Fishing Spiders in the genus Dolomedes are sometimes called Raft Spiders, Dock Spiders, and Wharf Spiders.There are over 100 species Worldwide and about 9 of them live in North America. These are large spiders, some females can reach impressive lengths with 3 1/4 inch leg spans. Their coloring is usually cryptic, and will be brown, reddish-brown, tan or grayish. These muted colors help them blend in with logs and vegetation on or near the water where they are frequently found. Almost always these spiders will be associated with water, there is one exception, there is a species that lives in trees in the Southwestern United States. They will sit with their front legs resting on the water, by doing this they are able to detect vibrations on the waters surface caused by potential prey. Some of the larger species within this genus are able to capture small fish, like minnows. They are covered in short velvety hairs, that are resistant to water, that enable them to basically walk on water, much like water striders do. They use the surface of the water, much like other spiders use their webs. The slightest movement can be detected by sensitive hairs on their legs. This alerts them to nearby prey. Typically they hunt at night, undercover of darkness. This gives them protection from predation from many species such as lizards, and birds which are sleeping.
The one pictured here was photographed this past summer at Happy Holler Lake in Savannah, MO while we were kayaking. It was in the middle of the lake on a stump protruding from the water. I was puzzled as to how it got there, and sent an inquiry to bugguide.net. Eric explained that they will stow away on watercraft and climb off onto logs and such in the water. Thankfully this huge girl didn't hitch a ride on my kayak, or I'm afraid I would have flipped the kayak in my frenzy to flee such a giant spider. Like all spiders they are hugely beneficial in the control of insect populations, and I'm pretty sure they are harmless to people, unless mishandled (for the life of me I can't imagine why you would want to handle one). I have to admit though, this was one of the prettiest and biggest spiders I've ever seen.. Next time you are at the lake or your local pond hunt around the edge of the water or sneak a peak at the logs along the shore, perhaps you will find one of these camouflaged beauties, laying in wait for unsuspecting victims to pass by.