These Bizarre, Centuries-Old Sharks May Have a Hidden Longevity Superpower
The very, very long-lived Greenland sharks were long thought to be practically blind. But a new study finds that they not only can see but also maintain their vision into old age
Photo by: Martin Zwick/REDA/Universal Images Group via Getty Images
Greenland sharks are a biological anomaly. The animals can grow to more than 20 feet long, weigh more than a ton and can live for nearly 400 years, making the species the longest-living vertebrate on the planet—a fact that could help unlock secrets to enhancing longevity.
And now, in a study published this week in Nature Communications, scientists dial in to one of the Greenland shark’s more remarkable features: it has functioning eyes and, more remarkably, maintains its vision well into senescence.
Biologists have long believed these sharks to be practically blind, in part because of their tendency to attract parasites that attack and lodge themselves inside the sharks’ corneas. But this work challenges that belief, the researchers write, showing that even centuries-old Greenland sharks retain a visual system “well-adapted for life in dim light.”
On supporting science journalism
If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
“Evolutionarily speaking, you don’t keep the organ that you don’t need,” said Dorota Skowronska-Krawczyk, an associate professor of physiology and biophysics at the University of California, Irvine, and a co-author of the paper, in a statement. “After watching many videos, I realized this animal is moving its eyeball toward the light.”
Skowronska-Krawczyk and her colleagues analyzed samples taken from sharks that were more than a century old and found no obvious signs of retinal degeneration, which, she notes, is a “remarkable” finding, considering their advanced age.
The researchers say the work offers a jumping off point for future research into how the sharks preserve their vision over such long periods of time, work that could eventually inform studies of age-related vision loss in humans—and how it might be prevented.
“Not a lot of people are working on sharks, especially shark vision,” said Emily Tom, a Ph.D. student at the University of California, Irvine, who is also a co-author of the study, in the same statement.
“We can learn so much about vision and longevity from long-lived species like the Greenland shark,” Tom said.
It’s Time to Stand Up for Science
If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.
I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.
If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.
In return, you get essential news, captivating podcasts, brilliant infographics, can’t-miss newsletters, must-watch videos, challenging games, and the science world’s best writing and reporting. You can even gift someone a subscription.
There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.
