In the vast ocean, sharks known as "Kings of the Sea" are found all over the world's oceans, and there are more than 70 species in the China Sea (about 350 species in the world). Most sharks are beneficial to humans but not harmful, and there are only more than 30 species. Sharks attack people and boats for no apparent reason. Sharks do have a reputation for eating people, but not all sharks eat people.
The nostrils of sharks are located in front of the mouth on the ventral surface of the head. Some have an oronasal groove, which is connected between the corners of the nose and mouth. The folds of the olfactory sac increase the contact area with the external environment. Someone has determined that the total area of the olfactory membrane of a 1-meter-long shark can reach 4842 square centimeters. Therefore, the shark's sense of smell is very sensitive. It can smell the smell of blood from a few kilometers away. Once animals in the sea are injured, they are often attacked by sharks. Killed in attack.
Man-eating shark - blue shark
Sharks generally only eat live food, and sometimes carrion. Their food is mainly fish. Some people have found dolphins, waterfowl, turtles, crabs and various fish in the stomach of tiger sharks; a very large sea lion was taken out of the stomach of man-eating sharks; the food of hammerhead sharks is fish and crabs; nurse sharks, stars Sharks feed mainly on small fish, shellfish, and crustaceans.
When sharks are looking for food, one or several sharks usually swim in the water. Once they find a target, they will quickly attack and devour it. Especially when a ship or plane crashes and there is a large amount of bait water, they swarm in. The sharks in a state of excitement and frenzy almost eat everything they encounter, and even kill each other in competition for food.
Sharks are cartilaginous fish and do not have a swim bladder. They mainly rely on their large liver to regulate their ups and downs. For example, the liver of a 3.5-meter-long great white shark found in the southern hemisphere weighed 30 kilograms. Scientists' research shows that shark livers rely on the increase or decrease of diacylglycerol ethers, which are much lighter than ordinary triglycerides, to regulate buoyancy.
Sea Wolf – Hammerhead Shark
Although sharks are ferocious and hideous in appearance, they are full of treasures and are important economic fish. The shark's liver is particularly large and rich in vitamins A and D. It is an important raw material for making cod liver oil; its skin can be used for tanning, and its fins are the treasure of seafood - shark fins. Sharks can also be used for medicinal purposes. According to research by scientists, sharks rarely suffer from cancer. Even if the most terrifying cancer cells are transplanted into sharks, the sharks will still be safe. Because its cells secrete a substance that not only inhibits carcinogens, but also reverses them.
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