What is the first thought that comes to your mind when looking at a photo where a shark’s teeth are exposed in an ominous grin?
Shark teeth are a wonderful tool that allows their owner to grab prey and hold it in the mouth, while large species of sharks can cut the victim's body in half as easily as a child bites off ice cream - piece by piece.
Not a single bone, even the thickest and strongest, can resist the multi-ton compression force of shark jaws, and the loss of several teeth will not bother the shark at all - the ocean predator's replaceable teeth grow throughout its life.
For comparison, the force of compression of the jaws of an adult Nile crocodile is about 1 ton per square centimeter, which is a lot in itself, but cannot be compared with the force of the jaws of a large shark.
You will notice, taking a closer look at the photo, that the teeth of a shark of one species differ from the teeth of individuals of another species - they are united only by their constant sharpness.
Sharks have teeth of a shape that allows them to securely grab their prey, tear off a large piece, or bite through its hard shell.
Photo of combtooth shark tooth
Photo of a whale shark tooth
Watch video - Deadly shark teeth:
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
Links[edit]
- "Shark Teeth".
- "Fossil Folklore".
- "Shark Rescuers:: Shark Teeth".
- ^ abc "What do sharks eat - diet for sharks". Types of sharks
. - ^ abcde Zen Cart® Team; and others. "On Fossil Shark Teeth".
- "6 plus inch megalodon shark teeth".
- ^ ab "FLMNH Ichthyology Division: Fossil Sharks".
- ^ abc Hennemann, Ralph M. (2001). Sharks and Rays: A Guide to the World's Elasmobranchs
. IKAN-Unterwasserarchiv. pp. 266–269. ISBN 978-3-925919-33-6. OCLC 223251653. - ^ abcd "Sink Your Teeth into It: 20 Facts About Shark Teeth". Deckchair Scientist
. - "Georgia State Fossil - Shark Tooth".
- Case, Gerard (1967). "Fossil sharks and fish remains of North America". clause 2.
- Heemstra, PC; Hiemstra, E. (2004). Coastal fishes of southern Africa. NISC/SAIAB. P. 47. ISBN 1-920033-01-7.
- Naylor, Gavin JP; Marcus, Leslie Floyd (1994). "Identification of individual shark teeth from the genus Carcharhinus by species." American Museum "Novitates"
. hdl: 2246/4942. ProQuest 51542224. - Ahonen, H.; Stowe, A. J. (29 July 2008). "Shark jaws and teeth: an unexplored resource for population genetic research." Journal of Fish Biology
.
73
(2):450–455. DOI: 10.1111/j.1095-8649.2008.01896.x. - Chen, Chunlin; Wang, Zhongchang; Saito, Mitsuhiro; Tohei, Tetsuya; Takano, Yoshiro; Ikuhara, Yuichi (February 3, 2014). "Fluorine in Shark Teeth: Its Direct Atomic Resolution Imaging and Enhancement Function." Angewandte Chemie
.
126
(6):1569–1573. DOI: 10.1002/ange.201307689. - Becker, Martin A.; Seidemann, David E.; Chamberlain, John A.; Buhl, Dieter; Slattery, William (July 2008). "Strontium isotope signatures in emeloid and dentin of Upper Cretaceous shark teeth from western Alabama: paleoenvironmental and geochronological implications." Paleogeography, paleoclimatology, paleoecology
.
264
(1-2): 188–194. DOI: 10.1016/j.palaeo.2008.04.006. - Whitenack, Lisa (November 7, 2008). "Biomechanics and evolution of shark teeth". Master's theses and dissertations
. ProQuest 304460308. - “Shark teeth are falling! - Dharma Beach is a slacker." Homeless man on Dharma beach
. Archived from the original on 2014-11-13. - Haven, Kendall (1997). The 100 Greatest Scientific Discoveries of All Time. Libraries without limits. pp. 25 -26. ISBN 1-59158-265-2.
- Bruner, John (1997). "Megatus Shark". FLMNH. Archived from the original on 2007-12-28. Retrieved January 16, 2008.
- "Treasures of Hawaii: Shark Tooth Weapons". bishopmuseum.org. Archived from the original on 2008-12-04. Retrieved November 27, 2008.
