Brazilian White Knee Tarantula

Acanthoscurria geniculata Care Guide

Brazilian Whiteknee Tarantula / Giant White Knee / Whitebanded Tarantula

Revision Date: March 2025

Introduction

Acanthoscurria geniculata, commonly known as the Brazilian Whiteknee Tarantula (also called Giant White Knee or Whitebanded Tarantula), is a fast‑growing New World terrestrial species native to the northern forests of Brazil. Valued for its dramatic feeding response and striking appearance, characterized by a dark body contrasted with bright white bands on its legs, this tarantula is a staple in the hobby. Although it grows quickly (with individuals sometimes reaching nearly 4 inches in leg span in just over a year), it remains relatively easy to care for. Like other New World species, it possesses irritating Type I and III urticating hairs and tends to be defensive when disturbed. Its robust nature and generally impressive display make it an excellent choice for beginner keepers.

Quick Species Snapshot

• Scientific Name: Acanthoscurria geniculata

• Common Names: Brazilian Whiteknee Tarantula, Giant White Knee, Whitebanded Tarantula

• Type: Terrestrial

• Category: New World

• Endemic Location: Brazil

• Body Length: Approximately 3.5” (9 cm)

• Diagonal Leg Span (DLS): Up to 8.25” (21 cm)

• Urticating Hairs: Yes, Types I & III

• Growth Rate: Fast

• Life Expectancy:

  • Females: Up to 20 years

  • Males: Approximately 4 years

• Recommended Experience Level: Beginner

Taxonomy & Research Update

Acanthoscurria geniculata is a well-documented species within the New World tarantula group, known for its striking appearance and impressive growth rate. Native to the dense rainforests of northern Brazil, this large terrestrial species has gained popularity in the hobby for its bold white leg banding, contrasting sharply against its dark body. While it shares similarities with other sizable terrestrial tarantulas, its robust build and distinctive coloration set it apart.

Recent studies have highlighted its remarkably fast growth rate, with some individuals nearly doubling their leg span within a year under optimal conditions. This rapid development, combined with its high activity level, makes A. geniculata an excellent display tarantula, often seen out in the open rather than hidden away in burrows. Unlike more reclusive species, it readily explores its environment, making it a favorite among keepers who enjoy an active, visually striking specimen in their collection.

What Makes Acanthoscurria geniculata So Special?

The Brazilian Whiteknee Tarantula (Acanthoscurria geniculata) is a true standout in the tarantula hobby, both in appearance and behavior. Its striking black body, covered in a fine velvety sheen, is sharply contrasted by bold white bands on its legs, giving it a dramatic and unmistakable look. This bold patterning, combined with its large size and stocky build, makes A. geniculata one of the most visually impressive species available to keepers.

Beyond its looks, this species is also known for its aggressive feeding response, one of the most enthusiastic eaters in the tarantula world. It doesn’t just catch prey; it pounces on it with force, often grabbing food mid-air if given the chance. This feeding behavior makes it an exciting species to observe, as it actively engages with its environment rather than waiting passively like more reclusive tarantulas.

Despite its voracious appetite and high activity level, A. geniculata is a hardy and resilient species, making it a great option for beginners looking for a large, impressive tarantula that doesn’t require overly complex care. While it can be defensive, readily kicking its urticating hairs if disturbed, it is generally not overly defensive or unpredictable. With respect and minimal unnecessary handling, this tarantula makes a fascinating and rewarding addition to any collection, offering both aesthetic appeal and dynamic behavior.

Natural Habitat & Enclosure Considerations

In the wild, Acanthoscurria geniculata is found in the northern forests of Brazil, where it thrives in a habitat that offers plenty of ground space and well-draining substrate for burrowing. In captivity, providing an enclosure that replicates these conditions is crucial. The design should ensure a deep, stable substrate to facilitate natural burrowing while preventing falls, as tarantulas are vulnerable to injury from even small drops.

Housing & Substrate – Terrestrial Setup

Spiderlings

• Enclosure Size:
  Use a small acrylic enclosure (e.g., Sling Crib, 3" Tarantula Cube, Small Slider Crib, Small Cuboid, Terrestrial Sling Crib, Slider Crib Mini, or Cuboid Mini) that is no smaller than three times the tarantula’s leg span.

• Substrate:
  Fill at least 2/3rds of the enclosure with Terra Aranea by The Bio Dude.

• Humidity:
  Maintain a slightly damp substrate (but not swampy) by offering a small water dish or gently dripping water on one corner once or twice a week, depending on how fast is dries out.

