Dorota Skowronska-Krawczyk, an associate professor of physiology and biophysics at UC Irvine, has been studying the vision of Greenland sharks, which are known for their remarkable longevity. In a video she reviewed, Skowronska-Krawczyk observed a Greenland shark tracking light with its eye, despite common assumptions that these animals are functionally blind due to frequent parasites on their eyes and the dark environment they inhabit.
Her latest research, published in Nature Communications on January 5 and co-authored with Walter Salzburger and Lily G. Fogg from the University of Basel, Switzerland, suggests that Greenland sharks have a DNA repair mechanism that allows them to maintain healthy vision over centuries. The study found no signs of retinal degeneration in these sharks, some of which can live up to 400 years. The species is also well adapted to extremely low-light conditions.
Skowronska-Krawczyk became interested in this topic after reading a 2016 Science paper by John Fleng Steffensen that noted many Greenland sharks have parasites attached to their eyes. "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 said. "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."
Greenland shark specimens for this study were collected between 2020 and 2024 near Disko Island in Greenland using scientific long lines. The team included Steffensen from the University of Copenhagen as well as Peter G. Bushnell from Indiana University South Bend and Richard W. Brill from the Virginia Institute of Marine Science. These researchers dissected and preserved shark eyeballs for further analysis.
Emily Tom, a Ph.D. student at UC Irvine working in Skowronska-Krawczyk's lab, described receiving one such specimen: "I opened the package, and there was a giant, 200-year-old eyeball sitting on dry ice just staring back at me," she said. She explained how her work involved scaling up procedures usually performed on much smaller mouse eyeballs and conducting analyses that showed no evidence of cell death in the tissue.
Tom’s analysis revealed that rhodopsin—a protein crucial for seeing in dim light—remains active in Greenland shark retinas and is especially tuned to blue light detection. "Not a lot of people are working on sharks, especially shark vision," Tom said. "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."
Skowronska-Krawczyk believes these findings could help develop new strategies for preventing age-related vision loss or treating diseases such as macular degeneration and glaucoma by learning how tissues remain healthy over long periods.
She expressed concern about ongoing threats to federal research funding but remains optimistic about future discoveries: "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," she said. "Then, being able to share this joy with students – that's the best part of it."
