Greenland Sharks

A new study on the lifespan of the Greenland shark has established that this fish may be the longest-lived vertebrate on Earth. While marine biologists have long suspected that this species of shark had a long lifespan — one individual, caught twice, with each catch more than a decade apart, had shown growth of less than a centimeter per year — researchers had no definitive way of dating individual specimens, as dating fish involves counting the layers in their bones. Sharks, on the other hand, have cartilage skeletons that don’t exhibit this layering, making dating them difficult.
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