Fish & Water - Sounds Wild
Old Sharks

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Greenland Shark - the oldest animal

A giant grey fish swims slowly in the dark, cold Arctic waters. It's a Greenland shark, 20 feet long and weighing close to a ton. Greenland sharks are closely related to sleeper sharks, found in Alaska waters. A recent study of 28 female Greenland sharks found that Greenland sharks are the oldest animals on Earth - some were at least 272 years old. The largest shark in the study, a 16-foot long female, was likely close to 400 years old.

The scientists used material from the lens of the sharks' eyes to age the animals. Tis kind of Radiocarbon dating also provides an added bonus - nuclear testing in the early 1960s created a signature pulse of carbon 14 that is incorporated into the eye during development, and that enables scientists to identify that specific time period. Scientists who age fish like halibut and rockfish by looking at their otoliths, or ear bones, also use the radiocarbon bomb pulse as a time marker.

Greenland sharks are large and slow-growing. They live in waters that are just above freezing. Their tissues are cold, and so are the chemical reactions that occur in their bodies - including all the metabolic processes that turn food into fuel and run their large bodies. Big animals have slower metabolisms than small creatures; and if the metabolic rate is slowed, everything in the body is slowed - including the process of aging. Researchers found that the age of sexual maturity is also remarkable. Greenland sharks become sexually mature when they are about 150 years old.