a danger to humans. The only thing is that the body of the katran is strewn with thorns, contact with which is fraught with negative consequences.

There are also rare cases when predatory species of sharks swam into the waters of the Black Sea. For example, a great white shark can temporarily swim to the southern part of the Crimean coast and the western territories of the Krasnodar Territory.

Wobbegong sharks

The peculiarity of the order is the unusually smooth and rounded shapes of predators among their relatives. Different types of sharks are united by their variegated colors and bizarre growths on their bodies. Many representatives lead a bottom-dwelling lifestyle.

Whale shark

An amazing giant up to 20 meters long. Found in reservoirs of tropical zones and subtropics. They do not tolerate cold water well. A beautiful, harmless predator whose food consists of mollusks and crayfish. Divers can pat him on the back.

It amazes with its grace and unique appearance. Small eyes on a flattened head hide in a fold of skin in case of danger. Small teeth are arranged in 300 rows, their total number is approximately 15,000 pieces. They lead a solitary life and rarely form small groups.

Carpal wobbegong

It is difficult to recognize this strange creature as a relative of the ocean predators that terrify all aquatic inhabitants. The aerobatics of camouflage consists of a flat body covered with some kind of rags.

It is very difficult to recognize fins and eyes. Sharks are often called mustachioed and bearded due to the fringe along the contour of their heads. Due to their unusual appearance, bottom sharks often become pets in public aquariums.

Zebra shark (leopard)

The spotted color is very reminiscent of a leopard, but no one will change the ingrained name. The leopard shark is often found in warm sea waters, at depths of up to 60 meters along coastlines. The beauty is often captured by underwater photographers.

The zebra shark in the photo reflects an atypical representative of its tribe. The smooth lines of the fins and body, rounded head, leathery protrusions along the body, and yellow-brown color create a spectacular appearance. Does not show aggression towards humans.

What does a shark eat?

The diet of sharks depends on the specific species, as well as its habitat. In general, it can be called diverse. Most representatives are carnivores. Some species are unpretentious, so they feed on everything that comes their way (for example, a tiger shark). The main part of the diet is fish, plankton, small mammals, and crustaceans.

Shark jumps out of the water

Thus, sharks that live on the bottom feed on crabs and other crustaceans. To do this, they have teeth that can bite through shells. Blue shark, mako, lamna hunt sea fish while on the move. The white shark prefers large fish and mammals. Whale and basking sharks, despite their impressive size, feed on plankton.

Interesting fact : a whale shark can open its mouth up to 4.6 meters.

Giant shark

The giant shark is the brightest representative of the largest species of fish. It is the second largest fish species after the whale shark. It reaches a length of up to 10 meters and weighs about 4 tons.

Like the whale shark, the basking shark feeds on plankton, but does not suck in water, but simply swims with its mouth open, filtering through its gills everything that gets into it. Thus, a giant shark is able to filter up to 2000 tons of water per hour.

Basking sharks are found in both the eastern and western hemispheres, preferring cool to warm-temperate latitudes and following the presence of plankton.

The basking shark is harmless to humans and today it is endangered.

Natural enemies of sharks

It is noteworthy that sharks exhibit predatory qualities from birth. For them, natural selection begins from the moment they are born. Cubs born earlier than others get rid of their brothers and sisters. Also, newly hatched sharks are preyed upon by larger species.

Natural enemies of sharks:

marlin;
swordfish;
dolphins, killer whales;
saltwater crocodile (freshwater).

Natural enemies of sharks
Representatives of the billfish family can attack sharks using their long and powerful “spear”. The same applies to swordfish, which, when attacked by a shark, pierces its gills with its long nose.

Dolphins and killer whales are the main rivals of sharks in terms of food production, since the former feed on fish, the latter on large mammals. And this is the basis of the diet for predator sharks. In addition, sharks suffer from bacteria and various parasites.

Lumniform sharks

The torpedo shape and powerful tail allow it to swim quickly. Large specimens are of commercial importance. Sharks are dangerous to humans.

