Brazilian White Knee Tarantula Caresheet and Bioactive Habitat Maintenance

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The Care and Maintenance of the Brazilian White Knee Tarantula

Acanthoscurria geniculata
Difficulty Level: Beginner

The Brazilian White Knee Tarantula, scientifically known as Acanthoscurria geniculata, is one of the most recognizable and popular large New World terrestrial tarantulas in the hobby. With a dark body, bold white banding on the legs, fast growth rate, and a crazy feeding response, this is the kind of tarantula that gets people hooked.

This is not a tiny little pet hole. This is a large, active, heavy-bodied spider that will usually let you know exactly when they are hungry. And with this species, that can be basically all the time if you let them convince you.

In the wild, Acanthoscurria geniculata is native to Brazil, specifically the northern forested regions associated with the Amazon basin. They are terrestrial tarantulas that use burrows, hollow stumps, retreats, and natural cover to stay hidden and secure. They are not desert animals and should not be kept bone dry, but they also should not be kept in a swampy enclosure with stagnant air.

Recreating those conditions in captivity means focusing on deep, moisture-retentive substrate, good ventilation, stable humidity, a secure hide, and enough floor space for a large terrestrial tarantula to move and dig. This is a hardy species and a solid beginner option, but beginner does not mean boring, slow, or easy to handle. They are big, strong, fast when they want to be, and more than willing to kick urticating hairs if they feel threatened.

Natural History, Description, and Related Species

Acanthoscurria geniculata belongs to the family Theraphosidae and the subfamily Theraphosinae. It was originally described as Mygale geniculata by C. L. Koch in 1841 and is currently recognized as the type species of the genus Acanthoscurria. In normal-person terms, this means A. geniculata is not just another species in the genus. It is one of the species that defines the characteristics of Acanthoscurria.

Adults are large and heavy-bodied, with females commonly reaching 7 to 8 inches in diagonal leg span, and some individuals pushing slightly larger. Females can live 15 to 20 years with proper care, while males grow faster, mature sooner, and usually live only a few years after reaching maturity.

Their appearance is the main reason most people notice them. The body is dark brown to black, with bright white bands on the legs and reddish or pinkish setae that become especially noticeable under good lighting. That contrast gives them the classic “Brazilian White Knee” look and makes them one of the most impressive display tarantulas in the hobby.

Like many New World terrestrial species, A. geniculata has urticating hairs. These are irritating defensive hairs on the abdomen that can be kicked into the air when the spider feels threatened. This species has Type I and Type III urticating hairs, and they can be very irritating if they get on your skin, in your eyes, or into your respiratory system.

There has also been some historical confusion around lookalike spiders from Brazil. Some tarantulas can resemble A. geniculata in general coloration and size, but differ in important anatomical traits. For the average keeper, this mostly means one thing: buy from reputable breeders and dealers who know what they are selling. A correctly identified, captive-bred Acanthoscurria geniculata is always the best option.

Recommended Supplies for a Brazilian White Knee Tarantula

Because this species is large, terrestrial, and appreciates access to moisture, the enclosure should focus on floor space, substrate depth, and environmental stability.

Terra Aranea Bioactive Substrate
Cork bark hide or cork flats
Bio Dude Leaf Litter
Bio Dude Sphagnum Moss
Or, you can use The Bio Dude's Terra Aranea Bioactive Kit for appropriately sized enclosures which contains biodegradables, substrate, and BioShot soil inoculant to help plants take hold.
Cuttings or smaller specimens of live tropical plants or hardy low-light plants
Tropical springtails to handle any organic waste
Shallow water dish
Secure terrestrial enclosure with strong ventilation
Feeding tongs or tools

Enclosure Size & Setup

Brazilian White Knees are terrestrial tarantulas, so floor space and substrate depth matter much more than height. They may dig, rearrange, sit out in the open, or bulldoze everything.

