Is a shark a fish or a mammal? Shark name. Katran - photo. Sharks - Information and Facts About Sharks What Sharks Eat

Due to misinformation, sharks have a bad reputation. However, you will 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 species of shark separately, since the range of each species covers a very large geographical area. But the total number of sharks in the wild is steadily declining.

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

On average, 30 to 50 shark attacks are reported annually, with only 5 to 10 of these attacks being 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 terrible cannibal predators, but in fact, only 3% of sharks - a tiny minority - are dangerous to humans.

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

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

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

Sharks are fish

Sharks belong to the cartilaginous fish family. 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 multiple 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 in the seawater completely dissolves its skeleton, leaving only its teeth.

Sharkskin is made up of a series of scales that act as an outer frame for easy movement in the water. The upper 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 from below. This helps the sharks to camouflage themselves.

Sharks have a very keen sense of smell, able to detect blood in water from miles away.

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

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

Some species live in shallow, coastal areas, other species live in deep waters, at the bottom of the ocean, and still others live on the surface in the open ocean.

The goblin shark lives along the outer continental shelves and underwater ridges. Their dwellings are too deep for humans, so we know next to 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 the time of their hunting.

Sharks are capable of migrating long distances - on a scale they can overcome entire ocean basins.

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

How do sharks eat and what do they eat?

• Some types of sharks, such as the great white shark, attack from below. As a rule, seals and sea lions become their prey.
• Shark species living at the bottom of the ocean have developed the ability to gather bottom food.
• There are species of sharks that attack schooling fish.
• Large and giant sharks feed like whales, filtering the ocean water through their wide-open mouths. During filtration, they swallow a large amount of plankton and krill.

Shark Facts You Should Know

Sharks mature slowly, reaching reproductive age at 12 to 15 years of age. 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 is 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.

Shortly after birth, sharks, while still puppies, swim away from their mother. They are able to stand up for themselves from birth. Sharks are born with a full set of teeth and are able to feed and live on their own.

All sharks are cannibalistic. At the same time, not only adults are cannibals, sharks show prenatal cannibalism, feeding on the eggs of their brethren, which the female produces during pregnancy. That is why only 1-2 sharks are born from a litter of 80 eggs.

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.

Sharks are miniature copies of their parents. Pictured are tiger sharks.

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

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

TOP smallest sharks:

1. Pygmy Spiny Shark (Squaliolus laticaudus) - the usual body length is 15-20 cm, and the maximum is 24 cm.
2. Pygmy Glowing Shark (Euprotomicrus bispinatus) - a fish 20-25 cm long.
3. The long-nosed shark (Heteroscymnoides marleyi) is a small fish, 12.5-30 cm long.
4. Lighttail shark (Euprotomicroides zantedexchia) - maximum length 20 cm.
5. Kunya Cuban shark (Triakidae barbouri) - maximum 35-40 cm.

Glowing shark - the champion of minimalism

Some of the known shark species drown if they stop moving. They do not have a swim bladder, so they must swim all the time - they consume a lot of energy in movement. Compare. The 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, Carcharodon carcharias), mako (black-nosed, mackerel, gray-blue) shark and salmon sharks (Lamna ditropis) of the herring family do not have muscles, they pump water through their mouths and gills. They keep their mouths open all the 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 that helps sharks keep their balance in the water.

Poke a shark in the nose or eyes to fend off their attack does not help. It is better to hit them in the gills (these are large gaps along the muzzle) - this tactic works much more effectively against sharks. Most sharks swim away when their target is hard to reach for their food. 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) attack people from behind most of the time. Their prey is that which has a human size. They are strong enough to attack and deliver a deadly bite.

On the extremely rare occasions when a shark bites you, it will most likely not attempt a second bite. When attacking humans, sharks usually hold them for a few seconds and then release them once they realize they have tasted a non-sea creature.

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

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

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

Shark eggs are very different in appearance from those 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 can see colors well. Divers claim that sharks are attracted to certain colors - yellow is "yummy" for them, the color of some wetsuits. While sharks' color preferences have not been proven, scientists know that sharks living in well-lit aquariums can see colors, which humans use as signals.

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

The shark is a formidable predator that lives in the waters of the world's oceans. Its real appearance was formed back in the Jurassic period, when dinosaurs still lived on Earth. That is, one can only imagine how ancient this mysterious creature is. The most interesting and common types of sharks will be discussed in detail below.

Shark and its characteristics

Science refers these formidable marine predators to the class of cartilaginous fish, the chordate type and the so-called "shark" superorder. The very name "shark" came to the Russian language from Scandinavia in ancient times, when the Vikings called the fish as a whole with the word Hakall. They mostly live in salt water, but there are some species that live quietly in fresh water.

The characteristics of the appearance and structure are as follows:

• small species (they are also called bottom ones) grow up to a maximum of 20 cm in length, while large ones (for example, whale) reach 20 m in length, and their weight can be about 34 tons;
• the skeleton has no bones, it consists entirely of cartilage tissue;
• the body has a streamlined shape;
• the skin is covered with scales and has embossed protrusions.

By the way, shark skin scales are very dense and durable. Many scientists say that they are not inferior in strength to the teeth of this water predator.