Fox sharks

A distinctive feature of the species is the elongated upper lobe of the caudal fin. Used as a whip to stun prey. A cylindrical body, 3-4 m long, is adapted for high-speed movement.

Some species of sea foxes filter plankton and are not predators. Due to the taste of the meat, they have commercial value.

Shark breeding

Sharks are characterized by internal fertilization. Moreover, depending on the type, they can be:

viviparous;
ovoviviparous;
oviparous.

Sharks have a long period of puberty - on average about 10 years. A whale shark is capable of procreation only at 30-40 years of age. The incubation period also varies significantly - from a couple of months to 2 years.

Fish that reproduce oviparously lay 2-12 eggs. In this case, the eggs are covered with several shells. Including the external horn-like one. It protects the offspring from predators. Cubs become independent immediately after birth.

Shark egg capsules

In ovoviviparous fish, the young remain in the oviduct for some time. It is at this stage that natural selection operates and out of all the offspring, a maximum of 2 strongest individuals remain. The size of the cubs varies depending on the species. The offspring of the tiger shark are about 50-76 cm in length, and the white one is one and a half meters long.

baby shark

Bull shark

Females reach a length of 4 meters, males - up to 2.5 m. The maximum documented weight of a bull shark caught was 316.5 kg. On average, a bull shark lives 27-28 years.

The bull shark rightfully ranks 3rd on the list of the most dangerous shark species for humans. This is an extremely aggressive animal that has the right to claim the title of an ideal and all-powerful predator. It is almost impossible to escape from a terrible monster attacking a swimmer.

Feeding a bull shark by scuba divers:

These bloodthirsty predators usually attack in the morning or late twilight, and, often, at a shallow depth - only 0.5m - 1m.

The behavior of bull sharks is impossible to predict. They can swim peacefully nearby for a long time, and then suddenly attack the swimmer. This attack can be a simple exploratory bite or an outright attack.

Population and species status

According to recent data, about 25% of all shark species are on the verge of extinction. The total number of fish is declining at a fairly high rate. There are several reasons for this:

Low reproductive capacity - sharks focus on the quality of the offspring produced, not the quantity. That is why, of all the cubs, only a few of the strongest remain.
Shark fishing, in particular, is illegal.
Reducing the amount of food that predators eat. This includes a decline in the number of mammals.
Pollution of the World Ocean waters with waste. This is especially true for plastic.

Garbage continents (the Great Pacific Garbage Patch is highlighted in red)
It is worth noting that sharks, especially hungry ones, tend to consume everything in their path. That's why they are attracted to large piles of garbage floating in the ocean - they create vibrations. Sharks are also quite curious.

Shark squads

Many representatives of sharks have long been extinct; information about them is found only on the basis of archaeological data. Modern representatives of the superorder are divided into 8 orders:

Polybranchiformes;
Carchariformes;
Lamniformes;
Heterodonates;
Squatinaceae;
Katraniformes;
Sawtooth;
Wobbegong-shaped.

Over 90% of sharks are predators, but there are 3 species that feed on plankton.

Shark fishing

More than 100 species of sharks are fished, as are many other fish. The fishing industry is interested in shark meat, fins, cartilage, liver and skin. Fishing is most active in the Atlantic Ocean, followed by the Indian and Pacific Oceans.

Up to 100 million individuals are caught every year. Bans and restrictions on fishing are gradually being introduced, but its intensity is only increasing. Sharks are caught not only as a target fishery, but also accidentally - during the catch of other fish.

Shark and diver

There is a separate type of fishing - shark fin fishing. It is banned in some countries. Other reasons for catching sharks include increased danger on beaches and the threat of a decline in the population of other fish species.

Hammerhead shark

Hammerheads are large sharks. This is the most unusual shark. The main distinguishing feature of the hammerhead shark family is the shape of their head - it is completely unusual in shape - T-shaped, along the edges of which there are eyes.

According to one theory, the shark's head acquired the hammer shape gradually over millions of years, expanding each generation by a tiny distance. According to another theory, such a hammer did not appear as a result of gradual changes, but was the result of a sudden, bizarre mutation.

