Brazilian Whiteknee Tarantula, Giant White Knee
Acanthoscurria geniculata
Theraphosidae (Tarantulas), Order Araneae. Mygalomorphae suborder characteristically featuring downward-pointing fangs.
Physical Description
A heavy-bodied terrestrial tarantula. It features a dark, velvet-like black prosoma (cephalothorax) and a bulbous abdomen covered in reddish-brown setae (hairs). The body is distinctly stocky with a robust build.
Size Estimate
Large; body length typically 3-3.5 inches, with a leg span reaching 7-8 inches (17-20 cm) in mature females. This specimen appears to be a sub-adult or adult.
Coloration & Markings
Deep black base color with brilliant, contrasting white bands on the joints (patella and tibia) of the legs. The abdomen features long, rust-colored or reddish hairs that provide a fuzzy appearance.
Web Type
Not an orb-weaver. It produces silk for lining its burrow or creating a 'molt mat,' but it is an active ground-dwelling hunter.
Eye Arrangement
Small ocular tubercle located at the front-center of the carapace containing eight eyes in a tight cluster, typical of the family Theraphosidae.
Leg Characteristics
Thick, powerful legs designed for terrestrial movement. Features white horizontal banding at the joints and vertical white striping on the patella. Legs are covered in both tactile and urticating hairs.
Venom & Safety Information
Venom Information
Possesses mild digestive venom. While painful due to the mechanical size of the fangs, the venom is not considered medically significant to healthy humans.
Medical Significance
Low danger level. The primary medical concern is the urticating hairs which cause severe itching and respiratory irritation. Bites cause localized pain and swelling similar to a bee sting.
Safety Recommendations
Do not handle this spider; the urticating hairs can cause eye damage or skin rashes. If kept as a pet, use long tongs for feeding and maintenance.
Habitat & Behavior
Habitat & Range
Native to northern Brazil, specifically the Amazon basin. They inhabit tropical rainforests where they live in burrows or under forest floor debris.
Behavior & Temperament
Known for a 'feeding response' that is very enthusiastic. While not typically aggressive, they are defensive and skittish; they are more likely to flick urticating hairs than bite, though they will stand their ground if cornered.
Diet & Prey
Opportunistic carnivore. Feeds on a wide variety of large insects, other arachnids, and occasionally small vertebrates like lizards or mice in the wild.
Seasonal Activity
Active year-round in tropical climates, with increased movement during the rainy season when males wander in search of mates.
Description
The Brazilian Whiteknee is a spectacular New World tarantula prized by enthusiasts for its bold black-and-white patterns and impressive size. It is a terrestrial giant that dominates the forest floor with its striking appearance and active presence.
Key Features
Distinct white banding on the leg joints against a jet-black background, reddish abdominal hairs, and a large, chunky body shape.
Similar Species
Nhandu chromatus (Brazilian Red and White) which has a lighter grey carapace; Acanthoscurria brocklehursti (Giant Black and White) which has narrower white bands.
Life Cycle
Females can live 15-20 years; males live significantly shorter lives (3-5 years). Females lay egg sacs containing 500-1000 spiderlings. Growth is relatively fast compared to other tarantulas.
Ecological Importance
Acts as a major apex invertebrate predator in its microhabitat, controlling insect populations and serving as a food source for larger birds and mammals.
Conservation Status
Not currently listed by the IUCN, but threatened by habitat destruction in the Amazon and the illegal pet trade.
Interesting Facts
Unlike many tarantulas that hide, this species is often 'on display' in the wild and in captivity. They are famous for their voracious appetite and will attack prey nearly as large as themselves.
Photography Tips
A low-angle shot from the front captures the white leg bands and fangs best. Use a diffused flash to highlight the contrast without washing out the deep black of the carapace.
Identified: 2026-07-06T19:38:27.608147