In the modern animal kingdom there are just under 250 of the most different types sharks Of this species diversity, representatives of only 27 species can attack humans. Among them are lemon shark, tiger shark, hammerhead fish, white shark. Many people are interested not only in what they eat, but also in how a shark eats.
What do sharks eat?
The most harmless to humans, oddly enough, is the giant whale shark, which feeds on small sea animals. The main food for these predators are mainly shrimp, lobsters, crustaceans and vertebrate fish. They also feed on birds, dolphins and turtles. Some species of sharks can eat their relatives.
There is plenty of documentation of how sharks eat people. However, it is necessary to note the fact that not a single shark attacks a person as a means of feeding. Ichthyological specialists say that predators can attack a person only in two cases: when there is an invasion of the territory protected by the shark, or if for some reason ordinary food becomes inaccessible to the shark.
A shark's mouth is located on the underside of its head. If the predator is under water, then it eats without changing its position. And in order, for example, to grab prey on the surface, it is forced to roll over on its back.
The teeth in a shark's mouth are arranged in rows, in some cases there are up to a thousand of them in one row. In different species of sharks, there are from 4 to 20 such rows. The teeth themselves are equipped with muscles and are embedded in the gums. If the first row falls out, the back row moves to its place. Newborn baby sharks already have a full set of teeth in their mouths and can bite. For example, a tiger shark can use and lose up to 25 thousand teeth over the course of ten years of its life.
How sharks attack
A shark can circle around its intended victim for a long time before deciding to approach it to deliver the decisive blow. Very often, a school of sharks becomes irritated to such an extent that they can eat everything in their path. The main thing is that the more the school does this, the more angry the sharks become. In this state, everything that comes across can be eaten - oars, boats, tin cans, rubber car tires. Scientists call this hunger rabies. In this state, even the weakest and smallest sharks pose a real danger.
How do sea fox sharks hunt? The jaws of this predator are relatively weak, and the teeth themselves are small. Therefore, the sea fox uses its tail to get food, with which it stuns the fish so that it can then swallow it unhindered. It feeds on small fish such as mackerel and herring.
The shark is the most dangerous marine inhabitant that can harm human life. The predator lives in sea waters and oceans. You can meet representatives of vertebrates in almost all the salty waters of the World Ocean, but there are so many varieties of fish that it doesn’t hurt to get acquainted with the brightest representatives of this family.
General characteristics of sharks
Sharks are 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.
Shark squads
Unfortunately, many species of sharks have become extinct, and information about them is hopelessly lost. Today there are 8 main orders of predators:
- carchariformes;
- heterodentate or bovine (horned);
- polybranchiformes;
- laminated;
- wobbegong-shaped;
- sawtooth;
- katran-shaped or spiny;
- representatives of flat bodies.
Of the large number of fish, not all are predators. Three species of sharks feed on plankton. There are also representatives of vertebrates that live in fresh waters.
Main types of sharks
You can meet dangerous predators in the Atlantic, Pacific, and Indian Oceans, as well as in the Mediterranean, Red and Caribbean Seas. The most unusual marine animals are:
Tiger shark
The tiger or leopard shark is one of the most greedy predators; the maximum length of the fish is 5.5 m. A distinctive feature of the sea inhabitant is the tiger pattern located throughout the body.
Hammerhead shark
The hammerhead shark is a unique shark that has a “hammerhead” on the front. The predator creates the appearance of a massive and unusual fish. Adults grow up to 6.1 m. Fish love to feast on seahorses, stingrays and stingrays.
Silky shark
Silky or Florida shark - has an unusual grayish-blue color with a metallic tint. The maximum body length of the predator is 3.5 m.
Snout shark
The blunt-nosed shark is one of the most aggressive fish. In some sources, the predator is called a bull shark. The marine inhabitant lives in India and Africa. A special feature of the fish is its ability to adapt to fresh water.
Blue shark
The blue shark is considered the closest fish to humans, as it often swims to the shore. The predator has a blue coloration and a rather slender body and generally grows up to 3.8 m.
Zebra shark
Zebra shark - distinguished by its unusual color in the form of brownish stripes on a light body. The fish species is not considered dangerous to humans. The shark lives near China, Japan and Australia.
Helmet shark
The helmeted shark is one of the rare species predators. The surface of the fish's body is covered with denticles, the color is represented by dark spots on a light background. Adults grow up to 1 meter long.