These sharks live in warm and temperate waters of the Pacific, Indian and Atlantic oceans at depths of up to 300-400 meters. These aggressive hunters feed on various types of fish, octopuses, squids and crustaceans.

Hammerhead sharks (except for the giant hammerhead) are up to 3.5-4.2 meters long and weigh about 450 kg.

In searching for food, the hammerhead shark is mainly helped not by its eyes, but by special receptors of electromagnetic pulses. The predator can detect electrical discharges of one millionth of a volt!

Due to its large size, many researchers consider the hammerhead shark to be one of the most dangerous sharks to humans. But she doesn’t specifically attack people. Many attacks that took place in front of numerous spectators are documented. One day, in 1805, three hammerhead sharks were caught in a net on Long Island. A human torso was found in the stomach of the largest of them.

One of the types of hammerheads - the giant hammerhead shark (average length 4-5 meters) - is listed in the International Red Book:

Shark attack on a person

According to international statistics, the largest number of shark attacks on people are recorded in countries such as the USA, Brazil, Australia, New Zealand and South Africa.

However, there is also unofficial data according to which African countries top the ranking of the most dangerous countries. Populations of dangerous and fairly large sharks live near Ghana, Tanzania, and Mozambique. Most attacks occur in ocean waters rather than in the seas.

White shark attacks (2015)

There are many myths surrounding sharks. They are considered the most dangerous predators, whose main goal is to attack people. This is only partially true. Sharks are indeed true predators and all safety tips must be followed.

However, most sharks attack people by mistake, confusing them with their real prey. Only some species, such as white, tiger and other sharks, can attack without any reason. In general, concerns about these fish are greatly exaggerated.

Interesting fact : in the list of threats that await a person in the water, the shark ranks last.

Mako shark

This species of shark, which lives in temperate and tropical seas, is terrifying not so much with its 4-meter body as with its agility. It is known that the speed of the mako shark reaches 74 kilometers per hour. At the same time, she can jump out of the water to a height of 6 meters - it’s scary to imagine how cruelly she can kill a person sitting calmly in a boat. There are as many as 20 such cases in history, but, fortunately, as a result, damage was caused only to swimming equipment.

As a rule, this type of shark hunts close to the shore, and sometimes eats fish caught in fishing nets. From 1980 to 2010, 42 attacks on humans were recorded, three of which were fatal. Usually the attack is made from the bottom up - the predator instantly bites off a piece of the victim's flesh. A person may well die from the injury he receives.

It looks creepy.

Keeping sharks in captivity

Only a few species of sharks can be found in captivity. Known or, conversely, rare species are of greatest interest. As a rule, they are distinguished by their large size and aggressive behavior. It is quite difficult to catch such sharks, as well as transport them. It is important not to damage them.

Whale shark in the aquarium

Specialists will also face difficulties when relocating an individual to an artificial tank. It must be spacious and durable enough, contain all the necessary equipment so that the shark feels safe. Support for normal functioning is required.

Interesting: What is the maximum overload when bungee jumping?

Sawtooth sharks

A distinctive feature of the representatives of the order is a jagged outgrowth on the snout, similar to a saw, and a pair of long antennae. The main function of the organ is to search for food. They literally plow up the bottom soil if they sense prey.

In case of danger, they swing a saw, inflicting wounds on the enemy with sharp teeth. The average length of an individual is 1.5 m. Sharks live in warm ocean waters, off the coasts of South Africa, Japan, and Australia.

Short-nosed sawnose

The length of the sawtooth outgrowth is approximately 23-24% of the length of the fish. The usual “saw” of its relatives reaches a third of the total body length. The color is gray-blue, the belly is light. With side blows of the saw, sharks injure their victims in order to then eat them. Leads a solitary lifestyle.

Dwarf saw-nos (African saw-nos)

There is information about catching dwarf (body length less than 60 cm) sawbills, but there is no scientific description. Very small shark species Like their relatives, they lead a bottom life on silt-sandy soil.

