The oldest Greenland shark in the world

The Greenland shark (also known as the gurri shark or gray shark) may not evoke the same mixture of terror and awe in humans as the great white shark, but this huge predatory fish is perhaps no less adorable. This species is an official member of the sleeping shark family, sharing a close relationship with the Pacific sleeping shark and the long-nosed sleeping shark. The family earned this name due to their slow swimming speed and non-aggressive behavior.

The Greenland shark, which lives in the North Atlantic and Arctic Ocean, moves leisurely through the water, hunting squid, flounder, wolf, seals and even smaller sharks. During the summer, the shark hides at depths of over 7,000 feet along the continental shelf, where water temperatures almost drop to freezing. In winter, it migrates to shallow water near the coast and gathers together with other representatives of the species. Certain molecules passing through the body help them survive under high pressure conditions (although this molecule can be very dangerous and possibly life-threatening if it enters the human body).

What does the Greenland shark look like?

While many people may not have heard of this species, it is as large, and sometimes larger, as a large white. With a rounded snout, small eyes, and relatively short fins, the Greenland shark can grow up to 23 feet in length and weigh a maximum of 2,200 pounds, although the average weight is 6.5 to 13 feet. Females are usually larger than males, probably due to the need to carry so many babies at the same time.

Perhaps the most remarkable fact about Greenland sharks is that they mature very slowly from conception to adulthood. They remain in the womb for a gestation period of eight to 18 years, and after birth are only 15 to 17 inches long. Since they grow less than an inch per year, it can take about 150 years to reach full maturity. This means that by the time this shark can begin to reproduce, several generations of people will be born and die.

What is the life expectancy of the Greenland shark?

Their slow maturation process suggests that they have a very long lifespan, possibly dwarfing any other vertebrate species. However, without any reliable data, no one could know exactly what the oldest Greenland shark in the world is. It turned out that it is surprisingly difficult to determine their age by anatomy alone. Scientists can estimate the age of most fish by observing the pattern of concentric rings on their ears. They are roughly analogous to the tree rings.

But sharks are instead made up of softer cartilage (such as joints or auricles in humans), in which these growth rings are completely absent. Some species, such as the great white shark, have calcified tissue on the spine that indicates their age, but the Greenland shark has very few hard body parts. Thus, without being able to directly observe their lifespan or estimate it from anatomy, scientists could only assume, based on their growth rate, that they probably lived for several hundred years. To correctly determine their age, they needed to develop other clever methods.

It wasn’t until 2016 that scientists finally found a way to solve this problem. The solution was to conduct a radiocarbon test on a shark’s eye. Radiocarbon is a method of measuring the decay rate of certain types of heavy carbon atoms. In the process of emitting radiation, all atoms are transformed at a constant rate. As long as the total number of atoms remains constant, scientists can determine the age of a sample simply by observing the number of decayed atoms in it. Much of the shark’s tissue is undergoing metabolism and change, making it difficult to date properly. But the proteins in the lens of the eye are created when the shark is still young, and they do not grow or change at any stage of its life. This makes the fabric an ideal candidate for radiocarbon dating.

For the experiment, scientists collected eye samples from 28 Greenland sharks, many of which have already died after being accidentally caught in fishing nets as a by-catch. They then carried out radiocarbon dating of the eye tissue samples. One interesting snag in this story is that sharks born after the 1950s had higher initial levels of heavy carbon in their eyes due to the effects of nuclear bomb tests penetrating the ecosystem. Scientists could use this information to provide more accurate estimates of growth rate and age.

Based on their estimates, which they published in the journal Science, the researchers confirmed that the Greenland shark did indeed reach sexual maturity at about 156 years old, give or take about 22 years. They also found that the oldest shark in the sample was likely between 272 and 512 years old, which means it was born somewhere between 1501 and 1744, possibly earlier than sharks like Shakespeare and Queen Elizabeth I.

Since the study was published, there have been articles or claims on the Internet from time to time that the bowhead shark is exactly 512 years old, but this is based on a misinterpretation of the study. Given some uncertainty with the radiocarbon dating process, they were unable to establish a more accurate age, only a general range. But even if the true age were only 272 years old, it would still be the longest-lived vertebrate ever known, easily overtaking the second oldest vertebrate, the bowhead whale, which may be about 211 years old. Only a few documented invertebrate species are known to have surpassed this lifespan, including a 500-year-old clam and an immortal jellyfish (although this species is sometimes disputed; jellyfish actually go back to an earlier stage in their life cycle and do not actually return). live forever in adulthood).

How fast does the Greenland shark swim?

Scientists have suggested that the shark’s slow swimming speed and exceptional lifespan may be related to each other. It is believed that the Greenland shark, traveling through water at less than a mile per hour (and only capable of short bursts of speed), has the lowest speed and tail-hitting frequency of any fish in the world. … They move much slower than most of their prey, suggesting that they are either scavengers or ambush predators that take advantage of favorable situations to forage for food.

More importantly, this means that they have an exceptionally low resting metabolic rate (the rate at which energy is produced in their cells). Animals with very low metabolism tend to live longer. But this is only part of the story. Scientists also believe that low temperatures underwater can activate anti-aging genes to help them fight infections and repair molecular damage.

Conservation of Greenland Sharks.

Their slow maturation and growth rate are of great importance for their preservation. Since a large number of Greenland sharks were killed in the early 20th century, they are still considered a vulnerable species on the IUCN Red List. The number one reason for this hunt was because humans harvested their livers to create engine oil. A far less important factor is that Greenland shark meat is also used as a delicacy called hakarl in Iceland (the meat is actually buried for several weeks to reduce the amount of toxic proteins).

When synthetic oil was finally discovered, demand for shark liver fell, but the numbers still hadn’t recovered from this low level because the baby sharks born after World War II had not yet reached full puberty. While new threats like climate change loom on the horizon, it may take decades for the population to grow again. Meanwhile, one can imagine that the now-born Greenland shark could live much longer than 2,300 years, which is a bit like science fiction.

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