- Taylor, Leighton R. (1993). Sharks of Hawaii: Their Biology and Cultural Significance. University of Hawaii Press. paragraph 28. ISBN 978-0-8248-1562-2.
- ↑
Anthony Meyer (1995)
Oceanic Art,
v. 2, p. 579. - Metro, Alfred (1946) Handbook of South American Indians,
vol. 1, p. 522, "Guaitaca" - Greg Perino, c. 1950, Cahokia Comes to Life,
pp. 66-67. - Metro, Alfred (1940), "The Ethnology of Easter Island". Bulletin of the Bernice P. Bishop Museum
(Honolulu: Bernice P. Bishop Museum Publishing) 160: 404
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: 10 most beautiful fish on the planet - list, names, photos and videos
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
Research and identification[edit]
The identification of most sharks is determined by a combination of the number and shape of teeth. The teeth may even lead to the identification of sharks such as the requiem shark. Fossil dental records help illustrate evolutionary history, and isolated teeth are used to study and analyze specific linear dimensions of a species. [13] To identify teeth and specific information about them, research can be done on a shark tooth. This research could reveal many different aspects of the tooth itself and the shark species. However, this proves difficult due to the fact that most fossilized teeth are found mixed and scattered. [7]Molecular technology is very effective in collecting information about the basic life history and assessing the distribution of the shark tooth. To further study shark populations, mtDNA can be extracted from shark jaws and teeth. [14] To study the effect of reducing tooth decay in sharks, studies are being conducted on fluoride atoms covalently bonded to calcium atoms in teeth. Each tooth has a complex fluorapatite emeloid structure. [15] To reduce the effects of dental deterioration, it is useful for this particular study to sample only the surface of the tooth's emeloid. [16]Studying shark teeth improves our understanding of shark feeding behavior, evolutionary changes, and mechanisms. [17] This helps us identify teeth and even species.
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.
Golden age
The Carboniferous period was the era of maximum shark diversity. It was a real Golden Age, which gave rise to many bizarre forms of these predators. Some, such as xenacanthiformes, even switched to living in fresh water bodies. The diversity of tooth types has allowed sharks to occupy a variety of ecological niches, feeding on a variety of prey. The three-meter-tall Stethacanthus carried a strange growth on its back that looked like an ironing board. In Helicoprion, the dentition formed a spiral, similar to a circular saw blade.
The main competitors in the seas were placoderms - monsters covered with bone armor, the most famous of which was Dunkleosteus. In contrast, sharks relied on speed and maneuverability, and this allowed them to dominate the seas until the end of the Carboniferous. The evolutionary price was bone tissue.
It seems natural to us that fish are able to swim in the water column. But let us remember that their evolution began at the bottom, in shallow coastal areas. The bony skeleton and outer shell gave them negative buoyancy, in other words, the fish were heavier than water. In this position, active movement in the water column requires increased muscle work and high energy consumption. There is only one way to reduce the load on the muscles - to acquire zero buoyancy. Bony fish achieved this thanks to their swim bladder. The growth of the intestines, filled with gas, allowed them to develop all the bodies of water on the planet and even reach land. As for sharks, their bone tissue was gradually replaced by cartilage, lightening the weight of the fish. The huge fatty liver, which makes up up to 30% of the shark’s mass, also helped reduce buoyancy.
The body structure that allowed sharks to dominate the Carboniferous was not effective enough. In the Permian period, the evolution of sharks slowed down sharply, and bony fish began to displace them from ecosystems. And 245 million years ago, the catastrophe at the end of the Permian period caused enormous damage to sharks. Climate changes that continued throughout the Permian period led to a critical drop in sea level. At the same time, volcanic activity increased. The release of toxic gases into the atmosphere caused a volcanic winter and acidification of ocean water. 95% of all species of sea creatures died. The few surviving species of sharks had to fight for life in a completely new world.
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.
Appearance of a great white shark
This is a stocky fish with a dense body, elongated in the shape of a torpedo. The head of the predator is very large, conical, with a pointed muzzle and mouth, curved into a parabola. On the sides of the head, closer to the pectoral fin, there are 5 huge gill slits that provide water respiration.
