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23 September 2016

The Greenland Shark - The Arctic's Ancient Leviathan

Image Source: National Geographic
The wildlife of the Arctic is endlessly fascinating, from the giant invertebrates roaming the ocean floor to the polar bears patrolling the ice fields. Despite being of the most hostile places in the world, it is staggeringly biologically rich, and mysterious. While we've studied some of the more well known creatures extensively, some remain enigmatic, to the point where every new discovery is a revelation.

Enter the Greenland shark, or rather, one specific female of the species, who was recently found to be about 400 years old. That makes the Greenland shark the oldest vertebrate on the planet, so far as we know. Previously, the record was held by another Arctic local, the bowhead whale, which has been recorded at 211 years old.

Greenland sharks are one of the most successful animals in the Arctic Ocean. It's an apex predator, largely preying largely on fish, but also scavenging carrion. They will often gather around fishing boats, and they've also been seen hunting seals and smaller varieties of shark.

Their ability to hunt such a broad range of prey comes in part from their size, as they can sometimes be more than 7 metres long and weigh 1,400kg, which is about as much as a Ford Focus. This means that they can overpower most of the animals they encounter out in the gloom. Their eyesight is poor at best, and at worst non-existent, as they often carry copepod parasites in their eyes, which consume the corneal tissue. Because of this, the sharks rely on smell and the special 6th sense for electrical signal which all sharks have.

For this reason, they live life in the slow lane, which goes some way to explaining why they live so long. Another factor is the fact that, even if predators like killer whales or even humans wanted to eat them, their flesh is toxic. The TMAO (trimethylamine) in their system, which basically acts as natural anti-freeze, can be fatal when consumed.

It's not just their approach to life that's slow, either, they grow at an average of less than 1cm a year, and don't reach sexual maturity until they're 150, which can't be much fun. The fact that they only live in the North Atlantic and Arctic oceans testifies to this lifestyle, you can't rush around in waters that cold, but nobody could have ever guess that there was something lurking in the depths which might have been alive at the same time as William Shakespeare.

Callum Davies

Callum is a film school graduate who is now making a name for himself as a journalist and content writer. His vices include flat whites and 90s hip-hop.