Greenland sharks, the longest-living vertebrates on the planet, swim for centuries. Rare photos reveal these deep-sea giants.
awoodward@businessinsider.com (Aylin Woodward)
https://teakdoor.com/images/imported/2020/09/162.jpgSeptember 10, 2020, 11:42 PM GMT+7
- Greenland sharks are the longest-living vertebrate species on the planet. One study found that they could live nearly 400 years.
- These Arctic sharks can reach lengths of up to 24 feet and can weigh nearly 2,500 pounds.
- Photos show the reclusive giants in their cold, deep-water habitats.
While time may feel like it's standing still for many of us in 2020, this pandemic year is but a blink of an eye for the world's longest-living vertebrates.
Greenland sharks, which are found in north Atlantic and Arctic waters, can live for centuries. Some of the oldest known members of the species are estimated to be close to 400 years old — which means they were swimming while the Pilgrims crossed the ocean on the Mayflower.
The sharks are difficult to study because they prefer the deepest parts of the ocean, at depths nearly 2 miles below the surface. They're uncommon relative to other shark species like great whites.
"These quiet giants spend hundreds of years below the ocean, slowly roaming the depths in near- to below-freezing waters, rarely seen by the human eye," Meaghan Swintek, a biologist at California State University, Fullerton, who coauthored a recent study on Greenland sharks, said in a press release.
That study, published last month, determined via genetic analysis that there are two geographically separate populations of Greenland sharks: One group swims near Canada's Baffin Basin, above the Arctic Circle, while the other occupies waters of the north Atlantic Ocean between Nova Scotia and Svalbard, near Norway.
The 'longest-living vertebrate known to science'
The more scientists study Greenland sharks, the more they realize these reclusive predators have mind-bogglingly long life spans compared with other vertebrates (the term for creatures with backbones).
According to a 2016 study, Greenland sharks don't reach sexual maturity until they are at least 134 years old.
"They have to wait more than 100 years to get laid — I'm sure they're not happy about that," Julius Nielsen, a coauthor of that study, told New Scientist in 2016.
The researchers on Nielsen's team used radiocarbon dating of the eye tissue of 28 female Greenland sharks to determine their ages.
The biggest and oldest shark they studied was likely 392 years old, the results showed. But radiocarbon dating can give scientists only a range of ages, so the shark could have been anywhere between 272 and 512 years old.
"But even the lowest part of the age range — at least 272 years — still makes Greenland sharks the longest-living vertebrate known to science," Nielsen told Live Science in 2017.
Greenland sharks grow to incredible lengths
Greenland sharks prefer frigid waters ranging from 29 degrees Fahrenheit (minus 1.6 degrees Celsius) to 61 degrees Fahrenheit (16 degrees Celsius).
That's why the sharks frequent deeper parts of the ocean — depths of 9,100 feet. But their natural habitats make Greenland sharks difficult to catch on camera and study.
To track the sharks' movements, Nielsen and his colleagues put GPS-tracking tags on sharks that have been accidentally caught as bycatch in fishing nets.
"Scary photo — A +1,000 kg monster tagged and released," Nielsen wrote in a 2017 Instagram post.
But even that giant is nowhere near the biggest Greenland shark ever recorded. Some can grow to 24 feet long and weigh up to 2,645 pounds (1,200 kilograms), even though they grow only up 0.4 inches (1 centimeter) per year.
Their size makes them an apex predator — the only animal that can threaten these sharks is a sperm whale.
Greenland sharks are primarily scavengers, eating everything (dead or alive) including fish, seals, polar bears, and whales.
Greenland shark meat can cause intoxication
There have been no confirmed Greenland shark attacks on humans. Some people in Greenland and Iceland commercially hunt these sharks, however, for their oil and meat. Though toxic, the meat is considered a delicacy by some.
A Greenland shark spotted in the north Atlantic Ocean on August 17, 2013.NOAA
Greenland shark tissue contains trimethylamine oxide (TMAO), a compound that helps protect the animal against the effects of severe cold and high water pressure.
When humans digest TMAO, it causes symptoms that mirror severe drunkenness.
"Back in the old days, when people ate Greenland shark for want of getting something better, they risked getting shark drunk if the meat wasn't treated the right way," the journalist Morten Strøksnes told National Geographic in 2017. "They would get totally intoxicated, like on heavy drugs and need days to sleep it off."
To consume the shark meat safely, Icelanders compress the carcass in a perforated container to leach out the TMAO, then hang the meat out to dry for up to four months. Then the meat is served as bite-sized cubes called hákarl or kæstur hákarl.
"Even if you do it the right way, it's disgusting," Strøksnes said, adding, "It's the worst thing I have ever tasted."