Like any other fish, the shark has gills, they are located in front of the pectoral fins. These predators have very low blood pressure, so they have to be on the move all the time to keep their blood flowing. However, some species of these predators can feel great lying on the bottom of the reservoir and pumping water through the gills.

Peculiarities

What distinguishes the shark from all other fish is the lack of a swim bladder. It is replaced by a huge liver, which occupies 1/3 of the entire body weight of this predator. In addition, fins and low cartilage density are responsible for buoyancy here.

The situation with the digestive system of these predators is interesting. Her stomach is very elastic, thanks to which she can absorb a large amount of food, but at the same time, it does not secrete enough gastric juice for digestion, and then the predator does the following: she turns his stomach inside out and get rid of excess food. The stomach itself does not suffer at all from such actions.

The vigilance of sharks exceeds the human by 10 times, and with the inner ear they are able to pick up infrasounds and low purity.

The sense of smell is also very developed in these predators: they smell not only in water, but also in the air. They smell blood very sharply, moreover, if there is very little of this very blood. The ratio is 1:1,000,000, which is equivalent to a teaspoon of blood diluted in a pool.

The shark swims quite slowly - only about 5-8 km / h. But if the predator pursues prey, then its speed can develop up to 20 km / h. And warm-blooded species (white or mako) are able to swim at a speed of 50 km / h.

The life expectancy of these predators depends on the species: some species live for about 30 years, while others (for example, whale, polar, and sand katrans) can live for more than 100 years.

Teeth and their structure

All types of sharks have very sharp, cone-shaped teeth, but the structure of the jaw itself will depend on the specific species. In general, this predator is able to easily bite through the flesh of its prey. For example, a class like gray sharks, has flat triangular teeth, with which it easily tears the meat of prey.

Such kind as whale shark, feeds on plankton, so the size of its teeth does not exceed 5 mm, however, their number can reach several thousand. A horned shark it feeds on bottom food, therefore the structure of its jaw is completely different: the front teeth are small, and the back teeth are large, with which it crushes food.

All types of these predators have a different number of teeth:

• comb-toothed - 4 rows of upper and 6 rows of lower ones (approximately 180-220 teeth);
• white brindle - lower jaw in 5-6 rows (about 280-300 teeth);
• frilled - from 20 to 28 rows, about 400 teeth in total;
• cetaceans - approximately 14,000 teeth.

Habitat and food of sharks

These formidable predators live throughout the world's oceans, that is, they can be found in the waters of any sea, any ocean. Basically, they prefer to live in equatorial and near-equatorial waters, in coastal waters, as well as in reefs.

By the way, blunt and gray sharks they feel good not only in salty, but also in fresh water, so they often swim in rivers.

The maximum depth to which a predator can swim is about 2000 m, but sometimes they can go down to 3000 m.

Food here also depends on the habitat, but mainly these predatory fish feed on plankton and other fish species, and those that live on the bottom eat crabs and other crustaceans. If considered in more detail, then food is the following:

• the white hunts cetaceans and seals;
• largemouth, whale, gigantic - food consists of plankton and small fish;
• tiger - eats everything.

shark species

As mentioned earlier, the world knows a large number of species of these marine predators, which are divided into 8 orders, implying about 450 species. About what sharks are, it will be said below:

How sharks breed

The main feature of these predators is a very long puberty: the female can give birth only to the 10th year of life, and some species even at 30-40 years of age.

Depending on the species, these predators bring offspring in different ways:

• laying eggs;
• ovoviviparity;
• live birth.

The incubation period also lasts depending on the species: from several months to 2 years.

These predatory fish lay on average from 2 to 12 eggs, covered with two shells: the first protein, and the second - horn-like, protective. When a baby shark hatches, it immediately begins to live an independent life without the participation of its mother.

An interesting fact: scientists have repeatedly noted cases of parthenogenesis in sharks living in captivity: they could be fertilized without the participation of a male.

The situation is different for ovoviviparous: first, the cubs hatch in the womb and live there for some time, feeding on unfertilized eggs and each other, as a result, one of the hardiest cubs (less often two) is born.

Human danger

Most often, sharks attack people in the waters of the oceans. The largest number of such cases is recorded off the coast of the United States, Brazil, South Africa, New Zealand and Australia. African countries such as Ghana, Mozambique, Tanzania are considered very dangerous areas.

Many believe that the shark is the most terrible water monster that attacks a person at any opportunity. In fact, all these speculations are greatly exaggerated under the influence of science fiction films: out of all the 450 types available only 4 of them are dangerous to humans:

• brindle;
• white;
• long-winged;
• bull shark.

By the way, the opinion that a shark loves human meat is nothing but another myth. Undoubtedly, such a predator from the 4 species listed above can attack, but after biting off a little human flesh, it will spit it out, since there is no benefit from an energy point of view in such "food".

Although they are considered the largest marine predators dangerous to humans, how much do we really know about sharks? Did you know that a human is more likely to be attacked by another human (ex-boyfriends and girlfriends don't count) than sharks? Or that, since the 16th century, there have been far fewer unprovoked shark bites than the number of text messages you send each month? Did you know that sharks are not only gray, but also all colors of the rainbow - for example, pink and yellow?

