Trapdoor spider, Brown trapdoor spider
Ummidia audouini
Family Ctenizidae, Order Araneae. Key family characteristics include stout bodies, robust digging rakes (rastra) on the chelicerae, and a generally fossorial lifestyle.
Physical Description
The spider has a robust, glossy, dark brown to black body with a smooth, hairless-appearing carapace and a plump, rounded abdomen. The front portion (cephalothorax) is large and shiny, housing powerful mouthparts adapted for digging.
Size Estimate
Body length is approximately 20 to 30 millimeters, with a leg span of around 40 to 50 millimeters. This specimen appears to be a mature adult.
Coloration & Markings
Uniform glossy dark brown to black coloration across the entire body without distinct patterns, stripes, or chevrons. The carapace has a high gloss finish that often reflects light.
Web Type
Trapdoor spiders do not build traditional aerial webs. Instead, they construct silk-lined subterranean burrows sealed with a hinged, camouflaged trapdoor made of silk, soil, and vegetation.
Eye Arrangement
Eight small eyes are clustered closely together on a small tubercle at the front center of the carapace, which is typical for mygalomorph spiders.
Leg Characteristics
The legs are thick, muscular, and relatively short compared to true spiders, designed for powerful pushing and digging rather than fast running. They feature strong spines and distinct claw tufts.
Venom & Safety Information
Venom Information
Contains mycotoxins typical of mygalomorph spiders, but the venom is generally weak and not medically significant to humans. Envenomation is rare due to their secretive nature.
Medical Significance
Harmless to humans. While a bite from their large fangs can be mechanically painful and cause minor localized swelling, their venom poses no serious health threat. Medical attention is rarely needed beyond basic wound cleaning.
Safety Recommendations
Avoid handling them bare-handed as they can deliver a defensive bite if cornered. If found indoors, gently guide the spider into a container using a piece of cardboard and release it outdoors in a shaded garden bed.
Habitat & Behavior
Habitat & Range
Found primarily in the southern and central United States, including Texas. They inhabit wooded areas, gardens, and embankments where they can burrow into damp, undisturbed soil.
Behavior & Temperament
Fossorial and sedentary ambush hunters. They spend almost their entire lives inside their burrows. When disturbed, they may rear up defensively with fangs displayed, but they generally prefer to retreat into their burrows and hold the door shut.
Diet & Prey
Feeds primarily on ground-dwelling insects such as beetles, crickets, grasshoppers, and occasionally other invertebrates that pass close enough to trigger the vibrations at the burrow entrance.
Seasonal Activity
Most active during warmer months, though mature males may wander out of their burrows in search of females during late summer or autumn mating seasons.
Description
The trapdoor spider is an engineering marvel of the arachnid world, spending its life hidden beneath a masterfully camouflaged hinged lid. With its glossy, dark armor and robust build, it is a formidable subterranean hunter that relies entirely on patience and vibrations to capture passing prey.
Key Features
Glossy dark brown to black coloration, very shiny and smooth carapace, robust and stout body proportions, absence of traditional webs, and construction of a hinged subterranean trapdoor.
Similar Species
Can be confused with tarantulas (Family Theraphosidae) or funnel-web spiders, but trapdoors are distinguished by their shiny, hairless-looking carapace and specialized burrowing habits with trapdoors.
Life Cycle
Females lay eggs inside the safety of their subterranean burrows. Spiderlings disperse a short distance to dig their own miniature burrows. Females can live for many years, sometimes up to 15 to 20 years in ideal conditions.
Ecological Importance
Acts as a localized predator controlling populations of ground-dwelling insect pests, and serves as prey for larger animals like birds, small mammals, and wasps.
Conservation Status
Not evaluated by the IUCN, but populations face local threats from habitat destruction, land development, and the use of pesticides.
Interesting Facts
Trapdoor spiders can pull against weights thousands of times heavier than their own body weight to keep their trapdoor shut when a predator tries to pry it open.
Photography Tips
Photograph at ground level using natural light. Avoid using harsh direct flash which creates intense glare on their shiny carapace. Maintain a safe distance and wait for the spider to settle into a natural posture.
Identified: 2026-10-02T05:51:32.809512