New research shows long-lived sharks retain retinal function for decades, challenging assumptions about ageing in vertebrates.
Greenland shark at the floe edge of the Admiralty Inlet, Nunavut. (Credit: Hemming1952 / Wikimedia / CC BY-SA 4.0)
Sharks are often portrayed as ancient survivors, but new research suggests their longevity extends to another remarkable trait: the ability to maintain good vision well into old age. A recent scientific study has found that some long-lived shark species show little to no decline in retinal structure or function as they age, offering rare insight into how vision can be preserved over decades—or even centuries.
In most vertebrates, ageing is closely linked to deterioration of the retina. Photoreceptor cells degrade, neural connections weaken, and vision gradually declines. In humans, age-related retinal degeneration is common and often unavoidable. Sharks, however, appear to follow a different biological pathway.
Retinas that resist ageing
The new study examined the eyes of several shark species known for their long lifespans, analysing retinal tissue across a wide range of ages. Researchers found that key components of the retina—including photoreceptors and supporting cells—remain structurally intact even in very old individuals. There was little evidence of the cumulative damage typically associated with ageing nervous tissue.
Crucially, the study also showed that sharks continue to produce new retinal cells throughout their lives. This ongoing regeneration appears to offset cellular wear and tear, maintaining visual performance stability over time. Rather than slowing down with age, the shark retina remains biologically active.
An advantage in the deep
Maintaining vision is especially important for sharks, many of which rely on sight in dim or variable light conditions. Whether hunting at dawn and dusk, navigating deep water, or tracking prey across open ocean, visual acuity remains a key sensory asset.
The ability to preserve retinal health may help explain how some shark species remain effective predators and navigators for decades. Unlike many animals whose sensory decline limits survival in later life, sharks appear to avoid this constraint altogether.
Implications beyond sharks
The findings are attracting interest well beyond marine biology. Understanding how sharks prevent age-related retinal degeneration could inform research into human eye disease and ageing more broadly. The mechanisms involved—particularly lifelong cell renewal and resistance to oxidative stress—may offer clues relevant to conditions such as macular degeneration.
