Photo gallery: Elusive cave spiders found at Norwich Research Park

Spiders from the colony of cave spiders found living in a manhole at John Innes.Photo: Bill Smith (Image: Archant © 2013)

Mystery surrounds the circumstances behind the presence of the unusual spider, near Norwich, which has had less than 80 recordings across the country over the last 100 years.

Officials from the centre invited a spider expert to take a closer look after being discovered last month.

Pip Collyer, of Norwich, who is Norfolk Spider Recorder and secretary of the British Arachnological Society brought his spider catching equipment with him, including a beaker and plastic cup to identify the cave spider species, which usually lives in complete darkness.

A male and female adult spider were retrieved from the manhole and were taken to a laboratory at the John Innes Centre using a microscope to discover what species of cave spider they were.

Four egg sacks were also discovered after lifting the manhole cover.

Maintenance man Richard Bruce made the unusual discovery after making his monthly check of the manhole to check the centre's irrigation system levels.

'I thought they looked a bit odd and when I checked a month later there were six egg sacks and a lot of spiders in there. I am not a spider fan, so if I had dropped anything down there I would have left it,' he said.

Mr Collyer, whose interest in spiders began more than 30 years ago, was invited to the research centre after staff worked out that the colony was the rarely-seen cave spider. However, they did not know which species it was.

He added that it was good to get up close to the spiders, which usually lived in caves, culverts, sewers, and railway tunnels.

'They are probably more common than we realise because they live in places where we do not look.' 'It is one of the biggest spiders and it does not like the day light. I do not often come across them and it is nice to be asked to see this species. It is fascinating.'

'A lot of people think they are false widows, which are related to the black widow and can give a nasty nip,' he said.

Mr Collyer added that it was a mystery as to how the cave spiders got in the manhole because it was not connected to any tunnels or sewers.

Ian Bedford, head of entomology at the John Innes Centre, added that they were happy for the spiders to stay where they were.

'Whenever there is a strange bug, I usually get a call and I get a lot of enquiries from the public wanting to identify what they have found. However, we could not identify this species.'

'These are not a rare species, but it is very unusual to find them because they are photophobic,' he said.