The pectoral fins are large, elongated in the shape of a sickle. The first dorsal fin is high, triangular in shape, growing slightly further than the base of the pectoral fins. Sometimes its top is rounded. The second dorsal fin is very small, as is the anal fin. On the pelvic fin of males there is an elongated element - a copulatory outgrowth.
The tail fin blades of the white shark are of the same width, which is typical of other herring sharks, which are capable of developing decent speed before attacking.
The name “white” shark does not quite accurately convey the coloration of the predator. Its upper part and sides are often gray, sometimes brownish or with a blue tint. There are dark, almost black specimens. But the belly of a white shark is dirty white.
Newborn sharks and adult individuals are completely identical in appearance, but differ only in size.
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.
Giants of the sea
As at the beginning of the Triassic, the extinction opened ecological niches in the ocean for a new group of animals. They became mammals. Throughout the Cenozoic, various groups of mammals transitioned to an aquatic lifestyle. Among them were predators, ungulates, and even waterfowl sloths. The toothy mouths of sharks were waiting for them all in the sea. A new type of teeth also appears - wide and triangular, bearing serrations along the cutting edge. In the Paleocene, super-predators, otodontids (Otodontidae), appeared. Large individuals exceed a length of 9 meters and hunt not only bony fish, but also other sharks. With the advent of marine mammals, otodontids included them in their diet.
Cetaceans, in order to resist sharks, became larger, reaching modern sizes in the Eocene. But the sharks are not far behind them. By the Miocene, about 23 million years ago, according to most scientists, it was the evolution of otodontids that led to the emergence of one of the largest predators in history. Megalodon - length 15-18 m, weight more than 30 tons. Huge teeth with a sawtooth edge, reaching 18 cm in length. The colossal power of the jaws allows you to open the chest or bite the tail fin of a whale. Megalodon was the ruler of warm shelf seas, preferring slow-moving, medium-sized cetaceans. Its large size and narrow specialization were the basis of its power and vulnerability.
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: What is the maximum overload when bungee jumping?
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.
Discovery history[edit]
Scapanorhynchus texanus
, Menuha Formation (Upper Cretaceous), southern Palestine.
Shark tooth
The oldest known records of fossilized shark teeth are those of Pliny the Elder, who believed that these triangular objects fell from the sky during lunar eclipses. [18]
According to Renaissance accounts, large triangular fossilized teeth, often found in rock formations, were thought to be the fossilized tongues of dragons and snakes, and were therefore called "tongue stones" or "glossopetras". Glossopetrae
usually considered a cure for various poisons and toxins;
they have been used in the treatment of snake bites. Because of this ingrained belief, many nobles and royals wore these "tongue stones" as pendants or kept them in their pockets as good luck charms. [ citation needed
]
This interpretation was corrected in 1611 by the Italian naturalist Fabio Colonna, who recognized them as the teeth of an ancient shark, and in 1667 by the Danish naturalist Nicholas Steno, who discussed their composition and created the famous image of a shark's head with such teeth. [19] He mentioned his findings in the book Dissected Shark Head
, which also contained an illustration of a
C. megalodon
, previously thought to be a tongue stone. [20]
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.
Today's day
By the end of the Pliocene, the climate again entered a period of change. The era of ice ages begins, sea levels fall, and the map of currents changes, which leads to the disappearance of a number of shelf ecosystems. Plankton fields and migration routes of small fish are shifting to cold waters. Following them, whales leave and new predators come. Orcas. Their warm blood allows them to hunt in both the tropics and polar waters. Fast and incredibly intelligent, pack hunters are capable of taking down any prey. They drive schools of fish into traps along rocky shores. They snatch seals right from the shore. Huge whales are gutted alive. And they look at shark liver, rich in fat, as a delicacy.
About 2.6 million years ago, megalodon became extinct, leaving no successors. But with its extinction, the story of sharks is not over at all. Today, as millions of years ago, they remain a successful class of fish, occupying a variety of ecological niches. Benthic species, with camouflage coloring and a flattened body, are common in the tropics. Pelagic hunters, such as lamniformes, roam the seas of the entire planet. The whale shark, although it feeds on plankton and not whales, is the largest modern fish and reaches 12–18 meters in length. And large sharks, such as white and tiger sharks, maintain their status as apex predators, being at the top of the food pyramid.
quick view add to cart
Museum quality megalodon tooth 16.2 on stand
649 000 ₽
quick view add to cart
Collection quality megalodon tooth 10.4 cm on stand
47 900 ₽
quick view add to cart
Collection quality megalodon tooth 8.5 cm on stand
41 900 ₽
quick view add to cart
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.
