The bull shark, or blunt-nosed shark (Carcharhinus leucas) is a species of shark from the family Carcharhiniformes.
Row - CarchariformesFamily - Gray sharks
Genus/Species - Carcharhinus
Basic data:
DIMENSIONS
Length: up to 3.5 m.
Weight: up to 50 kg.
REPRODUCTION
Puberty: achieved with a length of 1.5-2.5 meters.
Gestation period: 10-11 months
Number of cubs: from 3 to 13 fry.
LIFESTYLE
Habits: Males are territorial animals, aggressive towards any potential rivals, which can sometimes even be considered humans.
Food: All sharks of this group are omnivores and, along with live prey (coastal fish and crabs), devour any waste.
Lifespan: no data.
RELATED SPECIES
California tripletooth shark.
These sharks, reaching 3.6 m in length, inhabit coastal areas of the tropical region. The blunt-nosed shark and its relatives are undoubtedly dangerous to people.
FOOD AND HUNTING
These are rather lazy and slow-swimming sharks. The diet consists mainly of large invertebrates, small sharks, other fish and dolphins, along with live prey they devour any emissions. They can eat individuals of their own species. All sharks of this group are omnivores and, along with live prey (coastal fish and crabs), devour any waste.HABITAT
These sharks, reaching 3.6 m in length, inhabit coastal areas of the tropical region. These rather lazy and slow-swimming sharks are common in all oceans. Species belonging to this group often enter rivers and other fresh water bodies, moving 160 miles or more from the sea. They penetrate in particular into the Ganges, Zambezi and many other tropical rivers of Asia, Africa and America. In the freshwater lake of Nicaragua, located in Central America, there is even a living form of the blunt-nosed shark that never goes to sea. All sharks of this group are omnivores and, along with live prey (coastal fish and crabs), devour any waste.REPRODUCTION
This is a viviparous fish, the length of which at birth is about 60 cm. Sexual maturity is reached at a length of 1.5-2.5 meters. Pregnancy lasts 10-11 months, after which the female gives birth to 3 to 13 fry.BULL SHARK AND MAN
The blunt-nosed shark and its relatives are undoubtedly dangerous to people. Especially many attacks were noted in the waters of South Africa. Around 60 people have been attacked while swimming off the coast in the area over the past 50 years, with almost half of the incidents resulting in death. There, in 1942, there was a massive attack by a large number of sharks on passengers of a steamship that was torpedoed near the shore during the war. True, in this case the species of the sharks was not determined, and it is likely that representatives of many dangerous species. The number of victims of this bloody massacre also remains unknown. DID YOU KNOW THAT...
- Their testosterone levels are higher than any other vertebrate, which partly explains their aggressiveness.
- This species can be kept in special round or rectangular aquariums with a volume of at least 3000 liters.
- It is an object of fishing, the meat is eaten. The bull shark is an aggressive shark that is known for its attacks on humans.
CHARACTERISTIC FEATURES OF THE BULL SHARK
The body length of marine subspecies of the bull shark reaches 3.5 m, freshwater subspecies are slightly smaller.Coloring, as a rule, gray, only the belly remains white.
- Bull shark habitat
PLACES OF ACCOMMODATION
These sharks are ubiquitous and often enter rivers. Sometimes they climb many kilometers upstream. They penetrate in particular into the Ganges, Zambezi and many other rivers of Asia, Africa, America and Australia (for example, the Clarence River), were observed in the Amazon (near the city of Iquitos, 4000 km from the mouth!), in the Mississippi River (to St. Louis and the Illinois River), Lake Michigan. Lives permanently in Lake Nicaragua.
PRESERVATION
This species can be kept in special round or rectangular aquariums with a volume of at least 3000 liters. Aquariums must be provided with powerful filtration and aeration of water.
The bull shark or blunt-nosed shark belongs to the family of gray sharks, that is, it is the closest relative of the blue and tiger sharks. The habitat of this predatory fish is huge. It is found throughout the world in warm and shallow waters. Comes in deep rivers and rises upstream. These are the Amazon, Ganges, Zambezi, Mississippi. It can be found in small rivers, as well as lakes connected to the World Ocean.
