Some readers have asked me, why use sharks as the main character? First of all, I think sharks are very intelligent animals, and they are very intelligent. Pen × fun × Pavilion www. ｂｉｑｕｇｅ。 info and old enough, after a very long history precipitation, evolved perfectly. Fits the layout of the book.

Maybe you don't know where the charm of sharks is, so you haven't found a sense of substitution. When you read this shark profile, I believe you will soon like the perfect creature of sharks. You will also find a sense of substitution in this book, and your passion will rise.

Sharks have been on Earth since 300 million years before the appearance of dinosaurs, and it has been 400 million years since then, and they have barely changed in nearly 100 million years. Sharks, known as sharks, sharks, and sand fish in ancient times, are behemoths in the ocean, so they are called "wolves in the sea".

Sharks range in size from as small as 6 inches in length to as large as 18 meters.

The whale shark is the largest shark in the sea, reaching up to 6o feet in length when it grows up. Despite its large size, the whale shark has the smallest teeth among sharks. The smallest shark is the dwarf horn shark, small enough to fit in your hand. It's about 6 to 8 inches long and weighs less than a pound.

The largest fish in the world is the whale shark. It can be up to 18 meters long and weigh up to 4oooo kilograms. Luckily, their diet is plankton, otherwise, humans would be in trouble!

According to Australian shark experts who have been in the sea and the shark's long-term life, sharks can remain motionless at the bottom of the sea without suffocation. Sharks differ from bony fish in that they do not have a swim bladder to control snorkeling. If you stop swimming, most of the sharks will sink. In order to increase buoyancy in the water, the shark's liver has a large amount of oil.

organ

In addition to the five sensory organs of humans, sharks have other organs.

Sharks are particularly sensitive to smells in seawater, especially the smell of blood, and the low-frequency vibrations or small amounts of bleeding from the irregular cruising of sick fish can attract them from a distance, even past the sense of smell of land dogs. It can sniff out 1ppm (parts per million) of flesh in water. Japanese scientists have found that even if only 1 gram of amino acids are dissolved in 10,000 tons of seawater, sharks can sense the smell and gather together. For example, after a female shark gives birth, even after swimming thousands of miles in the sea, she can swim back to her birthplace with the smell. The area of the 1-meter-long shark with olfactory nerve endings in its nasal cavity can reach 4842 square centimeters, such as the 5~7-meter-long man-eating shark, and its sensitive sense of smell can smell the blood of injured people and marine animals several kilometers away.

Sharks' most sensitive organ is their sense of smell, which can sniff out even the finest substances, such as blood, miles away and track down the source. They also have a sixth sense, the power of sensory electricity, which allows sharks to perceive faint electric fields within several feet of an object. They can also sense vibrations caused by fish or animals up to 600 feet away through mechanical sensory action.

The shark's head has a special cellular network system called an electroreceptor that detects electrical current. Sharks use electroreceptors to hunt prey and swim freely in the water. American researchers have studied the embryos of the small spotted cat shark. Through molecular testing, they identified two separate genetic markers of neural crest cells in the shark's electroreceptors. Neural crest cells are embryonic cells that form various tissues in the early stages of embryonic reformation. Human neural crest cells play an important role in the formation of human facial bones and teeth. This suggests that neural crest cells move from the shark's brain to various areas of the shark's head, where they become electrical receptors.

Since sharks have an extremely sensitive sense of smell, it is very easy to sniff out smells that they fear or loathe. The smell of L-hydroxyalanine, a human secretion containing 1 in 8oo billion, can also be sniffed out by sharks. It is said that there was once a shark angler, and in later shark fishing, the sharks always did not catch his hook, while other fishermen in the same fishing ground caught more sharks. Why are sharks afraid of this shark angler? Ichthyologists have found that the shark angler had suffered from a skin disease, so the fingerprints left on the rod contain this L-hydroxyalanine. When the shark smelled this smell, it was natural for him to retreat, and this was the reason why he did not take the bait.

Sharks also have a sense of taste and touch, in addition, they have two special senses, one is the paralinear nervous system, which is a row of nerve endings that are distributed on both sides of the body. He can make sharks sense any activity in the water. Another special sensation is the ability to perceive subtle electrical charges from other living beings. It's called the ampulla of Lorenz.