White shark hunting methods
Carcharodons live and hunt solitarily, but sometimes exhibit social behavior. For example, in the coastal waters of Cape Town, a group of 2-6 individuals is regularly spotted, which behave quite peacefully in the flock.
Observations carried out in South African waters have proven that there are various kinds of hierarchies within such groups. Females dominate over males, large individuals over smaller ones. When meeting, representatives of different groups and individuals quickly determine the social position of each other and the alpha leader. Conflicts are usually resolved with warning bites and in most cases end there. However, white sharks always separate before hunting.
Unlike their relatives, white sharks often stick their heads out of the water, catching odors wafting through the air. This usually happens when patrolling archipelagos, where pinnipeds set up rookeries.
When the animals are in the water, the white shark begins the hunt. It swims towards the victim just under the surface of the water and makes a sharp throw, sometimes jumping half or completely out of the water. Seals or fur seals are grabbed from below across the body, large individuals are dragged to the depths and drowned, then torn into pieces and eaten. Small ones are swallowed whole.
In fog and at dawn, the chances of a white shark attacking the first time are 50/50. If the attempt is unsuccessful, the predator pursues the prey, reaching speeds of up to 40 km/h.
Northern elephant seals, which are found in abundance off the coast of California, are bitten from behind by white sharks, immobilizing them. Then they wait patiently for the victim to bleed out and stop resisting.
Dolphins are never approached from the front, excluding the possibility of detecting danger using echolocation.
If you don't try, you won't know. According to this principle, great white sharks determine the edibility of any object, be it a buoy or a person. According to statistics, between 1990 and 2011 there were 139 white shark attacks on humans, of which only 29 were fatal.
Even after an attack, carcharodons do not intentionally pursue people; the victims are single swimmers who die from painful shock. When there is a partner, the wounded man can be saved by driving away the predator and leaving the danger zone together.
Only newly born sharks hunt on their own and do not pose a danger to humans or large animals.
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
Age of Lizards
The restoration of the biosphere after the Great Permian Extinction proceeded very quickly. The liberation of many ecological niches spurred evolution, and sharks did not stand aside. But not only them. A sharp reduction in the number of large aquatic predators allowed reptiles to switch to an aquatic lifestyle. Primitive ichthyosaurs appeared already in the Early Triassic. Somewhat later, nothosaurs went to sea to give birth to plesiosaurs. Of the archosaurs, crocodylomorphs stand out, and by the Jurassic period, some of them also mastered the sea element. The seas are becoming the scene of intense competition between sharks and reptiles, in which bony fish largely remain the role of prey.
During the evolutionary race, pelagic sharks acquire their modern appearance. An ideal body shape, a large mouth with a movable upper jaw, an excellent sensory system, viviparity in some species - these features allow sharks to compete with ichthyosaurs on equal terms. And their sharp teeth, changing like on a conveyor belt, cause much more dangerous injuries. Gradually, sharks begin to displace reptiles from the ecological niches of medium-sized predators, but remain in the shadow of the giants. How intense the struggle was can be judged by the following fact. In the mid-Cretaceous period, as a result of the Cenomanian-Turonian extinction, ichthyosaurs went extinct. And immediately a replacement appears - large sharks from 6 to 10 meters long (Ptychodus mortoni, etc.).
Already in the Jurassic period, representatives of those orders of sharks that exist today appeared - carchariformes, lamniformes and others. The mass extinction at the end of the Cretaceous period brings an end to the century of dominance of reptiles, both on land and in the seas. Even mosasaurs, those highly successful relatives of monitor lizards that conquered the ocean at the end of the Cretaceous, do not survive. Losses among cartilaginous animals (including sharks) amounted to only 20% of species. Sharks are entering a new era as the absolute masters of the sea elements.
