A trapdoor spider is an arachnid known for its distinctive habit of constructing burrows with a camouflaged lid. These spiders belong to the infraorder Mygalomorphae, a group that also includes tarantulas and funnel-web spiders, distinguished by their fangs that point downwards. This unique door serves as both a protective barrier and a clever hunting tool.
The Trapdoor Spider’s Defining Characteristics
Trapdoor spiders typically have stout bodies with short, thick legs, ranging in color from yellowish-brown to reddish-brown or black. Their bodies are sparsely covered with hairs and may appear shiny. Most species average between 0.4 and 1.5 inches in body length, though some can reach up to 4 centimeters. They possess eight eyes, usually arranged with a pair in the middle and three on each side, though some species may have six.
A defining feature is their strong chelicerae, or jaw-like mouthparts, which contain large, downward-pointing fangs. These fangs are used for injecting venom and digging burrows. Many species also have a rake-like series of spines, called a rastellum, on their chelicerae, adapted for excavating soil. The trapdoor itself seamlessly blends with the surrounding environment using soil, moss, and twigs.
Engineering the Lair: Trapdoor Construction and Hunting
The construction of a trapdoor spider’s burrow begins with excavating a tube-like tunnel in the ground. The spider uses its fangs and legs to dig, rolling soil into balls and tossing them out of the developing burrow. Once formed, the tunnel is lined with silk, which stabilizes the structure, maintains humidity, and regulates temperature. Burrows typically extend up to 15 centimeters (about 6 inches) deep, with some species creating burrows up to 40 centimeters deep.
The trapdoor is crafted from silk combined with surrounding materials like soil, vegetation, and twigs, creating a camouflaged lid. This door is hinged on one side with silk, allowing the spider to open and close it swiftly. Some species construct thick, cork-like plugs, while others build thinner, wafer-like doors.
The spider waits just inside its door, often with its front legs extended, sensing vibrations from potential prey. When an insect or small invertebrate approaches, the spider rapidly opens the trapdoor, ambushes its prey, and pulls it into the burrow. Their diet consists primarily of crawling insects and other arthropods like crickets, moths, and beetles, but they may also consume small vertebrates such as lizards or frogs.
Habitat, Distribution, and Human Interaction
Trapdoor spiders are found across various continents, predominantly in warmer climates, including tropical and subtropical regions. They inhabit diverse environments, ranging from shady riverbanks to open deserts, often preferring loose or sandy soil for digging burrows. Their burrows are commonly found in gardens, forests, and grasslands. Females typically spend their entire lives within their burrows, while males venture out in search of mates, especially during humid weather.
Trapdoor spiders are generally timid and reclusive, preferring to retreat into their burrows when disturbed. Their venom is not considered medically significant to humans, and bites are rare, usually occurring only if the spider feels threatened. While a bite can be painful due to their large fangs, it typically results in only mild, localized pain and swelling, similar to a bee sting. They pose no significant threat to humans and are not aggressive unless provoked.