Dark Fishing Spider, Dock Spider, Fishing Spider
Dolomedes tenebrosus
Pisauridae (Nursery Web Spiders), Order Araneae
Physical Description
Large robust body with a distinctively flattened cephalothorax and elongated oval abdomen, covered in fine velvety hairs that provide excellent camouflage on tree bark and sandy surfaces.
Size Estimate
Body length ranges from 15 to 26 mm for females, with an impressive leg span reaching up to 70 to 90 mm. This specimen appears to be a sub-adult or adult.
Coloration & Markings
Mottled patterns of grey, brown, white, and black, featuring distinct alternating dark and light banding along the long legs and w-shaped markings on the dorsal abdomen.
Web Type
Does not build a traditional web to catch prey. Females construct a silk nursery web in vegetation when ready to lay eggs.
Eye Arrangement
Eight small eyes arranged in two curved rows, characteristic of nursery web spiders and wolf spiders, though pisaurids typically have a slightly different eye spacing.
Leg Characteristics
Long, robust, spreading laterally in a crab-like stance, featuring prominent dark and light rings or bands and covered with strong spines.
Venom & Safety Information
Venom Information
Contains mild neurotoxic and proteolytic venom used primarily to subdue invertebrate prey; rarely dangerous to humans.
Medical Significance
Not medically significant. A bite may cause localized pain, redness, and swelling similar to a bee or wasp sting, but severe reactions are extremely rare.
Safety Recommendations
Avoid handling bare-handed; if found indoors, gently guide into a container using a piece of card and release outdoors in a suitable wooded or damp area.
Habitat & Behavior
Habitat & Range
Found throughout eastern North America, typically near wooded areas, streams, ponds, swamps, and often found on tree trunks, wooden fences, and docks.
Behavior & Temperament
Active nocturnal hunter that relies on ambush and speed. Generally non-aggressive and prefers to flee rather than bite when disturbed.
Diet & Prey
Insects, tadpoles, small fish, and occasionally aquatic invertebrates, captured by detecting surface vibrations on water or ambushing on land.
Seasonal Activity
Most active from late spring through early autumn, mating in summer, and overwintering under loose bark or in sheltered crevices.
Description
The Dark Fishing Spider is a magnificent, large arachnid known for its ability to hunt near water and on vertical tree trunks. Its exceptional camouflage allows it to blend seamlessly into natural backgrounds.
Key Features
Large size, distinctive grey-brown mottled patterns, heavily banded legs, lateral resting posture, and a tendency to inhabit vertical surfaces near water.
Similar Species
Wolf spiders (Lycosidae) and other fishing spider species such as Dolomedes scriptus, distinguished primarily by subtle abdominal markings and habitat preferences.
Life Cycle
Females carry egg sacs in their chelicerae until late development, then construct a silken nursery web guarded fiercely until spiderlings disperse.
Ecological Importance
Acts as an important predator of aquatic and terrestrial insects, helping regulate populations near water bodies and serving as prey for birds and amphibians.
Conservation Status
Secure and widespread, with no special conservation status or major threats currently identified.
Interesting Facts
Fishing spiders can skate across the surface of the water using surface tension and can even submerge entirely for short periods to escape predators.
Photography Tips
Use a macro lens with a fast shutter speed to capture leg banding and eye arrangements, and maintain a respectful distance to avoid startling the spider into flight.
Identified: 2026-09-07T18:45:47.342538