Habitat
This predatory fish does not move away from coastal waters further than a depth of 150 meters. Its usual habitat is limited to a depth of 30 meters. In the Atlantic Ocean, it can be found in the coastal zone of America from the northern states of the USA to Southern Brazil, and near the African coast from Angola to Morocco. IN Indian Ocean her ancestral patrimony stretches along Africa from South Africa to Kenya. The fish also lives near the west coast of India and in Persian Gulf. As for the Pacific Ocean, these are almost all the islands of Oceania. This species is not found only along the southern coast of Australia. And off the west coast of America it lives from California to Ecuador.
In the muddy Amazon dangerous predator feels great. Upstream the fish rises 2 thousand km. Some representatives of the species were even seen in Peru. In the Indian rivers Ganges and Brahmaputra, the blunt-nosed shark is also common. Its native home is Lake Nicaragua in Central America. A toothy monster enters it from the Caribbean Sea through the San Juan River. At the same time, this species tends to warm currents and tries to avoid cold ones. Therefore, in latitudes with temperate climate the bull shark is missing.
The body of the fish has a stocky shape. This is where the association with the bull came from, and people included this word in the name of the shark. Females of this species are larger than males. The length of the toothy predator reaches an average of 2.5 meters, and the corresponding weight is 130 kg. The maximum length reaches 3.5 meters. It is said that fishermen caught females 4 meters long, but there is no evidence of this. But the maximum recorded weight of a blunt-nosed shark is 315 kg. Although experts admit that this is not the limit.
This species is characterized by 2 dorsal fins. Moreover, the front one is much larger than the rear one. But the caudal fin is longer than that of other members of the family, but located lower. When capturing prey, the fish's jaws compress with a force of 600 kg. This is one of the highest rates among all types of selachy. The fish's skin is gray on top and its belly is white. It is quite difficult to see a predator in water, especially in muddy river water. This toothy monster is even credited with attacks on people that he did not commit.
Reproduction
This species is viviparous. That is, it is not caviar that is born, but small fry. There are from 5 to 10 of them. Their sizes are quite large and reach a length of 60-70 cm. This is after 12 months of pregnancy. Sexual maturity occurs when the bluntnose shark grows to 1.5 meters in length. The female gives birth in lagoons and river mouths. Maximum sizes the fish reaches the age of 10 years.
Behavior and nutrition
The bull shark usually hunts alone. Sometimes there are exceptions, and toothy predators go hunting in pairs. By nature, the fish is aggressive and unpredictable. In water, it can attack both humans and large animals. This species is the most dangerous for people, as it lives in shallow salt and fresh waters. In terms of danger, it is on a par with tiger and white sharks.
The main diet consists of small sharks, various types fish and dolphins. A predator, without hesitation, can swallow a representative of its own species, if it is small in size. The toothy monster does not disdain waste, which is similar to a tiger shark. Representatives of the species are accused of many bloody crimes against people. Although there is a suspicion that some of these crimes were committed White shark.
Enemies
In the World Ocean, the bull shark has few enemies. These are tiger and white sharks. The remaining large selachians live in a different habitat. But the main enemy is man. He has been destroying this fish and eating its meat for many centuries. The most unprotected are the fry. They are caught by birds and more large fish, and in Australia crocodiles eat with pleasure. But when the fry grows up and turns into an adult fish, it becomes a real thunderstorm in coastal waters.
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This is one of the most aggressive species of sharks, which also poses a danger to humans. They are the subject of industrial fishing.
Taxonomy [ | ]
Original illustration depicting a blunt-nosed shark
This species was first scientifically described in 1839 by German scientists Johann Peter Müller and Friedrich Jacob Henle. Syntypes: male 161.5 cm long and female 190 cm long, caught in the Antilles. The specific epithet comes from the Greek word. λευκό - "white" . The shark is sometimes called the gray bull shark or bull shark. The colloquial name is associated with the stocky shape of its body, wide and blunt snout, as well as aggressive, unpredictable behavior.
Area [ | ]
These sharks are ubiquitous in tropical and subtropical waters and often enter rivers. They are found at depths of up to 152 m, but most often stay no deeper than 30 m. In the Atlantic, they range from Massachusetts to southern Brazil and from Morocco to Angola. In the Indian Ocean they are found from South Africa to Kenya, India, Vietnam and Australia. In the Pacific Ocean, bluntnose sharks are found from Baja California to Ecuador. .
