Wednesday, June 2, 2010
Six-Spotted Fishing Spider
This gorgeous spider is the Six-Spotted Fishing Spider Dolomedes triton and they are pretty common in Missouri and throughout most of their range. They are easy to identify from from their greenish-brown bodies and white stripes on their cephalothorax, and twelve white spots on their abdomen. It is the six black spots on their underside that gives them their common name. They can get pretty large with a body measurement up to one inch and a legspan twice that large.
They will be found along the shoreline of shallow, calm waters, like Ponds, Lakes, Marshes and Slow-Moving Streams. They will walk on the aquatic plants hunting for insects to eat. Thee spiders are unique in being one of the few creatures able to walk on water. They can also dive underneath the water, row across the surface, and glide. They can walk down aquatic plants beneath the surface of the water and can remain under water for up to 30 minutes by trapping an air bubble between it's legs that it will use to breath oxygen. They glide by remaining perfectly still on the surface of the water and letting the wind blow them wherever it wants to. They walk on water with specially adapted hairs on their legs. Rowing is done by using some of their legs as oars to motivate them across the surface of the water.
Fishing spiders can escape predators in a number of ways, by jumping straight in the air, or running rapidly across the water or diving below the surface. Even on land they are quite quick and able to run away from danger. They will always be found near a lot of plants whether in the water or on the shore. This allows them to hide from predators.
These spiders are excellent hunters and have a lot of choices available to them. They can feed on aquatic insects, terrestrial insects, but more often than not they will feed on insects that happen to fall into the water and cannot escape again. Larger fishing spiders will even attack young newts, small frogs, tadpoles and minnows.
Female fishing spiders are larger than the males and females will not hesitate to kill and eat a male fishing spider. If a male approaches a female that has already mated she will most likely eat him. The male seriously lives life on the edge. Females lay their eggs inside a silken sac that she will carry to the shore and hide among the plants. She will remain near the egg sac and guard it until the eggs hatch. She will even remain with the spiderlings until they are ready to disperse. The spiderlings will over winter two times before they are old enough to mate.
Even though these spiders are apex hunters they still have to be ever vigilant of predators such as frogs, fish and birds. Excellent eyesight gives them an added advantage when avoiding predation.
These spiders are active during the day and are easily seen as they rest on the aquatic plants floating on top the waters surfaces. I've seen a dozen or more of these spiders already this year.