Experts are baffled after a mystery animal was spotted lurking in the Thames by a family out for a stroll.
Ryan Linehan filmed the enigmatic presence swimming near Old Windsor Lock, Berkshire, while walking with his parents.
His mother Bernie, 63, said: ‘We were just passing by and it was actually the lock keeper that said to keep an eye out for what he thought was a seal.
‘My son just caught it as it bobbed up, but that was the best shot we could get.’
In the footage, the creature’s black head can be seen dipping in and out of the water as it swims through the river.
Being a long way from the ocean, the family were sceptical about it being a seal.
Mr Linehan, 21, said: ‘It looked slightly furry in its appearance, and it had quite a flat nose.
‘I’d say in length, it was the size of a medium to large dog, maybe like a German Shepherd or Alsatian.’
The creature’s black head can be seen dipping in and out of the water as it swims through the river
The footage, uploaded to Facebook, has been viewed tens of thousands of times and sparked a huge debate
Looking for answers, the family turned to the internet, sharing the footage with members of a naturalist group on Facebook.
It soon racked up tens of thousands of views and sparked a huge debate.
‘Nessie, but she’s a bit lost’, wrote one joker.
Several others identified it as an ‘escaped’ capybara – the world’s largest rodent species which comes from South America.
Further suggestions included a sea lion, a turtle, and a coypu – another South America species.
‘It’s 110 per cent a seal,’ wrote one viewer. ‘Definitely a beaver,’ another person said.
Several people thought it might be an otter, but just as many refuted that too.
And even the experts disagree.
The mystery animal was spotted lurking in the Thames near Old Windsor Lock in Berkshire by a family out for a stroll
The animal has even baffled experts, with some arguing that it can’t be a seal or a beaver while others saying it could potentially be an otter
Some believe the creature could be a seal (left) while others said it might be a beaver (right)
There has also been speculation it could be an otter, although others said the species has a concave ‘dip’ at the end of the muzzle that’s not visible in the footage
First the family contacted somebody at a local wildlife trust.
Mrs Linehan said: ‘Her opinion – and she checked with colleagues – was that she thought it was an otter. She said a seal and a beaver wouldn’t come up that far, and they wouldn’t be able to negotiate the locks.’
Florin Feneru, identification and advisory officer with the Angela Marmont Centre at the Natural History Museum, said he couldn’t tell ‘with any confidence’.
He said: ‘I wish I could see its tail, that would have clearly settled the debate. However, I can’t see this as a seal at all.
‘Between beaver and otter, I lean towards beaver. Their upper line of the cranium is flatter, a bit convex even, like a bull terrier’s for example.
‘Otters have a stop – the concave dip at the base of the muzzle, like a beagle for example.’
Richard Bennett of the Canal and River Trust also couldn’t be 100 per cent sure. He said: ‘Not a seal, and more beaver than otter from the shape of the head – something about the way it moves too.’
