The Greenland shark is the world's longest living vertebrate and one of the longest living animals ever.
Icelanders call it “Skalugsuak,” after an old Inuit legend that claims that it lives in the urine pot of Sedna, the goddess of the sea, and that its flesh can destroy human skin. But most people know it as the Greenland shark.
For years, scientists believed that Greenland sharks, like most sharks, had a lifespan of only about 100 years. However, recently scientists have discovered that their lifespans could be much greater than anyone ever thought: up to 500 years.
This is the story of longest living vertebrate.
The Whacky Characteristics Of The Greenland Shark
The Arctic Greenland shark’s native nickname actually inspires a fitting image for Skalugsuak, whose flesh, coincidentally, smells like urine, and if consumed raw can be toxic to humans.
Not quite as majestic, fearsome or awe-inspiring as some other large sea creatures, the Greenland shark is actually relatively ugly. Its long, thick, gray body is brown, and its small head consists of a short, rounded snout and tiny eyes, often plagued by worm-like parasites that trail from its head.
The shark survives on a diet of mostly halibut, and other large fish – though the remains of polar bears have been found in their stomachs. The Icelandic people consider the flesh of the Greenland shark to be a delicacy and put it through a months-long fermenting process in order to render it safe to eat. Without it, the effects of the meat cause symptoms similar to severe drunkenness.
One of the most recognizable features of the Greenland shark is its small, bright eyes. Its eyes are home to a stomach-turning parasite called Ommatokoita elongata.
These parasites render the shark partially blind, but thankfully the light-devoid environment in which the Greenland shark spends the majority of its life doesn’t call for much eyesight.
Instead, the shark uses its other senses and also practices patience to catch prey.
Greenland sharks are also called sleeper sharks in regard to their slow pace. According to the National Oceanic and Atmospheric Administration (NOAA), the sharks move at a pace of 1.8 miles per hour.
These slow-moving creatures often hunt anywhere from 700 to 2,200 meters under the freezing sea. They are the only shark that can live in these conditions in the Arctic year-round.
Immortal Sharks? The Greenland Shark Pushes Boundaries Of Longevity
What makes the Greenland shark so fascinating, however, is not what is known about it, but what remains a mystery.
Despite rumors to the contrary, the oldest living Greenland sharks are probably not 500 years old.
But, it turns out, the number isn’t actually that far off.
According to Live Science, in sharks like Great Whites, scientists can use the hard vertebrae to calculate the shark’s age. However, unlike most sharks, the Greenland shark is “soft” – its vertebrae don’t harden as much as others. So, scientists had to come up with a new method.
Using the crystalline from the eye of a Greenland shark, scientists were able to perform carbon dating on 28 sharks. What they found shocked them. The Greenland shark had the longest known lifespan of any living vertebrae, and that, even considering a wide margin of error, it could live anywhere from 250 to 500 years.
The longest shark surveyed, and likely the oldest, was roughly 392 years old. This five-meter female shark had prowled the waters of the Arctic for over three centuries.
So what is it that allows these sharks to live so long? The secret lies in their icy and unforgiving habitat.
An Unknown Life Under The Ice
Scientists attribute the Greenland shark’s advanced age to the cool temperatures that it lives in and its great size.
The cold environment that the sharks live in is just above freezing, which slows their metabolism, and due to their size, their metabolism is already slower than most creatures. When the metabolic process slows, everything slows – including aging.
However, it is not just their metabolism that allows them to live so long. Researchers are confident that further studies of their genome will reveal the secret to longevity in humans as well.
According to the Daily Mail, researchers from the Arctic University of Norway are exploring this question using DNA from the sharks’ fins.
Using the DNA from 100 Greenland sharks, the group mapped out their entire genomes and hope to identify the specific gene responsible for longevity.
“Together with colleagues in Denmark, Greenland, USA, and China, we are currently sequencing its whole nuclear genome which will help us discover why the Greenland shark not only lives longer than other shark species but other vertebrates. The results we presented here in Exeter will help us understand more about the biology of this elusive species,” one researcher explained, as per the Daily Mail.
Alongside decoding the secrets of their lifespans, researchers hope to uncover the mating patterns of the sharks as well.
Currently, researchers believe that the sharks may travel under deep Arctic fjords to mate, but this is only a theory. What researchers do know is that the Greenland shark can’t mate until it is over a century old, making it one of the oldest animals to reach sexual maturity.
More research must be done to piece together the mystery of the Greenland shark, but the research currently in the works already has incredible promise.
The Future Of The Greenland Shark
According to the World Conservation Union (IUCN), the Greenland shark is “near threatened.”
According to the IUCN, nearly 3,500 Greenland sharks are accidentally caught every year in the Northwest Atlantic, Arctic Ocean and Barents Sea.
Historically, fishermen have sought out the sharks for liver oil production.
It is hard to say how many Greenland sharks currently prowl the ocean, but researchers are confident that their species has been threatened by both human activity and climate change.
And speaking of climate change, the same researchers studying the genome for insights into longevity have also taken on the challenge of examining the tissues and bones of these sharks to measure the impact human behavior has had on the world’s oceans.
According to the Daily Mail, the sharks’ chemical composition may pinpoint exactly when pollutants began affecting them. Additionally, researchers can better understand the impacts of commercial fishing and other industries on the near-threatened species.
So while we marvel at the shark’s lifespan and funky-looking appearance, it is also important to remember just how much this incredible shark species has experienced and how much it can teach us.