Sharks are amazing creatures that play a key role in keeping the ecosystem in balance. Without these clever predators (well, not all of them are clever - some seem as lost as we are on Monday mornings) the ocean ecosystem would be so disrupted that man might have to say goodbye to fish and crustaceans.

Our list today contains some little-known facts about sharks, namely why baby sharks eat their brothers and sisters in the womb, what is the largest organ in sharks, and many others.

Since the great white shark is already very popular, we will focus mainly on facts about other types of sharks that live in our oceans.

So, before you - 25 facts about sharks that you still did not know!

25. The nastiest tasting on the planet

One of the national Icelandic dishes is called "haukarl" (hákarl). It is made from the meat of the Greenland polar shark or the giant shark, which is fresh, cut and left for 6-8 weeks to drain the juices, and then kept in the fresh air for 2-5 months to dry.

Renowned American chef Anthony Bourdain called it 100 times richer than blue cheese and said it was "the single worst, most disgusting, tastiest thing."

24. Sharks help humans fight infection


Since barnacles and microorganisms do not grow on sharks for some reason, scientists are examining their skin to find a way to fight bacterial infections in the human body.

23. The strangest thing that sharks eat


Sharks living in northern latitudes are known to often eat seals, but did you know that sometimes Greenland sharks eat horses, deer and even polar bears?

22. Why do sharks attack more people near California?


There are more shark attacks in the waters near California because there is more prey. By order of the US government, several different protected natural areas are located nearby. Populations of marine mammals are increasing, thereby attracting hungry sharks to the shores of the state who want to profit.

21. Number of shark bites recorded in the last 400 years


Between 1588 and 2011, there were only 2,463 reported cases of unprovoked shark bites. Less than 20% of these cases were fatal.

20. A shark can eat an underwater camera.


Since they are able to pick up electrical signals emitted by living beings, while hunting, they can mistake for prey and eat an underwater camera that emits an electrical signal.

19. Shark blood contains anticoagulants.


Scientists are also testing the blood of sharks to help patients with heart disease. In particular, they are studying the blood clotting system present in the blood of these predators.

18. The best place to survive a shark attack


If a person is bitten by a shark, then it is best for him to swim to the place where the water is the coolest, since in cold water the body temperature decreases, thereby slowing down blood loss. Even so, fewer people die from shark bites than while playing football in high school or college.

16. Baby sharks eat their siblings

Baby sharks often eat their siblings in the womb. Do you know why? Since a female shark can be fertilized by several males at once, small sharks eat each other so that only their father's children are born.

15. Great white sharks don't like the taste of human meat.


Ask any person which shark they are most afraid of, and the answer is likely to be the great white shark. Luckily, people shouldn't be too scared of great white sharks because they don't really like the taste of human flesh; they most often bite and release their prey.

14. Eyes with self-heating


Sharks that live in cold waters can use organs near their eye sockets to heat up their eyes, helping them see better and therefore better hunt in icy water.

13. Shark that swims while sleeping


The katran, or common spiny shark, is best known among sharks for its strange feature: it sleeps while swimming. Just like sleepwalkers who can sleep and walk, the katran can swim while sleeping.

12. The strange romance of blue sharks


Many species of sharks have unusual ways of seduction. To show his interest, the male blue shark bites the female. Strongly. And the skin of female blue sharks is naturally three times thicker than that of males to protect them during such courtship.

11. Colorful sharks


In addition to their well-known greyish appearance, there are sharks that are pink or yellow in color.

10 Barking Shark


The California swell shark, or the Chilean cathead shark, can pump up water and swell up, doubling its body size to prevent predators from being pulled out of the reefs and crevices in which they sleep during the day (these sharks are nocturnal). If they are pulled out of the water, they swallow air and, when deflated, make sounds similar to barking.

9. The smallest shark


The surprisingly small shark Etmopterus perryi has a body length of only 20 cm. Thanks to the presence of photophores, it can emit a glow.

8. A jaw nearly the size of three people


The whale shark can open its mouth up to 4.6 meters. Fortunately for humans, it feeds only on plankton.

7. Sharks have excellent peripheral vision.


An alarming fact about sharks for small fish: they can see almost 360 degrees around them. The only places they can't see are right in front of the muzzle and just behind the head.

6 Shark Playing Football


Atlantic herring sharks, or llamas, when not prowling in search of food, throw pieces of algae among themselves in a kind of game that can be compared to football.

5. The patron shark of travelers


If you are a tourist looking for inspiration from animals, then pay attention to hammerhead sharks. These migratory travelers sail from the Florida coast all the way to the polar region, adapting to changing water temperatures along the way.

4. The largest organ in sharks


Despite its seemingly gluttony, the largest organ is not the stomach at all, but the liver.

3. Shark teeth


One of the coolest shark facts on our list is that they never have holes in their teeth. This is because the outside of the teeth is coated with fluoride, the main active ingredient found in most toothpastes.

2. Under-shark


A disgusting looking (and strangely named) wobbegong or carpet shark can hardly even be called a shark. Being a poor swimmer, she lays in ambush on the seabed for days on end to unexpectedly attack fish passing by.

1. Shark vs. Human


Sharks kill less than 15 people a year - agree, more than a meager figure compared to 73 million sharks killed by man in the same period.