Mozambican shark
The Mozambican shark is a red-brown fish with white spots on its body. The marine inhabitant lives in Mozambique, Somalia and Yemen, grows up to 60 cm.
Sevengill shark
The sevengill or straightnose shark is distinguished by its aggressive character and ashen color. The fish has a narrow head and grows up to 120 cm.
frilled shark
The frilled or frilled shark is a unique marine inhabitant that can bend its body like a snake. The predator has an elongated gray-brown body, reaching 2 m, and numerous leather pouches.
fox shark
Fox shark - characterized by high speed of movement and a long upper blade of the caudal fin. The latter successfully stuns the prey. The length of the fish reaches 4 m.
sand shark
Sand shark - has an upturned nose and a massive body. Prefers tropical and cool seas. The average length of an individual is 3.7 m.
Blacktip shark
The mako or blacknose shark is a predator that is one of the most effective deadly weapons. The average length of the fish is 4 m, the speed of movement is phenomenal.
Goblin Shark
Goblin shark or brownie (rhinoceros) - this type of fish is called aliens. Sharks have an unusual snout, similar to platypuses. These deep-sea individuals grow up to one meter.
Whale shark
The whale shark is a true sea giant with stunning color and grace. The maximum length of a sea resident is 20 m. Fish of this species do not like cold water and do not pose a threat to humans, although they are frightening due to their mass. The main food of sharks are crayfish and mollusks.
Carpal wobbegong
The carpal wobbegong is a unique species of shark, unlike its “brothers”. The fish is perfectly camouflaged due to flat shape the body and the many rags with which it is covered. By appearance It is very difficult to recognize the eyes and fins of an animal.
Short-nosed sawnose
Shortnose sawnose - the fish has a gray-blue body with a light belly. A distinctive feature of the animal is its sawtooth outgrowth, which makes up a third total length bodies. Using a unique weapon, the shark injures its victims.
Sawtooth gnome
The gnome sawnose is one of the smallest fish of this species, the length of which is no more than 60 cm.
Southern siltworm - has a pointed head, light brown body. The marine inhabitant does not pose a threat to humans.
The heavy silt swallower has a massive body. This type of fish prefers to be at great depths.
Squatins
Flat-bodied sharks or squatins - this type of fish is very similar to stingrays in shape and lifestyle. The sea dweller prefers to hunt at night and burrows into the mud during the day. Some people call sharks sand devils.
There are many types of sharks. The variety of fish is influenced by its habitat and lifestyle.
Other shark species
In addition to the main, well-studied species of sharks, there are also lesser-known predators, including: lemon, granule, longtip, reef, cats, mustel, soup, herring, largemouth, carpet and arctic sharks. Also in sea waters there is a species of predator called the “nurse shark”.
And, of course, a white shark
Evolution has worked hard on these creatures, providing them with adaptation mechanisms that allowed them to bypass other ancient species at historical turns. Sharks appeared 450 million years ago and are rightfully considered the most advanced aquatic animals.
Description of sharks
Selachii (sharks) belong to the superorder of cartilaginous fish (subclass 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 Icelandic “hákall”: this is how the Vikings once called all kinds of fish. In Rus', the word “akul” (m.r.) began to be used in relation to any aquatic predators around 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 wave-like movements with its body/tail and using all its fins. The tail blade, which serves as the rudder and engine, consists of 2 blades, the upper of which includes the spinal column.
Side fins add speed and maneuverability, and also “steer” during turns, climbs and dives. In addition, the paired fins, together with the dorsal one, are responsible for balance during sudden stops and somersaults. Paradoxically, the shark, which has a complex arsenal of fins, never learned to “back up,” but it did learn some funny tricks.
This is interesting! Epaulette sharks walk along the bottom on pectoral and ventral fins, like legs. Small luminous sharks (no more than half a meter in height) “flutter” in the water like hummingbirds, quickly bringing their pectoral fins together and spreading them apart.
The cartilaginous skeleton is additionally strengthened with calcium in areas with greater load (jaws and spine). By the way, the lightness of the skeleton is another reason for shark mobility and resourcefulness. The predator’s thick skin, composed of placoid scales resembling teeth (in strength and structure), also helps the predator cope with the resistance of the environment. It appears smooth if you move your hand from head to tail, and rough as sandpaper if you move your hand from tail to head.