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.
Ghost Shark
This sharp-nosed blue chimera was captured by the MBARI Tiburon remotely operated vehicle near the top of Davidson Seamount off the coast of Central California at a depth of about 1,640 meters. (Image credit: Copyright 2007 MBARI)
Gliding through the dark ocean some 1,640 meters deep, the sharpnose blue ghost shark (Hydrolagus trolli) looks like a strange, silent phantom. For this reason, these elusive sharks are sometimes called "ghost sharks."
Ghost sharks were not officially identified until 2002, when researchers classified and named the species based on dozens of carcasses accidentally caught in fishing trawlers. Between 2000 and 2007, another team of scientists from the Monterey Bay Aquarium Research Institute (MBARI) in California filmed a series of videos off the coast of Central California showing live specimens.
Completing this species is the “oddity” of a spiny, club-shaped organ on the top of the males’ head. The organ is used to position the female during copulation, according to Lonnie Lundsten, a senior scientist at MBARI.
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.
Viper shark
The pit viper shark has triangular-shaped jaws and needle-like teeth. (Image credit: Hsuan-Ching Ho)
The viper shark (Trigonognathus kabeyai) may well be from another planet. This species of deep sea shark was only discovered in 1986 and has rarely been seen since. Like goblin sharks, viper sharks also have a protruding jaw with a nasty set of scruffy teeth. But these scary-looking creatures are not that big – viper sharks only grow to 18–53 centimeters in length.
The Viper Shark also glows. Bioluminescent organs called photophores line the underside of these sharks. The pit viper shark is part of the glow shark family (Etmopteridae), all members of which glow. This glow likely camouflages the sharks when viewed from below, as the subtle glow blends with the sunlight filtering through the water. The light can also attract small prey in the dark ocean depths.
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.
Where are white sharks found?
Despite the obvious trend towards reduction in the species, white sharks continue to inhabit all oceans except the Arctic. The most numerous populations are found off the coast of South Africa, the American state of California, the Mexican state of Baja California, Australia and New Zealand. This is where the best photos of the white shark come from, chillingly realistic with their realism.
Most carcharodon prefer coastal waters of the temperate zone with temperatures from 12 to 24 ° C and stay almost below the surface of the water. However, large specimens thrive in tropical waters, cold seas, the open ocean, and also at considerable depth. According to documented data, a great white shark was once caught at a depth of 1,280 m using industrial bottom tools.
Before the invention of radio beacons, it was believed that long journeys were characteristic only of male white sharks, while females stuck to their native shores all their lives. However, the ability to track the movements of fish using modern equipment has proven the fact of long migrations by individuals of both sexes.
For what purpose great white sharks travel enormous distances remains a mystery. For example, it took one individual 9 months to travel 20 thousand km from the coast of South Africa to Australia and back. Perhaps long migrations are associated with reproduction or seasonal fluctuations in the food supply in different parts of the range.
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: The most dangerous fish in the world - a list of why they are dangerous, names, where they are found, photos and videos
frilled shark
0
The shark owes its name to the unusual structure of its gills, which border its head like a medieval cloak. Fortunately, this creature can only be encountered at very great depths, otherwise it would become a nightmare for any diver. In the shark's mouth, researchers discovered more than three hundred renewable teeth: just imagine this two-meter monster that decided to splash around in shallow water.
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.
California bull shark
A baby California bull shark on the seabed. (Image credit: Julian Gunter/Getty Images)
California bull sharks, or California horn sharks (Heterodontus francisci), are quiet, unassuming small sharks. They spend their days hiding in rock crevices less than 12 meters deep. At night, these sharks come out to hunt, but they are not graceful nocturnal hunters. According to the Monterey Bay Aquarium, California bull sharks are clumsy swimmers and sometimes even use their fins to crawl along rocks rather than swim. They take advantage of this as they eat mostly molluscs and echinoderms such as sea urchins. ()
The California bull shark not only crawls, but is also distinguished by sharp spines that protrude from both dorsal fins. These spines help protect California bull sharks from predators - they are spiny from the moment they are born.