Evolution has worked hard on these creatures, providing them with adaptation mechanisms that have allowed them to bypass other ancient species at historical turns. Sharks appeared 450 million years ago and are considered to be the most advanced aquatic animals.

Description of sharks

Selachii (sharks) belong to a superorder of cartilaginous fishes (a subclass of elasmobranchs) with a characteristic appearance - a torpedo-shaped body with an asymmetrical caudal fin and a head whose jaws are studded with several rows of sharp teeth. The Russian transcription of the term goes back to the Old Norse “hákall”: this is how the Vikings once called any fish. In Rus', the word "sharks" (m. R.) began to be used in relation to any aquatic predators from about the 18th century.

Appearance

Not all, but many sharks have a torpedo body and an oval-conical head, which helps them easily overcome the hydrodynamic resistance of the water column, gaining decent speed. The fish swims by making undulating body/tail movements and using all fins. The tail, serving as a rudder and engine, consists of 2 blades, the upper of which enters the spinal column.

Lateral fins add speed and agility, as well as steering through turns, climbs and dives. In addition, paired fins, together with the dorsal fins, are responsible for balance during sudden stops and somersaults. Paradoxically, the shark, which has a complex arsenal of fins, never learned to “hand over backwards”, but it did learn funny tricks.

This is interesting! Epaulet sharks walk along the bottom on their pectoral and ventral fins, as if on their feet. Small luminous sharks (no more than half a meter tall) “flutter” in the water like a hummingbird, quickly bringing and spreading their pectoral fins.

The cartilaginous skeleton is additionally reinforced with calcium in areas with a greater load (jaws and spine). By the way, the lightness of the skeleton is another reason for shark mobility and resourcefulness. To cope with the resistance of the environment, the predator also helps her dense skin, made up of placoid scales resembling teeth (in strength and structure). It appears smooth when moving the hand from head to tail, and rough as sandpaper when moving the hand from tail to head.

Mucus from the glands in the skin reduces friction and promotes high speed. In addition, shark skin contains a lot of pigment responsible for the specific coloration of each species. Fish, as a rule, mimic the terrain, and are often decorated with stripes / spots to match the general background of the bottom or thickets. Most sharks have a darker top than their belly, which helps them camouflage when viewed from above. And the light shade of the abdomen, on the contrary, makes the predator less noticeable to those who seek out prey from the depths.

fish or mammal

Sharks are aquatic animals from the class of cartilaginous fish, which also includes close relatives of these predators, rays. Aquatic mammals (whales, seals, dolphins and others), living next to sharks and even somewhat reminiscent of the latter, do not belong to their family clan. Even sharks endowed with an extraordinary appearance still remain fish, like, for example, a frilled shark, similar in body shape to a sea snake or eel.

Carpet sharks and squatin sharks that live on the bottom are distinguished by a flat body with an inconspicuous sandy coloration that hides them among bottom plants. Some wobbegong sharks have acquired leathery outgrowths on their snouts (“wobbegong” is translated from the Australian Aboriginal language as “shaggy beard”). The hammerhead shark is also knocked out of the general row, whose name was influenced by the unusual T-shaped head shape.

Character and lifestyle

It is customary to think that a shark in splendid isolation plows the expanses of the ocean without creating numerous flocks. In reality, predators are not alien to social behavior: they huddle in huge groups during breeding seasons or in places with an abundance of food.

Many species are prone to a sedentary and sedentary lifestyle, but some sharks migrate quite far, overcoming thousands of miles annually. Ichthyologists suggest that the migration pattern of these predatory fish is more complicated than that of birds. Sharks have an interspecies social hierarchy, especially in terms of “distribution” of food rations: for example, the silky shark certainly obeys the long-winged one.

This is interesting! The predator has a couple of ways to take a nap: do it while moving (after all, it is controlled not so much by the brain as by the spinal cord) or turn off each hemisphere alternately, like dolphins.

The shark is constantly hungry and extremely voracious, which is why it chases suitable prey day and night with little or no rest. Ichthyologists have recorded sounds made by sharks as they cut through the water column and the cracking of their jaws, but concluded that these fish do not exchange sounds, but communicate with body language (including the position of the body and the turns of the fins).

Movement and breathing

Sharks are doomed to continuous movement - they need oxygen, but they (like most cartilaginous fish) do not have gill covers that drive water through the gills. This is why the predator swims with its mouth open: this is how it captures water (to get oxygen) and removes it through the gill slits. Some sharks still manage to slow down, organizing a short rest for themselves in areas with a strong undercurrent or pumping water through the gills (for which they inflate their cheeks and use sprinklers). It also turned out that certain types of sharks, mainly bottom sharks, are able to breathe with their skin.

In addition, an increased concentration of myoglobin (a respiratory protein) was found in the muscle tissue of sharks, due to which, unlike bony fish, they are able to endure the load caused by constant movement. The cerebellum and forebrain, which are related to the most developed parts of the brain, are responsible for complex movements and coordination in space.

