Fishing spider

Find the spiderlings (6) including on the legs - Click to enlarge

Our neighbor Garin brought me this spider.  You know that you are a natural Naturalist when you find a large spider around the house and you capture it rather than squashing it.  Here is his description:

"I found the spider this morning on the front deck of the cabin. It seemed very lethargic when got close to it. I then noticed all of the tiny things crawling on it.  My first thought was that they were ants feasting on a dead wolf spider but quickly realized baby spiders were clinging to and crawling around it."

Spiderlings with a ballpoint pen

They originally were clinging to her but when I received them they had spread out all over the container.  They are tiny and cute, dare I say adorable, unless you happen to be an arachnophobe.  They were all ready to disperse into the wild, so after their baby pictures, I put the container upside down in the garden under the kitchen window.

Fishing spider now on land - note the "W" on the abdomen.

The mother is a fishing spider of the genus Dolomedes.  Its marking include what looks like an upside down guitar on the front of the thorax and a white 'W' mark on its back.  I had previously sent an identical one above to Bugguide last year where it was confirmed as Dolomedes scriptus, (scriptus - Latin for writing).

Dolomedes spider egg sac - Whatsthatbug

Fishing spiders (FS) are members of the family Pisauridae, the nursery web spiders.  They are named by their habit of weaving a silk nest to hold their eggs, then hauling it around in their jaws until the young are ready to emerge.  Unlike the wolf spiders who carry their young on their back,  FS babies are on their own after birth.  Garin's spider must have been hanging around as they dispersed.

Dolomedes live in aquatic and forested habitats, eating aquatic insects.  We frequently see them around our house 10 feet above Bull Creek.  They have a unique spider power that even Spiderman would envy, hunting under water.

"They hunt by waiting at the edge of a pool or stream, then when they detect the ripples from prey, they run across the surface to subdue it using their foremost legs, which are tipped with small claws; like other spiders they then inject venom with their hollow jaws to kill and digest the prey. They mainly eat insects, but some larger species are able to catch small fish. They can also climb beneath the water, when they become encased in a silvery film of air." 

Supported by surface tension, moved by pressure on dimples - Timmtap87

One of their secrets to walking on water is the cohesion of water molecules.  We explored this with the WOLF School this week at the H20 Olympics.  The water drops on a penny experiment this video, and others, described here are fun for all ages and might even make your grandchildren think you are cool.

Dolomedes have water repellent hairs on their on their feet, letting them walk across the cohesive water molecules on the surface, almost like it was Saran wrap.  They have the same hairs on their bodies which trap a film of air around them.  They can dive under water and this air brings them right back up.  More incredibly, "Dolomedes breathe with book lungs beneath their abdomens, and these open into the air film, allowing the spiders to breathe while submerged."  Wikipedia

Dolomedes are frequently confused with wolf spiders because of their size.  The arrangement of a spider's eyes helps identify them into families but requires magnification or a closeup photograph.    Bugguide shows the eye arrangement of this genus below so you can compare them with our specimen.

Dolomedes in Bugguide

Wolf Spider

February 2022 update



With the Bugguide eye chart above you too can identify spiders.  All it takes is getting on your hands and knees, a good camera or a high power magnifier, and a hypnosis session to get over your arachnophobia.