“The good news! This morning I found a dead GREENLAND SHARK washed up on a beach in Newlyn, Cornwall!” tweeted Zoological Society of London (ZSL) senior research fellow Professor Rosie Woodroffe earlier this week. “The bad news – after reporting it to [Cornwall Wildlife Trust] marine Strandings network, I returned with veterinary pathologist only to find the tide had washed it away!”
These were the words that launched a search party just a few days ago, as scientists and wildlife enthusiasts joined forces to try and track down a drifting lump of 100-year-old Greenland shark. The exciting news? The shark was found and successfully retrieved, representing a rare opportunity to learn more about one of Earth’s longest-living animals.
Are Greenland sharks rare?
Greenland sharks (Somniosus microcephalus) are listed as vulnerable by the IUCN Red List with a population that's believed to be decreasing. Add to that, that they live in some of the coldest, deepest, and most inaccessible waters to human beings and you start to understand why there has been so little opportunity to study these animals.
The only other Greenland shark retrieved in the UK was found back in 2013, prompting the Natural History Museum, London to carry out a rare post-mortem. This new specimen represents another opportunity to get a closer look at one of Earth's most mysterious and remarkable ocean giants.
How long do Greenland sharks live?
It’s estimated that these cold water giants could live as long as 400 years in the wild, making it the world’s longest-living vertebrate. Aging them is a little complex, however, as unlike most sharks they can't be aged using their vertebrae.
Sharks are cartilaginous fish, meaning they don't have ossified bones. In most sharks the vertebrae exhibit "growth rings" which can be used to age them, like a tree. This isn't the case for Greenland sharks.
Instead, scientists look at the layers in Greenland sharks’ eye lenses, which keep growing throughout their life. This tissue can also be used for radiocarbon dating, but we need a specimen to work from in order to find it out.
Why is this specimen so exciting?
Living at such extremes of depth and temperature means that Greenland sharks don’t often cross over with human habitats and so finding them washed ashore on beaches, especially as far out as Cornwall, UK, is quite rare indeed.
“This is only the second record of Greenland sharks to strand in the UK – the last one being in 2013,” said the Marine Strandings Network as they announced that this most recent specimen had been found again and was off to post-mortem. They described its discovery as “an extremely rare find and exciting for fisheries biologists.”
The discovery comes shortly after a Greenland shark was sighted in France, and a comparison of the tails photographed from both sightings appears to confirm that it was probably the same animal.
The shark’s time may have come to an end in the ocean, but its arrival into the hands of scientists means we can now piece together the details of its life and learn more about the elusive species as a whole.