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
First blood
The history of sharks begins in ancient times, at a time when the only vertebrates on the planet were fish. Forced to defend themselves from cephalopods and crustacean scorpions, they dressed themselves in powerful armor. These armored creatures, ostracoderms, did not have jaws. They fed on detritus and invertebrates, filtering bottom mud. But by the middle of the Silurian period the situation changed. The ossified gill arches formed the jaws, and the scales covering them turned into teeth. The prey has become an active predator.
By the beginning of the Devonian period, the following evolutionary branches of fish took shape: - acanthodes and placoderms, now extinct; - bony fishes, which will be divided into ray-finned and lobe-finned; - cartilaginous, represented by sharks, rays and chimeras.
The first fossils of cartilaginous fish date back 400 million years, and they are, of course, represented by teeth. It is the teeth that will mark the entire path of the further evolutionary history of sharks. You could even say that their history is the history of teeth.
What do human teeth, shark teeth, and placoid scales have in common? Same structure. Placoid scales are the most ancient. It is a diamond-shaped plate of dentin embedded in the skin. The protruding spike is covered with vitrodentin (essentially tooth enamel), and the internal cavity of the scale is filled with pulp with blood vessels. Even in the Devonian, such formations became the first teeth of fish, both sharks and our ancestors. The smooth spike of the scale protruding from the skin has turned into the working part of the tooth. It was not fixed in the bone and was easily lost, but a new tooth grew in its place.
About 370 million years ago, Cladoselachidae emerged from the diversity of cartilaginous fish. These fish lived in shallow seas on the site of the future North America. They were the first fish to bear the basic structural features of sharks. The elongated, spindle-shaped body reached 1.8 m in length, and ended in a tail with identical upper and lower blades. The skin, unlike modern sharks, was almost devoid of scales. The horseshoe-shaped mouth on the lower part of the head was dotted with smooth teeth with several peaks. Five to seven gill slits ensured the flow of water to the gills. We know all this thanks to the well-preserved skeletons of cladoselachians with imprints of organs and tissues. It seems paradoxical, but the first sharks were cartilaginous only formally. And sharks still have genes responsible for the formation of bone tissue today.
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
CONTENT
- 1 Types and functions 1.1 Dense flattened teeth
- 1.2 Needle teeth
- 1.3 Pointed lower teeth and triangular upper teeth
- 1.4 Non-functional teeth
- 1.5 Transitional teeth
- 1.6 Special Mention: Megalodon Teeth
- 1.7 Deposits
MEGALODON'S SMILE
Science and life // Illustrations
Jaw of a modern shark.
Fossilized teeth of sharks of different species.
The author’s two-year-old daughter holds a megalodon tooth in her hands.
A mackerel shark tooth, Otodus obliquus (center), with other teeth found in phosphate mines in Morocco.
Common sand shark. The photo was taken at the Albuquerque Aquarium (USA).
Teeth of sharks from the genus Hemipristis.
‹
›
It is we, people, who have to take care of our teeth, brush them, visit the dentist - at least sometimes. Sharks don't have to worry about the safety of their teeth. In the process of evolution, they managed to acquire the ability to repeatedly replace damaged or broken teeth with new ones. Unlike the teeth of mammals, shark teeth are skin structures, modified scales, so they fall out easily. The shark's jaw is a real conveyor belt for the production of teeth, which grow, gradually moving to the outer edge of the jaw, ready at the right time to replace those that have failed. Over the course of its life, a shark can grow tens of thousands of teeth.
An unlimited arsenal of teeth is just one of the features that make up the image of a sea predator, a tireless machine with seemingly only one purpose: to kill. The shark is a cruel, unforgiving and... endangered predator. Like many other predators, sharks find it difficult to compete with a person who is capable of killing for sport or, at worst, for the sake of a pair of fins and a piece of shark liver. For example, the Chinese have a custom of serving shark fin soup as the main dish at weddings, and this tradition is difficult to break.
However, sharks have existed on Earth for hundreds of millions of years, and many species became extinct before humans appeared. Unlike bony fish, sharks have a spine made of cartilage, so after the death of the animal it quickly decomposes. In the vast majority of cases, all that remains from the “thunderstorm of the seas and oceans” are teeth. It is through them that paleontologists study the diversity of fossil sharks.
