striped fishing spider

not listed

NNR - Unranked

not listed

Striped fishing spider is a large, robust, nursery web spider. It occurs in the United States and southern Canada east of the Rocky Mountains, but it is mostly absent from the Gulf Coast region. It is found on bodies of water, including slow streams, ponds, lakes, and swamps; and near water, including on stream banks, bridges, and boat docks, and under rocks.

Adult females are 11⁄16″ to 15⁄16″ (17.5 to 24.0 mm) in length and have a 23⁄16″ to 3⅛″ (55 to 80 mm) legspan.

The front part of the body (cephalothorax) is longer than wide and is flattened. The upper side (carapace) is dark brown with dark margins and a very wide white or pale band near each lateral margin (submarginal). The submarginal bands are sometimes indistinct, sometimes represented as a series of pale spots. A furrow (cervical groove) extends forward and toward each side from about the center of the carapace. It defines the boundary between the head and the thorax. Another furrow or sometimes just a pigmented line (dorsal groove or fovea) extends in the middle from behind the cervical groove toward the rear of the carapace. In front of the dorsal groove there is a pair of small, dark, wedge-shaped marks. Slender dark lines radiate from the dorsal groove area.

There are eight eyes arranged in two parallel rows of four eyes each. All of the eyes are about the same size. They have a light-reflecting layer (tapetum) that shines green at night. The back (posterior) row is strongly curved backward, the front (anterior) row is nearly straight to slightly curved backward. The posterior middle (median) eyes (PME) and the outer (lateral) eyes (PLE) are larger than the four anterior eyes. The median ocular area (MOA), the area defined by the middle four eyes, is wider than long and narrower in front than behind.

The mouthparts (chelicerae), corresponding to the jaws, are large, powerful, and reddish-brown, with a pale longitudinal band in the middle. Each fang rests in a furrow between two ridges (margins). The inner, rearward-facing margin (retromargin), closest to the mouth, has four teeth.

The plate on the underside of the cephalothorax (sternum) is reddish-brown with an irregular gray band on the front half.

The abdomen is egg-shaped, cut off (truncate) in front, widest near the middle, and tapered to the rear. It is dark brown in the middle with an oval gray mark (cardiac mark) near the front; three or four distinct, W-shaped bands; and a distinct, slender, pale submarginal band on each side. The W-shaped bands have an unbroken white outline. The distinctness of the abdominal markings is diagnostic, helping to separate striped fishing spider from dark fishing spider. The underside of the abdomen is pale gray.

The legs are long, thin, and dark brown, usually with gray rings. They are covered with hairs and have long black spines. The last leg segment (tarsus) has 3 claws, but these are not visible without magnification.

Males are much smaller, ½″ to ⅝″ (13 to 16 mm) in length and are similar in coloration to females.

Female Body Length: 11⁄16″ to 15⁄16″ (17.5 to 24.0 mm)

Male Body Length: ½″ to ⅝″ (13 to 16 mm)

Legspan: 23⁄16″ to 3⅛″ (55 to 80 mm)

Striped fishing spider does not produce a web to catch prey. The female produces a nursery web for its young.

Slow streams, ponds, lakes, swamps, stream banks, bridges, boat docks, and under rocks

Mature adults in summer

Like other fishing spiders, striped fishing spider can lift its abdomen to catch the wind and sail across the water.

It often sits quietly at the edge of a lake or pond or on floating vegetation. It rests its front three pairs of legs on the water surface to detect ripples or vibrations of prey.

Aquatic insects and sometimes small fish

Sources

24, 29, 30, 82, 83.

Common

Lake Kabetogama, Voyageurs National Park, Minnesota, on the dock multiple sightings.

Spider on the dock at the picnic area at Lake Vermillion State Park.

Location: Lake Kabetogama, Voyageurs National Park, Minnesota

on the dock multiple sightings.

Location: Lake Vermillion State Park

Spider on the dock at the picnic area at Lake Vermillion State Park.