One of Britain's rarest spiders has successfully bred at a north Suffolk nature reserve for the first time.

Suffolk Wildlife Trust has confirmed that fen raft spiders, which were introduced onto the Castle Marshes, near Lowestoft, in 2010, have created the next generation of eight legged animals.

The spiders, which take two years to mature and prey on small amphibians and fish, were reared in captivity for the first three months n their lives before being released on to the nature reserve two years ago.

On Friday the first fen raft spider nursery, a large silk tent-like web with hundreds of spiderlings, was discovered at Castle Marshes in vegetation by a ditch.

The baby spiders are being guarded by the mother and they are expected to leave web in about a week to begin they new lives as predators.

It means that Castle Marshes is now the third site in England to have a colony of the rare spider.

The other colonies are Suffolk Wildlife Trust's Redgrave and Lopham Fen nature reserve, near Diss, and Pevensey Levels in Sussex.

The Castle Marshes spiders came from the two sites as part of a breeding programme, which saw project leader Dr Helen Smith keep them in her kitchen for the first three months of their lives.

They lived in individual test tubes and were fed on fruit flies.

Describing the discovery of nursery web Dr Smith said: 'This is a really exciting day and a major milestone in our work to establish new populations of this beautiful but extremely rare spider.

'Although it's still early days for assessing whether the new population in Suffolk will thrive, this is the best possible indication that this is a suitable new home for the spiders.'

Longstanding volunteer George Batchelor who has been involved with the project from the beginning.

He said: 'The adult spiders that have now bred and produced young on Castle Marshes are the same little spiderlings that Helen nurtured in her kitchen two years ago.

'When we released these tiny little things from their test tubes, the weather turned very cold shortly afterward and I feared for their future.

'The survival and success of these raft spiders in the numbers we have seen, proves the habitat of our water soldier filled dykes is ideal. 'The female spider even chose a water soldier plant to hatch her young brood.

'We are so proud to have these spiders on the reserve and monitoring will now become a priority.'

The programme to establish new populations of fen raft spiders is part of Natural England's species recovery programme.

Suffolk and Sussex Wildlife Trusts, their nature reserves and their volunteers, are playing a major role, with funding from Natural England, the BBC Wildlife Fund and the Broads Authority.

Eleven of Britain's Zoos are also playing a vital role in the work, acting as foster parents for the tiny spiderlings.

A second introduction of the spiders is also underway to Suffolk Wildlife Trust's Carlton Marshes nature reserve and it is hoped that introductions will soon begin on an RSPB nature reserve.