Mucus from glands in the skin reduces friction and promotes high speed. In addition, shark skin contains a lot of pigment, which is responsible for the specific coloring 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 darker tops than their bellies, which helps them camouflage when viewed from above. And the light shade of the belly, on the contrary, makes the predator less noticeable to those who look for prey from the depths.
Fish or mammal
Sharks are aquatic animals from the class of cartilaginous fish, which includes close relatives of these predators, stingrays. Aquatic mammals (whales, seals, dolphins and others) living next to sharks and even somewhat resembling the latter do not belong to their family clan. Even sharks endowed with an extraordinary appearance still remain fish, such as, for example, the frilled shark, whose body outline is similar to a sea snake or eel.
Carpet and squat sharks, which live on the bottom, are distinguished by a flat body with an inconspicuous sandy color, hiding them among bottom plants. Some wobbegong sharks have acquired leathery growths on their snouts (“wobbegong” is translated from the Aboriginal language of Australia as “shaggy beard”). The hammerhead shark, whose name is influenced by the unusual T-shape of its head, also stands out from the crowd.
Character and lifestyle
It is commonly believed that a shark plows the ocean in splendid isolation, without creating numerous schools. In reality, predators are no strangers to social behavior: they gather in huge groups during breeding periods or in places with an abundance of food.
Many species tend to be sedentary and sedentary, but some sharks migrate quite far, covering thousands of miles annually. Ichthyologists suggest that the migration pattern of these predatory fish is more complex than that of birds. Sharks have an interspecific social hierarchy, especially in terms of “distribution” of food rations: for example, the silky shark is certainly subordinate to the long-winged shark.
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 spends days and nights chasing suitable prey with virtually no rest. Ichthyologists recorded the sounds made by sharks as they cut through the water column and the crunching of their jaws, but came to the conclusion that these fish do not exchange sounds, but communicate through body language (including the position of the body and the rotation of the fins).
Movement and breathing
Sharks are doomed to constant movement - they need oxygen, but they (like most cartilaginous fish) do not have gill covers that push water through the gills. This is why the predator swims with its mouth slightly open: this way 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 strong underwater currents or pumping water through their gills (for which they inflate their cheeks and use squirters). It also turned out that certain species of sharks, mostly bottom-dwelling ones, can breathe through their skin.
In addition, an increased concentration of myoglobin (a respiratory protein) was found in the muscle tissue of sharks, due to which they, unlike bony fish, are able to withstand the load caused by constant movement. The cerebellum and forebrain, which are classified as 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 a shark's body is usually 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, since they are able to increase their own temperature due to the intense work of the muscles that heat the blood. The heart, located in the thoracic region (near the head) consists of 2 chambers, the atrium and the ventricle. The purpose of the heart is to pump blood through the gill artery into the vessels located in the gills. Here the blood is oxygenated and supplied to other important organs.
Important! The heart does not have enough power to maintain the blood pressure needed to distribute oxygen throughout the huge body. The shark's regular muscle contractions help stimulate blood flow.
The shark has a multifunctional and quite impressive (up to 20% of the total weight) liver, which is assigned several tasks:
- cleansing the body of toxins;
- storage of nutrients;
- replacement of a missing swim bladder.
Thanks to the liver, sharks stay afloat and almost do not feel pressure drops during sharp ascents and descents.
Sense organs
Sharks have terrible vision - they distinguish contours, but are not able to enjoy the color diversity of the world. Moreover, sharks may not notice a stationary object, but will perk up when it moves. Since predators attack with their heads, nature provided them with eyes protective devices such as skin folds or nictitating membranes. The inner and middle ears are designed to perceive even low-frequency vibrations (inaccessible to human hearing), for example, the movement of water layers.
The ampoules of Lorenzini also help to find prey, capturing insignificant electrical impulses, supplied by the victim. These receptors are found on the front of the head (there are especially many of them in the hammerhead shark) and on the body.
This is interesting! Sharks have an amazingly acute sense of smell, 10 thousand times more receptive than humans, which is explained by the developed anterior lobes of the brain responsible for the sense of 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’s not for nothing that a swimming shark constantly twists its nose and turns its head: this is how it tries to figure out where the alluring aroma is coming from.
It is not surprising that even a blinded predator can easily find fishing spots. But the shark goes into the greatest frenzy when it smells blood - a few drops dissolved in standard pool. It has been noticed that certain species of sharks have a so-called “aerial” sense of smell: they catch odors 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 long-livers, crossing the 100-year mark. These include types such as:
- spotted spiny;
- Greenland polar.