Juveniles

• Enclosure Size:
  Use a medium enclosure (e.g., Medium Slider Crib, 6" Tarantula Cube, 8" Tarantula Cube, or Medium Cuboid) that is at least 3–4× the tarantula’s leg span.

• Substrate:
  Fill the enclosure 1/2 to 2/3 full with Terra Aranea by The Bio Dude. This provides ample depth for burrowing while minimizing fall risk.

• Humidity:
  Keep the substrate mostly dry with a full water dish; occasionally overflow one corner to create a slightly damp area.

• Additional Features:
  Provide a half cork bark round for a secure hide.

Adults

• Enclosure Size:
  Use a large enclosure (e.g., Large Slider Crib, 12" Cube Switch, 12" Cube, 18" Cube, or Terrestrial XL) that is at least 3× the tarantula’s leg span (ideally 4× for enhanced natural behavior, while considering escape risks).

• Substrate:
  Fill the enclosure 1/2 to 2/3 full with Terra Aranea by The Bio Dude to provide sufficient depth for burrowing while reducing the risk of injury from falls.

• Additional Features:
  Include a secure hide (preferably a half cork bark round) and a shallow water dish. Ensure the enclosure is a horizontal rectangle (wider than it is deep) with secure ventilation and a tight, secure lid to prevent escapes.

Note:
The general rule of thumb for tarantula enclosures is that the enclosure should be no smaller than three times the tarantula’s leg span for spiderlings, 3–4× for juveniles, and 3–5× for adults. This ensures sufficient space for natural burrowing while minimizing fall risk. Remember, tarantulas are escape artists, so always verify that ventilation holes, lids, and gaps are too small for your tarantula to squeeze through.

Affiliate: Please use Tarantula Cribs (affiliate code TTC10) and Terra Aranea by The Bio Dude for substrate.

Temperature & Humidity

• Temperature:
  Maintain ambient temperatures between 68°F and 76°F (20°C to 24°C).

• Humidity:
  Aim for moderate humidity. Ensure that the substrate remains moist in the lower layers to support effective burrowing while allowing the top layers to dry between waterings to prevent mold growth.

Feeding Schedule

Spiderlings

• Frequency:
  Feed twice a week.

• Prey:
  Offer small prey such as flightless fruit flies, confused flour beetles, or pre-killed tiny crickets/roach nymphs. Remove any uneaten prey after 24 hours. increase the size of the prey as the spider grows. Prekill any prey that is over 2/3 the size of the sling. For more detailed information on feeding spiderlings, watch this video: How To Feed Spiderlings & Scorplings (Baby Tarantulas & Scorpions)

• Post-Molt:
  Wait 24–48 hours after a molt before feeding. Ensure that the tarantula’s fangs are solid black and its exoskeleton is not soft or shiny.

Juveniles

• Frequency:
  Feed every 7–10 days.

• Prey:
  Provide 2–3 small to medium crickets or a medium Dubia roach.

• Feeding Guidelines:

  • If the abdomen is thinner than the widest part of the carapace, feed more prey more often.

  • If the abdomen is wider than the carapace, feed less prey, less often.
    This strategy helps prevent obesity, which can lead to molting complications or increase the risk of an abdomen rupture from even a small fall.

• Post-Molt:
  Wait 3–7 days after a molt before feeding, ensuring that the tarantula’s fangs are solid black and its exoskeleton is fully hardened.

Adults

• Frequency:
  Feed every 2–3 weeks (or as needed).

• Prey:
  Offer 4–5 large crickets or one large Dubia roach.

• Feeding Guidelines:

  • If the abdomen is thinner than the carapace’s widest part, increase feeding frequency.

  • If the abdomen is wider than the carapace, reduce feeding frequency.
    This is crucial to avoid obesity, which can interfere with proper molting or cause dangerous issues such as an abdomen rupture.

• Post-Molt:
  Wait 5–10 days after a molt before feeding, ensuring that the tarantula’s fangs are solid black and its exoskeleton is fully hardened.

Behavior & Temperament

The Brazilian Whiteknee Tarantula is noted for its enthusiastic feeding response and dramatic appearance. It is an active and dynamic eater, often pouncing on prey with remarkable force. While spiderlings and juveniles can be nervous and quick to retreat into their burrows when disturbed, mature specimens tend to be calm and make excellent display animals. However, they are known to kick their urticating hairs when provoked, so handling should be approached with caution, especially since these hairs can be quite irritating if they come into contact with skin or eyes.

