Dorota Skowronska-Krawczyk sits in her office, her gaze fixed on the computer monitor in front of her. On the screen, a Greenland shark glides slowly through the dark, clouded waters of the Arctic Ocean. She points to the image as it plays. “You can see the eye move,” says the UC Irvine associate professor of physiology and biophysics. “It’s tracking the light. That’s what’s so fascinating.” What looks like a sluggish, indifferent animal reveals a subtle awareness that immediately challenges long-standing assumptions.
The video shows the world’s longest-living vertebrate: a thick, grey shark with a heavy body, small head and blunt snout. Its eyes appear opaque and lifeless, further obscured by a parasite attached to one eyeball. For years, scientists believed Greenland sharks were functionally blind, citing both the frequent presence of these parasites and the extremely dim, murky environment in which the animals live. Vision, it was assumed, was not necessary. Yet the deliberate movement of the eye towards light tells a different story, hinting at an unexpected sensory resilience.
New research led by Skowronska-Krawczyk is now reshaping what scientists understand about ageing, vision and longevity. Co-authored with Walter Salzburger and Lily G. Fogg from the University of Basel, the study examines Greenland shark vision through an evolutionary lens. Published in Nature Communications on 5 January, the findings suggest that these sharks rely on a powerful DNA repair mechanism that allows them to preserve retinal health over centuries. Some Greenland sharks are estimated to live for as long as 400 years, yet their eyes show no signs of retinal degeneration and appear finely adapted to extreme low-light conditions.
Skowronska-Krawczyk traces her interest in the Greenland shark’s visual system to a 2016 paper by marine biologist John Fleng Steffensen. That study noted how commonly parasites attach themselves to the sharks’ eyes, raising an evolutionary puzzle. “You don’t keep an organ you don’t need,” she explains. After watching numerous videos, she noticed something others had missed: the sharks actively moved their eyeballs towards light. That observation prompted a deeper investigation and ultimately led to the current study.
The sharks used in the research were caught between 2020 and 2024 using scientific long lines near the University of Copenhagen’s Arctic Station on Disko Island, Greenland. Their eyeballs were dissected, preserved and sent for analysis to Skowronska-Krawczyk’s lab. Emily Tom, a PhD student and physician-scientist in training, remembers opening the package to find a massive, centuries-old eyeball resting on dry ice. Used to working with mouse eyes, she had to adapt quickly. Through careful histological analysis, Tom found no signs of cell death and confirmed that rhodopsin, a protein crucial for low-light vision, remained active. For Skowronska-Krawczyk, these findings offer promising insights into how vision might be preserved as humans age.
More information: Lily G. Fogg et al, The visual system of the longest-living vertebrate, the Greenland shark, Nature Communications. DOI: 10.1038/s41467-025-67429-6
Journal information: Nature Communications Provided by University of California – Irvine