Sharks in culture

Sharks, as unique and interesting creatures, could not help but become part of the culture for many peoples of the world. At a minimum, everyone has probably seen Western films in which sharks act as real monsters.

But this is not the entire role of fish in cultural heritage. They are mentioned in Greek mythology, Japanese, Polynesian culture. In particular, for the inhabitants of the Hawaiian Islands, sharks are not dangerous predators, but sea guardians who protect the local people.

Australian aborigines regard them as gifts of nature intended for humans. The Chinese consider sharks as a fishery, namely, they are considered valuable in the field of food industry and traditional medicine.

In popular culture, a shark is an essential element of a horror film or thriller about sea monsters. Examples of films featuring predator sharks:

"Jaws" (1975);
"The Abyss" (1977);
"Deep Blue Sea" (1999);
“The Shallows” (2016), etc.

Hedgetooth sharks

Typical bottom inhabitants are of medium size. Many species are called bulls, which creates confusion with dangerous gray individuals called bulls. The squad contains rare species of sharks that are not dangerous to humans.

Zebra shark

It lives in shallow waters off the coast of Japan, China, and Australia. Narrow brown stripes on a light background resemble a zebra pattern. Dull short snout. It poses no danger to humans.

Zebra shark

Helmet shark

A rare species found off the Australian coast. The skin is covered with rough teeth. Unusual color of dark spots on a light brownish background. The average length of individuals is 1 m. They feed on sea urchins and small organisms. It has no commercial value.

Mozambican shark

The length of the fish is only 50-60 cm. The red-brown body is strewn with white spots. A little-studied species. It feeds on crustaceans. It lives on the coasts of Mozambique, Somalia, and Yemen.

Types of sharks, names and photographs

In total, there are about 500 species of sharks. They have a rather complex classification, but experts identify 8 main orders (in brackets are typical representatives of the order):

Carchariformes (basking hammerhead, silky, tiger, bull shark, blue);
Lumniformes (giant, white, fox, herring, false sand, sand, largemouth);
Heterodontoids (zebra bull, helmeted, African horned);
Polygillidae (fried, sevengill);
Sawtooth (pilonose);
Wobbegongs (whale);
Katraniformes (southern Katran);
Flat-bodied (California squatina).

The most famous species

The white shark is characterized by aggressive behavior. Average age is about 70 years. It reaches 6 m in length or more, and such individuals weigh up to 2 tons. It is distinguished by good camouflage in the form of skin on the upper part of the body in shades of gray, brown, and green. The lower part of the body is much lighter. Has a highly sensitive sense of smell. Distributed in all oceanic waters.

White shark

The whale shark reaches an average length of 6-8 m. But this species is characterized by external diversity, so there are both small individuals and giants up to 20 m long. Considered the largest shark. Despite its possible dimensions, it is not dangerous for people. The structure of the jaws and teeth is designed to capture small sea food along with water. The characteristic color is dark skin with large white spots on the back and sides.

Whale shark

The height of a giant shark is up to 15 m, weight – up to 4 tons. It ranks second in size. It also feeds on plankton. It can lead a solitary lifestyle or form flocks. It has an unremarkable brown-gray color.

Giant shark

The largemouth shark grows up to 5 m in length. It is dark brown in the upper part and light brown in the lower part. A characteristic feature is a large mouth, up to 1.5 m long, with small teeth. It feeds on small sea creatures, attracting them with luminous phosphorites.

Largemouth shark

The tiger shark is a 4-meter specimen with bright striped colors. But this color is characteristic only of young fish, while in mature ones the skin becomes gray. It is dangerous for people because it moves quickly and has sharp teeth.

Tiger shark

The bull shark is common in all waters, including the ability to swim into fresh water bodies. It also poses a danger to people. The average length is 3 m. It is distinguished by a specially shaped muzzle with which it attacks enemies. Therefore, it has a second name - blunt-nosed.