There are entire populations of these sharks in rivers. More than 500 individuals live in the Brisbane River. During the 2010–2011 Queensland floods, a blunt-nosed shark was observed in the flooded streets of Brisbane. Several individuals were spotted on one of the main streets in the Ipswich suburb of Goodney shortly after the peak of the floods, which occurred in January 2011. A large bull shark was caught in the canals Scarborough (Australia) en, residential suburb Moreton Bay Ridge en, Queensland.
Sometimes blunt-nosed sharks rise many kilometers upstream. They penetrate, in particular, the Ganges, Brahmaputra, Zambezi and many other rivers in Asia, Africa, America and Australia. Sharks have been seen in the Amazon (near the city of Iquitos, 4,000 km from the mouth), Mississippi (all the way to Illinois), as well as in Lake Michigan and Lake Nicaragua, where they live permanently.
Description [ | ]
Bull sharks reach quite large sizes. The maximum recorded length is about 3.5 m, and the weight is about 360-450 kg. According to other sources - 4 m and 575-600 kg. Females are larger than males, their average length is 2.4 m and their weight is 130 kg, while for males these figures are 2.25 m and 95 kg, respectively. Bull sharks are the stockiest of the gray sharks and are more robustly built than their comparable sized relatives. They have the most powerful bite of any living shark. The bite force of a 2.85 m 193 kg bull shark was calculated to be 2128 at the front of the jaws and 5914 N at the base, which relative to weight significantly exceeds the jaw force of other sharks (for example, the bite force of a 423 kg white shark is only 4577 N).
Blunt sharks have a dense spindle-shaped body, a short, blunt and rounded snout. The distance between the nostrils is 0.7-1 times the distance from the tip of the snout to the mouth. The eyes are small and round, their diameter is 0.8-1.8% of the total body length. The wings of the nostrils form triangular lobes with a wide base. The superior labial grooves are short and inconspicuous. The sublingual-mandibular pore line, located directly behind the corners of the mouth, is slightly enlarged. The gill slits are quite long, the length of the third pair is 3.1-4.1% of the total length, but less than 1/3 of the base of the first dorsal fin. The wide upper teeth are shaped like triangles and their edges are heavily jagged. The narrow lower teeth with a wide base are covered with small teeth. The front teeth are set almost vertically. There is no ridge between the dorsal fins. The first dorsal fin has the shape of a wide triangle, the posterior edge is slightly concave. The base of the first dorsal fin is located above the posterior edge of the base of the pectoral fins. The second dorsal fin is opposite the anal fin. The pectoral fins are wide and large, in the shape of a triangle or crescent with narrow pointed tips. The length of the anterior edge of the pectoral fins is 18-21% of the total length. The number of vertebrae ranges from 198 to 227. In the precaudal spine there are 101-123 vertebrae. The color is usually gray, only the belly remains white.
Biology [ | ]
Ability to live in fresh water[ | ]
Front view
Bull sharks are one of the few cartilaginous fish that live in fresh water. This is the most known species of 43 species of elasmobranchs, belonging to 10 genera and 4 families, capable of living in fresh or slightly salty water. In addition to blunt-nosed sharks, they include stingrays, river stingrays and saw-nosed rays. Some diamondback rays, mustelids, and blue-gray sharks regularly enter river estuaries. Blunt sharks are able to easily swim from salt water to fresh water and back. They fall into the category of euryhaline organisms, capable of existing in a wide range of water salinities. Most euryhaline species are bony fishes, such as salmon and tilapia, and are not physiologically related in any way to blunt-nosed sharks. Such an evolutionary inconsistency can be explained, for example, by a hypothesis suggesting that bull sharks experienced a bottleneck effect during the last ice age. This effect may have separated them from the rest of the elasmobranch subclass, giving an advantage to genes responsible for osmoregulation. The ability of elasmobranchs to enter fresh water is limited by the fact that their blood usually has at least the same salinity as seawater due to the accumulation of urea and trimethylamine oxide, however, blunt-nosed sharks living in fresh water have a reduced concentration of urea in the blood. Despite this, the osmotic concentration of bull sharks in fresh water is still significantly higher than in the external environment. This leads to a large outflow of water through the gills and leaching of sodium and chlorine from the sharks' body. However, they have several organs that maintain proper water-salt balance in fresh water: rectal gland en, kidneys, liver and gills. All elasmobranchs have a rectal gland. Its function is to remove excess salts accumulated in the body as a result of living in sea water. While in fresh water, blunt-nosed sharks reduce the excretory activity of the gland, preserving sodium and chlorine. The kidneys produce a large number of dilute urine, and also play an important role in the active reabsorption of substances dissolved in the blood. The gills of these sharks also likely absorb sodium and chlorine from environment, whereas as the salinity of the water changes, the liver produces urea.
