This spider is the one that may startle you a bit when you examine a ditch or pond by its sudden appearance and by It�s racing on eight legs towards a safe place. I see them often on dried up banks of ponds and ditches and other moist places in meadows or trenches. This is not a water spider, but a member of the family of wolf spiders (Lycopidae, from Lycos = wolf). Though his family does make funnel shaped living web, this is not a catching web, but they hunt actively for their prey. Once one thought they did this in groups, hence the name wolf spiders. Many spiders of this family, and especially Pirata, like to hunt near or on the water. This spider walks quick and easy over the surface by means of water-repellent hairs on its legs, though it is quicker on duckweed and other floating leafs. It may even go under water, and with air caught between the hairs on the abdomen, may stay there for hours like the true water spider. The female spins a sturdy cocoon for her eggs and carries this with her, attached to her behind.
More information and many nice pictures at the spider site of Ed Nieuwenhuys.

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Pirata female with egg-cocoon
(also two Helophorus beetles)

Same spider, flown under water