Bull shark

The frilled shark looks more like a snake and is considered one of the ancient representatives that has retained its original appearance. It reaches a maximum length of 2 m. Due to the structure of the jaw, fairly large fish are swallowed whole.

frilled shark

The mako shark grows up to 3 meters and weighs about 100 kg. It is distinguished by its aggressiveness, developed sense of smell, and high speed. Dangerous for people. It has a gray-blue color with light skin in the abdominal area.

Mako shark

Interesting fact : when hunting, a mako shark can jump 6 m out of the water.

The hammerhead shark has a characteristic feature - a flattened hammer-shaped head. Poses a danger to people. Some individuals reach 8 m in length.

Hammerhead shark

Interesting fact : The location of the hammerhead shark's eyes allows it to have a 360° vision.

The fox shark reaches 5 m. It has a unique tail with a long upper blade and a short lower one. Using its tail it stuns fish and thus feeds.

fox shark

Whiskered shark , also called a dog shark because of its specific appearance - whiskers and folds at the corners of its mouth. The length is up to a meter, with the tail taking up most of it. Swims quickly and successfully hunts small fish.

Whiskered nurse shark

Reef shark with a thin body and a wide head. It grows up to 1.5 m and weighs only 20 kg. Usually has a dark gray color with sparse spots. Distributed among coral reefs, lagoons, and sandy shallows.

Reef shark

The lemon shark has a yellow skin tone mixed with pink and gray. Grows up to 3 m in length. Often forms groups, especially young individuals. Shows aggression towards people.

lemon shark

The freshwater shark is a rare representative of fish that lives in fresh water all its life. Length – up to 3 m. Dangerous for both people and other animals approaching the water. It has a gray-blue color with a light belly.

Freshwater shark

The dwarf shark is the smallest representative, about 17 cm long. It is considered little studied, since it belongs to deep-sea fish. Capable of emitting green light from her eyes.

Dwarf shark

The cat shark is a small specimen up to 1 m long with a bright coloration in the form of a dark shade with numerous spots. It is distinguished by its flexible body and elegance. Does not pose a danger to people.

cat shark

Whiskered nurse shark

This shark can reach 4 meters in length, but usually does not exceed 2.5-3 meters. Looks a bit like a catfish:

It lives at a depth of 0.5 to 3 meters, can gather in schools of up to 40 individuals

Slow and inactive nurse sharks feed on crabs, octopuses, sea urchins, and small fish.

As a rule, nurse sharks are harmless to humans.

The largest sharks in the world

Species of sharks that are particularly large in size:

Megalodon is a long-extinct species, but according to the teeth found, the length was about 15 m, weight up to 40,000 kg.
Large whale shark - length 12 m or more, weight 21,000 kg.
Giant shark - length 9-10 m, weight 4000 kg.
Tiger shark - length 7.5 m, weight 939 kg.
Great white shark - length 6 m, weight 1500 kg.
Greenland shark – length 4-6, weight 1020 kg.
Hammerhead shark - length 5-6 meters, weight 844 kg.

Megalodon and white shark teeth

Carcharine sharks

They are found in the waters of the Atlantic, Pacific, Indian oceans, the Mediterranean, Caribbean, and Red seas. Dangerous species of sharks . Typical representatives:

Tiger (leopard) shark

Known for its prevalence in the coastal zones of America, India, Japan, and Australia. The name reflects the color of the predators, similar to the tiger pattern. The transverse stripes on a gray background persist until the shark grows over 2 meters long, then they turn pale.

Maximum size up to 5.5 meters. Greedy predators swallow even inedible objects. They themselves are a commercial object - the liver, skin, and fins of fish are valued. Sharks are very prolific, with up to 80 live-born pups in one litter.

Hammerhead shark

Lives in warm ocean waters. The record length of the giant specimen was recorded at 6.1 m. The weight of large representatives is up to 500 kg. The appearance of the shark is unusual, massive. The dorsal fin is sickle-shaped. Ahead of the “hammer” is almost straight. Favorite prey: stingrays, poisonous stingrays, seahorses. They bear offspring once every two years, 50-55 newborns. Dangerous for humans.

