Sharks, an ancient sea creature, have a variety of amazing properties that amaze scientists,
The first sharks on Earth appeared more than 4.2 billion years ago, predate the time when dinosaurs appeared. By the Jurassic, modern types of sharks had formed.
Over the course of time, sharks have bred and differentiated into more than 440 different species, as small as the deep-sea lantern shark, which is only 17 centimeters long.
Deep-sea lantern shark
Whale sharks, which are about 12 meters long and feed on small fish and shrimp.
Sharks are found in temperate and tropical oceans around the world. With the exception of a very small number of sharks such as the Greenland shark,
Greenland shark
There are almost no sharks that can survive in the cold zone. Sharks are generally less active in water temperatures below 20°C.
Except for a few sharks that can live both in seawater and freshwater, such as the bull shark
Bull shark
Unlike river sharks, sharks usually only live in seawater. Some sharks have the ability to go deep 2,000 meters underwater.
Different species of sharks have different feeding habits, some are carnivorous, devouring seals, horns and even humans, and some only eat plankton.
Some well-known shark species, such as the great white shark,
Great white sharks
Tiger shark
and hammerhead sharks, etc.,
At the top of the marine chain, it is the "top" predator in the ocean.
There are about 30 species of sharks that actively attack people, of which 7 may cause death, and others are dangerous for people due to their body shape and habits.
The latest research has unraveled the mystery of sharks' powerful sense of smell
Sharks are animals that spot prey through a keen sense of smell, and their sensitivity to the smell of blood is staggering — some sharks can even smell the blood of a drop of blood 500 meters away. So where does the shark's powerful sense of smell come from? A new study proves that the delay in odor perception of the two odor receptors on the nostrils on both sides of the shark's head is less than 05 seconds (that is, the interval between odors reaching the other nostrils from one of the shark's nostrils), and the shark thus becomes a very experienced "hunter" who will run in the direction of the first perceived odor in the first place.
The researchers studied the sharks in a large fish tank filled with seawater and found that the sharks relied on the combination of odor and water flow to make judgments to find their prey. If the delay in the arrival of the prey odor in both nostrils is between 0.1 and 0.5 seconds, the shark's head will turn sideways in the direction of the first smell; if the delay time is greater than 1.0 seconds, or if the prey odor reaches both nostrils, the shark will turn right or left.
This finding overturns a previously popular view that animals track odors as scent concentration-oriented. It has long been thought that most animals have two odor receptors on their nostrils or antennae, and animals compare the concentration of odors felt by the two odor receptors and then run in the direction of a strong signal.
The new discovery of the mystery of shark smell has brought new enlightenment to people, and it may be possible to create underwater robots that are easier to detect chemical leakage based on this principle. Robot programs have been set up in the past to track the source of chemical leaks based on odor concentrations, but these robots are significantly less efficient than animals like sharks. For example, in the oil spill in the Gulf of Mexico, the main and obvious sources of spills are easier to detect, but smaller sources of spills are more difficult to find.
Sharks are an ancient marine creature with a variety of amazing properties that amaze scientists. Scientists have made several new advances in shark research in recent years.
Rex Tyrannosaurus is difficult to defeat the Ancient Megalodon
Rex Tyrannosaurus rex , also known as Tyrannosaurus rex , was a large carnivorous dinosaur about 13 meters long. If we let the sharks of ancient times duel against the Rex Tyrannosaurus, what would happen? Recently, researchers in Australia and the United States used computer simulations to analyze the bite marks left by ancient megalodons and dinosaurs, and the results showed that the bite force of The Lake Glutinous Tyrannosaurus was about 3.1 tons, which was much more powerful than the great white sharks living on Earth today. The bite force of the larger living great white shark can reach 1.8 tons, while the bite force of the large African lion is about 560 kg, and the bite force of humans is about 80 kg, and the great white shark is undoubtedly the most powerful creature in the existing life on the earth. However, compared to the ancient megalodon shark, rex tyrannosaurs are small and magical - the huge megalodon shark can be up to 16 meters long and weigh up to 100 tons, and the bite force generated by their huge teeth is as high as 10.8 tons to 18.2 tons! It can be seen that the ancient megalodon is the most feared predator that the earth has ever seen.
The researchers first obtained anatomical and biomechanical data on the skull and muscle tissue of ancient megalodon sharks using computer simulation techniques, and then created a three-dimensional model of the skull of a 2.4-meter-long male megalodon based on the images generated by the X-ray tomography scanner (CT). Imaging and analysis software was used to reconstruct the megalodon's huge skull, jawbone and muscles. Subsequently, the researchers used digital technology to simulate different scenarios, and finally revealed the huge bite force of this huge marine predator.
Sharks are distant relatives of humans
Sharks are distant relatives of humans, and sharks and humans share a common ancestor. This is a latest study by scientists.
