Bushy Park, famed for its deer, can now add a large crab to its list of wildlife after a dog walker was "surprised" to see the invasive species casually walking around on land.

The Chinese mitten crab originates in South East Asia with the first recording in the UK of the crafty crustacean dating back as early as 1935 in the River Thames. 

It wasn't until 1990 when the multi-legged critter became established before spreading into other river catchment areas – and their numbers are being tracked.

Andy Litchfield, who recorded the sidewalker near the Leg of Lamb pond in the ancient royal park next to Hampton Court Palace, has seen them a few times in the past "but never on land". 

He said: "I was walking my labrador in Bushy Park on Friday morning (October 6) when he stopped to sniff something on the ground, and I was surprised to see that it was a crab.

"I recognised it as a mitten crab as I've caught a few of them in the Thames when I've been fishing, but I've never seen one out on dry land before."

In the video the crab adopts a defensive position raising its claws in the air as a warning when the camera gets too close.

According to Natural History, the crabs are distinguishable by their "furry" claws and they damage riverbanks and compete with native species.

The Natural History Museum is asking people to make a note of when and where people spot mitten crabs and to submit the details, together with a photograph to [email protected].

There have been 800 recorded sightings of invasive animals so far with its range extending across the UK.