New research has upended long-held beliefs about the Greenland shark, one of the least understood species on the planet. Scientists have discovered that the sharks are not blind, as previously thought, and are questioning estimates that they can live up to 500 years.
The study, published in early January by researchers from five universities, found that the sharks' retinas are structurally pristine and capable of detecting light and contrast. This contradicts the common assumption that the cloudy eyes and parasitic copepods hanging from the cornea render them functionally blind.
Canadian marine ecologist Jena Edwards described the Greenland shark as an "absolute mystery," noting that even established knowledge is uncertain. The sharks, which can reach 20ft in length, have been found with remains of caribou, polar bear, and beluga in their stomachs, suggesting they are more active predators than their sluggish appearance suggests.
Nigel Hussey, a leading Greenland shark expert, observed the sharks diving vertically and using their fins for fine-tuned movements during a submersible trip off Svalbard, Norway. He questions the 2016 study that used carbon dating to estimate a lifespan of up to 500 years, arguing that the method has significant margins of error for such time frames.
Doctoral student Eric Ste Marie, who worked with Hussey, likened studying Greenland sharks to assembling a thousand-piece puzzle with only a handful of pieces. The findings highlight the challenges scientists face in understanding the species and predicting how climate change may affect them.
