What is the oldest animal? This undated photo made available by Julius Nielsen on Aug. 11, 2016 shows a Greenland shark in the icy waters of Disko Bay, western Greenland. (Julius Nielsen via AP)
What is the oldest animal?

In the cold waters of the Arctic, a denizen of the deep lurked for centuries. Now scientists calculate that this female Greenland shark was the Earth's oldest living animal with a backbone.
They estimated that the gray shark, part of the species named after Greenland, was born in the icy waters roughly 400 years ago. It died only recently. That conclusion puts the entire species at the top of the longevity list.
Using a novel dating technique, an international team of biologists and physicists estimated the age of 28 dead female Greenland sharks based on tissue in their eyes. Eight of the sharks were probably 200 years or older. Two likely date back more than three centuries, according to a study published in the journal Science.
Until now, that record holder was a bowhead whale that hit 211 years old, according to study lead author Julius Nielsen and AnAge, an animal longevity database.
The oldest of the Greenland sharks examined was nearly 16.5-feet long and estimated to be 392 years old. It was caught around four years ago. But that calculation comes with a huge margin of error, plus or minus 120 years. This is due to the newness of the dating technique, said Nielsen, a marine biologist at the University of Copenhagen.
That means the shark was probably born sometime between 1500 and 1740. Its most likely birth year was 1620.
"It's an estimate. It's not a determination," Nielsen said. "It is the best we can do."
Even at the lowest end of the margin error, the shark would have been 272 years old when it died. That still would be the longest-living animal with a backbone, Nielsen said. Other experts agreed.
Joao Pedro Magalhaes, a University of Liverpool aging researcher, said because the study is based on an indirect measurement, he wouldn't necessarily concentrate on exact numbers, especially when they exceed 400 years. That is where the upper end of the margin of error goes.
"But the study is convincing enough for us to say that these animals live way longer than human beings and possibly longer than any other vertebrate," said Magalhaes. He runs the longevity database and wasn't part of Nielsen's team.
Some animals without backbones live longer. An ocean quahog, a clam, lived 507 years, and two different types of sponges are said to survive for 15,000 and 1,500 years.
While not surprised that Greenland sharks live a long time, "I'm really shocked by the magnitude of that longevity," wrote Christopher Lowe. He is the director of the shark lab at California State University Long Beach. He wasn't part of the study, but praised it as creative and compelling.
Greenland sharks love cold water. They prefer temperatures near freezing, and are all over the Arctic. The cold water and the slow metabolism that comes with it might have something to do with their long lives, Nielsen said. Lowe, in an email, said "the rule of thumb is deep and cold = old when it comes to fishes."
"I don't know why they get as old, but I hope someone will find out," Nielsen said.
For the age estimates, he uses a complex and indirect system that combines chemical tracking, mathematical modeling and growth measurements. He focuses on the shark eye lens. Those form while the shark is still developing inside the mother's uterus and measures of carbon in them won't change after birth. It gives a good, rough sense of when the shark was born.
National Oceanic and Atmospheric Administration shark expert Allen Andrews said the dating method "is novel and is likely robust" but he said there are still a number of uncertainties.

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Why do cold temperatures promote longevity?
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  • pjack-dav
    8/23/2016 - 07:36 p.m.

    In response to "What is the oldest animal," I agree that the Greenland shark is the oldest animal. One reason I agree is the cold water helps energy burn off more slowly. Another reason I agree is they Greenland shark has a slow metabolism. It says in the article the scientists are able to estimate how long the Greenland shark can live by testing the tissue in their eyes. A third reason is animals with a backbone tend to live longer. Even though they are just estimating I think the Greenland shark can live to be a few hundred years old.

    • asali078-eva
      9/02/2016 - 01:50 p.m.

      I agree with you

  • jcharles-dav
    8/24/2016 - 06:23 p.m.

    In response to "What Is The Oldest Animal," I think that the Female Greenland Shark is not the oldest animal. One reason I believe this is some animals like the sponge live up to 15,000 years or more. In my opinion they should be the oldest living animal in the scientist book not the Female Greenland shark. More evidence I support my opinion is sponges are a lot more adaptable. As it says the Greenland sharks only have one climate cold and sponges can live in a diverse climate hot or cold.

  • jacobh4-moo
    8/25/2016 - 09:34 a.m.

    i would havenever guessed that the oldest animal is a shark. most people dont really think about that stuff but that is just incredible

  • billiejo-moo
    8/25/2016 - 09:37 a.m.

    The sharks are awesome looking! Where can I get a poster of it!

  • rileyb2-moo
    8/25/2016 - 09:41 a.m.

    I enjoyed learning about this, it was very fascinating and interesting to me.

  • coltenc1-moo
    8/25/2016 - 09:42 a.m.

    it helps longevity because the freezing water helps slow their metabolism and slows their old ageing.

  • addisonm1-moo
    8/25/2016 - 09:43 a.m.

    I think there could be older animals in Africa.

  • wyatts1-moo
    8/25/2016 - 09:44 a.m.

    Thats a really old shark.

  • josieb1-moo
    8/25/2016 - 09:45 a.m.

    I wish I could live to be that old!

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