Dark Fishing Spider, Dock Spider
Dolomedes tenebrosus
Pisauridae (Nursery Web Spiders), Order Araneae. Key family characteristics include anterior median eyes of similar size to other eyes, use of nursery webs for brooding eggs, and the tendency of females to carry egg sacs in their chelicerae until just before hatching.
Physical Description
Robust, large-bodied spider with a rounded to slightly oval abdomen and a broad carapace. The body surface is covered in fine, velvety setae that provide excellent camouflage against tree bark and leaf litter.
Size Estimate
Body length ranges from 15 to 26 mm for females and 7 to 13 mm for males, with a remarkable leg span that can reach up to 70 to 90 mm. The pictured specimen appears to be a medium-to-large subadult or adult.
Coloration & Markings
Mottled patterns of gray, brown, and dark charcoal, featuring distinct dark, W-shaped or chevron markings across the dorsal surface of the abdomen. The legs show prominent dark banding.
Web Type
Fishing spiders do not use webs to capture prey. Instead, they are active nocturnal or crepuscular hunters that roam vegetation, tree trunks, and shorelines, constructing a temporary nursery web of silk only when females are ready to protect their egg sacs.
Eye Arrangement
Eight eyes arranged in two distinct, slightly recurved rows of four. The eyes are relatively equal in size compared to wolf spiders, which helps distinguish Pisauridae from Lycosidae.
Leg Characteristics
Long, robust legs featuring distinct dark bands and numerous prominent spines. When resting on surfaces like tree bark, they often spread their legs outward in a flattened, stealthy posture to minimize shadows.
Venom & Safety Information
Venom Information
Neurotoxic and proteolytic venom designed to subdue insect prey rapidly. While capable of delivering a defensive bite if trapped against skin, the venom is generally not medically significant to humans.
Medical Significance
Harmless to humans. A bite may cause localized pain, redness, and swelling similar to a bee or wasp sting, but severe systemic effects are extremely rare. No special medical treatment is usually necessary beyond standard antiseptic care.
Safety Recommendations
Wear gloves when moving stacked firewood or clearing leaf litter where these spiders may be resting. If found indoors, gently guide the spider into a container using a piece of cardboard and release it outdoors.
Habitat & Behavior
Habitat & Range
Found throughout eastern and central North America. Prefers wooded areas, tree trunks, forests near streams, ponds, swamps, and occasionally ventures onto building foundations and woodpiles.
Behavior & Temperament
Timid and fast-moving. Rather than showing aggression toward humans, they typically bolt away or flatten against a surface when disturbed. They are active primarily at night.
Diet & Prey
Generalist predators consuming large insects, other spiders, and occasionally small aquatic vertebrates such as small fish or tadpoles by resting on the water's surface.
Seasonal Activity
Most active from late spring through autumn. They overwinter as juveniles or subadults hidden beneath loose bark, leaf litter, or within woodpiles.
Description
The Dark Fishing Spider is an impressive forest dweller known for its generous proportions and excellent arboreal camouflage. Often found resting flat against tree trunks or woodpiles, this stealthy hunter relies on keen vibrations and speed to capture prey rather than spinning a traditional orb web.
Key Features
Distinctive W-shaped or chevron markings on the abdomen, prominent dark banding on long spiny legs, large size, and the characteristic nursery-web spider eye arrangement.
Similar Species
Wolf spiders (Lycosidae), which can be distinguished by their prominent enlarged posterior median eyes and the habit of females carrying egg sacs attached to their spinnerets rather than in their jaws.
Life Cycle
Females construct a silken nursery web for their egg sac near hatching time, guarding it fiercely. Mating occurs in spring or early summer, and spiderlings disperse via ballooning or walking.
Ecological Importance
Acts as an effective natural predator helping regulate insect populations in forest and riparian ecosystems, serving as an important food source for birds and small mammals.
Conservation Status
Not evaluated by the IUCN, but populations are generally stable and widespread across their native range.
Interesting Facts
Despite being called fishing spiders, many species in this genus live far from water in deep forests, hunting entirely on tree trunks and wooden structures.
Photography Tips
Use a macro lens with a fast shutter speed to capture leg and abdominal details. Approach slowly to avoid startling the spider, and photograph from a top-down or slight side angle to highlight the distinct chevron markings.
Identified: 2026-09-04T16:18:07.685371