The role of the heart and liver

The temperature of the shark's body, as a rule, is equal to the temperature of its native water element, which is why these fish are called cold-blooded. True, some pelagic sharks are partly warm-blooded, as they are able to raise their own temperature due to the intense work of muscles that warm up the blood. The heart, located in the thoracic region (not far from the head), consists of 2 chambers, the atrium and the ventricle. The purpose of the heart is to pump blood through the gill artery to the vessels in the gills. Here the blood is saturated with oxygen and supplied to other important organs.

Important! The heart does not have enough power to maintain the blood pressure necessary to distribute oxygen throughout the huge body. Regular muscle contractions performed by the shark help to stimulate blood flow.

The shark has a multifunctional and rather impressive (up to 20% of the total weight) liver, which has several tasks:

• cleansing the body of toxins;
• storage of nutrients;
• replacement of a missing swim bladder.

Thanks to the liver, sharks stay afloat, and also almost do not feel the pressure drop during sharp ascents and descents.

sense organs

Sharks have disgusting eyesight - they distinguish contours, but are not able to enjoy the color diversity of the world. Not only that, sharks may not notice a stationary object, but start up when it starts to move. Since predators attack with their heads, nature has provided their eyes with protective devices such as skin folds or nictitating membranes. The inner and middle ear are designed to perceive even low-frequency vibrations (inaccessible to human hearing), for example, the movement of water layers.

Ampoules of Lorenzini also help to find prey, capturing minor electrical impulses supplied by the victim. These receptors are on the front of the head (the hammerhead shark has a lot of them) and on the body.

This is interesting! Sharks have an amazingly sharp sense of smell, 10,000 times more receptive than a human, which is explained by the developed anterior lobes of the brain responsible for smell, as well as the presence of nostril pits / grooves on the snout.

Thanks to the latter, the flow of water to the nostrils increases, the receptors are washed and read information about odors. It is not for nothing that the swimming shark constantly twists its nose, turning its head: this is how it tries to figure out where the alluring aroma comes from.

It is not surprising that even a blinded predator can easily find fishing spots. But the shark falls into the greatest frenzy when he smells blood - a few drops dissolved in a standard pool are enough for this. It has been noticed that certain species of sharks have the so-called "air" sense of smell: they catch odors that are distributed not only in water, but also through the air.

how long do sharks live

Almost all representatives of the superorder do not live very long - approximately 20-30 years. But among sharks there are also centenarians crossing the 100-year mark. These include types such as:

• spotted prickly;
• Greenland polar.

The third, by the way, became the absolute champion not only among relatives, but among all vertebrates. Paleogeneticists have estimated the age of a 5-meter-long caught individual at 392 years (± 120 years), which led to the conclusion that the average lifespan of the species is 272 years.

This is interesting! Shark teeth are responsible for the shark's life, or rather, their relentless "rotation": from birth to death, the predator changes up to 50 thousand teeth. If this did not happen, the mouth would lose its main weapon, and the fish would simply die of hunger.

The teeth are updated as they fall out, moving out (as in a conveyor) from the inside of the mouth. The structure of the teeth / jaws is determined by the type of diet and lifestyle: in most sharks, the teeth are set on cartilage and resemble sharp cones. The smallest teeth are in species that eat plankton: no more than 3–5 mm in a whale shark. Carnivorous species (such as sand sharks) wield long, sharp teeth that easily fit into the flesh of the victim.

Bottom sharks, such as different-toothed ones, nature has equipped with crushing (flat and ribbed) teeth that can split shells. Wide and serrated teeth of a tiger shark: they are needed to cut and tear the meat of large animals.

shark species

Their number is still a question: some ichthyologists call the figure 450, others are sure that the species diversity of sharks is much more representative (about 530 species). The only thing that the opponents agree on is the number of units that unite all the sharks of the planet.

According to the modern classification, there are only eight such groups:

• carchariformes– detachment with the maximum (among sharks) diversity of species, some of which are prone to oophagy;
• heterodentate- detachment of bottom sharks with nocturnal activity, having a dense body, 2 dorsal studded fins and one anal;
• polygilloid- includes 2 families, distinguished by the shape of the body: torpedo-shaped in polygills and eel-shaped in frilled sharks;
• lamniform– pelagic huge sharks with a torpedo-shaped body predominate in the detachment;
• wobbegong-like- inhabit warm and tropical seas. All but the whale shark live on the bottom;
• sawtoothed- they are easily recognizable by their long, saw-like muzzle with many teeth;
• caterpillar– are found at great depths throughout the world, including latitudes near the poles;
• squatinous- with a short muzzle and a flattened body, they resemble stingrays, however, shark gills do not open from below, but on the sides.

This is interesting! The most inconspicuous among the sharks is the small catranoid (17–21 cm long), and the most impressive is the whale shark, which grows up to 15–20 m.

Range, habitats

Sharks have adapted to life throughout the oceans, and some species (and the common gray shark) periodically enter the estuaries of fresh rivers. Sharks prefer equatorial / near-equatorial waters, as well as coastal waters with a rich food supply. Usually predators stay at a depth of 2 km, occasionally descending to 3 km or even lower.

shark diet

Sharks have wide gastronomic preferences, which is explained by the structure of the stomach: it incomprehensibly stretches and is able not only to digest prey, but also to leave it in reserve. The main component of gastric juice is hydrochloric acid, which easily dissolves metal, varnish and other materials. It is not surprising that some sharks (for example,) do not limit themselves to food at all, swallowing all the objects they encounter.

