Friday, July 8, 2016

Fishing spider

Fishing spider on land - REK
Our team of young naturalists* found this fishing spider walking on the surface of the creek.  We commonly see lots of dainty water striders skittering across the water but a large body like this on the surface is really impressive.
Fishing spider now on land - note the "W: on the abdomen.
The arrangement of a spider's eyes helps identify them into families but requires magnification or a closeup photograph.  Luke helped me identify it as a fishing spider of the genus DolomedesBugguide shows the eye arrangement of this genus below so you can compare them with our specimen.
Dolomedes in Bugguide

Ventral view - click to enlarge
We settled on D. scriptus (scriptus - Latin for writing) by comparing the white 'W' mark on its back and sent it into Bugguide where it was confirmed.  These Dolomedes live in aquatic and forested habitats, eating aquatic insects and an occasional small fish.

Supported by surface tension, moved by pressure on dimples - Timmtap87
Now back to the incredible walking on water.  Both the water strider and the fishing spider depend upon the surface tension of water to keep from submerging.  They both have a waxy substance on their feet that repels water further.  The dimples in the water from their weight are pushed backward when they stride, allowing them to move forward as described in Scientific American.

* Naturalist team - Taylor, Allie, Kate and Luke.

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