New insight into an ancient hunter
The Greenland shark, a colossal Arctic resident and the longest-living vertebrate known to science, is renowned for surviving in some of the planet’s darkest, coldest waters. But a new wave of research is challenging the long-held image of this slow-moving predator as nearly blind in the deep blackness. Scientists are uncovering evidence that the shark’s eyes can still detect light, even after centuries roaming the dim, plankton-free abysses of the North Atlantic.
How their eyes work in near-dark conditions
In the velvet darkness of Arctic waters, vision is a matter of life and death for many species. For the Greenland shark, the key may lie in specialized photoreceptor cells and adapted retinas that respond to faint light levels. Dorota Skowronska-Krawczyk, an associate professor at UC Irvine, explains the phenomenon: “You see it move its eye. The shark is tracking the light — it’s fascinating.” This ability to respond to light even in an environment with minimal illumination suggests a functional, if slow, sensory system that can guide cruising and hunting in the deep, shadowy realm.
What researchers are finding
Archaeic in age and scope, Greenland sharks spend their lives in cold, low-energy habitats where food is scarce and distances are vast. The new findings indicate that the shark’s visual system isn’t dormant but is tuned to detect bioluminescence and residual daylight that pours into the upper layers of the water column. The neurons responsible for light detection may be highly efficient at low-contrast scenes, allowing the shark to navigate toward potential prey or explore new territories without the need for rapid, high-intensity vision.
Beyond sight: a multi-sensory hunter
Vision is just one part of the Greenland shark’s toolkit. Behavioral observations and animal tracking data suggest the species relies on a combination of tactile sensing, olfaction, and perhaps electrical cues in the water. In the dim Arctic, a mixed-sensory approach can help the shark locate meals and avoid hazards as it moves stealthily through briny currents and foggy twilight zones.
Implications for science and conservation
The evolving picture of Greenland shark vision reshapes our understanding of deep-water ecology and vertebrate aging. If these sharks retain functional visual capability in extreme environments, it could influence how researchers study Arctic food webs, predator-prey dynamics, and the species’ surprisingly long lifespan—an incredible four centuries or more. Understanding their sensory biology also informs conservation strategies as climate change shifts light penetration, water temperature, and ecosystem structure in Arctic regions.
Why this matters to a broader audience
Historically, long-lived wildlife living in dark waters has been assumed to rely less on vision. The Greenland shark challenges that assumption, reminding us that life adapts in surprising ways across the animal kingdom. For divers, scientists, and policymakers, these revelations emphasize the importance of preserving the delicate balance of Arctic ecosystems, where even the most patient and enduring creatures rely on tiny signals of light to survive.
Bright futures for the Greenland shark’s research
As scientists continue to examine the retina and neural pathways of these ancient swimmers, new technologies—such as low-light imaging and deep-sea telemetry—will illuminate how Greenland sharks allocate their time, territories, and sensory attention. The ongoing work promises not only to decode how a centuries-old predator makes sense of its world but also to reveal broader truths about vision, aging, and survival in the planet’s coldest seas.
