Remember the shark that was called the longest-lived from the Ming Dynasty to the present? What is the status quo?

2019-12-30 | Zhong Ming talks about science original |

Greenland sleeping sharks are the longest-lived vertebrates currently known on the planet. According to Science, the Greenland sleeping sharks may reach 400 years of age. In other words, an adult sleeping shark may have experienced the MingThings, and survive to this day.

Long-lived Greenland sleeping shark

A biologist at the University of Gohagen, Denmark, was very curious about the age of the Greenland sleeping shark. He obtained a bone from a Greenland sleeping shark and used the radiocarbon dating method to calculate the age of the sleeping shark.Nothing was found. Later radiocarbon dating experts introduced that it would be better to observe with the eyes of a shark.

So a group of scientists analyzed the eyes of 28 female Greenland sleeping sharks captured by fishermen. The analysis results show that the two oldest sleeping sharks are between 335 and 392 years old, with an error of 10 years, that is, thisThe two sleeping sharks were probably born during the reign of Emperor Zhengde of the Ming Dynasty.

But unfortunately, the science that observes the age of the sleeping shark itself will kill the poor sleeping shark first. After the scientific researcher or commercial fishing boat catches the sleeping shark, they will choose the object of research value, generally the body sizeThe bigger the better, this is because the body size of the sleeping shark is positively related to its age. The larger the body size, the older it is; moreover, some individuals with fatal injuries are selected, and the remaining sleeping sharks are released.

After capturing sleeping sharks, they will be euthanized first, and then the eyeballs will be removed for radiocarbon dating. The reason why glasses are chosen is because the Greenland sleeping sharks belong to the cartilage class, and their body structure will not be as hard-bone fish.Calcified tissue.

You can use your eyes to judge the age because there are so many protein crystals in the lens. These protein crystals will not change, but they will grow, so you only need to peel the lens layer by layer and remove the lens core.

Since the nucleus of the lens already existed during the infancy of Greenland sleeping sharks, the age of Greenland sleeping sharks can be observed by radiocarbon dating.

At present, the detected Greenland sleeping shark may be over 400 years old.

Why do Greenland sleeping sharks live so long?

The longevity of Greenland sleeping sharks may be related to its slow metabolism.

We know that in tropical forests, trees usually grow quickly; but in cold high latitudes, trees usually grow slowly. That is, cold regions slow the metabolism in living organisms, and Greenland sleeping sharksIt belongs to the deep sea shark, and the area where it lives is relatively cold, so the body metabolism is very slow. According to research statistics, the Greenland sleeping shark sometimes grows only 1cm per year.

Greenland sleeping sharks are not fast, the speed is about 0.34 meters / s, and humans are about 1.1m / s, which is about the speed of turtles relative to their huge size.

Slow parade speed can avoid consuming too much energy. Although they are not fast, they are swimming prey, such as seals, cod, catfish, etc. At present, scientists have not studied how they are.Hunting.

In addition to slow metabolism, American geneticists have suggested that cold can activate anti-aging genes and help animals to extend life. At present, anti-aging genes have not been found in sleeping sharks, so this statement is just a hypothesis.

Current Status of Sleeping Sharks in Greenland

The growth cycle of Greenland sleeping sharks is very long, only about 156 years of age. Its breeding method is different from mammals and cold-blooded animals. It adopts "ovum birth", which means that their cubs do not grow up in the womb.Instead, it develops in the body's eggs. After it grows to a certain degree, it slips into the uterus and finally landes and is born.

Greenland sleeping sharks contain biotoxins in their bodies, but local people will cut the flesh of sleeping sharks and hang them outdoors or bury them in the snow to detoxify them. Because Greenland sleeping sharks have an indescribable odor after fermentation, soApart from locals, few tourists are willing to try.

However, due to early commercial fishing and marine pollution caused by human activities, the population of Greenland sleeping sharks has declined slightly, and there is a danger of extinction.

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