What causes the difference in tooth shape? One of the main reasons is the way of eating. Long and thin teeth are convenient for grasping and holding small prey, and those with a serrated edge are used for cutting the flesh of larger victims. The shape of the teeth also depends on where they are located. Usually the front teeth are symmetrical, while the cut teeth (back teeth) have the tip bent in one direction or the other. The upper ones may have serrations along the edges, the lower ones do not, for example, sharks from the genus Hemipristis
. The graceful curve of the profile in the form of the English letter S (the so-called labiolingual curve) is characteristic of the teeth of the lower jaw. It is this feature that helps sharks hold prey in their mouths. The term characterizes a change in the inclination of the tooth in relation to the jaw and comes from the Latin words labial (from the side of the lip, external) and lingual (from the side of the tongue, internal).
Fossil shark teeth are among the most common fossils, and their collecting is popular among amateur paleontologists. It’s rare that someone won’t be surprised by the tooth of a megalodon, the largest shark in the entire history of life on the planet. Megalodon literally means “giant tooth”, and indeed a shark tooth of this species sometimes hardly fits in a man’s palm. The information is reliable, since the author owns a copy that is 15.5 centimeters long. Megalodon teeth, like other sharks, are measured from the tip to the outermost point on the root. Considering that the size of the shark's tooth and body are proportional, scientists suggest that megalodon could reach a length of 17 meters or more. The maximum size of the legendary sea killer, the great white shark, is only slightly more than 7 meters. And the largest living shark, the whale shark, grows up to 15 meters, but it is safe because it feeds on plankton and small crustaceans.
Scientists are still debating whether Megalodon was the ancestor of the great white shark or not. Previously, the generic name of megalodon was Carcharodon
like a great white one.
Currently, scientists are inclined to believe that megalodon belongs to a separate species, and prefer to call it Carcharocles megalodon
.
The following sequence of forms in the evolution of megalodon is proposed: Cretolamna appendiculata
-
Otodus obliquus
-
Otodus mugodzharicus
(transitional form) -
Carcharocles angustidens
-
Carcharocles hubutensis
(transitional form) -
Carcharocles megalodon
.
During evolution, the size of the teeth increased, notches appeared on the cutting surface, and secondary (lateral) tips were lost, apparently due to a gradual increase in the thickness of the teeth. Russian paleontologists V.I. Zhelezko and V.A. Kozlov believe that megalodon should not be classified as a separate genus. They proposed to classify this species using the generic name of its ancestor - the mackerel shark Otodus obliquus
.
Shark teeth can be seen in jewelry such as necklaces and earrings. And for good reason. Residents of the South Pacific Islands are convinced that a shark tooth amulet protects against troubles, primarily from attacks by live sharks. This belief is associated with the legend of the battle between the god of the seas, Ohav-Lai, and a giant man-eating shark. The battle took place in the depths of the ocean and lasted the whole day, and when the victorious god emerged from the sea, the tooth of the shark he had defeated hung on his neck.
For a long time in Europe, fossilized shark teeth were called snake or Maltese tongues. The origin of these fossils was explained in the legend of the Apostle Paul, who was shipwrecked on the island of Malta on his way to Rome (those interested can find accounts of Paul's adventures in Acts 28:2-7). The rescued sailors lit a fire on the shore to keep warm. Suddenly a snake crawled out of the fire and bit Pavel. The poison had no effect, which surprised the local residents. The apostle grabbed the snake and threw it into the fire, after which he cursed all the snakes of the island of Malta, depriving them of their eyes, tongues and the ability to produce poison. Fossilized shark teeth found on the island became associated with the tongues that snakes lost as a result of Paul's curse. In the Middle Ages, in wealthy Maltese houses it was fashionable to hang “stone tongues” on coral branches and place them on the table next to the treats. Dipping shark teeth in wine was supposed to neutralize the effect of the poison. Therefore, after the procedure of immersing amulets in the drink, guests could be sure that it was not poisoned.
