Great Raft Spiders
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Scientific name: Dolomedes plantarius
Size: Body and head up to 23mm
Distribution: Found in only a few locations in the UK; Redgrave and Lopham Fen in Suffolk, Pevensey Marshes in Sussex, Crymlyn Bog, and on the Tennant Canal next to Pant y Sais Fen near Swansea
Months seen: March to October
Habitat: Swampy areas with pools of water, fens, ditches and canals
Food: Invertebrates, tadpoles and small fish
Special features: Great Raft Spiders (Dolomedes plantarius), also known as Fen Raft Spiders, have a brown or black coloured body, usually with a distinctive cream coloured stripe running along both sides of the body, although this is not always present.
They are a semi-aquatic species, hunting for their food on the surface of water. They wait on vegetation at the edge of the water with their front legs resting on the surface of the water. When they detect vibrations, on or in the water, they grab whatever is there. This is why they are sometimes called 'Fishing Spiders'.
Because of their rarity Great Raft Spiders are a protected species.