Initially, scientists believed that the sharks living in Lake Nicaragua belonged to an endemic species Carcharhinus nicaraguensis. In 1961, a comparative analysis of the specimens was carried out and it was recognized as a synonym for the bluntnose shark. Bull sharks are capable of jumping out of the water, overcoming the rapids of the fast San Juan River, which connects Lake Nicaragua with the Caribbean Sea, no worse than salmon. Sharks tagged in the lake were subsequently caught in the open sea and vice versa. It takes them from 7 to 11 days to complete the transition.
Female bluntnose shark in a marine reserve, Fiji
Theoretically, blunt-nosed sharks are capable of living in a river or lake all their lives, but for some reason this usually does not happen, primarily due to reproduction. Young bull sharks leave the brackish waters in which they are born and swim out to sea to meet conspecifics of the opposite sex. A shark, which was placed in a fresh lake for the sake of an experiment, lived in it for 4 years and died. Two small fish were found in her stomach, the species of which could not be determined. The cause of death was likely starvation, as the primary food sources of adult bluntnose sharks are in seawater.
In a 460-day study in an estuary in southwest Florida, 56 juvenile bullnose sharks were tagged and divided into three cohorts. Approximately 1/3 of the fish from each cohort were constantly present in the estuary. The distribution of sharks was most influenced by salinity and freshwater influx, while temperature played a secondary role. The range of water salinity in the study area during this time was 0.1-34 ‰, however sample survey showed that sharks avoided being in water with salinity below 7 ‰, preferring areas where this indicator fluctuated between 7-20 ‰. The relationship between the average position of the cohort in the estuary and the salinity of the water; as salinity increased, the sharks moved higher up the river. This relationship was most pronounced in young sharks and decreased with age. This is probably due to the fact that through migration they choose optimal environmental conditions in order to reduce energy costs for osmoregulation.
Behavior [ | ]
Behavioral studies of bull sharks have confirmed that they can rely on visual cues to differentiate between different objects or animals. The shark can see colors right underwater. It was found that sharks tend to avoid colors that stand out against the background of the bottom, especially bright yellow shades. This is interpreted as identifying inedible and potentially dangerous objects.
Bull sharks are considered the most aggressive of all sharks.
Diet [ | ]
Bull shark teeth.
These are fairly lazy and slow-swimming sharks, but when hunting they become quite active. Their diet consists mainly of bony fish and small sharks, including even smaller members of their own species. If possible, blunt-nosed sharks eat crustaceans, echinoderms, stingrays, sea snakes and small terrestrial animals caught in the water, and also prey on marine mammals (especially dolphins) and small sea turtles. Unlike most other sharks, they can attack prey that is equal in size to themselves. Cases of attacks by blunt-nosed sharks on domestic animals are known from Australia: in one case, a bull shark in the river bit a bathing racehorse, and in another, a 3.5-meter shark grabbed an American Staffordshire Terrier near the shore.
Most often they hunt in muddy water, where it is more difficult for the prey to notice the approach of a predator. When attacking, bluntnose sharks use a thrust and bite technique. After initial contact, they continue to bite and grab the victim until it loses the ability to flee. As a rule, they hunt alone. Along with live prey, bull sharks eat any waste. To escape persecution, bull sharks are able to regurgitate swallowed food. This distracting maneuver allows them to divert the attention of the predator and escape.
Reproduction and life cycle[ | ]
Like other gray sharks, bluntnose sharks reproduce by viviparity. Mating occurs in late summer and early autumn. Pregnancy lasts 12 months, in a litter of up to 13 newborns with a length of 56-81 cm. Males and females become sexually mature at a length of 157-226 cm and 180-230 cm, respectively. Puberty occurs at the age of 10-15 years. Salty river estuaries serve as natural nurseries. Maximum life expectancy is estimated at 15 years or more.
It is believed that during mating, the male bites the female's tail until she turns over with her belly up. Sometimes such “courtship” becomes violent; after mating, adult females show scratches and marks from the males’ teeth.
