"Greenland sharks are a biological anomaly. The animals can grow to more than 20 feet long, weigh more than a ton and can live for nearly 400 years, making the species the longest-living vertebrate on the planeta fact that could help unlock secrets to enhancing longevity. And now, in a study published this week in Nature Communications, scientists dial in to one of the Greenland shark's more remarkable features: it has functioning eyes and, more remarkably, maintains its vision well into senescence."
"Biologists have long believed these sharks to be practically blind, in part because of their tendency to attract parasites that attack and lodge themselves inside the sharks' corneas. But this work challenges that belief, the researchers write, showing that even centuries-old Greenland sharks retain a visual system well-adapted for life in dim light. Evolutionarily speaking, you don't keep the organ that you don't need,"
Greenland sharks can grow beyond 20 feet, weigh over a ton, and live nearly 400 years, making them the longest-living vertebrates. Their eyes, previously thought nearly blind due to corneal parasites, are functional and adapted to dim-light conditions. Observations include eyeball movement toward light and preservation of retinal structure in specimens more than a century old. Samples from very old individuals show no obvious retinal degeneration, indicating maintained visual capacity into senescence. Persistent vision despite decades of life and parasite presence suggests visual function remains important throughout the species' lifespan.
Read at www.scientificamerican.com
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