Slow and Steady

Greenland Sharks (Somniosus microcephalus) are impressive beasts, often reaching lengths of 4 or 5 metres as they slowly cruise the cold, deep waters of the North Atlantic for prey. Indeed so sluggish are they that they’re also commonly known as “sleeper sharks”. But because of their habit of rarely coming up to the surface, very little was actually known about their lives beneath the waves, including how long those lives normally last.

Scientists at the University of Copenhagen had a theory that Greenland sharks are long-lived creatures due to their slow pace and the slower metabolism that their frigid environment would require for survival. However actually checking the age of a Greenland Shark is tricky, as they lack the bony structures in their ears that would normally be examined for accurate dating. Luckily the scientists hit upon the clever alternative of using radio-carbon dating to examine proteins found in the lenses of the eyes instead - and they were stunned by the results.

Examining a five metre-long female that was collected as “by-catch” during a scientific survey, the scientists discovered that their specimen was approximately 400 years old – easily the longest-living vertebrate ever recorded so far. The team also found that the sharks grow at just 1cm a year and don’t reach sexual maturity until approximately 150 years old – a fact that has serious implications for their conservation as they may still be recovering from being over-fished during WW2 when their livers were used for machine oil.

The find means that the female they examined would have been a pup during the reign of King James I, proving that if you want to live to a ripe old age, it’s best to take things nice and easy...