Dark Fishing Spider, Dock Spider
Dolomedes tenebrosus
Pisauridae (Nursery Web Spiders), Order Araneae
Physical Description
Large, robust body with a distinctively patterned cephalothorax and a slightly elongate abdomen. The texture appears somewhat fuzzy or velvety due to a dense covering of fine setae. Females are considerably larger than males.
Size Estimate
Body length ranges from 15 to 26 mm for females, with a sprawling leg span that can reach up to 70 to 90 mm. This appears to be a large adult specimen.
Coloration & Markings
Mottled brown, gray, and black coloration with distinctive alternating dark and light bands clearly visible on the legs. The abdomen features irregular W-shaped or chevron markings, and the cephalothorax often has lighter lateral margins.
Web Type
Does not build a capture web. These are roaming hunting spiders that rely on stealth and speed, though females spin temporary nursery webs in vegetation when guarding their egg sacs.
Eye Arrangement
Eight eyes arranged in two distinct, slightly curved rows of four, typical of pisaurids, with the eyes being relatively uniform in size compared to wolf spiders.
Leg Characteristics
Long, powerful legs held out to the sides in a sprawling crab-like posture. The legs feature prominent dark and light alternating bands and numerous strong spines, adapted for running across water and tree trunks.
Venom & Safety Information
Venom Information
Contains neurotoxic components typical of large wandering spiders, but the venom is generally weak regarding human physiology and optimized for subduing invertebrate and small vertebrate prey.
Medical Significance
Not medically significant. A bite can cause localized pain, swelling, and redness similar to a bee or wasp sting, but severe systemic effects are extremely rare. They are reluctant biters.
Safety Recommendations
Avoid handling with bare hands to prevent defensive bites. If found indoors near a door, gently guide it into a container using a piece of cardboard and release it safely outdoors.
Habitat & Behavior
Habitat & Range
Found throughout eastern and central North America. Prefers wooded areas, often near streams, ponds, and swamps, but frequently ventures onto vertical surfaces such as tree trunks, wooden fences, and the exterior walls of houses near water.
Behavior & Temperament
Active nocturnal hunter, though often seen resting motionlessly on vertical surfaces during the day. Generally non-aggressive toward humans, preferring to flee or hide, but females guarding egg sacs will defend their brood vigorously.
Diet & Prey
Generalist ambush and pursuit predator feeding on large insects, tadpoles, small fish, and occasionally small aquatic amphibians, caught by detecting surface ripples on water.
Seasonal Activity
Most active from late spring through early autumn. They overwinter as juveniles or sub-adults under loose tree bark, in rotting logs, or occasionally sheltered structural crevices.
Description
The Dark Fishing Spider is an impressive giant among wandering spiders, often startling homeowners when it appears on exterior walls or near entryways. Despite its intimidating size and ferocious hunting abilities, it is a beneficial and ecologically fascinating predator that roams woodlands and watersides.
Key Features
Large size, distinctively banded legs, mottled gray and brown camouflage, habit of resting flat against vertical surfaces with legs splayed, and lack of a traditional orb or sheet web.
Similar Species
Wolf spiders (Lycosidae) which carry their egg sacs attached to their spinnerets rather than in their jaws, and larger funnel-web grass spiders (Agelenidae) which build sheet webs with funnels.
Life Cycle
Mating occurs in spring or early summer, after which the female carries a large spherical egg sac in her jaws. Before the eggs hatch, she constructs a silken nursery web in foliage, guards it fiercely, and lives for a single season or up to two years.
Ecological Importance
Acts as an important apex predator among invertebrates, regulating populations of large insects and occasionally small aquatic vertebrates while serving as food for birds and small mammals.
Conservation Status
Common and widespread throughout its native range; not currently evaluated by the IUCN but populations remain stable.
Interesting Facts
Despite their common name, fishing spiders do not exclusively live in water and can often be found quite far from bodies of water on woodland trees and residential buildings.
Photography Tips
Photograph from a low angle to capture the sprawling leg span and banded patterns. Use natural side lighting to emphasize texture, and maintain a safe distance to avoid startling the spider into fleeing.
User Notes
Back door
Identified: 2026-08-08T17:07:20.900556