THOUSANDS of “creepy” giant spider crabs mysteriously swarmed a popular UK tourist hotspot overnight.

Commercial Daniel Gilbert, 37, was heading out on his boat when he was confronted with the astonishing sight.

Thousands of spider crabs on the seabed in Newquay Harbour.Thousands of crabs gathered at Newquay Harbour Credit: Jam Press/The Cornish Fisherman Two seals swim in green and light blue water.Local seals came to investigate Credit: Jam Press/The Cornish Fisherman

Daniel was left stunned after discovering hordes of giant spider crawling around .

Footage shows the huge crustaceans carpeting the harbour floor and clambering over each other, trying to scale the harbour wall.

The gathering of appeared to have arrived overnight, covering the shallows of the harbour.

In the video, Daniel tells viewers that “these are not stones”, but instead a “vast invasion” of spider crabs.

Spider crabs covering the sea floor of a harbor.Local fisherman Daniel Gilbert was surprised by the influx of crustaceans Credit: Jam Press/The Cornish Fisherman Thousands of spider crabs on the seabed in Newquay Harbour.He called the ‘invasion’ of the critters ‘creepy’ Credit: Jam Press/The Cornish Fisherman

Pictures show the harbour walls covered in limpets and barnacles, which the grey-blue crabs seemed to be using to climb up.

Daniel was also joined by local seals called Jimmy and Sandra.

They appeared intrigued by the influx of crabs and bobbed next to his boat.

The fisherman said the crabs were in the middle of their annual shedding process, during which they lose their hard outer shells and temporarily become incredibly soft.

Daniel Gilbert, a commercial fisherman, holding a large monkfish on his boat.Daniel has been a fisherman since he was young Credit: Jam Press/The Cornish Fisherman A seal swimming in clear green water.The seals bobbed next to his boat Credit: Jam Press/The Cornish Fisherman

He said: “The shedding process takes a month – they go like jelly. You can pick them up; they’re just like jelly.

“They look dead but they are alive. Honestly, it’s quite creepy.”

Daniel said the spectacle is an annual occurrence around July and August, and is something he has witnessed throughout his years as a fisherman.

He said: “I see it every year. I’ve been a fisherman since a young lad.”

Thousands of spider crabs covering the sea floor of a harbor.Daniel reassured viewers that these were not stones Credit: Jam Press/The Cornish Fisherman Daniel Gilbert, a fisherman, holds up a large flatfish.Daniel encouraged people to visit the harbour to see the sight for themselves Credit: Jam Press/The Cornish Fisherman

However, even though he is accustomed to seeing the crabs arrive, he was taken aback by the sheer scale of this year’s gathering.

Daniel said: “I was very surprised; I’d never seen so many at one time at the harbour.

“Honestly, I can’t get over how many there are. Imagine standing on all that. It would hurt, wouldn’t it?”

The fisherman also urged people visiting Newquay to head down and see the unusual sight for themselves.

He added: “You very rarely get to see this. It’s an amazing sight, to be honest.”