Diagnostic characters
- Chelicerae strike downward in parallel rather than pinching inward
- Two pairs of book lungs, visible as four pale patches on the underside
- Dense covering of setae over the whole body
- Persistent silk-lined burrow occupied for years
- Tarsal claw tufts allowing climbing on smooth surfaces
Habitat and seasonality
Desert grassland, scrub, rocky slopes, and canyon walls in Arizona, New Mexico, Texas, Nevada, Utah, Colorado, Oklahoma, Kansas, Arkansas, and southern California.
Mature males wander conspicuously in late summer and autumn seeking females, producing the seasonal road crossings often reported as migrations.
Medical significance
Very low. Venom of North American species causes only local pain. The primary hazard is urticating setae, which cause intense irritation to skin and, if inhaled or contacting the eye, more serious inflammation.
Longevity and life history
Female Aphonopelma may live 20 to 30 years or more and continue to molt after reaching maturity. Males mature in roughly 8 to 12 years, leave the burrow permanently to search for females, and die within a year. This asymmetry is why nearly every tarantula seen wandering in the open is a mature male at the end of its life.
Urticating setae
New World theraphosids bear specialized barbed setae on the dorsal abdomen which are flicked toward a threat with the hind legs. These setae embed in skin and mucous membranes and cause persistent itching and inflammation. Ocular contact is a documented cause of ophthalmia nodosa and requires clinical evaluation. This defense, not venom, is the practical risk associated with the family.
Conservation status
Several United States Aphonopelma species have small, isolated ranges and slow reproductive turnover, which makes them vulnerable to collection pressure and habitat conversion. Taxonomic revision of the genus in the last decade has substantially increased the number of recognized narrow-range species.
Families most often confused with Theraphosidae
| Family | How to separate it |
|---|---|
| Antrodiaetidae | Folding trapdoor spiders are much smaller and have hardened abdominal tergites |
| Ctenizidae and relatives | Trapdoor spiders build a hinged door over the burrow and have a rastellum for digging |
| Sparassidae | Huntsman spiders are flattened, laterigrade, and have pincer-action fangs |
References
- [1]World Spider Catalog, version 26 - Natural History Museum Bern. Accessed 2026-06-14.
- [2]Spiders of North America: An Identification Manual, 2nd ed. - American Arachnological Society. Accessed 2026-06-14.
- [3]Common Spiders of North America - University of California Press. Accessed 2026-06-14.