Sharks have hard, muscular bodies that are spindle-shaped to varying degrees. The muzzle and nose parts vary depending on the species: there are pointed, such as the mako shark and the great white shark; There are also large and round ones, such as the tiger shark and the wide tiger shark with a flattened head. The tail (caudal fin) is vertically upward, roughly crescent-shaped, and the upper part of the caudal fin is much larger than the lower part in most species.

Marine biologists at the University of Hawaii in the United States say they have obtained first-hand evidence that sharks can sense changes in the Earth's magnetic field. This now provides a new example of the existence of an internal "compass" system for marine fish to guide them to orient themselves.

The latest findings are published in the Proceedings of the Royal Academy of Sciences. Carl Meyer, a marine biologist at the University of Hawaii, and his colleagues designed and planned the trial. They trained six sandbar sharks and one hammerhead shark in an artificial magnetic environment. This artificial magnetic environment is a 7-metre-diameter water tank with a copper cable wrapped around it, and whenever food is placed in the tank, the cable switch turns on to simulate the magnetic environment.

After six weeks of training, the cable's switch is turned on whenever the sharks are flocked, even if no food is being placed in the tank. This reaction proves that they sense the presence of a magnetic field.

Before scientists conducted this experiment, some of the shark's peculiar habits had led scientists to speculate that sharks might have this particular ability. Tiger sharks and blue sharks can swim long distances in the ocean, which is impossible with their sense of smell alone. Hammerhead sharks often congregate near undersea mountain ranges, which are areas of change in the Earth's magnetic field.

The next step in the scientists' research is to figure out how sharks recognize the Earth's magnetic field and how sensitive they are to it. Not so long ago, scientists knew that some other animals also had the ability to recognize magnetic fields. Researchers at the University of North Carolina in the United States have proved through experiments that the upper beak of a pigeon has tiny magnetic particles that can help the pigeon complete long-distance flight.

Many people think that sharks are very bad and have been attacking humans, but in fact, sharks are very timid, and the reason why they attack humans is because we humans invade the territory of sharks and attack us.

Swimming

Sharks swim mainly by their bodies, moving like snakes and swinging like a tail fin to move forward. Stabilization and control are mainly based on the use of a somewhat vertical dorsal fin and a horizontally dispatched pectoral fin. Most sharks can't go backwards, so it's easy to get caught up in obstacles like gillnets, and once you do, you can't get out of it. Sharks do not have swim bladders, so the specific gravity of these animals is mainly determined by the amount of oil stored in the liver. Sharks are slightly denser than water, that is, if they don't swim actively, they sink to the bottom of the ocean. They swim very fast, and in the water, great white sharks can shuttle at a time of 43 kilometers, but they can only stay high for a short time.

Sharks have 5~7 gill cleft on each side (unlike carp that we usually buy from the market, there is a pair of gill covers to protect the gills), and the seawater is sucked in through the half-open mouth when swimming, and flows out of the gill slit for gas exchange. Sharks swimming with their mouths open do look scary, but can you keep them from breathing? A few shark species are able to stop at the bottom of the ocean to breathe.

tooth

Tens of thousands of teeth need to be replaced in a shark's lifetime.

Many sharks, including great white sharks, have rows of sharp teeth in their mouths. As soon as the teeth in the front row are lost due to eating, the teeth in the back will be replaced. New teeth are larger and more durable than old teeth. Sharks such as horn sharks and horn sharks have entire rows of teeth replaced. Sharks have jagged teeth, which allows them to bite their prey tightly and cut them apart effectively.

The jaws of the great white shark are not closely connected to the head.

Because the jaws of the great white shark are not tightly connected to the head, it can extend its palate upwards and forwards to swallow its prey, and sometimes even swallow it in one gulp.

The tooth structure of the shark is another of its unique ecosystems. Anyone familiar with the shark knows that its teeth are like sharp knives that can easily bite through cables as thick as fingers. Like a devil shark, it has a long, pointed snout and sharp teeth. Different species of sharks have almost all the size, shape, and function of their teeth. Therefore, ichthyologists can tell which order, genus, or family a shark belongs to just by looking at the shape and size of its teeth.