By comparing genomes and chromosomes and sequencing their genes, Singaporean scientists have concluded that at least one species of shark possesses several genes that are very similar to humans, and that sharks that share several genes with humans are elephant sharks.
Elephant sharks
Studies have shown that the elephant shark's genome bears many similarities with humans, even more than some other species in the evolutionary tree that are closer to humans, such as teleost fish.
The researchers also analyzed and compared the genes of animals such as pufferfish, chickens, mice and dogs, and found that humans had a total of 154 genes similar to rats, dogs and elephant sharks. The similarity between human genes and those of mice and dogs is to be expected, as all three belong to mammals, but sharks belong to the cartilaginous fish class and have little physical resemblance to mammals.
Further research also found that sharks and humans share some of the same physiological and biochemical reactions. For example, elephant sharks and other sharks, as well as humans, are fertilized in vivo, while teleost fish are in vitro; sharks and humans have very similar immune systems; sharks have all four types of white blood cells found in mammals; and some sharks reproduce their offspring in the same way as mammals, in vivo rather than oviparously.
Sharks are the oldest surviving vertebrate jaws, and studying them has the potential to unravel the evolutionary mysteries of humans and other mammals.
Shark blood volume varies with the environment
The latest research has found that sharks can regulate the amount of blood and body fluids in their bodies based on changes in salt concentrations in seawater. In other words, the blood volume in the shark's body can change with the environment.
Sharks suck up seawater through their gills, while also drinking seawater and excreting urine to adapt their body systems to their surroundings. Therefore, for sharks, the importance of humoral regulation is very similar to that of humans, without proper regulation of body fluid content and other physiological systems, including cardiovascular and renal systems, sharks can not achieve optimal physical function.
Canadian scientists recently found that sharks living in low-salt or freshwater environments have significantly higher blood volumes than their counterparts living in saltwater environments. Apparently, in order to adapt to low-salt and freshwater environments, sharks evolved over the course of evolution, increasing their plasma levels in their bodies while maintaining the same number of cells, ultimately making blood concentrations lower.
Researchers in the study of bull sharks, bamboo sharks,
Bamboo shark
Horned sharks
Studies with other species of sharks have found that sharks regulate blood and body fluid levels in at least the following ways:
Take a big gulp of water. Sharks let seawater into their permeable gills, but this infiltration method is sometimes not enough for sharks, so there are two species of horned sharks that, when they enter 100% saltwater from 80% saltwater, swallow seawater in large mouths, just as humans do when they are thirsty. In the case of environmental changes leading to a lack of water in the body, drinking water is a very effective regulatory measure.
Increase or decrease urinary output. As blood pressure rises and falls, the shark's kidney system also begins to speed up, by increasing or decreasing the amount of urine that is urinating, excreting or retaining water.
to respond to water environments where salt concentrations have changed.
Drain excess salt. The rectal glands of sharks are made up of specialized salt-secreting tissue. It plays a role in assisting the work of the kidneys. The intestinal system of sharks also plays an important role in maintaining fluid balance. Although sharks live in an endless marine environment, they can also dehydrate if the salt content of the sea is too high. When this happens, the shark's gut system gets up and down, draining excess salt while retaining water.
Scientists point out that global warming may pose serious challenges for sharks, but the complex body changes that sharks have acquired over the long years of evolution can make them constantly adapt to changing environments.
Spot whale sharks "Boys Club"
Whale sharks are shark species covered with striking stripes and spots that scientists know very little about to this day. Whale sharks are mainly distributed in tropical and warm temperate waters in India, the Philippines, Australia, Mexico, Indonesia and other regions. Less than 350 whale sharks were identified and detected before the mid-1980s, but large populations of whale sharks have since been spotted off the coast of Nigalu in western Australia.
The researchers found that in March and April each year, when a large number of polyps lay eggs, as many as 200 whale sharks gather around coral reefs in the waters off Nigalu and stay there for up to three months. The researchers called the event a "boys' club" because about 85 percent of the whale sharks that appeared here were juvenile male whale sharks no longer than 8 meters long, about two-thirds of them had been here in previous years, and 1/3 had come here for the first time. Male whale sharks can grow to 8 to 9 meters in length as adults, and most of them do not come here after adulthood, replacing them with smaller individuals. Researchers speculate that adult whale sharks may be busy looking for their mate in the vast ocean.
Whale sharks are "big-mouthed" filter-eaters with thousands of small teeth, but these small teeth are not used for feeding.
They feed on krill, crab larvae, jellyfish and coral eggs. As the whale shark swims in the water, it opens its one-meter-wide mouth, swallows the seawater in a big mouth, and then filters the seawater through a fine "gill raker" to sift the food as small as 1 mm. The researchers observed whale sharks occasionally suspending their bodies vertically in the sea to feed, which they suspect is a way to save physical energy. More rarely, sometimes several whale sharks will unite and open their mouths to rush to a "krill ball" made of countless krill.
