The blunt-nosed shark that lives near the shore is a very dangerous and voracious predator, which is associated with a large part of the attacks on people. Although she is not very large, she is strong, and it is difficult to fight her off, therefore it remains only to avoid meetings. Pointy sharks tolerate captivity well and are often kept in it.
Origin of the species and description
The oldest sharks lived on the planet in very ancient times – in the Upper Devonian. These were hybodus, and they looked like sharks, although it has not been revealed for sure whether they are evolutionarily related. In those days, the number of genera and species of Paleozoic sharks grew rapidly, but everything ended with the extinction of the vast majority in the Permian period.
Already in the Mesozoic era, the first modern sharks appeared: the elasmobrachs then divided into sharks and rays. The vertebrae in the skeletons of sharks calcified, which made them stronger and helped to survive high pressures (this allowed some species of sharks to move to depth), made them more maneuverable and dangerous predators.
Video: Bullhead Shark
The brain grew, mainly due to sensory areas – then the sharks acquired their famous sense of smell, which allows them to feel a drop of blood for kilometers. The jawbones have changed, allowing the mouth to open much wider. In a word, they became very similar to those sharks that we know back in the days of the dinosaurs.
At the same time, the main part of modern detachments appeared, in particular, carchariformes, which include the blunt-nosed shark. Included in the family and genus of gray sharks: in total, 32 species stand out in it, and one of them is the blunt-nosed shark. Its scientific description was made by Müller and Henle in 1839, the specific name in Latin is Carcharhinus leucas.
Interesting fact: Due to the lack of a swim bladder, sharks have to move all the time, and this takes a lot of energy. It is the need to constantly replenish it that caused their appetite, but besides, they know how to save money – for this they turn off unclaimed parts of the brain.
Appearance and Features
The body is elongated, spindle-shaped. The coloration is gray: the back is a darker shade, and the fins are even darker, and the belly is light. In the water, such a shark stands out little, so it can swim up unnoticed at fairly close distances, especially if the water is cloudy. In addition, it is able to change the color intensity, adjusting it to the light: lighter during the day, darker at dusk.
Outwardly, they are distinguished primarily by the shape of the head: it is not pointed and looks much different than in most other species, so it is easy to distinguish it. The flattened snout provides greater maneuverability.
Triangular teeth with serrated edges. They are arranged in several rows, and when a tooth falls out of the front one, the one in the next one moves into its place. New ones grow only in the last row, and this happens all the time: a shark has to change them many times during its life.
The jaws are very powerful, they are compressed with a force of 600 kilograms, and the teeth securely capture prey. If someone gets into them, then it will be very difficult to leave alive. They have a developed nictitating membrane over their eyes. Sexual dimorphism is expressed by the difference in size: females are larger than males and weigh more, although the difference is small, about 15%.
There are two dorsal fins, a large anterior, and a smaller posterior one. The tail fin is long. The blunt shark is capable of a fairly high speed, although it is inferior to the fastest of the predatory sharks in both maximum speed and maneuverability.
In length 2-3 meters, weight – 120-230 kilograms. Occasionally grow up to 4 meters and 350 kilograms. Such parameters make it especially dangerous for humans: if the largest aquatic predators often do not pay attention to people at all, then sharks of this size are very fast and aggressive, and can purposefully hunt them.
Where does the blunt shark live?
Lives along coasts and in estuaries – what’s more, they can even climb high along the course of some large rivers, and are found thousands of kilometers from the mouth. This is possible because blunt-nosed sharks are perfectly adapted to life in both salt and fresh water – therefore, they are even found in some lakes.
They need salt, but their rectal gland and gills are able to accumulate this salt, and at the right time to release it – thanks to this, they do not experience inconvenience in fresh water, but only if the reservoir communicates with the sea, like Lake Nicaragua.
The most common blunt-nosed shark can be found:
- off the east coast of North and South America;
- west of Africa;
- off the west coast of India;
- in the Persian Gulf;
- in the seas of Southeast Asia;
- off the western and northern coasts of Australia;
- in Oceania;
- in the Caribbean;
- in the major rivers – the Amazon, the Ganges, the Mississippi;
- in Lake Nicaragua.