Hammerhead shark

Silky (Florida) shark

Body length is 2.5-3.5 m. Weight is about 350 kg. The color includes different shades of grayish-blue with a metallic sheen. The scales are very small. Since ancient times, the streamlined body of the fish has terrified the depths of the sea.

The image of a cruel hunter is associated with stories of attacks on divers. They live everywhere in waters with water heated to 23°C.

Silky shark

Snout shark

A species of gray shark known for being the most aggressive. The maximum length is 4 m. Other names: bull shark, tub head. More than half of all human victims are attributed to this predator. Lives in coastal areas of Africa and India.

The peculiarity of the bovine species is in the osmoregulation of the body, i.e. adaptation to fresh water. The appearance of a blunt-nosed shark at the mouths of rivers flowing into the seas is common.

Blunt shark and its sharp teeth

Blue shark

The most common variety. Average length up to 3.8 m, weight more than 200 kg. It got its name from the color of its slender body. The shark is dangerous to humans. It can approach the shores and go to great depths. Migrates across the Atlantic.

Blue shark foraging for food

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A Guide to the Common Marine Fishes of Southern Africa
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Interesting facts about sharks

A heightened sense of smell allows sharks to smell blood diluted in water in a ratio of 1:1000000.
Adult white sharks are capable of biting through metal rods up to 1 cm in diameter.
Most species of predators do not live in captivity. Captive fish refuse to eat and die of hunger.
Sharks only attack prey that is smaller than them. That is why, before attacking, they swim around the victim several times, assessing its size.
The lemon shark is one of the few species that can tolerate captivity and can even be domesticated.
A shark's stomach can hold a large amount of food. If the fish cannot digest all its contents, it turns the stomach through its mouth and thus removes the remaining food.

Saw shark

The saw shark has a distinctive feature in its gills; they are located not like many sharks on the sides, but on the bottom of the belly. They cannot boast of size, the maximum length is approximately 180 centimeters, so people should not be afraid of them. They live mainly in shallow coastal depths of about 30-50 meters. They got their name from the fact that their nose is similar to a hand saw, which is used in the household.

Tags
Australian chimera shark goblin shark goblin shark hammerhead shark saw shark largemouth shark types of sharks basking shark frilled shark

Goblin shark (goblin shark)

The exact name is Goblin Sharks . A fairly rare species of shark, and this is good for both them and people. Living hundreds of meters below the surface of the sea, the goblin shark has translucent skin that gives it a pinkish tint. The bizarre projection on top of their heads is believed to contain an advanced electro-receptive system that helps them live and hunt at great depths in the absence of light.

Diversity of aquatic predators

Among these predators, up to four hundred species are distinguished, and there are both small and very large sharks. Not all of them are dangerous to humans. Despite this diversity, there is no doubt which group of animals the shark belongs to.

The main thing that does not make it a mammal is that it does not feed its young with milk. Over many years of evolution, the inhabitants of the oceans have developed into dangerous and skilled predators with excellent hearing and sense of smell, which really helps these creatures smell blood at a great distance. However, sharks do not even have a hint of feeding with milk.

Therefore, the answer to the question of whether a shark is a fish or an animal is obvious - a fish. You can also highlight the following differences between marine mammals and fish:

the cubs are born immediately independent, there is no need to take care of them or teach them how to hunt;
sharks hardly sleep, they move non-stop;
fish have a large set of sensory organs that help in obtaining food.

Another name for these creatures is selachia. All the myths, legends and speculations that surround them arose due to a lack of knowledge about them. However, during World War II, predators often attacked people participating in battles in the Pacific and Indian Oceans. There was a need to study them and find a way to protect against selachy.

Baby sharks are born immediately independent and do not need to be cared for

Dwarf shark

Dwarf sharks are among the smallest members of the shark family, reaching a maximum length of only half a meter. A deep-sea fish, like its close relatives, the lantern shark, the pygmy shark has a network of bioluminescent photophones that run along its body. Photophones are thought to help them blend in with ambient light conditions, thereby camouflaging themselves from both predators and their prey.