The migrations of blunt-nosed sharks differ in nature from the migrations of other sharks. They can be found in rivers around the world. They are able to live in both sea and fresh water. They are born and grow in freshwater rivers, so they are not threatened by predators.
Natural enemies[ | ]
Adult blunt-nosed sharks are considered apex predators and have virtually no natural enemies In the open sea. People and possibly killer whales are their main threat. Juveniles, however, can become prey marine mammals(pinnipeds), their older relatives, or other sharks such as the white shark, tiger shark and bluegrass shark.
In riverine or coastal ecosystems, even adult blunt-nosed sharks can be eaten by crocodiles. Saltwater crocodiles have been well documented to attack sharks of all ages and sizes in northern Australian waters, and Nile crocodiles have been reported to prey on these sharks in South Africa. The smell of chemical secretions from sharp-snouted crocodiles repels even large blunt-snouted sharks, but specific examples of predation have not yet been observed. Central American crocodiles, Mississippi alligators, and marsh crocodiles are also potential predators of juvenile or adult sharks.
Human interaction[ | ]
Caught bull shark
It is an object of fishing, the meat is eaten, and the liver and skin are also valued. In addition, these sharks are caught as bycatch and are valued by recreational fishermen. They are hardy and can be kept in public aquariums. The International Union for Conservation of Nature has assigned the species a conservation status of Near Threatened.
Their large size, powerful jaws, aggressive nature, and the fact that tip sharks are found in murky, shallow waters and rivers likely make them one of the most dangerous shark species to humans, along with the tiger, whitetip, and tiptoe sharks. It is likely that one or more bull sharks carried out a series of infamous attacks on people off the coast of New Jersey in 1916 that inspired Peter Benchley's novel Jaws. Suspicion fell on this species as several tragedies took place in the river. It was bull sharks that caused panic off the coast of Sydney in 2009. Previously, most attacks were attributed to a white shark. In India, blunt-nosed sharks swam into the Ganges and attacked people, and responsibility for this was blamed on the Gangetic sharks, which are on the verge of extinction. IN International list of shark attacks on humans en until 2013, there were 67 unprovoked non-lethal attacks and 26 cases that resulted in the death of the victim.
Notes [ | ]
- T. S. Race, ch. ed. V. E. Sokolov. - 2nd ed. - M.: Education, 1983. - P. 38. - 575 p.
- , Gerd, A.S. , Russ, T.S. Dictionary of marine names commercial fish world fauna. - Leningrad: Science, 1980. - P. 38. - 562 p.
- Reshetnikov Yu. S., Russ T. S., Five-language dictionary of animal names. Fish. Latin, Russian, English, German, French. / under the general editorship of academician. V. E. Sokolova. - M.: Rus. lang., 1989. - P. 31. - 12,500 copies. - ISBN 5-200-00237-0.
- Gubanov E. P., Kondyurin V. V., Myagkov N. A. Sharks of the World Ocean: A Guide. - M.: Agropromizdat, 1986. - P. 152. - 272 p.
- Life of animals. Volume 4. Lancelets. Cyclostomes. Cartilaginous fish. Bony fishes / ed. T. S. Rassa, ch. ed. V. E. Sokolov. - 2nd ed. - M.: Education, 1983. - P. 22. - 300,000 copies.
- Carcharhinus leucas (English) . The IUCN Red List of Threatened Species.
- Snout shark (English) in the FishBase database.
- Compagno, Leonard J.V. 2. Carcharhiniformes// FAO species catalogue. - Rome: Food and Agricultural Organization of the United Nations, 1984. - Vol. 4. Sharks of the World: An Annotated and Illustrated Catalog of Shark Species Known to Date. - P. 478–480. - ISBN 92-5-101383-7.
- Müller, J. & Henle, F.G.J.(1841) Systematische Beschreibung der Plagiostomen. Berlin, Veit, pp. 1-200.
- Carcharhinus leucas (undefined) . Shark-references.com. Retrieved February 23, 2015.
- Large Ancient Greek Dictionary (undefined) . Retrieved February 23, 2015. Archived February 12, 2013.
- Bull shark (undefined) . National Geographic. Retrieved February 23, 2015.
- Christ, Rick. Carcharhinus leucas (undefined) . University of Michigan Museum of Zoology, Animal Diversity Web. Retrieved February 23, 2015.
