Fishing Spider – Dolomedes sp.

Fishing Spider – Dolomedes tenebrosus
Live spiders photographed at Ogle County, Illinois.
Family Pisauridae
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Fishing Spider - Dolomedes tenebrosus
Fishing spider on the rocks in Mud Creek near Oregon, Illinois has caught a water strider.

This large spider was hunting on rocks semi-submerged in a creek, and appeared to be at home qually on a solid or liquid surface. The prey did not stand a chance against the sudden burst of speed ambush this gal mounted. These tiny micro-dramas are going on, all the time, all around us. You don't have to go to Africa to see some of the most exciting hunters doing their thing!
Fishing Spider - Dolomedes tenebrosus
Size: 60mm (almost 2½ inches) from tips of back legs to tips of front legs.
The semi-aquatic fishing or "raft" spiders of Europe and North America are quite large. The females can reach a body length of 30mm (over 1 inch). They hunt on the surface of still or slow-moving fresh water. They row themselves across the surface much like pond skaters, supported by the surface tension, and can also sail across on the wind.

Pond Skater
Here is a picture of the water strider species this big spider is feeding on. Also called pond skater or Jesus bug. Fast as these guys are, they don't see well enough to detect the wait-and-pounce ambush the spider practices (below).
Fishing Spider
Although this species is alleged to be found far away from water, (usually in wooded settings) I find them readily only hunting in fresh water streams. They hibernate as immature adults under stones or tree bark or other similar hiding places.
D. tenebrosus matures in the spring and will subsequently mate and produce egg cases that are carried around by the females until ready to hatch. The young are guarded by the female in a nursery web and may number 1,000 or more in each brood. See: nursery web spider.

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