In a quiet office at the University of California, Irvine, Dorota Skowronska-Krawczyk watches a grainy video on her computer.
A massive Greenland shark drifts slowly through the dark Arctic water. Its eyes look cloudy and damaged. A parasite clings to one eyeball. Then something unexpected happens—the shark’s eye moves, following a beam of light.
“That moment changed everything,” says Skowronska-Krawczyk, an associate professor who studies how eyes age.
For years, scientists believed Greenland sharks were mostly blind. They live in deep, icy waters with almost no light, and many have parasites attached to their eyes. Since these sharks can live for 250 to 400 years—the longest lifespan of any known vertebrate—researchers assumed their vision simply wore out over time.
But new research published in Nature Communications tells a very different story.
Skowronska-Krawczyk and her international team found that Greenland sharks maintain healthy vision for centuries.
Their retinas show no signs of age-related damage, even in sharks estimated to be hundreds of years old. The key appears to be an unusually strong DNA repair system that protects eye cells from breaking down over time.
The idea began after Skowronska-Krawczyk read a 2016 study showing how long these sharks live. One detail stood out: if sharks truly didn’t need vision, evolution would likely have removed the organ entirely.
Curious, she watched video after video of Greenland sharks and noticed their eyes subtly responding to light.
That observation led to hands-on research. Between 2020 and 2024, scientists collected Greenland sharks near Disko Island in Greenland using scientific long lines. The sharks’ eyes were carefully preserved and sent to Skowronska-Krawczyk’s lab for analysis.
For Emily Tom, a PhD student working on the project, the experience was unforgettable. She still remembers opening a package containing a preserved eyeball from a shark that may have been alive before the Industrial Revolution.
“It was huge—about the size of a baseball,” she recalls. “We usually work with mouse eyes, which are tiny. This felt unreal.”
Despite the challenges of working with such large and delicate tissue, the results were striking. The retinal cells were healthy. There were no signs of cell death. Even more surprising, a key vision protein called rhodopsin was still active and finely tuned to detect blue light—the kind that travels best in deep, dark water.
This means Greenland sharks aren’t just seeing a little. Their eyes are perfectly adapted to their extreme environment and remain functional for centuries.
The discovery could have major implications for human health. Age-related eye diseases like macular degeneration and glaucoma affect millions of people worldwide. Understanding how Greenland sharks protect their vision for hundreds of years may one day help scientists slow or prevent vision loss in humans.
For Skowronska-Krawczyk, the excitement goes beyond the lab results. It’s about discovery itself.
“We are seeing things no one has ever seen before,” she says. “And being able to share that joy with students—that’s the best part.”
In the dim Arctic depths, a slow-moving shark is quietly rewriting what we know about aging, vision, and what it really means to grow old.