- Queensland rebuilding huge task (undefined) . BBC News. Retrieved February 23, 2015.
- Bull sharks seen in flooded streets (undefined) . Dailyexaminer.com.au. Retrieved February 23, 2015.
- Weston, Paul. Bull sharks using Gold Coast canals as nurses (undefined) . Redcliffe & Bayside Herald. Quest Community Newspapers ((20 September 2009)). Retrieved February 24, 2015.
- Mike Collis. Jaws Sharks in the Amazon? (undefined) . http://www.iquitostimes.com/.+ Retrieved July 10, 2015.
- Sharks In The Amazon River? (undefined) . http://www.rainforestcruises.com/.+ Retrieved July 10, 2015.
- Sharks In Illinois (undefined) . In-fisherman (July 16th, 2012). Retrieved February 24, 2015.
- /Bull Shark (Carcharhinus leucas) (undefined) . sharks-med.netfirms.com. Retrieved February 24, 2015. Archived July 14, 2011.
- High number of sharks reported in Lake Pontchartrain (undefined) . wwltv.com. Retrieved February 24, 2015.
- Todd Masson. Shark attacks Lakeview boy swimming in Lake Pontchartrain (undefined) . Nola. Retrieved January 25, 2015.
- Shark-Infested Australian Golf Course Believed to Be World's First (undefined) . Fox News (October 11, 2011). Retrieved February 24, 2015.
- Tobey Curtis. Bull shark - biological profile (undefined) . Florida Museum of Natural History Ichthyology Department. Retrieved February 24, 2015.
- The Biggest Bull Shark...Ever? (undefined) . Rosenstiel School of Marine and Atmospheric Science. Retrieved February 24, 2015.
- Compagno, L. J. V., F. Krupp and W. Schneider. Tiburones = In W. Fischer, F. Krupp, W. Schneider, C. Sommer, K.E. Carpenter and V. Niem (eds.) Guia FAO para Identification de Especies para los Fines de la Pesca. Pacifico Centro-Oriental. - Rome: FAO, 1995. - T. 3. - P. 647-744.
- Summary of Large Bull Shark Carcharhinus leucas (Valenciennes, 1839) (undefined) . elasmollet.org. Retrieved September 22, 2017.
- Carcharhinus leucas:: Florida Museum of Natural History(English) . www.floridamuseum.ufl.edu. Retrieved June 28, 2017.
- Matt Walker. Bull sharks have the strongest bite of all shark species (undefined) . BBC (12 October 2012). Retrieved February 24, 2015.
- Maria L. Habegger, Philip J. Motta, Daniel R. Huber, Mason N. Dean. Feeding biomechanics and theoretical calculations of bite force in bull sharks (Carcharhinus leucas) during ontogeny // Zoology (Jena, Germany). - December 2012. - T. 115, issue. 6. - pp. 354–364. -
The tiptoe shark is also known as the gray bull shark or bull shark ( Carcharhinus leucas listen)) is an aggressive species of shark found throughout the world in warm, shallow waters along coastlines, estuaries and lakes. Although sharks have been spotted far upstream along the Mississippi River in Illinois, they are not a true freshwater species. According to the International Union for Conservation of Nature (IUCN), the bull shark is classified as a "near threatened species."
Basic Facts About the Bull Shark
- The bull shark gets its name not only because of its appearance, but because of its behavior. They are large and stocky sharks, with a wide, flat snout and an unpredictable, aggressive nature. Females are larger than males. The average female bluntnose shark is about 2.4 m long and weighs 130 kg, while males on average reach 2.25 m in length and weigh 95 kg. The largest recorded gray bull shark had a body length of about 4 m. The bite of a bull shark is 5914 newtons, which is the highest for a fish of its size.
- Sharks are capable of osmoregulation, meaning that they can control their internal osmotic pressure when the salinity of the water changes. They are euryhaline (able to adapt to varying levels of salinity) and diadromous (swim easily between fresh and salt water). Bull sharks give birth to four to ten young sharks in fresh water. Juvenile bull sharks swim in sync with the tides to conserve energy for movement and osmoregulation. Over time, sharks gain tolerance to the salinity of the water. Newborn or young sharks are usually found in fresh water, while older ones tend to live in salt water. However, they can live their entire lives in fresh water. Adulthood in fresh water is not ideal, since most of the sharks' food lives in the sea.
