Greenland shark's 400-year-old eyes defy aging in the Arctic depths

Deep in the Arctic and North Atlantic, the Greenland shark thrives where few creatures survive. This slow-moving giant holds the record as the world's longest-living vertebrate, with some individuals exceeding 400 years. Now, new research reveals how its remarkable vision defies the usual effects of aging—even in total darkness.

Scientists have long wondered how the Greenland shark navigates the freezing, lightless depths. A study published in Nature Communications uncovers adaptations that keep its eyes functional for centuries. Unlike most animals, its retina shows no signs of decay, thanks to a unique DNA repair system that prevents cellular damage over time.

The shark's eyes are packed with elongated rods, specialised to capture the faintest traces of light. These rods contain rhodopsin, a pigment finely tuned to detect the blue wavelengths that penetrate the deep ocean. Even more unusual, the retina holds 41% DHA—a rare fat acting as molecular antifreeze. This keeps cell membranes flexible despite the near-freezing temperatures.

Perhaps most surprising, the shark's vision remains sharp even with parasites like Ommatokoita elongata clinging to its cornea. Researchers found no evidence that these hitchhikers impair sight, raising questions about how the species maintains clarity in such harsh conditions.

The Greenland shark's ability to see without retinal decay challenges long-held ideas about biological aging. Its adaptations—from antifreeze fats to light-sensitive rods—show how life can thrive in extreme environments. The findings may also offer clues for medical research into age-related vision loss in humans.