The identification of funnel-web spiders (Atrax and Hadronyche genera) is important due to the potent venom of several species. These spiders are native to eastern Australia and are often found in gardens and homes. Recognizing the spider’s physical features, web structure, and distinguishing it from look-alikes are the most reliable methods for accurate identification.
The Defining Physical Traits
Funnel-web spiders are robust, medium-to-large arachnids, typically measuring between one and five centimeters in body length. They are characterized by a dark coloration, ranging from dark brown to glossy, jet black.
The hard plate covering the front section of the body, known as the carapace, is characteristically shiny and sparsely haired. This smooth, hairless appearance sets them apart from many other ground-dwelling spiders, which often have a duller, hairier texture. The glossy carapace is a reliable visual identifier.
The structure of the fangs and chelicerae is a unique physical trait. Funnel-web spiders are mygalomorphs; their fangs are large, powerful, and point straight down, parallel to each other, rather than crossing like pincers. When defensive, the spider often rears up to display these prominent fangs.
Funnel-web spiders often have visible silk-spinning organs, called spinnerets, extending from the rear of the abdomen. In the Atrax genus, these spinnerets are particularly long and finger-like. Male funnel-web spiders, which are often encountered wandering, can be identified by a distinct, conical spur found on the second pair of legs.
Identifying the Funnel Web and Burrow Structure
Funnel-web spiders are sedentary ambush predators, so their web and burrow structure often provides the first clue to their presence. Their characteristic habitat is a silk-lined burrow in the ground, typically found in cool, moist, and sheltered locations such as under logs, rocks, or dense shrubbery.
The burrow entrance gives the spider its common name, consisting of a sheet-like, messy silk structure that funnels down into a tunnel. Unlike the neat, hinged door of a trapdoor spider, the funnel-web entrance is open and often camouflaged with debris. The silk structure extends into a retreat up to 30 centimeters deep.
A key feature is the irregular, messy network of silk trip-lines radiating across the ground from the burrow’s entrance. These lines act as an early warning system, alerting the spider to the vibrations of potential prey or intruders. The presence of these radiating, messy threads is highly indicative of a funnel-web spider.
Key Differences from Harmless Look-Alikes
Many ground-dwelling spiders are mistaken for the funnel-web, but several features prevent misidentification. Trapdoor spiders are common look-alikes, but their burrows are sealed with a neat lid of silk and soil, lacking the open funnel and messy trip-lines. The trapdoor spider’s body also tends to be duller and hairier, lacking the glossy carapace.
Mouse spiders are another species sometimes confused with funnel-webs, as they are large and dark. Mouse spiders possess a more bulbous, wider cephalothorax, and their eyes are spread across the front of the head, unlike the funnel-web’s closely grouped eyes. Mouse spiders also do not line their burrows with silk or construct the expansive trip-lines.
The Black House Spider is significantly smaller than a funnel-web and is typically covered in fine, velvety hairs, contrasting with the funnel-web’s smooth, shiny appearance. It constructs a messy, lacy-looking retreat above ground, such as near eaves or window frames, and does not create silk-lined ground burrows.
The most definitive difference is the fang orientation. Funnel-web spiders have fangs that operate in a straight, up-and-down motion, while most other common spiders possess fangs that cross over like pincers. This feature, combined with the male’s distinct tibial spur on the second leg, provides the most reliable identification for a wandering funnel-web.