- Bull sharks primarily eat a variety of bony fish and small sharks, including their relatives. As opportunistic predators, they also eat land mammals, birds, turtles, and dolphins. They use a strike-and-bite strategy to attack prey, usually hunting in murky waters. Sharks are usually solitary hunters, although they are capable of hunting in pairs to deceive prey. Although sharks hunt in murky waters, they can see colors and use this to find prey. Sharks hunt both during the day and at night.
- Mature bull sharks mate in late summer or early fall. It takes them about 10 years to reach sexual maturity. In the mating ritual, the male bites the female's tail until she turns belly up, allowing him to copulate. Mature females often show signs of bites and scratches.
- Bull sharks are aggressive predators at the top of their game, so their main threat is humans. However, they can be attacked by great white sharks, tiger sharks and crocodiles. Average duration The lifespan of a bull shark is 16 years.
How dangerous is a blunt-nosed shark?
The bull shark is believed to be responsible for most shark attacks in shallow waters, although international statistics shark attacks (ISAF) is led by the great white shark ( Carcharodon carcharias), responsible for the largest number of human bites. ISAF notes that white sharks are easily identified, which is not the case with tiptoe sharks and other members of the gray shark family ( Carcharhinidae). In any case, the great white shark, bull shark and tiger shark are the “big three” that are responsible for the majority of shark attacks on humans. All three live in areas frequented by humans, have teeth designed for cutting flesh, and are large and aggressive enough to pose a threat.
How to recognize a bull shark?
If you see a shark in fresh water, chances are good that it is a bull shark. Genus of freshwater gray sharks ( Glyphis) includes three species, but all of them are very rare and are found only in some parts South-East Asia, Australia and New Guinea.
Snout sharks are gray above and white below. They have a small bull-like face. Such appearance and the color helps to camouflage, so they are difficult to see in the water, as they blend in with the sea or river bottom.
First dorsal fin more than the second and tilted back. The caudal fin is lower and longer than that of other sharks.
If you're swimming in the surf, it's not wise to get close enough to identify the shark, but if you're seeing it from a boat or land, you may want to know what species of shark it is:
- Sandbar sharks also have rounded snouts, but their dorsal fins are larger and more triangular in shape than those of bull sharks.
- Blacktip sharks are very similar to sharks, but they have sharp snouts and white anal fins. Please note that juvenile bull sharks may have black fins, so the color is not in a good way identification of this species.
- Lemon sharks have blunt snouts, but they are yellow-green or olive-gray in color, and both dorsal fins are about the same size. The dorsal fin faces backwards, like a bull shark.
- Tiger sharks have dark stripes on their sides.
- White sharks are very large, with black eyes and a sharp snout. Their coloration is similar to that of bull sharks (gray above, white below).
For most people, the shark is a symbol of bloodthirstiness and outrage - it terrifies sea creatures, and per person. Gray sharks are considered the most common predators, found in almost all rivers that flow into the oceans. And such an individual as a blunt-nosed shark is also called a bull shark or bull shark.
Description
huge aggressive predator. In this species of fish, females are larger than males. The bull shark is about 3.5 meters long, weighing more than a hundredweight (130-140 kg). It has no special distinctive features, except for its slightly flattened snout, this predator was nicknamed the bull shark.The color of the blunt-nosed shark varies depending on its habitat. The body of the bull shark is a grayish steel color, sometimes a light brown color is possible. Has no spots or inclusions, the back is darker than the belly.
This representative's eyes underwater world round, small in size, with a black iris and equipped with a nictitating membrane. This type of fish has five pairs of gill slits. The dorsal fin is strong, triangular in shape, the pectoral fins are well developed, the jaw of the bull fish is considered its main weapon, the teeth are strong and very sharp, located in the upper jaw, triangular in shape, slightly curved to the side. The lower jaw is decorated with sharp teeth that curve inward, and new ones soon grow in place of diseased or fallen teeth.
The only representative of its family that can live perfectly in fresh water.
It's all about the salt content in the bull shark's blood. In all other subspecies, the concentration of salt in the blood coincides with the concentration in the water, but in the bull shark, salt is only 50%, which allows increasing the outflow of water through the gill openings; sodium and chlorine, which are necessary for the shark’s body, are washed out with water from the body of a representative of the species, therefore the fish accumulates the necessary supply of salts in the rectal gland, liver, kidneys and gills - this allows maintaining the water-salt balance in the body of a representative of this species of underwater predator.
