Theraphosidae

Theraphosidae is distinguished from other spider families by several morphological features: large body size with robust, often hairy legs; two pairs of book lungs (a primitive trait of Mygalomorphae); chelicerae that move parallel to each other rather than opposing; and the presence of clavate (club-shaped) trichobothria (sensory hairs) on the tarsi of all species, with some also bearing them on tibiae. The family can be separated from other mygalomorph families by the combination of large size, dense hair covering, and the specific arrangement of trichobothria—typically in two parallel or diverging rows on the tarsi. Unlike trapdoor spiders (Halonoproctidae, Ctenizidae), tarantulas lack a hardened, door-like operculum for burrow closure. Unlike funnel-web spiders (Dipluridae, Hexathelidae), they lack the distinct funnel-shaped web architecture and the associated aggressive defensive behavior. The dense covering of urticating hairs on the abdomen of New World species (absent in Old World species) provides an additional diagnostic feature for regional identification.

Tarantulas occupy diverse habitats spanning tropical rainforests, cloud forests, pine-oak woodlands, deserts, and high-elevation mountainous regions. Terrestrial species construct silk-lined burrows in soil, often beneath stones or vegetation, with some creating turreted entrances ornamented with debris. Arboreal species inhabit trees and vegetation, constructing retreats in crevices or under bark. The family demonstrates remarkable elevational range, from sea level to high Andean and Himalayan elevations. Specific microhabitat preferences vary by genus and species: some are obligate burrowers in well-drained, sloped rocky ground with sparse vegetation; others are found in bamboo fences, roadside embankments, or forest floor litter. Many species exhibit narrow habitat specificity, contributing to high endemism and restricted geographic distributions.

Theraphosidae has a pantropical and subtropical distribution with extensions into temperate zones. The family is well-represented in the Neotropics (Central and South America, Caribbean islands), where the highest diversity occurs. Significant radiations exist in the southwestern United States and northern Mexico (Madrean Pine-Oak Woodlands Hotspot), with the genus Aphonopelma particularly diverse in this region. South American tarantulas are distributed across the Amazon basin, Atlantic rainforest, Andean slopes, and Chocó Biogeographic Region. The family extends into the Old World with representation in sub-Saharan Africa, the Mediterranean region (including Crete and the Middle East), South Asia (India, Sri Lanka), Southeast Asia, and Australia. Recent discoveries have expanded known ranges: Chaetopelma has been documented in northwestern Iran, extending the genus eastward by approximately 350 km. The Colombian Pacific region and Ecuadorian Andes have yielded multiple new species, indicating substantial undescribed diversity in poorly surveyed regions.

Tarantulas are predatory, feeding primarily on insects and other arthropods. Larger and more agile species have been observed to capture small vertebrates including small mammals, birds, lizards, and frogs. Prey is captured through stealth, speed, or ambush from burrow entrances. Following capture, prey is ground into a ball and external digestion is employed—digestive enzymes are secreted onto the prey mass, and liquefied contents are consumed. Specific dietary composition varies by habitat, body size, and foraging strategy; no comprehensive dietary studies across the family are available.

Tarantulas exhibit extended lifespans compared to most spiders. Females of many species live 20 to 30 years, with some records exceeding this range; males typically have shorter lifespans. Females lay several hundred eggs in a silken egg sac, which is stored in the burrow and guarded until hatching. Development proceeds through multiple instars with gradual growth. Some species exhibit possible ontogenetic niche shifts, with juveniles and subadults occupying different microhabitats or burrow types than adults. Sexual dimorphism is pronounced in many species, with males typically smaller and more slender than females, often with distinct coloration or leg proportions.

Tarantulas are predominantly nocturnal. Defensive behaviors include rearing with forelegs extended, stridulation (in some species), and—characteristic of New World species—release of urticating hairs from the abdomen by rubbing with hind legs. These barbed hairs can irritate mucous membranes and skin of potential predators. Mating involves elaborate courtship rituals: males construct sperm webs for sperm deposition, transfer sperm to pedipalps, and engage in species recognition displays involving leg tapping, drumming, and vibrational signaling. Males approach females with extreme caution; post-copulatory cannibalism of males has been documented. Some species exhibit high burrow density in suitable habitat (over 50 burrows per kilometer of roadside embankment documented in some populations).

