Greenland sharks are among some of the longest-lived vertebrates on the planet, with lifespans ranging from 300 to 500 years. Scientists studying these sharks in their native waters of the North Atlantic Ocean have recently found a specimen who is estimated to be 512 years-old. By comparison, the oldest known Galapagos Tortoise, a species often referred to for their longevity, lived to be only 152 years old.
The Key To A Long Life
What makes these giants live such long lives? Part of their longevity is believed to come from their slow metabolisms. Larger animals, like whales and elephants, tend to have longer lifespans due to slower metabolisms. Smaller animals, such as parrots, also tend to live longer, leading us to conclude that size isn’t all that matters.
For Greenland sharks, their habitat has a significant effect on their metabolisms. The icy waters of the North Atlantic mean lower body temperatures and a need for more efficient energy use. As a result, their bodies age more slowly, extending their lifespans.
A side-effect of their long lifespans is their lengthy growth cycle. Greenland sharks don’t reach adulthood until they are 100 years old, which means that they cannot produce offspring until they have survived for at least a century.
The sharks grow 0.4 inches per year up to their full-grown length of 21 to 24 feet. As fully-matured adults, Greenland sharks weigh in at anywhere from 2,200 to 3,100 pounds. On average, scientists have observed these giants to be between 8 and 15 feet long and about 880 pounds.
A Bizarre Delicacy
One of the Greenland shark’s adaptations for survival makes their meat inedible without the right processing. Their bodies contain high concentrations of trimethylamine oxide and urea. The former is what makes it toxic, and the latter gives it an unpleasant, urine-like odor. When consumed in small amounts, trimethylamine oxide produces effects similar to extreme drunkenness. Dogs that have eaten unprocessed shark meat are unable to stand or walk until their bodies process the toxin.
As a precaution, when humans prepare the flesh, they often bury it in the ground for anywhere from six to eight weeks to press out the chemical before digging it up and hanging it to dry for several more months. Even then, the smell of urea persists, and that odor has given rise to many origin stories and legends in local folklore.
A Species Steeped In Legend
According to an Inuit creation story, a woman washed her hair in urine and dried it with a cloth that blew into the ocean to create Skalugsuak, the first Greenland shark. A different story from the same culture says that different sea creatures were created from the severed fingers of a drowned girl, one of which was Skalugsuak. The Igloolik Inuit believe Greenland shark flesh to be an aid to their shamans. In their cosmology, the Greenland shark lives in the urine pot of their goddess of the sea, Sedna, and that is why its flesh smells so strongly.
While its place in legend has been set for centuries, as it doubtless will for centuries, the Greenland shark’s mark in the history books is freshly made. Outlived only by immortal jellyfish, the ancient sharks continue to awe and intrigue marine biologists and geneticists alike as we search for the keys to human longevity.