In fresh waters Mostly young individuals live there. Adult fish prefers fresh water mating season, since in fresh water the survival rate of the brood is much higher.
Habitat
- Amazon.
- Ganges.
- Zambezi.
- Mississippi.
- Brahmaputra.
The blunt-nosed shark tries not to move more than 150 meters from the shore. The optimal depth is considered to be 30 meters. It is found in the Atlantic Ocean, in regions of America and the southern regions of Brazil, on the coasts of Africa near Morocco and Angola. This predator is a frequent visitor to the Indian Ocean and lives in some areas of Kenya and South Africa, the Persian Gulf and Pacific Ocean found almost everywhere. The only place where the bull shark is not found is the southern coast of Australia.
The muddy water of the Amazon does not prevent the predator from feeling great in it. The fish rises 1-2 km upstream, sometimes even swimming into Peru during migration. But the bull representative of the Ganges and Brahmaputra rivers has long since settled down. In Nicaragua, a lake located in America, the bullfish is firmly established. A representative of this species is not found in bodies of water with cold currents; it cannot be found in places with a temperate climate.
What does this predator eat?
This aquatic inhabitant is quite voracious. If bull fish feels hungry, she destroys everything in her path. Most often this predator feeds:
- dolphins;
- bony fish;
- carrion;
- crustaceans;
- shellfish;
- capable of attacking other relatives;
easily capable of attacking a person. She is one of the three most dangerous cannibal predators.
Reproduction
A distinctive feature of representatives of this species is considered to be that female bulls are viviparous. After fertilization, the female carries them in herself until full maturity. Pregnancy lasts almost a year, about 10-11 months. The birth period occurs mainly in the summer months. Females give birth in flocks, specially gathering in one place. One individual is capable of bearing and giving birth to about 10 cubs. The representative of this species does not care about the offspring at all; immediately after birth, the baby sharks are left to their own devices; from the first days of life, the cubs learn to defend themselves from predators and get their own food.
Full puberty in blunt-nosed animals occurs at the age of 4 years. Males begin to look for females and reproduce independently.
Blunt ocean predator lives about 28 years.
IN natural environment In their habitat, adult individuals have practically no enemies. With the exception of predator whales, which can even cope with major representative shark family.
The character is quite aggressive. These fish rarely form schools and prefer to hunt alone. Adapted for life in muddy water, they can navigate well in the dark. Males zealously guard their territory, attacking strangers without warning. If a representative of this species considers a person dangerous, she will definitely attack. It attacks almost with lightning speed, despite its large size, the bull shark moves silently.
For humans, this type of underwater predator is extremely dangerous. Known cases mass attack bull sharks on people.
Shark and industry
Today, industrial catching of blunt-nosed predators has been established. Often they are exterminated simply to reduce their numbers and protect, for example, tourists from attacks by cannibals.
Shark meat is also eaten. Dishes prepared from bull fish are considered exotic, and many restaurants attract visitors in this way.
Nowadays, shark fins are considered especially valuable. Widely used in cooking and folk medicine. Often, a still living individual with its fins cut off is released back into the water; the bull dies from oxygen starvation at the bottom of the reservoir, since without fins it is unable to fully move.
Shark skin is renowned for its durability. People call it shagreen. Since ancient times, craftsmen have used shagreen for the manufacture and decoration of household items: boxes, cases. Today, shark skin is used in the shoe industry. Shoes made from shagreen are considered one of the most durable.
Shark liver is widely used to make medicines. Shark liver oil resembles cod oil and is rich in vitamins A. It is believed that shark liver oil has wound-healing properties, and when consumed orally it can relieve a person from cough, tuberculosis and even stomach cancer.
Bull sharks have unique immunity. During research, scientists found that not a single disease took root in the shark’s body, so a cure for AIDS is being actively tested on these predators.
A substance called squalene is extracted from shark oil. Squalene is mainly found in shark liver oil. It is widely used in cosmetology as a natural supplement. Products containing squalene have a pleasant smell, are stored for a long time and do not lose their medicinal properties.
Bull shark oil is used in the production of margarine, added to solvents for oil paints, for finishing leather.