A large venomous spider could be on the loose in Bristol.

Mum-of-three Heather Underwood found what appeared to be the body of a tarantula as she was walking along Williams Close, Longwell Green, with her sons Louis, aged seven, Ben, four and three-year-old Jake.

But the bad news for arachnophobes in the area is that her discovery was not a dead body but merely the shed skin of a spider that could still be very much alive.

An expert has told the Bristol Evening Post the skin is of an Indian ornamental tarantula, which would be capable of surviving during the current warm weather with a plentiful supply of prey.

First Great Western train manager Mrs Underwood found the skin as the family were on their way to do a nature trail but what they found against a wall in the road was certainly more exciting than the butterflies and other insects they had set out to spot.

"I was completely shocked at first," said Heather, 41, who lives in Williams Close. "We had been hoping to spot some butterflies and we found a tarantula. Well, we didn't expect that at all!

"My boys were absolutely fascinated by it. It was so exciting!"

Heather did not initially know whether what she had found was a dead spider or a shed skin.

She picked it up, put it inside an egg carton and placed it in her fridge.

Heather said that if it had been picked up by a bird and dropped, it would not have been propped against a wall, so she thinks it may have been from an escaped family pet. The skin could also have been shed elsewhere and deliberately placed in the street for a prank.

Heather said: "We were completely baffled. Its body is bigger than a two-pence piece, it's really hairy and its legs seem to go on for ever, although I would guess that they're about two-inches long, which is big enough.

"I've shown the spider to my neighbour. She thought I was going to give her a box of eggs, but was a bit panicked when she realised what was inside. She couldn't believe that we had found it in Longwell Green – that kind of thing doesn't normally happen around here."

Mark Pennell of The British Tarantula Society, who lives in Shirehampton, confirmed that the object was the shed skin of an Indian ornamental tarantula.

Most tarantulas ambush and eat insects and other bugs but bigger examples can eat lizards, mice and even small birds.

Mr Pennell said: "The way the abdomen is crinkled up suggests this is an empty skeleton and the spider is still alive and probably thriving in this weather.

"It could quite easily be living in someone's roof space and surviving quite happily.

"It can give an incredibly painful bite with its fangs, but it has never been known to cause a fatality."

"The spider is long gone. It looks like an incredibly old skin.

"In this weather, if that spider was out and about it would survive for quite a while. In my opinion it could survive until August but it certainly couldn't last a British winter."