A photograph of a Greenland shark widely described as being 392 years old has resurfaced on social media, reviving long‑running fascination—and some confusion—around the species’ extraordinary longevity.
The image first circulated several years ago across platforms including Facebook, Pinterest and Reddit. It was taken during a study led by Julius Nielsen in 2016, the findings of which were published in the journal Science.
The photograph has recently reappeared online in a post shared on X by user @awkwardgoogle on March 8. The caption accompanying the post reads: “A 392‑year‑old Greenland Shark that was located in the Arctic Ocean. He’s been wandering the ocean since 1627.” The post has drawn significant attention, amassing more than 676,000 views.
The claim references findings from the 2016 study conducted by Nielsen and other researchers, which examined the ages of 28 female Greenland sharks. Most of the sharks analyzed had died after becoming entangled in fishing nets. Using their methodology, the researchers estimated that the oldest shark tested had lived somewhere between 272 and 512 years. The midpoint of that age range—392 years—has often been cited in discussions of the species.
In the study, the researchers noted that determining the age of marine species presents unique challenges. “We tend to think of vertebrates as living about as long as we do, give or take 50 to 100 years,” the study said. “Marine species are likely to be very long‑lived, but determining their age is particularly difficult.”
To estimate the sharks’ ages, Nielsen and his team relied on radiocarbon dating techniques. Specifically, they examined carbon‑14 produced by nuclear weapons testing in the 1950s and how it became incorporated into the sharks’ eye tissue during development. According to the study, Greenland sharks are large but slow‑growing animals. The oldest shark sampled had lived for nearly four centuries, and the researchers concluded that the species reaches maturity at around 150 years of age.
Nielsen later clarified the origins of the image itself. He told USA TODAY in 2021 that the widely shared photo is actually a screenshot taken from a video, which he posted on Instagram in 2020.
In the caption of that Instagram post, Nielsen explained that the footage shows a giant Greenland shark measuring 4.4 meters that was caught and released with satellite tags in 2017. He wrote that he originally shared a screenshot from the video, which has since been reposted and circulated hundreds of times online. According to Nielsen, the image is frequently accompanied by captions claiming the shark is 400 or even 500 years old.
“The shark was big yes, but we can’t say anything that precise about its age,” Nielsen wrote. He added that his personal guess was that the shark shown was older than 150 years, though he emphasized that this was only a guess. Nielsen also reiterated that previous estimates suggested Greenland sharks have a lifespan of at least 272 years, based on marine radiocarbon dating of the eye lens nucleus. He noted that this estimate remains unverified and may change as new methods and calibration curves, such as the Marine20 curve published more recently, are applied.
In an earlier Instagram post in 2017 addressing public reaction to the research, Nielsen acknowledged the surge of interest surrounding the species. “Social media are going beserk over old greenlandsharks these days,” he wrote. He emphasized that the research team has not found any sharks to be 500 or 600 years old. Instead, the researchers estimated—with 95.5 percent certainty—that one shark was between 272 and 512 years old, an estimate that has not yet been independently verified, he noted in the post.
Nielsen concluded in the post that the key takeaway from the study is not the precise age of any single shark, but the broader finding that Greenland shark longevity is measured in centuries, echoing the title and central message of the original research.
Do you have a tip on a science story that Newsweek should be covering? Do you have a question about sharks? Let us know via science@newsweek.com.
