Raft spider footage details behaviour never filmed before

Thursday 17th January 2013

Fen raft spider

Wildlife documentary film making student James Dunbar has produced a short film on the secret life of the raft spider.

Based at Suffolk Wildlife Trust’s Redgrave and Lopham Fen nature reserve last summer, James worked closely with spider expert and reintroduction project leader Dr Helen Smith to obtain the unique footage.

James explains:

"I made this film because I wanted to tell the story of the Fen’s raft spider, and hopefully show people a side of these creatures that they wouldn’t otherwise have seen. Many invertebrates have complex and wonderful behaviours that we very often overlook. Perhaps this is because they are small or, for some ridiculous reason, people are afraid of them.

Some of the behaviour shown in this movie has never been filmed before, namely the egg sac spinning sequence. I was able to do this thanks to the cooperation of Dr Helen Smith, manager of the raft spider conservation program, who allowed me to have access to her captive bred spiders."

Helen says:

"The fen raft spiders at Redgrave have been the focus of study for many years. The size, striking markings and unique life style of these magnificent animals, together with their struggle to recover from extreme rarity, continue to attract media interest and accompanying film crews. But most encounters between camera and spider are brief, often staged affairs, offering only tantalising glimpses of a remarkable life.

Last summer, James Dunbar, a student on Salford University’s Masters degree course in Wildlife Documentary Making, was able to change the way we see the spiders. Spending much of his summer with the spiders at the Fen, he captured many aspects of their breeding behaviour on film for the first time. The delicacy of the spiders’ courtship on the water surface, the nocturnal spinning of their fabulous silk egg sacs and eventual emergency of tiny, translucent spiderlings are all set against stunning footage of the passing summer days on the fen.

Behind the 15 minutes of James’ finished film lie an enormous amount of work and many hours of footage. Summer 2012 will be remembered as a testing one by everyone working outside – and not least by James. Deep water and perpetual deluges were added to the usual trials of the wildlife film maker; a long-awaited egg sac was spun on the night when his alarm failed, female spiders spurned amorous males, and this sit and wait hunter would sit and wait…… and wait. The spiders tested thoroughly the virtues of patience and perseverance so essential to this profession."

Submitted as part of his degree course, this unique and beautiful film gained James a well-deserved Distinction – but of course he was working with a very distinguished animal!

About Fen Raft Spiders:

•The fen raft spider (Dolomedes plantarius) is one of the UK’s rarest, largest and most spectacular spiders.
•The spiders can literally walk on water and hunt for prey both at the water surface and underwater. They feed on a wide range of wetland invertebrates and can also take small amphibians and fish.
•The adult females can lay in excess of 700 eggs into a beautiful silk sac which they carry in their mouths for at least three weeks until the tiny spiderlings emerge.
•Although they don’t spin webs to catch their prey, they care for their young in a large tent-like nursery webs built in vegetation above the water.
•The spiders usually take two years to mature: once adult, the females can produce two egg sacs during the summer but dies before winter.
•This species was first discovered in the UK at Redgrave & Lopham Fen National Nature Reserve at the source of the river Waveney, in East Anglia, in 1956. This relatively recent discovery almost certainly results from earlier confusion with the very similar but commoner raft spider species Dolomedes fimbriatus.
•Since 1956 it has been found at just two other sites – in East Sussex and in South Wales. This is a wetland species depending on a reliable, year-round supply of unpolluted water. It is usually found in fens and grazing marsh ditches. These habitats have declined in extent and quality and this almost certainly accounts for the spiders rarity and fragmented distribution. At Redgrave & Lopham Fen the spider population was reduced to very low levels by artesian abstraction which desiccated the site. Although the fen has now been restored, the spider population there remains very small and fragmented. A population has been reintroduced at Castle Marshes.
•The England Biodiversity Strategy commits a landscape scale approach to conservation so that “we will see an overall improvement in the status of our wildlife and will have prevented further human-induced extinctions of known threatened species” by 2020. The Strategy acknowledges that some species will need specifically tailored action and fen raft spiders (one of only two British spiders to be fully protected by law) are listed as “requiring special help if they are to recover and thrive again in England".