# data[].attributes.attachment_link.title
Largest Mosasaurs vs Extinct Sharks Comparison

# data[].attributes.attachment_link.title
All About Sharks for Children: Animal Videos for Kids - FreeSchool

# data[].attributes.body
Article News ELA

# data[].attributes.attachment_link.readable_text
She was born when James I ruled England and was a youngster when the great fire of London raged in 1666. She lived her teenage years as George II ascended the throne and reached adulthood around the time that the American revolution started. The animal is a female Greenland shark. She is estimated to be 400 years old. The shark has set a new record for long life, scientists have revealed.

The discovery places the lifespan of the Greenland shark far ahead of even the oldest elephant in captivity, Lin Wang, who died at age 86. It is also far longer than the official record for humans, held by 122-year-old Frenchwoman Jeanne Louise Calment.

"It kicks off the bowhead whale as the oldest vertebrate animal," said Julius Nielsen, author of the new research at the University of Copenhagen, Denmark. Bowhead whales have lived as long as 211 years. Nielsen said this shark is the oldest creature with a backbone living on earth, though.

How Long They Live Was A Mystery

Grey, plump and growing to lengths of around 16 feet, the Greenland shark is one of the world's largest carnivores. They are known to grow less than half an inch a year, which shows that they live long lives. But just how long they lived was a mystery.

"Fish biologists have tried to determine the age and longevity of Greenland sharks for decades, but without success," said Steven Campana, a shark expert at the University of Iceland.

Writing in the magazine "Science," Nielsen and an international team of researchers describe how they set about determining the age of 28 female Greenland sharks. They caught them during scientific surveys between 2010 and 2013.

The ages of many fish can be determined by counting the growth layers of calcium carbonate "stones" in their ears. Scientists use a similar method to find the age of trees by counting rings in their centers. Sharks, however, do not have such earstones, or other calcium-rich tissues that could be studied.

Eye Lenses Told The Story

Instead, the team had to rely on a different approach: scrutiny of the lenses in their eyes.

The lens of the eye is made of proteins that build up over time. The proteins at the very center of the lens are laid down while the shark is developing in its mother's womb. Scientists say if they can figure out how old these proteins are, they can get an estimate of the shark's age.

In order to determine when the proteins were laid down, the scientists turned to radiocarbon dating. This method looks for levels of a type of carbon, known as carbon-14, in a material. Carbon-14 is radioactive and is found everywhere. It's in the air, water and ground. All living things have carbon-14 in them, and they usually get it through the plants or animals they eat. Over time, the radiation in carbon-14 decays. When the radiation leaves a substance, its chemical makeup changes. That is how scientists can tell how old it is.

1950s Atomic Tests Helped Tell The Story

The scientists also used information from a side-effect of atomic bomb tests that took place in the 1950s. When the bombs exploded, they increased the levels of carbon-14 in the atmosphere. The extra carbon-14 entered the marine food supply across the Atlantic ocean in the 1950s and early 1960s.

That provides a useful time-stamp, says Nielsen.

Nielsen and the team found that the eye lens proteins of the two smallest of their 28 Greenland sharks had the highest levels of carbon-14. This suggested they were born after the early 1960s. The third smallest shark, however, had carbon-14 levels only slightly above those of the 25 larger sharks. This hinted that it was born in the early 1960s, just when bomb-related carbon-14 began to get into the sharks' food supply. Nielsen said that showed that most of the sharks they tested were older than 50 years.

The scientists then combined the carbon dating results with estimations of how Greenland sharks grow. They created a model that allowed them to estimate the age of the 25 sharks born before the 1960s.

Their findings revealed that the largest shark of the group, a female measuring just over 16 feet in length, was most likely around 392 years old. Nielsen points out, though, that she could be anywhere from 272 to 512 years old.

"The Greenland shark is now the best candidate for the longest living vertebrate animal," he said.

What's more, adult female Greenland sharks can only become pregnant once they reach more than 13 feet in length. Therefore, the scientists found that females have to be around 150 years old before they can produce young.

Evidence Doesn't Convince Everyone

Not everyone is convinced Greenland sharks can live for four centuries, though. Clive Trueman, a professor of marine ecology, agrees it is possible to get a record of the early life of a vertebrate from eye lens proteins. However, the proteins in the eye lenses - and the carbon-14 within them - came from nutrients taken in by the shark's mother. This adds a number of uncertainties to the calculations, he says.

Campana says while the approach taken by the researchers is sound, he remains unconvinced that Greenland sharks live for almost 400 years. But, he adds, "future research should be able to nail the age down with greater certainty."

# data[].attributes.attachment_link.title
Greenland sharks claim the crown for longest living vertebrates - 400 years

# data[].attributes.attachment_link.description
She was born when James I ruled England and was a youngster when the great fire of London raged in 1666. She lived her teenage years as George II ascended the throne and reached adulthood around the time that the American revolution started. The animal is a female Greenland shark.