Review
Although the technology of the ancients is not as developed as it is now, it does not mean that their exploration of the world is not referenced, on the contrary, their perception is beyond our imagination. In ancient times, there was a classic book", "The Classic of Mountains and Seas", which recorded many strange animals, including a huge fish, called Kunpeng. Now we understand that this Kunpeng is not actually a fish, but a mammal called a whale.
The largest whale in the world is the blue whale, and interestingly, despite their large size, they are docile in temperament and feed only on small fish and shrimp.
Whales have also undergone a long evolution since their existence on earth, and the ancestors of whales lived on land tens of millions of years ago, and later had to dive into the ocean in order to obtain abundant food, and after a long period of evolution, they have become what they are today.
The hind legs evolved into tails, the front legs evolved into wings, and the dorsal fins evolved to swim more stably, but whales did not evolve gills that were almost essential for marine life, and still retained the original lung breathing style.
In order to ensure oxygen intake, they also need to come to the surface of the sea every once in a while for gas exchange. So why didn't whales evolve gills, and shouldn't that be a vital part of their evolution?
Whales' evolutionary journey
Over the years, scientists have studied the evolution of whales and mapped them in detail.
In the beginning, the ancestors of whales did not live in the ocean, but on land, and at that time it was still very small, far more than the huge body it is today. Later, due to various reasons, the food available on land decreased, and the ancestors of whales tried to hunt in the shallow sea in order to obtain food, and slowly they were able to adapt to life in the ocean.
There is a saying called survival of the fittest, which also simply summarizes the laws of evolution, since hunting in the sea will certainly use the limbs frequently, so the limbs of whales gradually evolved to form webbing, somewhat similar to the webbeds on the soles of today's ducks.
After the evolution of webbing, whales become more convenient to prey, and after obtaining sufficient food, they become larger and larger, which means that whales have a greater demand for food, and the shallow sea can no longer meet their living environment, so they come to the deep sea.
After tens of millions of years of evolution, today's whale breathing has become the upper part, the body has become smooth and smooth, and sharp teeth have grown in the mouth, all of which is the best adaptation to the current environment, so only the way of breathing has not changed? Are lungs really better than gills?
To know that large ocean overlords like sharks have evolved gills is enough to show that fish gills are powerful.
Oxygen content of seawater
In fact, we are wrong, even in the ocean, breathing with lungs is still the best choice. It should be known that whales evolved from terrestrial mammals, which need to consume a lot of oxygen to survive in order to supply their huge bodies and brains.
The oxygen content in seawater is very low, about less than nine percent, while on land it is 21 percent, far less than air. Even if a whale does evolve its gills, the oxygen it inhales simply cannot meet its own oxygen consumption.
In addition, whales are also a thermostatic animal, it needs to carry out metabolism to maintain its body temperature, and too low oxygen is also detrimental to their living environment. You might argue that fish like sharks don't also breathe on their gills? So why don't sharks experience hypoxia? This brings us to the difference between the body structure of sharks and whales.
Someone did a comparison chart comparing the brains of sharks with the brains of whales and dolphins, and found that sharks have simple brain structures, so shark brains do not need to consume a lot of oxygen to maintain functioning.
In addition, whales did not evolve their lungs to store oxygen. Whales are accustomed to operating in the deep sea, and having lungs is a problem with sea pressure.
In the deep sea, the whale's alveoli are basically compressed, that is, the gas in the lungs almost all come to the blood vessels, in this case, the whale is difficult to store or exchange air.
But it also has the benefit of avoiding small bubbles in the blood when whales travel between the deep and shallow seas.
Because it can not frequent ventilation, usually can only rely on oxygen in the blood to maintain life, we can also see that whales usually have a very high blood oxygen content, and their blood proportion is also larger, three percent higher than humans.
In addition, its tidal volume (the amount of a breath or inhalation when breathing calmly) is also very large. One set of data shows that the tidal volume of ordinary mammals is generally 15 percent of lung capacity, while whales can be as high as 90 percent.
So when the oxygen in the body is about to run out, the whales come to the surface of the sea for a breathing, and the carbon dioxide concentration in their bodies has almost tripled.
Shark advantage
Since lung breathing is better than gill breathing, how did sharks become ocean overlords?
You know, the reason why the shark is called the overlord of the sea is its brutal behavior and hunting behavior, and the evolutionary route it takes is different from that of whales and dolphins, and its main evolution is its own sensory organs and attack organs. Sharks have an extremely sensitive sense of smell, and even a drop of blood sharks can smell it at great distances.
Therefore, sharks do not need a high IQ to survive in the ocean, to put it bluntly, they are all blessed with "developed limbs and simple minds".
The crisis of whale survival
Most whales in the ocean are found in swarms, and they are so large that they rarely encounter deadly opponents, but their survival is very optimistic. However, with the development of human beings, because of the interests, some human beings have made fishing practices, and in the face of advanced fishing boats, large whales can not be overwhelmed, resulting in their existential crisis.
In addition, marine litter and pollution are still affecting the survival of more fish, and some stranded news often appears in people's vision, and we should also reflect deeply when we feel sad.
Don't always wait until it is really lost to learn to cherish, those endangered animals that have been extinct are blood lessons, we should take history as a lesson, take advantage of the current situation, stop these acts that damage the ecological and natural balance as soon as possible, and make our own modest efforts.