As you can see, the habitat is very wide. These are mainly coasts, clusters of islands and large rivers. The fact is that it does not swim far into the open sea and usually lives within a kilometer from the coast – this is what makes it so dangerous for people. The range of the bull shark is limited by another circumstance: it does not like cold waters, and therefore lives only in subtropical and tropical climates.
Interesting fact: Bull sharks do not feel pain, but because for increased testosterone levels are very aggressive – this combination leads to the fact that they can continue to attack even in the worst situation for themselves. It happened that the blunt shark was gutted, and she tried to eat her own insides.
Now you know where the blunt shark is found. Let’s see what it eats.
What does the blunt shark eat?
It is unpretentious and can eat almost anything: from the largest prey that it can catch, to small fish and even carrion. He likes to find places where edible garbage is dumped into rivers and seas, and live nearby, feeding on this garbage.
A lot of blunt-nosed sharks have chosen the Ganges River because of the religious tradition of sending the dead along it – sharks simply eat corpses passing by . Do not mind eating living people, too, and representatives of their own species. But the basis of the diet is usually not people – living and dead, and not other sharks, but:
- mullet and other schooling fish;
They usually hunt alone, slowly moving around the chosen area – at this time it seems sleepy and slow. Such behavior can calm the victim, especially since, due to the camouflage color, she may not notice the approach of a predator for a long time.
But the slowness of the blunt-nosed shark is deceptive – it can continue to swim just as slowly, having already seen the prey and targeting it as a victim, until the most opportune moment for the attack comes. All the efforts of the shark’s brain at this moment are aimed at calculating the time of its onset, and when it arrives, it accelerates sharply and grabs the prey.
If the victim is large, then at first the shark hits it with its head, trying to knock out the spirit, then it bites, if necessary, it hits again and bites again, alternating these actions until the resistance stops. Thus, it is capable of killing not only marine life, but also land mammals that have come to the watering hole – jumping out of the water, grabs them and drags them away.
Interesting fact: Precisely because when attacking hits the victim with her head, got a different name – a bull shark, because during the attack she really resembles a bull butting the enemy. character and lifestyle
They usually hunt in the morning and at dusk – at this time they are most difficult to notice. The blunt-nosed shark is not afraid to attack fish and animals larger than itself: there are cases when it dragged away horses or antelopes. Moreover, a person is not able to scare her. On account of these creatures, many human victims – they are among the leaders among all types of sharks.
But, if they see groups of people, they rarely attack, most often single targets are chosen as victims. They are hardly noticeable and therefore especially dangerous, while they are able to attack even in shallow water, where a person does not expect this: for example, they often attack when fording rivers. These are common occurrences in tributaries of major rivers like the Amazon or the Ganges.
In places populated by a blunt shark, it is better to avoid muddy water and not swim at dawn and dusk – this will significantly reduce the risk of an attack. In addition, you should not go swimming immediately after a rainstorm – there will be a lot of organic matter in the water, and the shark will probably go to feast on it.
If the blunt shark still did not calculate the balance of forces, and she had to run – or if on she herself was attacked by a larger shark, then she can empty the contents of the stomach to confuse the attacker. Such a trick really helps to slip away sometimes, because if the stomach was full, then visibility becomes much worse.
If a blunt-nosed shark usually goes hunting in bad weather, in the morning or in the evening, then in the middle of a sunny day it rests near the shore, exposing its back or belly to sunlight. This is how she usually spends a large part of the day – although even at this time she is ready to eat something that is in her field of vision.
Interesting fact: Despite the fact that the blunt shark is significantly inferior in size to the largest sharks, it was she who became the prototype for the monstrous monster from the movie “Jaws”. It is many times larger in size, while outwardly almost identical, reminiscent of a blunt shark and habits.
Social structure and reproduction
They live alone, if individuals of the same sex meet, then most often this leads to a fight, or they simply blur. But individuals of different sexes can sometimes form a pair, although most often for a short time, and even hunt together – this happens with a good food supply.
