The first sharks lived 400 million years ago, 200 million years earlier than the earliest dinosaurs. Over time, they have changed very little.
The shark has no vocal cords. They communicate through body language, such as head butt, shaking their head or even bending over.
Scientists recently discovered a new type of shark that is only 5 1/2 inches long: aptly named American Pocket Shark. Not only is it small, but it also glows in the dark.
Sharks belong to a group of fishes known as bouncers or cartilaginous fishes. Rays and skates that may have evolved from sharks also belong to this category.
Since sharks rarely get cancer, scientists have studied their cartilage, hoping to find a cure for this disease.
Herodotus (c. 484-425 BC) described the group of "monsters" that swallowed the shipwreck of the Persian fleet, and this was the first written record of a shark attack.
Although blood may not trigger an attack by sharks, nearby sharks may be able to detect blood. In the absence of any conclusive evidence about how sharks react, some scientists advise women not to enter water during menstruation.
When sharks eat indigestible food (such as turtle shells or tin cans), they can vomit by pulling their stomachs out of their mouths and then pulling them back.
The shark’s jaw is not attached to its skull. Since the shark’s mouth is on the underside of the head, the shark can temporarily dislocate its jaw and extend it forward to take a bite.
Before sandpaper was invented, people used shark's rough skin (called shark skin) to sand and polish wood. The Japanese warrior wrapped the skin on the hilt to prevent the sword from slipping out of the hand.
The first cub that hatched in the mother sand tiger shark swallowed its siblings until only two cubs remained, on either side of the womb. This form of cannibalism is called "cannibalism".
The first use of the word "shark" in English appeared in 1569. Previously, British sailors and fishermen used the term "sea dog" or Spanish tiburón. It may come from Schorck in Germany, which is a variant of Schurke ("Smelly Man") from Shürgen ("poke, stir").
Strange things were found in the shark's belly, including shoes, chairs, the back part of a horse, a box of nails, torpedoes, iron barrels and several bottles of wine.
In 1977, Happy Days's Arthur "Fonzie" Fonzarelli jumped over a fixed shark on a water ski, so the term "jumping shark" was born, which described a desperate dramatic measure in a TV show.
There are at least 400 species of sharks that can be divided into eight categories and are always looking for new ones. Among so many species, only about 30 are known to attack humans, especially great white sharks, tigers, bulls, mako sharks and hammerhead sharks. Most sharks are completely harmless.
For every person a shark killed, humans will kill 2 million sharks.
In the 1980s, the efficiency of a shark was compared with that of a submarine. By weight, the driving force required by the shark was reduced by a factor of six. This discovery led to compelling new experiments for racing cars, submarines and swimsuits that explored "rough" rather than smooth surfaces in the water.
Recent studies have shown that when a shark slides on surface water (when its dorsal fin pierces the ocean surface), it may be detecting pressure waves associated with nearby struggling animals.
The biggest fish caught with rods and fishing reels is the great white shark. It weighs 2664 pounds and is almost 17 feet long.
By regulating the salt and other substances in the blood, male sharks can live in salt and fresh water at the same time. Bull sharks may be the cause of a shark attack in a creek in New Jersey in 1916. They were also found in the Mississippi River.
It wasn't until 1976 that the most unusual shark in the world was discovered, namely Megachasma pelagios (Megachasma pelagios). Its mouth can reach 3 feet, while the rest of the body is about 16 feet long.
I have only seen 14 big mouths.
The longest-lived shark is the spiny or spiny dogfish (Acanthias). They usually live to 70 years old, but some may live to 100 years old. Fish sharks are named for their tendency to attack prey, just like a group of wild dogs.
Most sharks cannot pump water on the pump like most fish. They must swim constantly to force water to flow through their mouths and gills. In addition, there are some sharks that lie flat on the bottom of the sea, such as the angel shark (through a small hole behind its eyes, it will inhale water, the shark will inhale water, and the shark will open and close its mouth to move) Water on g).
About 100 million sharks are killed every year. Shark teeth are used to make necklaces. Cartilage is used to make fertilizer; skin is used to make leather; liver is used to make creams, juices and fuel; fins are used to make soup. The mass killing of sharks has a negative chain effect in the global environment.
All living things emit small electrical signals when they breathe or move. Some sharks, especially hammerhead sharks, can use electricity to help catch prey-they pick up small electrical pulses through hundreds of small holes in their faces (called the ampulla of Lorenzini).
Sometimes sharks will attack metal objects. This may be because metal emits weak electrical signals in salt water, which may confuse sharks.
Although almost the same number of men and women spend time in the ocean, no one knows why sharks seem to prefer to attack men. In fact, nearly 90% of shark attacks occur on men.
Wow educative.