The third, by the way, has become an absolute record holder not only among its relatives, but among all vertebrates. Paleogeneticists estimated the age of the 5-meter-long specimen to be 392 years (±120 years), which led to the conclusion that the average lifespan of the species was 272 years.
This is interesting! A shark’s life is controlled by its teeth, or rather, by their tireless “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 renewed as they fall out, moving out (as in a conveyor belt) from the inside of the mouth. The structure of the teeth/jaws is determined by the type of diet and lifestyle: most sharks have teeth set on cartilage and resemble sharp cones. The smallest teeth are in species that eat plankton: no more than 3–5 mm in the whale shark. Carnivorous species (for example, sand sharks) use long, sharp teeth that easily penetrate the flesh of the prey.
Nature has equipped bottom-dwelling sharks, such as heterotoothed sharks, with crushing (flat and ribbed) teeth capable of splitting shells. The tiger shark has wide and serrated teeth: they are needed to cut and tear the meat of large animals.
Types of sharks
Their number is still a question: some ichthyologists put the figure at 450, while others are confident that the species diversity of sharks is much more representative (about 530 species). The only thing the opponents agree on is the number of squads that unite all the sharks on the planet.
According to the modern classification, there are only eight such groups:
- carchariformes– an order with the maximum (among sharks) diversity of species, some of which are prone to oophagy;
- heterodentate– a detachment of bottom-dwelling sharks with nocturnal activity, having a dense body, 2 dorsal spiny fins and one anal fin;
- polybranchiformes– includes 2 families, distinguished by the shape of the body: torpedo-shaped in polygill sharks and eel-shaped in frilled sharks;
- laminated– the group is dominated by huge pelagic sharks with a torpedo-shaped body;
- wobbegong-shaped- inhabit warm and tropical seas. All except the whale shark live on the bottom;
- sawtoothed– they are easily recognized by their long, saw-like snout with many teeth;
- katran-shaped– found at great depths throughout the world, including latitudes near the poles;
- squatinous- with a short muzzle and flattened body they resemble stingrays, however, shark gills open not from the bottom, but from the sides.
This is interesting! The most inconspicuous among the sharks is the small dogfish (17–21 cm long), and the most impressive is the whale shark, growing up to 15–20 m.
Range, habitats
Sharks have adapted to life throughout the oceans, and some species (including 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. Typically, 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 is incredibly stretchable and is capable of not only digesting prey, but also storing it in reserve. Main component gastric juice - hydrochloric acid, which easily dissolves metal, varnish and other materials. It is not surprising that some sharks (for example,) do not limit themselves at all in food, swallowing all objects they encounter.
This is interesting! The tiger shark has little trick, saving from the consequences of uncontrollable gluttony. The predator knows how to turn its stomach inside out through its mouth (without damaging the walls with sharp teeth!), spewing out 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 is more like rape, since 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 method of birth of offspring):
- oviparous;
- ovoviviparous;
- viviparous.
All methods of reproduction are aimed at preserving species, as they reduce embryonic/postembryonic mortality. Oviparous sharks (over 30% 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 (goose-like) 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. Just over 10% of current sharks give birth to “ready” babies (from 3 to 30). By the way, newborns often die in the teeth of their own mother if they do not have time to swim to a safe distance.
This is interesting! In females in captivity, cases of parthenogenesis were observed, when offspring appeared without the participation of males. Ichthyologists consider this a protective mechanism designed to preserve the population of the species.
Great white sharks primarily feed on seals and sea lions. They also eat other fish and even sea turtles. Seals are a good source of energy for great white sharks due to their significant body fat content.
Great white sharks tend to feed on larger prey such as pinnipeds, including fur seals and seals. However, they will also eat almost anything that gets into their teeth, such as small whales, sea otters, and even other sharks. Great white sharks typically hunt live prey, but will also eat dead animals floating in the water when the opportunity arises. These sharks do not chew their food and instead tear their prey into smaller pieces, which they then swallow whole. They can survive on one meal for about two months if it is large enough.
White sharks use one of three main attack methods to hunt. They typically swim to their prey underwater and then quickly rise to the surface to grab the prey and tear it to pieces. In rare cases, white sharks may swim belly up to confuse their prey.