Greenland shark study may lead to new ways to preserve vision as we age

by Cynthia Rebolledo, UC Irvine
Irvine CA (SPX) Jan 06, 2026

Dorota Skowronska-Krawczyk sits in her office, eyes fixed on the computer monitor in front of her. "You see it move its eye," says the UC Irvine associate professor of physiology and biophysics, pointing to an image of a Greenland shark slowly drifting through the murky Arctic Ocean. "The shark is tracking the light - it's fascinating."

The video shows the longest-living vertebrate in the world - long, thick, grey body; small head; and short, rounded snout - with opaque eyes that appear lifeless, except for the parasite latched to one of its eyeballs. Scientists have long suspected the large species to be functionally blind, given the frequent presence of the parasite and its exceptionally dim and obstructed visual environment.

Now, new research from Skowronska-Krawczyk on Greenland shark vision - co-authored by University of Basel, Switzerland researchers Walter Salzburger and Lily G. Fogg, who worked on the evolutionary aspect of the study - is challenging what we know about aging, vision and longevity.

Published Jan. 5 in Nature Communications, her findings suggest that a DNA repair mechanism enables these sharks - some of which live for 400 years - to maintain their vision over centuries with no signs of retinal degeneration and that they are well adapted to extreme low-light conditions.

Skowronska-Krawczyk, who gleans insights into the molecular mechanisms of aging by studying processes that control age-related eye diseases, attributes her interest in the visual system of the Greenland shark to a 2016 research paper by John Fleng Steffensen published in the journal Science.

"One of my takeaway conclusions from the Science paper was that many Greenland sharks have parasites attached to their eyes - which could impair their vision," she says. "Evolutionarily speaking, you don't keep the organ that you don't need. After watching many videos, I realized this animal is moving its eyeball toward the light."

This left Skowronska-Krawczyk wanting to learn more.

The Greenland sharks used in her co-study were caught between 2020 and 2024 using scientific long lines off the coast of the University of Copenhagen's Arctic Station on Disko Island, Greenland. Steffensen, professor of marine biology at the University of Copenhagen, and colleagues Peter G. Bushnell, who teaches at Indiana University South Bend, and Richard W. Brill, who's based at the Virginia Institute of Marine Science, dissected and preserved the eyeballs in a fixative solution for examination.

Emily Tom, a UC Irvine Ph.D. student and physician-scientist in training who works in Skowronska-Krawczyk's lab, recalls receiving the box that held a fixed eyeball.

"I opened the package, and there was a giant, 200-year-old eyeball sitting on dry ice just staring back at me," the 28-year-old says with a laugh. "We're used to working with mouse eyeballs, which are the size of a papaya seed, so we had to figure out how to scale up to a baseball-sized eyeball. Luckily, Dorota is very hands-on, both in her mentoring style and in the lab - which you don't see a lot of with professors."

Tom then let the eyeball defrost. "The lab smelled like a fish market," she says.

She emphasizes that it was a careful balance of not letting it thaw too much because once tissue samples reach room temperature, they begin to degrade. Her role involved histological and vision-specific analyses of the eyeball, finding no signs of cell death, and revealing that rhodopsin (a protein essential for vision in dim light) in the shark retinas remains active and is tuned to detect blue light.

"Not a lot of people are working on sharks, especially shark vision," Tom says. "We can learn so much about vision and longevity from long-lived species like the Greenland shark, so having the funds to do research like this is very important."

For Skowronska-Krawczyk, the findings open the door to discovering new approaches to avoiding age-related vision loss and eradicating eye diseases such as macular degeneration and glaucoma - and to more questions about how vision evolves, the mechanisms that help keep tissues alive and healthy for many years, and how to apply this knowledge to humans.

She notes that with federal research funding under threat, future support for her studies is a concern, but she believes that "we will prevail."

"What I love about my work is that we are the first in the world to see results - at the forefront, finding new mechanisms, rules and discoveries," Skowronska-Krawczyk says, looking over at the paused shark on the screen. "Then, being able to share this joy with students - that's the best part of it."

Research Report: The visual system of the longest-living vertebrate, the Greenland shark