Fishing for a compliment

After seeing this article on the European species that has been brought back from the brink of extinction, it got me thinking on some of the fishing spiders we have in the US.  There are about 100 species of Dolomedes (family Pisauridae) in the world and only about nine species in North America.

adult male fen raft spidercropWhile not actually a misnomer, they are often found far from water.  Come to find out, there is one species (D. albineus) that is arboreal!  I have gotten a few ID requests and most people confuse these with wolf spiders.  They are both large spiders and have a similar color pattern, so it’s understandable.  Like wolf spiders, they have decent eyesight and are “sit and wait” predators.  They don’t spin a big pretty web to snare their prey.  They will sit at the edge of a water source, half on and half off, and feel the vibrations of the water to cue them to their prey.  Due to their tarsi, hydrophobic hairs, and water surface tension, they can run on the water to chase after small fish, insects, and other invertebrates to feast on.  Once caught and suitably immobilized, they will drag their freshly caught dinner to a dry, stable spot and chow down like it’s Thanksgiving dinner.

Cool video here of a spider taking down quite a large piece of prey.  Though I always root for the predator, I will admit I feel just a little bit for the prey!

There is sporadic research on mating and reproduction.  Once mated, the female dolomedes4produces and egg sac and carries it with her until right before it hatches.  Then she builds a nursery web and hangs the sac in it like an ornament on a Christmas tree.  Once study (Kaston 1981) found 1400 eggs in a single egg sac.  Wow.  Once hatched, the new spiderlings will hang out in the web until after their first molt when they disperse like teenagers at a party when the cops are called.

While not brightly colored like jumping spiders or garden spiders, I still think these have a very pretty color pattern to them.  With whites or yellows or tans, they usually have some type of contrast to the mostly brown and grey body and legs.  Not too shabby, and bonus points for being watchful mums.  Share the entomological awesomeness!  Dolomedes_fimbriatus


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