When you think of sharks, you always have the shark fins you see when you are alone in the vast sea. This ferocious carnivorous fish, known for its bloodlust, is at the top of the food chain in the ocean. But there are many types of sharks, and the great white shark common in movies and the cat shark that sea chasers can pick up are just one of them. There is a kind of shark, not only in the ocean across the sea, but also in the freshwater river to come and go freely, seriously threatening the life safety of residents along the river, that is, the bull shark.
In the impression of our ordinary people, sharks live in the ocean, as we all know, seawater salt content is very high, marine life is almost impossible to survive in fresh water, because of the osmotic pressure, after adapting to high concentrations of seawater, once it enters fresh water, it will lead to imbalance of cell osmotic pressure, a large amount of fresh water penetrates into the cell, and the organism will be alive and dead. Conversely, freshwater fish cannot survive in the seawater because they will infiltrate the body fluid outward, resulting in dehydration and death.
However, there are no absolutes, there will be some exceptions, some fish live at the confluence of seawater and fresh water at the mouth of the river, so the salt tolerance is also strong, also known as broad salinity fish. Salmon, for example, usually live in the seawater, but when it comes to spawning period, it will go up the stream and go to the freshwater river to spawn. There are also eels like eels, which usually live in freshwater, but will go to the seawater area to lay eggs.
Salmon that follows the creek
Most sharks, too, encounter the same problem. Sharks have a large amount of trimethylamine and urea in their bodies, they need to use seawater to adjust to a balanced and stable value, in the ocean to survive in order to make the two substances in the body and the environment to achieve saturation, but if you go to the fresh water to survive, it will make this balance break or even cause death.
Over the course of their long evolution, bull sharks have developed a unique ability to maintain the balance of salinity in their bodies by regulating the amount of salt in their blood, as well as other substances. Its kidneys are stronger than other sharks and can quickly metabolize the fresh water that comes into its body, draining it at a normal rate of 15 times faster urination. This amazing skill, which allows it to come and go freely in both fresh and seawater, is often found in inland rivers hundreds or even thousands of kilometers away from the sea.
In 1937, two fishermen caught a bull shark near Alton, Illinois, about 1,750 miles (2,800 kilometers) upstream from New Orleans. Bull sharks can reportedly swim upstream along the Amazon River, as far as Iquitos, Peru, nearly 2,200 miles (3,500 kilometers) from the ocean.
The ferocity of sharks in the ocean has a recognized ranking, the great white shark > the tiger shark > bull shark, and in terms of size, the size of the bull shark is the smallest, so the ranking is a little lower. They can generally grow up to 2-3 meters, of which the male individual will be slightly larger and can grow to a weight of about 200 kg. Don't underestimate it because of its small size, for humans, it is actually more terrifying than the great white shark.
The bull shark is also known as the bull shark, and its personality is also like a bull, with a strong body and a fiery personality. Used to enter the fresh water, the abnormal secretion of testosterone in the body makes them like bulls in heat, wanting to crush all obstacles. The diet of bull sharks is very extensive, as long as the animals they can see, whether it is the great white shark that is also the overlord of the sea, or the hippopotamus and crocodiles in freshwater rivers, are the objects of their predation. Humans are also one of its key targets.
Bull sharks are considered one of the most common human attackers. The mere ability to launch an attack in a freshwater river makes humans invincible. According to the International Shark Attack Archive, they rank third in terms of total number of attacks, with a total of 116 attacks on record, 25 of which were fatal. It is second only to the Great White Shark (326 attacks, 52 fatal) and the Tiger Shark (129, 34 deadly).
There is a movie called "Jaws" that makes people know great white sharks, and in the process of creating the film, it used to refer to a series of shark attacks that occurred on the coast of New Jersey in July 1916.
The incident killed four people and injured one. The film features a great white shark, a species that has also been widely blamed for the 1916 attacks. However, according to some experts, great white sharks are relatively rare in New Jersey, especially in inland waterways, where two of the attacks occurred in a small stream in Mata Bay, 10 miles (16 kilometers) from the ocean, and from all indications, it is more likely that the attack was caused by bull sharks.
In fact, most of the shark attacks were done by this guy, and the great white shark carried a lot of pots for it.
Bull sharks are extremely greedy and gluttonous like gluttonous. Someone once found a stranded bull shark, the examination found that it turned out to be dead, in its stomach found many animal debris and some marine debris, they will swallow everything they can swallow into the stomach.
The bull shark's mouth is densely packed with sharp teeth. The upper and lower teeth also have their own division of labor: sharp lower teeth are convenient for grasping the prey and firmly grasping the prey; the triangular jagged upper teeth are used to swallow and cut food, pierce the prey, and tear the flesh of the prey.
Their stomachs have a large capacity and can store food for about ten days, like a natural refrigerator, but because it is very gluttonous, it will prey every two or three days.
summary:
Sharks don't like to eat human flesh, but they are aggressive and curious. When encountering a small boat driven by humans, the bull shark will rush it, and if someone falls into the water, the bull shark will take a bite, and then find that it is not delicious, and will give up the attack. But because they are still too large compared to humans, they are still too big to die in one bite, and if they go out in groups and a shark takes a bite, the hope of survival is really slim.