A population of rare orb weaver spiders was discovered in tombs at the famous Highgate Cemetery in London.

As many as 100 spiders, belonging to the Meta bourneti species, were discovered at the site. They measure over 30mm in diameter with leg-span included. This is the first time that a Meta bourneti species has been recorded in London.

The discovery was made by staff at London Wildlife Trust while they were working with the staff and local community of Highgate Cemetery.

"The discovery of this important spider population in the heart of London shows just how valuable cemeteries such as Highgate can be in providing refuges for wildlife," Tony Canning, the project lead and London Wildlife Trust Community Outreach Officer for Camden, said in a press statement.

Meta bourneti is the rarer of the two species of Britain's largest orb weavers. These spiders prey on small insects and woodlice. They are a cave-dwelling species and hence, require total darkness. The outdoor nighttime environment is too bright, so these spiders never leave the tombs.

The tombs date from the late 1830s and it is possible that the spiders could have lived in the structures for about 150 years without being detected, said officials at the London Wildlife Trust.

Meta bourneti can also be found in cellars and abandoned railway tunnels. They need constant temperatures and high levels of humidity for their survival. The females of Meta spiders produce teardrop-shaped eggsacs that are suspended on a silk thread from the roof of their dwelling. Unlike the adult spiders, the spiderlings get attracted to light as they first emerge. This helps them search for new areas to colonize.