Great White Shark: Cannibalism? It's just a bit of carelessness!

If you want to choose an animal that has been most misunderstood by humans, the Great White Shark (Carcharodon carcharias) must be on the list.

The Great White Shark is the largest predatory fish known to exist in the world (bigger sharks and whale sharks that are larger than the great white shark are filter-feeding). An adult great white shark usually exceeds 4 meters in length, a large mouth with blood, and several layers of teeth that are as sharp as a razor. The impression is definitely very shocking. So biologists chose the Latin "karcharos" and "odous" as the genus and species name of the species.

Today the protagonist is old white. It can be said that it is a star species in the shark world. Just find a passerby and let him say a shark. The great white shark will almost certainly be mentioned.
But compared to "sharks with sharp teeth", the nickname "great man-eating shark" is more famous.

White sharks don't like to eat people

In 1975, Steven Spielberg released a movie based on Peter Bunchley's novel The Great White Shark (JAWS). The "great white shark" in the film can be regarded as "killer without blinking, eating without salt". Since then, the great white shark's stigma of "actively attacking humans" has become famous.

Spielberg's classic movie "Great White Shark" made the image of old white fiercely popular. Picture: Poster for the movie "Great White Shark"

Great white shark attacking fake bait.
In fact, humans are not on the Great White Shark's recipe. Compared to skinny and fat-free humans, sea lions and seals are the favorite of great white sharks, and there seems to be no record of anyone being eaten by the great white sharks in history.

But then again, "don't eat" doesn't mean it won't "accidentally hurt"-because the human lying on the surfboard looks from below, especially like the sea lion seal that the great white shark likes to eat, people are mistaken for food There have been cases of attacks. Even if the great white shark finds that the taste is wrong, it will not continue to swallow, and it will be very fatal to be bitten by them.

But if the prey is mistaken for certain marine debris that is the right size and doesn't need to be bitten, the great white shark may swallow them directly. The discovery of various plastic litter and fishing nets in the stomach of predatory sharks is no longer news.

Like other predatory sharks, great white sharks have rows of life-growth teeth that can be replaced constantly. The edges of these huge teeth also have some small sawtooth, which looks a bit like a knife for cutting steaks when we eat Western food-of course, it is similar in function.

Jaws 'jaws' teeth can be seen with tiny jagged edges.

Because the great white shark does not have a "claw" that can assist in hunting itself, this steak knife-shaped tooth can reduce the resistance to pull the tooth from the prey, and it is more conducive to piercing the prey's body, causing complex damage that combines puncture and cutting. . Therefore, after being attacked by a great white shark, it is more difficult to bandage the wound.

Not a cold-blooded killer

Although great white sharks always give the impression of a "cold-blooded killer", they are a semi-constant animal. Although not as able to maintain a relatively constant body temperature as mammals or birds, great white sharks have a very unique structure that allows them to maintain their own digestive tract temperature at a relatively high level, sometimes even at a high level At a temperature of about 10 ° C.

The higher body temperature allows great white sharks to be ready to attack in the cold ocean at any time.

So how is this "warming stomach" temperature made? This comes to the liver of the great white shark.

Our human liver is usually located on the lower right ventral side of the stomach, and the two liver lobes of the great white shark almost cover the entire digestive tract. On the inner surface of the liver lobes, there is a huge vascular system.

Most of the blood flowing through the liver and digestive tract of the great white shark is supplied through the upper hepatic artery. This blood can directly transfer the metabolic heat generated by muscle movement to the stomach and digestive tract. At the same time, the vascular system on the inner surface of the liver lobes is like two warm babies, which transfer heat to the digestive tract through heat conduction, further increasing the temperature of the stomach.

At the same time, the fat-rich liver can also provide good insulation and prevent heat from being lost from the relatively thin ventral side. In this way, the great white shark can maintain a relatively high temperature in its digestive tract to promote digestion.

Increased body temperature can also keep great white sharks in a relatively "excited" state, reducing the reaction time required to transition from a "standby" state to a "predatory" state-this is also how they can become top predators in the ocean An important reason.

There are also disadvantages

As a top predator, great white sharks have few natural enemies in the sea, but there is one animal that they absolutely do not want to encounter, and that is the killer whale we just introduced a few days ago.

The killer whale's approach to hunting great white sharks is also quite interesting: swarms of killer whales will find a way to flip the great white sharks-and when the sharks are flipped into a big-bellied posture, their brains will "short-circuit" and directly In a state of pseudo-paralysis, it can't move ... At this time, the killer whale can easily divide the great white shark and eat it.

Killer whale predating a killer shark.

Of course, compared with killer whales, the humans who gnaw the dorsal fin (shark fin), liver, teeth and bones of the great white shark are the biggest threats.

Although the widely distributed great white shark is still in the vulnerable category, the shark reserves established in many areas also provide conditions for the protection and restoration of great white shark populations, but the great white shark's reproductive efficiency is quite low.

It was once thought that it took about 12 to 18 years for the great white shark to reach sexual maturity, but in a 2014 study on the growth and development of the great white shark, researchers estimated the time required for the great white shark to "grow into a fish" Might be much longer than we think: it takes 26 years for male great white sharks to reach sexual maturity, and 33 years for female great white sharks.

In addition to the extremely long time required for development, the great white shark that lays offspring in a viviparous manner also has a very long pregnancy. It takes about 12 months from fertilization to the birth of young sharks, and only 2 to 10 small sharks can be laid at a time. .

The seemingly cruel great white shark is actually a baby who is not yet an adult.

It can be seen that sharks that have not reached sexual maturity or are "pregnant" will have a very fatal impact on the population of great white sharks if they are killed.

After all, great white sharks don't eat people, but people eat great white sharks ...