This video is called Dolomedes plantarius – the Fen raft spider.
From Wildlife Extra:
Britain’s rarest spider being bred in captivity for release
Help for Rare Spider
July 2012. A special collaboration between Sussex Wildlife Trust and Suffolk Wildlife Trust is helping to save one of Britain’s rarest spiders. The fen raft spider, one of the UK’s largest and most spectacular wetland spiders, is known to occur on only two sites in England.
To establish new populations in Suffolk, spiders from Sussex Wildlife Trust’s nature reserve at Pevensey Levels in East Sussex were used in a captive rearing programme and cross bred with fen raft spiders from Redgrave and Lopham Fen as part of a special translocation project.
Over 600 tiny spiderlings were nurtured by Project Leader, Dr Helen Smith, in special bottled nurseries before being released on to Suffolk Wildlife Trust’s Castle Marshes nature reserve in 2010. The spiderlings had to be reared in captivity for three months, in individual test tubes, to prevent them eating each other and fed on tiny fruit flies.
As the fen raft spider takes two years to mature, the first evidence of successful breeding has just been recorded this July with the appearance of spider nurseries – a large silk tent-like web with hundreds of spiderlings – on the north Suffolk reserve.
Pevensey Levels in East Sussex is an incredibly important site in the UK for the fen raft spider as the population is so large and successful.
Alice Parfitt, Sussex Wildlife Trust Reserves Officer at Pevensey Levels explains “Given the rarity of this extraordinary spider, and the strength of the population on our nature reserve in Sussex, it was a straightforward decision to support their introduction to Castle Marshes – we’re delighted to now hear they’re thriving.”
Fen raft spiderlings al ZSL London zoo: here.