Fen Raft Spider

Pevensey Levels is by far the most important site in Britain for this rare and protected species. It was first located in the UK in a fen on the border of Norfolk and Suffolk where it is still barely hanging on. Since the Pevensey  population was discovered this large chocolate brown,white-striped spider has also been found in a fen in South Wales. As in the first site the spiders are just about surviving there. In contrast Dolomedes occurs over the whole of the Pevensey catchment including the Eastbourne Levels in good numbers. It is found in most of our ditches as long as they are not overgrown.

Even so it is a hard animal to find. It needs deep clean water next to short, sunny tussocky vegetation. This swamp-type environment is rich in prey species and provides the aquatic refuge the spiders need as they dive underwater to avoid predators. Dolomedes feed on almost any smaller creature. They take animals from tussocks and from the surface film but also pull swimming animals such as small fish out of the water. In the best ditch margin habitat numbers can be high. The easiest time to locate them is in mid-summer when the breeding females create a hazy fist of fine silk in a sunny spot above the water level. Early morning dew makes these “nursery-webs” stand out as luminous white objects that can be seen clearly from many metres away. Otherwise the best hope of finding one lies in sitting still, quietly watching a patch of sunny ditch-side vegetation. If any spiders have hidden at your noisy approach they will take up a position basking in the sunshine after several minutes and, with eagle-eyes, you will spot them.