This shark lives for centuries. Scientists discover how it resists aging.

There are Greenland sharks older than the United States.

This deep sea species has an expected lifespan of at least 270 years. Some may live longer than 500 years. And biologists have identified an important reason for their impressive longevity. The sharks, an Arctic species dwelling thousands of feet underwater, do not age like other animals: Their metabolisms should slow as they grow older, resulting in cellular changes. But the researchers' analysis of differently aged Greenlands sharks show their metabolisms don't diminish.