This is interesting! The tiger shark has a little trick to save him from the consequences of indomitable gluttony. The predator is able to turn the stomach inside out through its mouth (without injuring the walls with sharp teeth!), Spewing indigestible food and then rinsing it.

In general, the diet of sharks looks something like this:

• mammals;
• fish;
• crustaceans;
• plankton.

Reproduction and offspring

Sharks, like all cartilaginous fish, reproduce by internal fertilization, when the male introduces sexual products into the female's body. Coitus looks more like rape, as the partner bites and firmly holds the partner, who is subsequently forced to heal love wounds.

Modern sharks are divided into 3 categories (according to the way offspring appear):

• oviparous;
• ovoviviparous;
• viviparous.

All methods of reproduction are aimed at the conservation of species, as they reduce embryonic / post-embryonic mortality. Oviparous sharks (over 30% of known species) lay from 1 to 12 large eggs, hanging them on algae. The thick shell protects the fruit from dehydration, damage and predators. The largest clutches are observed in polar sharks, laying up to 500 (similar to goose) eggs.

In ovoviviparous sharks (more than 50% of species), the egg develops in the mother's body: the offspring hatch there. Pregnancy lasts from several months to 2 years (katrans), which is considered a record among all vertebrates. "Ready" cubs (from 3 to 30) give birth to a little more than 10% of current sharks. By the way, newborns often die in the teeth of their own mother if they do not have time to sail to a safe distance.

This is interesting! In females in captivity, there were cases of parthenogenesis, when offspring appeared without the participation of males. Ichthyologists consider this a protective mechanism designed to preserve the population of the species.

Sharks are predatory fish, dangerous and aggressive inhabitants of the ocean, the oldest known animals. This is commonly believed, and millions of people believe in it, drawing knowledge about these unique creatures from Hollywood horror thrillers. Let's figure out what we know about these amazing creatures that appeared much earlier than all the civilizations of the world and perfectly adapted to modern life. What is a shark? Is it a fish or a mammal?

amazing fish

All scientific and encyclopedic publications claim that sharks are cartilaginous fish, that is, they have absolutely no bone tissue in their body, which strikingly distinguishes them from their modern counterparts in their habitat. Together with the absence of gill covers and the structural features of the scales, the cartilaginous ostyak indicates the primitive organization of the species, or rather, its ancient origin: it is known that 400 million years ago these fish already swam in the world's oceans. Despite this, sharks are one of the most advanced species of predatory ocean fish. Adapting to a constantly changing environment for a long time, they have perfectly adapted and now get along well with modern bony fish and marine mammals, not inferior to them in speed, agility, or hunting skills. The list of sharks includes more than 400 species, polarly different: from the smallest deep-sea, barely growing to 17-20 cm, to the giant - the whale shark, a huge 20-meter multi-ton individual.

An important difference from bony fish are the methods of reproduction. Some species of sharks are viviparous, that is, they give birth to live young. Some lay eggs protected by a dense cornea. Far from all the secrets of their life are open: there are species whose secrets of reproduction of offspring are still sealed. Therefore, the question often arises: "Is a shark a fish or a mammal?"

View features

The cartilaginous skeleton and the absence of bones are the main signs of the relationship of these fish to a group of animals of a primitive organization. But, as mentioned above, this does not prevent the shark from living in almost all the oceans of the planet, having long gained fame as the most dangerous and aggressive predator. In addition, nature took care of the protection of this amazing animal. It is difficult to find something more protective than the scales that a shark possesses. Located from head to tail, it feels like a satin finish to the touch, but you should not run your hand in the opposite direction - from tail to head: sharp teeth dig into the skin. Coarse-grained sandpaper in comparison with this perfect protection is a weak semblance.

Consider the scale device. Each scale of cartilaginous fish is equipped with a small spike with a point pointing backwards. From above, the spike is covered with a layer of the strongest enamel, and its expanding base is fused with the skin of the fish. In the cavity of this outgrowth are blood vessels and nerve branches. The size of the scales on the body of the fish is different: the largest is located on the head, the spikes in the shark's mouth, having somewhat transformed, ceased to be a protection of the skin and turned into a sharp and extremely dangerous weapon of attack - magnificent teeth.

Main weapon

Being a modified scale, shark teeth are arranged in a strict checkerboard pattern, in several rows. Throughout the life of a predator, the teeth grow constantly, and when one row is abraded, new ones sprout, located in the depths of the mouth. Shark teeth are not for chewing food. She is unable to do this. Their main purpose is to hold prey, tear it apart in order to swallow it without interference. Different types of sharks have different shapes of teeth, which is dictated by the peculiarities of their lifestyle. Bottom, feeding on crustaceans in a hard shell, have flat teeth with a ribbed surface that can crush lime protection. Predatory fish have long, sharp teeth to grasp moving prey, or wide, serrated teeth designed to tear the flesh of large prey. In planktonic sharks, there is practically no need for teeth, in these species they are small, barely reaching 3-5 mm.