The waters off Nigalu are clear, and whale sharks are easy to spot, sometimes from planes flying overhead. However, whale sharks usually prefer to lurk in deeper waters, up to 1500 meters below water. No one knows why they dive to such depths. Experts speculate that they may have done so for food, and that strong currents in the deep sea allow them to dive thousands of kilometers over long distances.
One of the reasons why whale sharks are so little known is that when whale sharks reach a certain depth of seawater, the satellite tracking transmitter placed on them will temporarily lose its effect due to the huge pressure of the seawater, and will not resume transmitting data to the satellite until the whale shark floats to the surface again. Another reason is that satellite tracking launchers often come off, making it very difficult to track whale sharks throughout. Researchers have tracked their route from Negaluru to Christmas Island, Indonesia and East Timor, but where they went after that remains a mystery.
Whale sharks have a long lifespan, they can live to the age of 100 years, and the maturity age is around 30 years old. Although it is known that whale sharks are in vivo fertilized, the mating habits of whale sharks are concerned. As well as breeding time and place, etc. are still not well understood. So far, only one pregnant female whale shark has been spotted and caught by fishermen. In the belly of the female whale shark, more than 300 pups that look exactly like their mother's will-grow pups were found. In this way, whale sharks reproduce in a way that resembles a turtle: they give birth to large numbers of pups, but only a few survive.
A few years ago, a 38-centimeter-long whale shark puppy was caught near Donsol Island in the Philippines and put back into the sea after taking photographs and archiving it. The discovery of the whale shark's pups suggests that the waters in this area are likely to be "baby-rearing areas" for whale sharks. Unfortunately, no traces of female whale sharks have been found.
"Boys' clubs" like Nigallu also appear in other places, usually related to the emergence of seasonal food in large quantities, such as the spawning period of polyps and the season of large breeding of copepods. But. Scientists have not observed swarms of female whale sharks. In order to figure out the mysterious whereabouts of female whale sharks, scientists have made positive efforts, and finally made exciting discoveries in the Galapagos Islands: several places where female whale sharks have congregated there. Unlike Nigaluru, whale sharks in the waters around galapagos are active close to the surface of the sea, so they are easier to spot. Female whale sharks dive there to 20 to 25 meters to feed, and the nutrient-rich upwelling water contains the food they need. Divers wearing underwater breathing apparatus can spot them.
Why do male and female whale sharks "rally" in different seas? Scientists have yet to find the answer.
Sharks full of mysteries
The earliest sharks on Earth appeared more than 420 million years ago, earlier than dinosaurs. Sharks have evolved over a long period of time, differentiating into a multitude of species and possessing a variety of amazing traits. So, with what kind of survival mechanism and strategy do they rely on to become "pre-level" members of the marine biological chain?
Shark cartilage, teeth and tail
Compared to bony fish and land vertebrates, shark bones are very different. The bones of sharks and other cartilaginous fish are made of cartilage and connective tissue, and the bone density is only half that of the hard bone, which greatly reduces the weight of the bone. Saves energy in the body. However, since there is no chest cavity supported by ribs. If sharks reach land, they will be crushed by their own weight.
Shark teeth are constantly being replaced with old and new,
Some sharks lose as many as 30,000 teeth in their lifetime. Replacement speeds also vary, ranging from 8 to 10 days to months. Most sharks have teeth that are replaced one at a time, and a shark called a cigar shark (also known as the Brazilian Dharma shark) is replaced by a whole row of teeth at the same time.
Brazilian Dharma shark
The shape of shark teeth depends on the type of food they eat. Sharks that feed on molluscs and crustaceans have dense, flattened teeth that are convenient for crushing carapace; sharks that feed on fish have needle-like teeth to facilitate catching slippery fish; sharks that feed on large prey such as mammals have complex teeth, the lower teeth are sharp and sharp, used to grab prey, and the upper teeth are triangularly serrated and used to tear and cut prey; and the sharks that feed on plankton, such as basking sharks, have their teeth have been greatly degraded and basically cannot play the function of their teeth.
Sharks have very unique tails, and different species of sharks have different tails in order to adapt to different environments. But in general, the fish tail can produce thrust and speed. So the shape of the tail is crucial. The tiger shark has a large circular protrusion above its tail that gives the tiger shark great explosive power when it turns around while hunting. The round protrusions on the tail of porbeque sharks are located below the tail, which helps them to catch mackerel and herring, always keeping pace with large groups of prey that are fast escaping. Some sharks have a different purpose for their tails, such as the long-tail shark feeding on fish and squid, and its long, powerful tail can be used to repel schools of fish and even stun them.
