| scientific wormhole
Everyone yearns for longevity, and the elderly over 100 years old will be called "longevity old people", and their village will be called "longevity village".
But for Greenland sleeping sharks, 100 years is only 1/4 of their lifespan; ordinary people are about to die, and they are still underage.
Greenland sharks live up to 400 years, and they reach adulthood at 156 years, making them the longest-lived vertebrates known on Earth. Today, we're going to learn about the longevity puzzle of the Greenland shark.
Greenland Sleeping Shark: The longevity champion among vertebrates
The right whale was once the "longevity champion" of vertebrates, living to 211 years, and the name later fell on the head of the Greenland shark.
North Atlantic right whales
Greenland shark, also known as small-headed sleeping shark and Atlantic sleeping shark, is a close relative of the Pacific sleeping shark. They live in the North Atlantic ocean around Greenland and Iceland, and are the northernmost shark, active daily at depths of 200-2200 meters.
With a body length of between 2.5-7 meters and a weight of 700-1020 kg, the Greenland shark is one of the largest sharks in the world. Their snouts are short and round; the dorsal and pectoral fins are very small; and the overall color ranges from brown to black, with dark lines or white spots.
Greenland sharks have few predators in nature, partly because of their large size and partly because of the toxins they have in their bodies.
They are the most toxic sharks in the world, and the fish contain a neurotoxin called trimethylamine oxide, which may cause diarrhea, vomiting, and severe coma and death after consumption.
However, the most remarkable thing about greenland sharks is not the toxin, but longevity.
In 2016, a paper in the journal Science pointed out that scientists measured Greenland sharks in the Atlantic Ocean using radiocarbon dating technology and found that their average age reached 272 years, and the longest life expectancy was estimated to be more than 400 years old.
It is said that the female Linglan sleeping shark does not mature until it grows to about 4 meters, which translates to an age of about 156 years.
At the age of 156, more than a century, the Greenland shark has just reached adulthood, and it is only then that it can find a mate and begin to breed.
Regarding the longevity of the Greenland shark, there have been speculations. But in the past, the scientific community often used the calcified tissue of animals to date, but this tissue is very rare in Greenland sharks, so scientists at the time could not figure out their true lifespan.
Later, after consulting experts with marine biologist John Steffensen, it was decided to replace the bone with the eyes of the Greenland shark for testing.
For the first time, Steffensen and colleagues measured the age of sharks using radiocarbon dating, which measured the eye lens of 28 female lennon sharks.
The largest of these sharks is 502 centimeters long, and analysis shows that it has a lifespan of about 392 years. There is also a 120-year-old error here, which means that it is possible that the Greenland sleeping shark is 272-512 years old.
It is understood that a longer Greenland sleeping shark has been spotted. It is about 6 meters long, and its age after measurement is about 517 years old, and it was born in the middle of the Ming Dynasty on the mainland.
Uncover the mystery of the longevity of the Greenland sleeping shark
Why do Greenland sleeping sharks live for hundreds of years? Scientists believe that this is related to the environment in which they live and their own characteristics.
Greenland sleeping sharks move in cold-water areas, and scientists believe that cold water can help them slow down their growth rate and biochemical activity to achieve the effect of prolonging their lifespan.
A geneticist in the United States pointed out that cold can activate anti-aging genes, help animals remove DNA destroying molecules, and even defeat infections to become long-lived, which may be part of the reason for the longevity of Greenland sharks.
In addition to the living environment, the longevity of greenland sleeping sharks lies in the fact that they are very "lazy". "Lazy" here refers to their slow growth and slow movement.
This shark grows very slowly, even growing only 1 centimeter per year. Scientists believe that slow growth may be one of the secrets of their longevity.
When the Greenland sleeping shark is idle, it moves only 0.2 m/s, and only 0.7 m/s when it is "fast" hunting...
Slow movements lead to lower consumption, effectively reducing the metabolic rate and making the Greenland sleeping shark live longer.
So the question is, will sharks that move so slowly really not starve to death? What do they eat?
Teeth of the Greenland sleeping shark
The Greenland sleeping shark is slow, but it has a fierce personality. They feed mainly on seabirds, squid, crustaceans, carrion, etc., and also eat marine mammals.
When it comes to predation, they sometimes need a small helper – the yellow-and-white copepod "Ommatokoita elongata" that parasitizes their eyes.
This copepod can devour the cornea of the Greenland sleeping shark, causing necrosis of corneal tissue and local blindness, although not all Greenland sleeping sharks will encounter this situation.
Greenland sleeping sharks can sense light in the dark, while parasitic copepods can bioluminescent, acting as bait to attract prey. As a result, greenland sleeping sharks can eat prey that moves faster than itself.
Therefore, some people say that the "lazy" Greenland sleeping shark is the price of "sacrificing his own eyes" in exchange for the "delivery" of the prey. In order to eat a full meal, the sacrifice is too great.
Near-threatened species
Usually, greenland sharks have only their own enemies and humans, and they can eat their own kind, but are immune to toxins in meat. Humans are the main enemy of greenland sharks, and historically, greenland sharks have been fishing targets in Norway, Greenland and other waters.
People catch this Greenland sleeping shark for resources, sharp teeth made into knives, cod liver oil made into oil lamps.
They also eat the shark's meat, which is marinated and dried to reduce and destroy the toxins in the fish. An Icelandic dish, kæstur hákarl, is also made with the meat of the Greenland shark.
Greenland's fishery began in the early 19th century, and in the 1850s the annual catch was around 2,000-3,000 head; by the beginning of the 20th century, annual catches had soared to 32,000 heads.
It was not until the 1960s that commercial fishing for shark liver oil in Greenland stopped, but commercial fishing still exists in other regions.
The Norwegian government has issued a fishing subsidy policy to reduce the fishing of Greenland sharks, but fishermen still mistakenly catch Greenland sharks when catching other fish. Today, this long-lived shark is classified as a near-threatened species.
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