Mild winters are thought to have led to an increase in false widow numbers
Two exotic species of spider have been discovered in caverns at a Sussex visitor attraction.
Colonies of a false black widow spider and an arachnid that has yet to be identified have been found at Smugglers Adventure, St Clements Caves, Hastings.
Both species are concentrated in an area known as the Monk's Walk - a long passageway carved through the rock.
Stuart Hine from the Natural History Museum said the Steatoda Grossa, false widow, posed no real threat to people.
Mr Hine, who runs the Insect Identification Service at the museum, thinks the other species may be a European cave spider Meta but has yet to confirm it.
'Reluctant to bite'
The Steatoda Grossa was first recorded in the UK in 1846. It is thought that recent mild winters have led to an increase in numbers along the south coast of England.
Trevor White, manager of Smugglers Adventure, said: "We'd been aware that there were spiders in the caves for a while now.
"To find out that we've actually got two completely different species of cave spiders here did come as a bit of a surprise but it would explain the large numbers of cobwebs we have to clean each week.
"Most visitors are fascinated to discover there are insects that spend their entire lives underground in virtual darkness and we're planning to add some information panels in the caves so people can find out more about them."
He added: "Apparently they're extremely reluctant to bite and, if they do, the effect is rather like a mild wasp sting."
St Clements Caves in Hastings were used as a military hospital by the Duke of Wellington's troops, acted as an air raid shelter during World War II and as a dance hall in the 1950s.