Tarantulas function as mid-level to apex invertebrate predators in their respective ecosystems, regulating populations of insects and other arthropods. Their burrowing activity contributes to soil aeration and nutrient cycling. As large, long-lived predators with specific microhabitat requirements, they may serve as indicator species for ecosystem integrity. The silken lining of burrows and prey remains may provide microhabitat for other organisms. Their potential role in stratified micro-ecosystems of forest habitats has been noted, though specific ecosystem functions remain understudied.

Tarantulas are extensively collected for the international exotic pet trade, with legal and illegal trade documented across multiple continents. Ecuadorian tarantulas have been subject to smuggling for over 30 years, with newly described species appearing in online markets within months of scientific publication. This trade threatens wild populations, particularly of rare, restricted-range species. Some species are considered Critically Endangered due to habitat destruction from mining, agriculture, and urban expansion combined with collection pressure. Tarantula bites are generally not dangerous to humans except in cases of anaphylaxis; bites typically cause localized pain, swelling, and itching. Urticating hairs can cause skin and eye irritation. The family has cultural significance: the name "tarantula" derives from the Italian city of Taranto, where historical associations with a wolf spider (Lycosa tarantula) and the dance called tarantella originated. Tarantulas are subjects of scientific research in systematics, behavior, and sensory biology.

• Lycosidae (wolf spiders)Historically confused with tarantulas; the European wolf spider Lycosa tarantula was the original source of the name "tarantula." Wolf spiders are smaller, have different eye arrangement (two large posterior eyes), lack urticating hairs, and are active hunters rather than ambush predators.
• Halonoproctidae (trapdoor spiders)Share mygalomorph features and burrowing habit, but possess a hardened, hinged operculum (trapdoor) for burrow closure; generally smaller with different burrow architecture.
• Dipluridae (curtain-web spiders)Mygalomorph spiders that construct sheet or funnel webs rather than burrows; lack the dense hair covering and large size typical of Theraphosidae.
• Barychelidae (brush-footed trapdoor spiders)Share some trichobothrial characteristics and mygalomorph features, but differ in burrow construction, size, and leg morphology; some species have clavate trichobothria but in different patterns.

The name "tarantula" properly refers only to Theraphosidae, but is commonly misapplied to other large spiders including wolf spiders (Lycosidae), huntsman spiders (Sparassidae), and other mygalomorphs. The historical association with tarantism—a condition supposedly cured by dancing—originated with the European wolf spider Lycosa tarantula, not true tarantulas. Contrary to popular belief, tarantulas are not aggressive toward humans; defensive displays are typically bluff behaviors. While all tarantulas possess venom, no species is known to be lethal to humans except through anaphylactic reactions. The belief that all large, hairy spiders are tarantulas is taxonomically inaccurate.

• Mygalomorphae
• tarantula
• burrowing spider
• arboreal spider
• urticating hairs
• exotic pet trade
• conservation
• longevity
• nocturnal predator
• sensory biology
• trichobothria
• systematics
• endemism

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
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• Persian Gold Tarantula: a new species from Iran for Tarantula Appreciation Day 2023 |
• Trichobothrial morphology of Theraphosidae and Barychelidae spiders (Araneae, Mygalomorphae)
• A new synonym in the subfamily Thrigmopoeinae Pocock, 1900 (Araneae, Theraphosidae)
• Description of Catumiri n. gen. and three new species (Theraphosidae: Ischnocolinae)
• Insights Into Spatial Orientation and Cognition in Tarantulas (Araneae: Theraphosidae) Under Natural Conditions, With Notes on Possible Ontogenetic Niche Shifts.
• Testing the Limits of Morphology: A Comprehensive Morphometric Study of the Sister Lineages Lasiocyano Galleti-Lima, Hamilton, Borges and Guadanucci, 2023 and Lasiodora C. L. Koch, 1850 (Theraphosidae, Mygalomorphae).