Another feature of cartilaginous fish is the absence of gill covers. Their role is played by 5-7 gill slits located behind the head, the number of which is determined by the type of sharks, and the presence is a distinctive feature. However, like all fish, these predators, getting oxygen from the water, pass it through the gills. The presence of a respiratory system characteristic of waterfowl gives an exhaustive answer to the question: "Is a shark a fish or a mammal?"

Amazing abilities: sense of smell, electroreceptor apparatus and lateral line system

It is impossible to overestimate the ability of sharks to smell. It is one of the most advanced basic sensory systems. Experiments have shown not just a high sensitivity of fish to odors, but truly amazing. The shark can smell blood diluted 1:1,000,000 in water and constantly uses its sense of smell when looking for prey or breeding mates during the mating season. In determining the location of an object, probably, in addition to a highly developed sense of smell, other organs and systems are also involved: hearing, as well as a lateral line located on the surface of the body of a fish, capable of sensing both negligibly weak mechanical movements, and the slightest in water, and playing an important role when hunting, communicating with brothers and orienteering.

There are still unproven scientific assumptions about the ability of these predators to capture odors distributed through the air, which led researchers to the strange behavior of the great white shark. She often raises her muzzle above the surface of the water surface, as if sniffing.

The unique ability of sharks to detect the victim by the movements of the respiratory and cardiac muscles created by it, electric fields with negligible voltage has been scientifically proven. Long-term observation of the migration of some species over fairly long distances in a straight line made it possible to reveal the possibility of their orientation along the Earth's magnetic field.

Vision

The uniqueness of this representative of the fauna once again emphasizes the special structure of the eye, which provides both protection from external stimuli and excellent visual acuity. Features of the device of the shark's organ of vision are the presence of a blinking eyelid that closes the eye at the time of the attack on the victim, thereby protecting it from damage. In fairness, it should be noted that not all species have eyelids. These individuals roll their eyes when attacking a prey.

Moreover, the shark eye has a special reflective layer located behind the retina, which enhances the sensitivity of this organ and significantly increases visual acuity even in low light. Today, the fact that the vision of some species of these fish is many times greater than that of a human does not require proof.

shark breeding

Unlike most bony fish, which produce millions of eggs, shark reproduction is more about quality than quantity. Characteristic features of cartilaginous fish - internal fertilization, widespread ovoviviparous and live births significantly reduce the mortality of offspring, making it possible to ensure a high survival rate and lower fertility.

Depending on the species, sharks can be oviparous, viviparous, and ovoviviparous. Oviparous is almost a third of all species. After internal fertilization, the female lays eggs covered with a protein gelatinous layer, protected over it by a hard shell that protects the contents from dehydration and external damage. The supply of nutrients in the egg is colossal, it does not dry out during the full development of the embryo, which, it should be noted, is quite long. As a rule, a small number of eggs are laid at the same time: from 1 to 12. The only exception is the polar shark, which lays up to 500 eggs up to 8 cm long. The slow development of the embryo pays off handsomely - the hatched little shark is perfectly adapted to life and differs from an adult individual only in size.

A distinctive feature of ovoviviparity is that, having hatched from fertilized eggs, the cubs remain in the mother's oviduct for some time, being born developed and perfectly adapted to independent existence. Information about the timing of gestation in ovoviviparous species requires clarification. According to some reports, this period is from several months to two years, like a spiny shark, which is a record among all vertebrates.

In the womb of viviparous individuals, up to 30-80 embryos can develop simultaneously. Regardless of the type of shark and the method of reproduction, everyone is distinguished by the reproduction of a few, but capable of independent offspring.

planktonic sharks

For the most part, these fish are common in the oceans and seas, living in the water column from the surface to two kilometers deep, and are classified as real predators. But there are exceptions in this family: largemouth, giant, whale and some other types of sharks are filter feeders, feeding on plankton, small fish and squid.

The largest are whale and giant sharks, reaching a length of 20 and 15 meters, respectively. Being planktonic fish, they slowly move, opening their mouths, in the center of plankton accumulations, driving water through gill openings with special outgrowths-plates, filtering out a huge amount of water and extracting from it all living organisms larger than 2 mm.

There is very little information about the reproduction of planktonic species. So, the life of a giant shark is completely unknown so far. Whale - oviparous. The eggs she lays reach very impressive sizes: the length can be 0.7 m, the width is 0.4 m. Despite its huge size, the planktonic shark fish, the photo of which is presented in this article, is completely non-aggressive and very slow.

The world of sharks is amazing and diverse. Some of them lead a benthic lifestyle and feed on crustaceans and invertebrates, such as small cats, no larger than 1 meter in length. The object of the fishery is the spiny katran shark, a photo of which is also presented in the article.

Fishing katran

Katran, having a wide distribution, is the only species that lives in the Black Sea. This sea shark is extremely cold-loving and does not favor warm waters. Perhaps this explains the fact that the Black Sea katran rarely reaches 1 meter in length, although in the North Sea the size of this fish is 1.5-2 m. Spiny sharks practically do not rise to the surface of the water and do not approach the shore. They live at a sufficient depth, straying into large shoals. Katrans feed on benthic invertebrates and bottom fish - flounder, whiting, they successfully hunt shoals of anchovy.

