Raft Spider

The raft spider, Dolomedes fimbriatus, is a large semi-aquatic spider of the family Dolomedidae, one of only two Dolomedes species found in Europe, occurring across the northwest and center of the continent. Adults have dark brown bodies marked by a conspicuous white, cream, or yellow stripe along both sides of the abdomen and thorax, with females measuring 9 to 22 millimeters and males 9 to 15 millimeters, and young spiders often showing translucent greenish legs. It lives in freshwater wetlands such as wet heaths and acid swamps, with young spiders more often found in vegetation at the wetland edge, and hunts across the water surface with its front legs outstretched to feel prey through surface vibrations, taking water beetles, pond skaters, dragonfly larvae, and occasionally small vertebrates such as sticklebacks and frogs. When threatened by birds it can submerge fully and hide underwater for several minutes.