Breeding Acanthoscurria geniculata in Captivity

Breeding Acanthoscurria geniculata can be a rewarding, yet challenging endeavor. With the right conditions and careful pairing, successful reproduction is very achievable.

Sexual Maturity & Pairing

• Male Maturity: Males mature in about 2–3 years, developing tibial hooks and enlarged pedipalps for sperm transfer.

• Female Maturity: Females take longer, around 4–5 years, and should be at least 3–4 weeks post-molt before introduction.

• Pre-Pairing Preparation: Ensure the female is well-fed before pairing to reduce the risk of cannibalism.

Mating Process

• Introduce the male at night when both tarantulas are naturally more active.

• The male will drum on the substrate to signal the female.

• If receptive, the female will drum back or remain still, allowing the male to lift her and insert one or both emboli.

• Once mating is complete, remove the male immediately to prevent the female from attacking him.

Egg Sac Production

• If fertilized, the female will begin developing an egg sac within 1–3 months.

• Maintain 75–80°F (24–27°C) with 60–70% humidity to support egg sac production.

• The female will guard the sac aggressively for 6–9 weeks.

Egg Sac Handling (Optional)

• Some breeders pull the sac at 30 days to artificially incubate the eggs.

• If left with the mother, 1st instar spiderlings will emerge in about 6–8 weeks and molt into 2nd instar after another 2–3 weeks.

Raising Spiderlings

• Once the spiderlings reach 2nd instar, separate them into individual enclosures.

• Feed them pinhead crickets, flightless fruit flies, or small roaches every 2–3 days.

Challenges & Considerations

• Female aggression: A. geniculata females can be unpredictable—have a catch cup ready in case of sudden attacks.

• Multiple pairings: Some breeders pair the female multiple times over a few weeks to increase fertilization chances.

• Male survival: Males have short lifespans post-maturity, so breeding should be attempted soon after their final molt.

Successful breeding requires patience and caution, but with the right approach, Acanthoscurria geniculata can produce large, healthy egg sacs with hundreds of spiderlings.

Final Thoughts

Acanthoscurria geniculata (Brazilian Whiteknee Tarantula) is a vibrant and dynamic species that makes for an exceptional display tarantula. Its fast growth, striking white banding on dark legs, and robust feeding response make it a favorite in the hobby. With proper husbandry, including an enclosure with substrate filled 1/2 to 2/3 full (to ensure ample burrowing depth while minimizing fall risk), controlled temperature and humidity, and a balanced feeding routine adjusted based on abdomen size, you can maintain a healthy, thriving specimen for many years.

Additional Recommendations:
For enclosures, consider Tarantula Cribs (use affiliate code TTC10 for a 10% discount), and use Terra Aranea by The Bio Dude for substrate. For tarantula supplies, check out Spider Shoppe (use code TTC10 for 10% off), and visit the Dealer & Discounts section on my website for a curated list of recommended dealers and discount codes.

Additional Scientific Information

• Ecological Adaptations:
  Native to the northern forests of Brazil, Acanthoscurria geniculata thrives in a habitat where rapid growth and a dramatic display are advantageous. Its ability to grow quickly and its vigorous feeding response help it compete effectively in its native environment, where food sources can be abundant but predation pressure is high.

• Sensory & Behavioral Adaptations:
  Like many New World tarantulas, this species relies heavily on chemotactile setae to sense vibrations and chemical cues in its environment. This sensory adaptation is crucial for detecting prey and avoiding predators. Its aggressive feeding response is a testament to its evolved efficiency as a nocturnal ambush predator.

• Feeding & Health Management:
  Preventing obesity is critical to avoiding molting complications. Regularly monitoring the abdomen relative to the carapace is essential: a thinner abdomen signals that more frequent feedings may be necessary, while a wider abdomen indicates that feedings should be reduced to avoid health risks. Always ensure that feeding occurs only after the tarantula’s fangs are solid black and its exoskeleton is fully hardened (Spiderlings: 24–48 hours; Juveniles: 3–7 days; Adults: 5–10 days post-molt).

• Etymology & Genus Relevance:
  The genus name Acanthoscurria (or the similar alternative Acanthoscurria) is derived from Greek roots referring to "spiny" or "thorny," which reflects the distinct setae covering the tarantula’s body. This nomenclature highlights the species’ evolutionary adaptations for defense and sensory perception, underscoring its significance among New World theraphosids.

(For further reading, consult recent publications in the Journal of Arachnology and ZooKeys for comprehensive taxonomic and ecological insights on New World Theraphosidae.)