Scientific Name
Dolomedes tenebrosus
Common Name
No official English name; one of the “fishing spiders” in the genus Dolomedes.
Other Names
Dark Fishing Spider
Explanation of Names
- Author: Nicholas Marcellus Hentz. First year published: 1844, as Dolomedes tenebrosus.
- Pronunciation: Doh-low-MEE-deez tenna-BRO-suss.
- Meaning: Dolomedes apparently means “wily” or “contriving” in Greek; the species name tenebrosus translates to “dark, gloomy” in Latin.
Appearance
- Size: Body length of mature female 15-26 mm; male 7-13 mm.
- Color: Overall a mottled brown or gray with black markings. Rear end of abdomen has multiple black ‘W-shaped’ stripes. One color morph has a white band around the entire outside of the body (not to be confused with adult males of other species of Dolomedes). Legs banded in brown, black, and gray.
- Eyes: Eye arrangement typical for nursery web spiders in the family Pisauridae. Total of eight eyes.
- Legs: Legs quite long, very long in males in proportion to body size. Long, black spines are visible when closely examined. Mature individuals are very large, “sprawling” spiders.
- Body: Cephalothorax and abdomen of about equal size. Robust spiders. Abdomen rounded in the front, widest in the middle, and tapered towards the rear.
Range
Found in the eastern U.S. and adjacent southeastern Canada (southern Manitoba to Nova Scotia, south to Texas and Florida).
Habitat
This is a spider of deciduous forests. Despite the moniker of “fishing spider,” this particular species is frequently found far from water. Look for the spiders waiting motionless in ambush on tree trunks, fenceposts, walls, and other vertical surfaces, mostly at night. The spiders dash into tree holes, under bark, and into crevices when startled.
Web
This is a powerful hunting spider that does not spin a prey-catching snare. Females will, however, construct a tangled “nursery web” among foliage where they will suspend their egg sac and guard the emerging spiderlings.
Season
These spiders mature in late spring, and reproduce in mid-summer. Nearly adult spiders overwinter in protected places, such as under rocks or loose bark.
Food
Prey is composed of large insects and even small vertebrates that the spider can overpower. This includes small fish (e.g. minnows) and various aquatic insects when this spider hangs out near bodies of water.
Life Cycle
The egg sac is a grayish sphere, approximately 15mm in diameter, held in the jaws of the female as she wanders. Eventually the spider suspends her egg sac in a tangled “nursery web” amid foliage well off the ground. There she stands guard over the package and the spiderlings that later emerge from it. The spiderlings will remain in the nursery web until their next molt, at which time they disperse.
Remarks
The fishing spiders are frequently mistaken for wolf spiders, but the arrangement of the eyes is graphically different between the two families; and fishing spiders are more likely to be seen in the vertical plane (whereas wolf spiders, while they can climb, are mostly seen in the horizontal plane on the ground, stones, and logs).
