"You didn't hear it because your ears are not good." Chen Qingsheng on the side replied.
Fang Youqun didn't believe it, "Why, you all heard it just now, but I didn't hear it?"
Xiang Yang smiled and said, "No, including me, we didn't hear it just now."
The blue whale is the noisiest animal in the world.
When communicating with their partners, blue whales emit a low-frequency, deafening sound that can sometimes exceed 180 decibels, louder than the sound of a jet taking off when standing on a runway.
Scientists once used a sensitive instrument to detect the sound of a blue whale from 80 kilometers away and estimated that the sound of a blue whale can reach 150 to 185 decibels at the source.
Even taking into account the different impedances of water and air, and the different standard reference pressures, the equivalent sound range in air is still around one hundred and twenty decibels.
For comparison, the sound of a pneumatic drill is about one hundred decibels.
But humans cannot appreciate that the blue whale is the loudest animal.
Because the fundamental frequency of the blue whale's vocalization is around ten Hz, while the lowest frequency that humans can hear is twenty Hz.
However, just because humans cannot hear the calls of blue whales does not mean that humans cannot feel the calls of blue whales.
In the past, many KTVs and bars had infrasonic subwoofers. The sound produced by this kind of sound waves is inaudible to humans, but it can make people extremely excited.
But now this kind of subwoofer is not allowed to be used, because the residents around will suffer from serious insomnia and other effects if they listen to it for a long time.
Just now, Xiang Yang suddenly felt dizzy. It must be the blue whale's sudden roar. Although Xiang Yang did not hear the huge sound wave, it caused an impact on Xiang Yang's nerves.
"So it was this guy who was yelling. No wonder I felt so uncomfortable just now." After Fang Youqun understood the situation, he immediately shouted loudly.
Then, Fang Youqun asked Xiang Yang, "Brother Yang, do you know why the blue whale screamed? Is it trying to scare these humpback whales?"
Xiang Yang shrugged, "How would I know why this blue whale is making such a noise?"
Not to mention that Xiang Yang didn't know why the blue whale made such an extremely sad call, even scientists didn't know why the blue whale made sounds. In 1995, scientists put forward several hypotheses. One is that blue whales rely on sound to maintain the distance between individuals, the second is to recognize the same species and individuals, and the third is to transmit environmental information such as foraging, warning and courtship.
Others have suggested that blue whales make sounds to maintain group connections, such as communication between females and males, or to use echoes to locate terrain features and food like bats.
In the 1960s, some scientists thought it would be cool to drop a bunch of radios into the world's oceans to record the songs of blue whales.
Decades later, some scientists who had studied blue whale singing for decades made a strange discovery: the songs of every blue whale in the world were becoming deeper every year, but they didn't know why.
This is a very strange phenomenon. Take humans as an example. Despite differences in language or location, the speaking speed of every person living on Earth changes very little from year to year. The slowdown is so small that it only decreases by less than one Hertz per year, and the overall trend is relatively stable and continuous.
Biologists have tried to analyze changes in blue whale sounds from global warming to increasing noise pollution.
Some people believe that many factors may cause this phenomenon.
However, Xiang Yang believes that the impact of global warming on the ocean cannot explain the change in the sound of whales, because the change in the sound of blue whales is not that of a single individual, but of the entire population, and the impact of the environment is mainly reflected in the changes in the acidity and density of seawater, and the sound emitted by blue whales will not change significantly as a result.
In contrast, noise pollution may be a more convincing explanation.
Xiang Yang once boldly imagined that in a crowded bar, customers could only raise their voices to attract the waiter's attention.
"I really envy this blue whale. It is free and almost at the top of the food chain in the entire ocean, and it doesn't need to worry about food." Xu Fang lit a cigarette for himself and sighed with envy.
In the entire ocean, killer whales are almost the only ones that can kill blue whales.
Xiang Yang smiled and said nothing.
In fact, in addition to killer whales, blue whales have another natural enemy, which is humans.
Blue whale stranding is rare. Due to its special group structure, Xiang Yang has never heard of a group of blue whales stranded.
But blue whales can also get stranded, and most of the time, they are stranded because of humans.
In 1920, a blue whale was stranded on the Isle of Lewis in the Outer Hebrides of Scotland. It was shot in the head by a whaler, but the harpoon did not explode.
Like other animals, an injured blue whale instinctively continues to breathe at all costs, and stranding can prevent it from drowning.
Although blue whales are not easy to hunt and preserve, their huge size, weight, swimming speed and power mean that they are not usually targeted by whalers.
But when some countries whose economy depends on whaling are killing sperm whales and right whales in large numbers, and when the numbers of these two whales decrease, whalers have to turn their attention to blue whales.
The earliest hunting of blue whales began in 1864.
In 1864, Norwegian Svend Foin equipped his ship with harpoons specially designed to catch large whales.
Although initially cumbersome to harpoon, the method quickly caught on, and by the end of the 19th century, blue whale populations in the North Atlantic began to dwindle.
Ever since the first blue whale was killed by humans, the fate of the blue whale has been sealed.
Because there is a thick layer of fat under the skin of blue whales, it can be used to make soap, shoe polish, etc.
Therefore, blue whales will inevitably be killed in large numbers by whalers.
Since 1864, the killing of blue whales has increased rapidly worldwide. By 1925, the United States, Britain and Japan had joined the ranks of blue whale hunting.
Whalers use whaling ships to kill blue whales and then lift them to huge processing mother ships for processing.
In 1930, there were only 41 recorded whaling ships that killed 28,325 blue whales.
By the end of World War II, the blue whale population was close to extinction.
In 1946, the United Nations introduced the first international whale trade quotas.
But these quotas are ineffective because the agreement does not take into account differences between species.
Rare species can be hunted to the same extent as more numerous species. Due to human hunting and pollution of the marine environment, the International Whaling Commission began to ban the hunting of blue whales in 1960.
But by then, 350,000 blue whales had been killed, and the world's blue whale population had been reduced to less than one percent of what it was a hundred years ago.
By the end of the 19th century, there were less than 50 blue whales left in the world.