Fossilized shark teeth are mentioned in the folklore of many peoples. In Japan, megalodon teeth were considered the nails of a colorful character, the mountain monster Tengu, whose nose was long, like Pinocchio. This belief spread during the Edo era (the name of this period of the Japanese Middle Ages comes from the fishing village of Edo, where the castle of the Tokugawa clan that ruled at that time was located). In a number of famous Japanese temples, megalodon teeth were carefully kept in treasuries. In Switzerland, shark teeth were hung around the necks of children, hoping to relieve them of the pain that accompanies the appearance of new teeth. In Italy, shark teeth, along with petrified corals, were used for a special type of amulets: they were supposed to protect against the evil eye and witchcraft.
Man used the teeth of a sea predator not only as amulets, but also as a weapon - so to speak, for its intended purpose. In Hawaii, the wooden swords and brass knuckles of Haio-Mano are known, to which are attached sharp, blade-like shark teeth. This weapon is very effective in close combat and is capable of leaving deep bleeding wounds on the body of the enemy. Most often, wooden swords are shaped like an oar. At the same time, the pointed handle was used for piercing blows, and the oblong thickening at the far end served not only as a place where the teeth were attached, but also as a shield, helping to fight off enemy attacks. The aborigines of Australia also made similar weapons, only they secured their teeth to the club not with a tourniquet, but with wax produced by special bees that do not have a sting ( Trigona sp.
).
The nature-oriented mythology of the indigenous Pacific Islanders views sharks as a species of aumakua, the guardians of the human race. Creatures called aumakua (these can be whales, birds and even trees) act as messengers of the gods and store the wisdom of their ancestors. They are a kind of family (clan) gods or the reincarnation of ancestors. The relationship between them and the Hawaiians resembles family ties. There is a ritual when old people go to sea with their grandchildren to introduce them to the sharks - aumakua.
I would like to believe that people who consider themselves representatives of the so-called Western civilization will someday stop seeing these animals as the embodiment of horror. Perhaps, having managed to curb the trembling in our knees at the sight of a shark’s “Hollywood smile,” we will understand something important about the world around us and about man’s place in wildlife. The question of whether humanity has reached a level of development where it is not necessary to destroy everything that causes a sense of danger has long been on the agenda. I really want this to happen before we exterminate all predators, including sharks.
Katran Gini
Katran Gini has big blue eyes, like anime characters. (Image credit: MarAlliance)
The strangest sharks include the Genie, which has large blue eyes. These sharks (Squalus clarkae) are deep-sea creatures found in the Gulf of Mexico and the western Atlantic Ocean. They are small in size (50 to 70 cm) and their large blue eyes make them look like cute anime characters.
The shark species was discovered and officially described in 2022.
Types of hyperdontia
Polyodontia or shark syndrome in patients takes on various forms. Based on the location of the teeth and pathological factors, there are 4 main types:
- Typical hyperdontia is a disease in which an abnormal number of teeth does not disturb the overall row.
- Atypical hyperdontia is a disease in which shark teeth erupt in unusual places.
- True polyodontia is a disorder in which shark teeth grow from the extra rudiments that appear.
- False polyodontia is a condition when a baby tooth has not yet fallen out and a permanent one appears at the same time.
Complications of polyodontia
If polyodontia is not treated, a complication of the disease is the worsening of the curvature of the dentition and, accordingly, the proportions of the face. Shark teeth grow out of place, which is clearly visible when smiling and laughing. Sometimes the pathology is noticeable even with closed lips, and the upper or lower lips may rise. Also, the jaw closes incorrectly, speech is impaired, and malfunctions of the mandibular joint appear.
Polyodontia disrupts the bite - teeth can shift and rotate in a row. Shark teeth cause crowding and hygiene in their area is difficult. This leads to the formation of caries and subsequent complications. The gums become inflamed and gingivitis and periodontitis develop.
California bloat shark
California bloat sharks can swallow water and double in size. (Image credit: Douglas Klug/Getty Images)
Even sharks need to avoid predators. California bloat sharks (Cephaloscyllium ventriosum), which spend their days hiding in rocky crevices, have developed a cunning plan to defeat potential predators: they swallow huge amounts of seawater to swell to twice their normal size.
California bloat sharks are found everywhere from the California coast to the waters near the Philippines. Their inflation trick can frighten predators if they come out hunting at night; and during the day, sharks can deflate to take refuge in their rocky hiding places, preventing predators from dragging them out. ()