Shark speed, intelligence and sleep
Sharks swim at an average speed of 8 kilometers per hour, but can reach speeds of up to 19 kilometers per hour when preying and attacking. The barramundi shark is the fastest of the sharks,
Barramundi shark
It is also one of the fastest of all fish, with eruptions of up to 50 kilometers per hour. The speed explosion of the great white shark is also considerable, and they can become the speed champion among sharks. Probably thanks to the fact that they are warm-blooded animals.
It was once widely believed that sharks were simply instinct-driven "hunting machines," but recent studies have shown that many species of sharks have problem-solving and social skills
Competent, and extremely curious. The ratio of brain weight to body weight in sharks is similar to that of mammals and birds. In 1987, it was discovered near the Gulf of South Africa. A group of seven great white sharks work together to move a whale that has died of stranding to eat in deep water. Sharks also engage in playful activities. Porbeagle sharks are often seen using kelp as a toy and playing chase games with each other.
Some sharks lie on the ocean floor while their eyes are open. Sharks no longer breathe through their nostrils when resting, but breathe through water spray holes. Sharks resting on the ocean floor who try to breathe through their nostrils will inhale sand instead of seawater. Many scientists believe this is one of the reasons sharks have water-spewing pores. White-spotted sharks use their spinal cord rather than their brains to regulate swimming activity, so they can continue to swim even while they sleep. Sharks may sleep in a similar way to dolphins, with both halves of the brain taking turns resting, maintaining some consciousness and brain activity at all times.
The amazing abilities of sharks
From camouflage to electrical signal sensing, from being aggressive to being able to coexist peacefully with small fish, sharks are dazzling and surprising in their various characteristics.
Camouflage ability There are about 50 species of sharks that emit strange rays of light that can make them disappear in front of predators or prey in an instant. The researchers found a shark called the velvet belly lantern shark. Rays of light can be emitted from under its body, mimicking the natural light of its surroundings, and both the hunter and the prey will be fooled by them without knowing it.
Supersensory Abilities Sharks possess a variety of perceptual abilities that are no less than those of humans. For example, some sharks have supersensitive ability to electrical signals, and their bodies are extremely sensitive to the electrical signals emitted by injured or trapped fish; some sharks' eyes can control light, adapt well to the dark seabed environment, and see the underwater situation clearly; some sharks have a sensitive sense of smell and can sense changes in the chemical composition of the water; some sharks have an incredible sense of touch and can sense small changes in the water body; some sharks have a keen taste of food, and they will bite the prey first. To determine whether it is worth the effort to hunt; some sharks are keenly aware of the activity of any object around them. Sharks possess such diverse sensory abilities that it's no wonder that, as one of the oldest creatures on Earth, they were able to survive hundreds of millions of years of species boom and bust to this day.
Long-term memory with such a diverse range of sensory abilities that sharks seem to have a very strong advantage in the ocean. However, the surprise that sharks bring us is much more than that. Tiger sharks, for example, obviously possess incredible memory abilities, especially those who have found delicious food in the past, which is difficult for them to forget. Tiger sharks remember the last time they got delicious food, and will revisit the old place many times in the future, even if they are thousands of miles away. Sharks near the Galapagos Islands can also remember where they last found delicious food, although they are not as capable of finding places thousands of miles away like tiger sharks.
Self-confidence and adventurous spirit Judging by the shark's incredible sensory abilities, memory abilities, and other abilities, they must feel good about themselves, as if they have the aura of overlordship that no one in the ocean can afford. A recent study revealed a surprising sense of confidence and adventurousness in sharks: some species of gill sharks dive 250 meters deep to enjoy the animal bodies that researchers have thrown onto the ocean floor. In order to obtain food, these sharks will bravely enter the death zone, where oxygen content is extremely low, and the possibility of serious consequences of suffocation is high, but they have no choice but to pay attention to food. While some sharks like to be stimulated, studies have shown that certain depths are too deep and too dangerous for even the most confident sharks.
Six-gill shark
The gentle side Sharks also have a gentle side. Some sharks can live in peace with small fish. For example, at Osprey Reef, more than 1,100 sharks gathered spectacularly, which turned out to be a "shark cleaning station", where the sea bully sharks appeared to be very easy-going and gentle, they took a vertical posture, signaling the small fish to move closer, and they stood there obviously waiting to be "cleaned". The researchers found that sharks have never eaten small fish here. In this way, sharks value this cleaning process, and are grateful to the small fish that let them benefit, so they will not hurt them, and the small fish feed on the debris on the shark's body to objectively help the shark remove the mucus, algae and necrotic tissue from the body. Maybe sharks aren't as vicious and bad as we think, especially when they're good for them, and sharks show an extremely gentle and kind side.