The Fen Raft Spider

Nature, Series 9 Episode 4 of 4

Fen Raft Spiders as their name implies are water-loving spiders. They are also large and distinctive looking spiders with white, cream or yellow stripes along the sides of both the carapace and abdomen which contrast with their dark body. They were first discovered in the mid-1950s in Redgrave and Lopham Fen in Suffolk which today is one of the sites where Helen Smith, leader of the Fen Raft Spider Recovery Programme has been introducing these spiders after their populations declined as a result of degradation and loss of lowland aquatic habitat. The spiders are also found at on the Pevensey Levels in East Sussex and Crymlyn Bog near Swansea in South Wales. For this programme, Helen, who has a license to handle these spiders, very kindly agreed to collect a male and female Fen Raft Spider and bring them indoors in a tank so that wildlife sound recordist Chris Watson could not only get a really close look at these spiders, but also try and record their courtship behaviour. This is a complex and elaborate affair, which includes the males vibrating his front legs in arcs on the water surface. After mating, the female lays her eggs in an egg sac and spins a nursery web in which to protect them. The webs are usually spun on vegetation above the water's surface, but Helen also had one in tank so Chris was able to examine the tiny spiderlings which had hatched from the egg case. Back out on the fens, Chris also lowered a couple of underwater microphones (hydrophones) into a ditch and captured the extraordinary world of sound in which these creatures live as diving beetles, backswimmers and water boatman communicated to one another below the water surface. Producer Sarah Blunt.

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28 minutes

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Thu 25 May 2017 23:30