With great age comes great respect, as the famous saying goes. If that’s the case, these ancient animals command a great deal of admiration! What’s the secret to long life, and is it really possible to live forever?
These super seniors really have got time on their side
The shark that lives for centuries
Like most things that dwell in the depths of the ocean, Greenland sharks have long been a mystery. Native to the icy waters of the northern Atlantic and Arctic, they favour the bathypelagic, or ‘midnight’, zone where no natural light penetrates and pressure levels reach 800 times that at the surface.
Greenland sharks aren’t ever going to be hot favourites to win a beauty contest. They can rival great whites in size, with larger specimens exceeding seven metres (23 feet), but they lack the streamlined body of their famous cousins. Their fins are stunted, their skin is mottled brown-grey and they often have parasites dangling from their eyeballs. But looks aren’t a concern for these fish – they’re playing the long game.
There’s been a suspicion that they are long-lived since the 1950s, when a lucky scientist caught the same individual twice and determined its
growth rate was less than a centimetre per year.
This theory was borne out by a paper published in 2016 that radiocarbon-dated crystals in their eyes. The largest and oldest shark examined was aged at 392 years old – give or take 120 years. Taking the uppermost end of that estimate range, this means the shark could have theoretically been born as long ago as 1504 – when Henry VII was king! This makes them the longest-lived vertebrates on Earth.
One explanation for their record-breaking longevity is their cold habitat, with low temperatures often associated with slow metabolism and development. It’s estimated these sharks don’t even reach sexual maturity until 150 years old! Another contributing factor may be their slow heart rates, which is about one beat per 12 seconds versus one beat per second in a resting human adult.