Greenland Sharks Can Survive for Centuries—and Maintain Long-Lasting Vision, Despite Living in the Dark

The long-living sharks aren’t as blind as once thought and have DNA repair mechanisms that may help prevent their vision from degrading, a study suggests

Sara Hashemi | Daily Correspondent

January 16, 2026

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Greenland sharks—the longest-living vertebrates in the world—dwell in the deep, frigid waters of the Arctic and North Atlantic for up to roughly 400 years. Scientists have long suspected that the creatures were basically blind due to pesky eye parasites and spending their lengthy lives in such a dimly lit place.

New research has found, however, that the animals seem to have surprisingly good vision and DNA repair mechanisms to maintain it throughout their lifetimes. The findings, published on January 5 in the journal Nature Communications, not only shed light on a long-lasting visual system but could also lead to ways to prevent human sight problems, such as macular degeneration.

Evolutionary biologist Lily Fogg says that the study came about after John Fleng Steffensen, a marine biologist at the University of Copenhagen who recently died, offered her and her colleagues some specimens from his other work. Steffensen previously helped discover the creatures’ centuries-long life span via eye samples.

“He said, ‘I’ve got these eyes; would you like to do a study on them?’” Fogg, of the University of Basel in Switzerland, tells Mongabay’s Bobby Bascomb. “And we said, ‘Why not? That’s a great opportunity.’ If they’re going in the bin, then that would just be a waste.”

The eyeballs were then sent out to the researchers. “I opened the package, and there was a giant, 200-year-old eyeball sitting on dry ice just staring back at me,” recalls study co-author Emily Tom, a physiologist at the University of California, Irvine, in a statement.

Overall, the research team examined eyeballs from ten Greenland sharks that were caught off the coast of western Greenland between 2020 and 2024 and ranged in age from about 100 to 134 years old. An analysis revealed no signs of degeneration in the light-sensitive parts of the old organs, and the sharks’ eye parasites didn’t seem to interfere with the animals’ vision.

Additionally, most vertebrates have two types of light-sensitive eye cells: cones, which differentiate color and work well in bright light, and rods, which don’t detect colors but work well in dim light. But the Greenland sharks had only rod cells, which means they see in black and white, the team found.

“[As a Greenland shark] you don’t have high resolution,” study co-author Dorota Skowronska-Krawczyk, a physiologist at the University of California, Irvine, tells the Australian Broadcasting Corporation’s Peter de Kruijff. “You see light and darkness, but you really don’t see the shapes very well, or you cannot distinguish probably fast movements.”

What’s more, a close look at genetic material from some of the eyeballs hinted that the secret to the sharks’ long-lasting vision might be the genes ERCC1 and ERCC4. They code for proteins that help repair DNA and seem to be important for maintaining eyesight. Only shark species with the longest lives have the ERCC1 gene, the team found, and Greenland sharks had an elevated amount of ERCC4 likely being made into proteins compared with other sharks.

“The high expression of DNA repair genes suggests a powerful molecular mechanism that helps maintain retinal health over centuries—a cool finding,” Laura Ryan, a comparative neurobiologist at Macquarie University in Australia who was not involved in the research, tells the Australian Broadcasting Corporation.

The researchers suspect their work could pave the way for future work relevant to human health, such as how to avoid age-related vision loss and eye diseases like macular degeneration and glaucoma.  

“We can learn so much about vision and longevity from long-lived species like the Greenland shark,” Tom says in the statement.

Sara Hashemi | Read More

Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.