Hunting together allows them to deceive the prey, which at first is attacked by only one shark, and when the attention of the victim is absorbed, the second suddenly attacks. If the union gives a result and it becomes easier to hunt, they can repeat such a move several times, but such a “union” still does not last long, because by nature these fish are solitary.
They reach puberty by 10 years. The mating period begins in August-September, it is preceded by a mating ritual in which the predatory habits of blunt-nosed sharks are fully manifested: during its course, males bite females by the tail, making them turn upside down – this is how they make it clear that they are ready for mating.
The bites are very strong, and wounds can remain from them for a long time – although the females still do not feel pain due to substances produced in the body that block pain sensations. Males, on the other hand, produce a lot of testosterone at this time, which is why they become very aggressive.
Its level in blunt-nosed sharks is generally increased, which explains their behavior. Sometimes they have hormonal disruptions at other times, then they literally start throwing themselves at everything, even inanimate objects, and can get hurt on a rock or attack a shark much larger than themselves and die.
Females have no maternal instinct , and when the birth ends, they just float away. Small sharks – they usually appear from 4 to 10, have to immediately take care of themselves. At first they live in fresh water, and only when they grow up they acquire the ability to live in salt water – although they do not always move into it.
In the rivers, young sharks are threatened by fewer predators, and they go to sea after they mature, often because there is more prey. This usually happens by the age of 3-5 years, when they reach a size of about 2 meters and they do not have many worthy opponents in coastal waters.
Natural enemies of blunt sharks
There are not many of them, primarily white and tiger sharks. They prefer the same areas as blunt-nosed sharks, and therefore can be found – and are prone to attack. They are larger in size, at the same time they are also fast and maneuverable, therefore they are a great danger even for adult blunt-nosed sharks, and when they meet them, they usually have to flee.
Relatives are also dangerous – sharks of this species without sentimentality kill and eat each other, therefore, until they fully grow up, they have to avoid meeting with another blunt-nosed shark. People are the most dangerous, it is from their hands that most of these fish die, because they are being hunted, albeit not on the largest scale.
Orcas and crocodiles can also threaten adult sharks. The latter quite often attack them: combed and Nile crocodiles, as well as alligators can attack even adults, smaller reptiles – growing ones. For young sharks, even aggressive pinnipeds can be a threat.
But fry have the most problems: not only are all of the above not averse to eating them, they can also get caught by predatory fish. They are also hunted by birds. Both are numerous, so the young shark is in many dangers, and it is not easy for her to survive the first 2-3 years.
Fun fact: This shark sees colors well and tries to avoid objects that are colored in intense yellow – she associates them with danger.
Species population and status
The blunt-nosed shark is fished for, its skin, pancreas and liver are considered valuable, the meat is edible and is part of the delicacies in some countries. Therefore, the species is of commercial importance, and besides, it is relatively easy to catch a blunt-nosed shark, because it constantly lives near the shore, and it can be lured by meat with blood – it feels it from afar.
Although it is usually among the objects of fishing not among the priorities, but there is another factor leading to the active extermination of this species – they are very dangerous for people, and therefore in many areas a targeted struggle is being waged against them, residents want to clear their shores from these aggressors so that they can swim more calmly .
As a result, despite the wide range, the number of blunt-nosed sharks has been rapidly declining for a long time. Researchers do not have exact data, but it is believed that over the past 100 years it has decreased by 3-5 times. So far, the species is not in the Red Book, but its position is already defined as “close to vulnerable”.
If the same trend continues, and so far nothing indicates a change, blunt sharks may soon be among endangered species, but so far no measures have been taken to protect them. The positive aspect is that they easily adapt to living in an artificial environment and are able to breed in it.
The blunt shark is one of the assets of our planet, although coastal residents suffering from them may have a different opinion . They are an important part of the food chain, they are involved in the selection of fish and other marine life. Alas, due to frequent attacks on people, they are actively exterminated, and so far it looks like their population will continue to decline in the near future.