Surprisingly, the shark's teeth are not a constant row like other animals in the ocean, but have 5~6 rows, except for the outermost row of teeth is the real function of teeth, the rest of the rows are "supine" as a backup, like the roof tiles cover each other, once the outermost layer of teeth is lost, and the teeth in the inner row will immediately move to the front, used to fill the cavity position that replaces the lost teeth. At the same time, the shark's larger teeth continue to replace the smaller ones as they grow. As a result, sharks often have to replace tens of thousands of teeth over the course of their lives. According to statistics, a shark has to replace more than 20,000 teeth in 1o years. Its teeth are not only strong and powerful, but they are also extremely sharp. For example, some sharks have teeth as long as razors, which can be used to cut food; Some teeth are jagged and can be used to tear food; Some teeth are flattened and molar-shaped, which can be used to crush food shells and bones. It is as if the Indians of North America used shark teeth as a tool for shaving. But the terrible thing is that when they compete with each other to eat, the sharks often indiscriminately, even their own children, shark cubs, do not let go, and eat them all; When a shark struggles with another shark's mistake, the shark is unlucky, and other brothers of the same clan will also attack it in groups until it is completely devoured; There is even more terrifying is that sharks are viviparous, a litter can give birth to more than 1o shark cubs, up to more than 8o more, these sharks in the mother's womb actually kill each other, people have been on the Atlantic coast now a tiger shark belly, made an autopsy to come to this conclusion: the mother's womb has become a battlefield, which is a precedent that has never been seen in any animal.

The reason why the shark replaces its teeth in this way is not only related to its brutality and ferocity, but also inseparable from the different shapes of its teeth. Because the bite power of sharks can be said to be the most powerful among all animals in the ocean. A metal biting device was used to measure the bite force of an 8-foot-long shark, which was known to be as high as 18 tons per square inch. Therefore, it is not surprising that some merchant ships have recorded in their nautical diaries that the propellers of the ships were bitten by sharks and the hull of their ships was bitten by sharks. The shape of the shark's teeth is peculiar. For example, the edges of the teeth of the man-eating shark are finely serrated and triangular in shape; The teeth of the blue shark are large and sharp; Although the whale shark is huge, its teeth are as short as a needle; The teeth of the conetooth shark are tapered and long, pointed; Thresher shark teeth are flattened and horn-shaped; The teeth of basking sharks are small and resemble grains of rice; Tiger sharks have wide, molar-like teeth, and so on. The reason why sharks have a wide variety of tooth shapes is closely related to their ecological diet.

In a sense, sharks are all teeth, and the shield scales covered by their body are similar to those of teeth, which can be called skin teeth. Sharks have hundreds of teeth that can be moved, so sharks don't have to worry about running out of teeth, so they have a lot of attack power.

The great white shark is by far the most powerful shark in the ocean, with powerful teeth.

Edit this paragraph's habits

Eating

Sharks mostly feed on marine animals such as fish

Sharks feed on injured marine mammals, fish, and carrion, culling weaker members of the animal. Sharks also eat litter and other waste left behind by boats. In addition, some sharks also hunt a variety of marine mammals, fish, and animals such as turtles and crabs. Some sharks can go months without feeding, and the great white shark is one of them. Great white sharks have been reported to feed only once every one or two months.

The great white shark is a predator that is good at camouflage.

Great white sharks are not as agile as other sharks due to their large size. But the great white shark is an excellent hunter because it can always surprise you. Its upper body is dark and its lower body is bright, and they can use this protective color to sneak closer to their prey. When it comes from below, due to its proximity to the depths of the ocean, it will not be visible until it attacks food. It rarely attacks from above, but when it comes from above, the white underside blends with the bright sky reflected by the sea.

Sharks, known as sharks, sharks, and sand fish in ancient times, are behemoths in the ocean, so they are called "wolves in the sea". The nostrils of sharks are located in front of the ventral mouth of the head, and some have an oronasal groove that connects between the corners of the nose and mouth, and the folds of the olfactory sac increase the contact area with the outside environment. Sharks are cartilaginous fishes that do not have swim bladders on their bodies, and they mainly rely on their large livers to regulate their ups and downs.

In line with the principle that pearls will always be bright, adhere to the code word upload, three changes a day, and insist on completing the book. At the beginning, it was said that the "Legend of Mortal Cultivation of Immortals" was signed with more than 800,000 words, but in this process, he has been unremittingly updated. It can be seen that success is persistent, and reputation is also persistent. My diligence and hard work can be seen by all the judges.

My persistence will bring me credibility and success, I firmly believe!

Book lovers who like this book, please bookmark and vote to give me more motivation. Thank you very much. If you talk about the approximate word count of this book, it will be completed in about two million words! It's almost 10,000 words updated every day, which is not slow. Hard work pays off!