It is striking that the katran is an ovoviviparous fish, whose pregnancy lasts an incredibly long time - up to 2 years. Sharks are born absolutely ready for the adult life of a predator. Inaccessible to humans, protected and cautious, they grow to adulthood without any problems. These sharks are safe for humans in the sea. They never swim close to swimmers. An incredible system of highly developed sense of smell and sensation of the slightest frequency fluctuations helps the katran to avoid meeting people.

Flocks of this fish approach the shores in late autumn. Then the fishing season begins. The second name of sharks - prickly - is given to katrans not in vain. This fish is capable of delivering a lot of trouble when it is taken out of the trawl. It has not only strong scales, but also sharp spines in front of the dorsal fins, at the base of which are poisonous glands. Upon contact with them, you can get a portion of poison, although not fatal, but bringing certain inconveniences. The Atlantic Ocean is the most generous in the catches of the katran: sometimes it is possible to catch up to 20 thousand fish in one note.

The spiny shark is not just a delicious fish, it is very gentle and definitely healthy. In the skillful hands of a good cook, katran meat turns into magnificent delicacies, healthy and delicious dishes. An immutable rule in the preparation of shark meat is the obligatory draining of blood immediately after the fish is caught. It has a high concentration of ammonia. If you do not get rid of the blood, the product will be hopelessly spoiled. The advantage of such dishes is the fact that there are no bones in their meat, because this fish is cartilaginous.

The skin of katrans is also valued. The abrasive properties of katrany skin have always been used by masters of many industries: from carpenters, cabinetmakers and joiners to furriers.

Tiger shark

Fully justifying the reputation of a thunderstorm in tropical seas, the tiger shark, inferior to the white in the number of recorded attacks on humans, significantly exceeds it in the percentage of deaths after encounters with it. The name of the shark is determined by its external features. The tiger shark (or sea tiger) is so named due to the dark transverse stripes on a gray, brown-gray or greenish body background, which fade over time. Preferring shallow water, these sharks rarely go below 300 meters, cold waters do not attract them at all. The outstanding size of the fish - 7-8 meters in length and a weight of about a ton - puts it among the largest species. A streamlined body shape with a large head, a blunt snout and 5 gill slits, as well as a large mouth with jaws equipped with 280-300 flat, scraper-like jagged teeth, and a well-developed upper lobe of the caudal fin - this is an incomplete portrait of this dangerous fish.

Sea tigers are attached to their favorite places, they do not like to leave the limits of their own residence. Being solitary predators, tiger sharks sometimes form groups if there is enough food. But most often they patrol their area one by one.

The diet of these predators consists of dolphins, fish, and even small representatives of their own species. They are so omnivorous that the contents of their stomachs, representing a set of objects far from organic food, surprise researchers. For their exorbitant omnivorousness, tiger sharks have received the stigma of "marine scavengers." But more than relevant for them is the ability to twist the stomach through the mouth for rinsing in water, which allows you to get rid of completely indigestible items, such as cans, bags, and various garbage.

This dangerous shark is ovoviviparous, carrying its offspring for 14-16 months and giving birth in a litter of up to 80 sharks, each up to half a meter in size.

Great white shark

An exceptionally large aggressive predator - the white shark or carcharodon, which has long and firmly held the sad championship in the number of attacks on people, is found in the surface waters of all the oceans of the Earth, except for the Arctic, preferring a temperate and warm climate. It does not occur in cold waters, and also does not live in low-salt or desalinated seas. For example, Carcharodon does not appear in the Black Sea. The most likely encounters with great white sharks are on the coast of California, near the Mexican island of Guadeloupe, in the Mediterranean and Adriatic Seas, off the coast of New Zealand, where they can swim in small flocks. The waters of the seas, where seals are found in abundance, are especially loved by these predators. For a long time there was an opinion about the permanent coastal existence of white sharks, but it has been proven that the fish migrates from the coast of California to African latitudes, swimming more than 20 thousand km a year.

Being the largest modern predator (some specimens reach a length of more than 10 meters with a body weight of up to 3.5 tons), the white shark does not give the victim any chance of salvation. This species owes its name to the color of the abdominal part - light or off-white. Its dorsal part is darker tones: gray, greenish. Like all types of sharks, the white shark lacks an air bladder, which explains the constant movement of the fish.

She is more partial to food than her brindle sister. The little shark feeds on small fish and mammals. Grown up carcharodons prey on seals, dolphins, and smaller representatives of the species. Adult individuals do not bypass young or sick whales, often performing extraordinary tactical moves during an attack, which only confirms their intellectual abilities. This dangerous shark has long proved that it can handle any prey.

Little information is available on the reproduction of offspring. Like many species, these are ovoviviparous with a gestation period of 11 months, after which 1-2 cubs adapted to independent life appear. Today, the population of white sharks is rapidly declining, there are no more than 3,500 pieces worldwide. The species is listed in the Red Book.

Sharks in the ocean are a fascinating and frightening sight at the same time. It can both delight and shock. Those who have seen not only photos of big sharks, but also a flock of white hunters with their own eyes will never forget this. After all, even pictures with images of predatory fish excite the imagination. The world of sharks is amazing, fantastic and dangerous. An ancient creature and a modern brutal predator coexist in a unique animal, attracting attention, again and again giving rise to the question: "Is a shark a fish or a mammal?"