Spiderlings

Enclosure: Small secure acrylic enclosure or sling setup
Substrate Depth: 2 to 3 inches of Terra Aranea
Humidity: Keep part of the substrate slightly damp, not swampy
Decor: Small cork bark hide, leaf litter, and a small amount of sphagnum moss

Spiderlings should not be placed into overly large enclosures. They need security, stable moisture, and easy access to prey. A small setup allows you to monitor feeding, hydration, and molts much more easily.

Juveniles

Enclosure: Medium terrestrial enclosure or appropriately sized acrylic display box
Substrate Depth: 4 to 6 inches of Terra Aranea
Ventilation and Humidity: Good airflow with a slightly moist lower layer
Decor: Cork bark hide, leaf litter, sphagnum moss, and a shallow water dish

Juveniles usually grow quickly when fed well and kept in stable conditions. They may spend more time visible than some slower-growing species, but do not worry if they decide to disappear into a burrow for a while. That is normal tarantula behavior.

Adults

Enclosure: Large terrestrial enclosure with generous floor space (10 gallon minimum)
Substrate Depth: 6 to 8 inches of Terra Aranea
Ventilation and Humidity: Good ventilation with moist lower layers and a drier surface layer
Decor: Large cork bark hide, leaf litter, sphagnum moss, live plants, and a shallow water dish

A 10-gallon enclosure should be considered the bare minimum for an adult, and a larger setup with more floor space is even better if you can provide it safely. A 20-gallon long or similarly sized terrestrial enclosure gives you more room to create substrate depth, plant cover, moisture gradients, and a more naturalistic display.

Avoid tall enclosures. This is a heavy-bodied terrestrial tarantula, and a fall can be dangerous or fatal. Keep the distance between the substrate surface and the lid low enough that a fall will not rupture the abdomen.

Substrate & Humidity

This species does best with a setup that provides stable moisture without becoming wet and stagnant.

Keep the lower layers of substrate slightly damp
Allow the surface to dry somewhat between waterings
Provide a full water dish at all times
Overflow the water dish occasionally to hydrate one section of substrate
Use leaf litter and sphagnum moss to help hold pockets of humidity
Avoid swampy, stagnant conditions

Terra Aranea works well for this species because it holds moisture while still supporting burrows and tunnels. The goal is not to chase a random humidity number. The goal is to provide choices. One area can be a little more humid. Another can be drier. The lower substrate layers can stay damp while the surface has more airflow. That gives the tarantula options instead of forcing them into one flat condition across the entire enclosure.

Temperature & Lighting

Maintain temperatures between 70 and 78°F
Normal room temperatures are usually fine
Avoid heat lamps and direct overhead heat
If supplemental heat is needed, heat the room or use controlled side/back heat with a thermostat
Lighting is only needed for plants, display, or a consistent day/night cycle

This species does not need bright lighting. If you are keeping live plants, low-output LED or fluorescent lighting can be used on a timer. Make sure the tarantula has hides, leaf litter, cork bark, and shaded areas so they can avoid direct light when they want to.

Do not place a heat pad under the enclosure. Terrestrial tarantulas often burrow to escape heat, and bottom heat reverses that natural gradient. If they dig down and the enclosure gets warmer instead of cooler, you have created a trap instead of a refuge.

Feeding Schedule

Acanthoscurria geniculata is famous for its feeding response. They are bold, quick, and often hit prey with enough enthusiasm to make you question your life choices for a second.

That does not mean they need to be fed every time they act hungry.

Feeding should always be based on body condition, not just appetite. If the abdomen is smaller than the carapace, feed more often. If the abdomen is larger than the carapace, cut back. Overfeeding can lead to obesity, mobility issues, molting complications, and a greater risk of injury from falls.

Spiderlings

Frequency: Once or twice weekly
Prey: Flightless fruit flies, confused flour beetles, small roach nymphs, pinhead crickets, or pre-killed prey pieces (cricket legs or cut up meal worms)
Post-molt: Wait 24 to 48 hours before feeding

Spiderlings often grow quickly with steady feeding. Pre-killed prey is completely fine at this size, especially if the sling is nervous or the prey item is close to their body size.

Juveniles

Frequency: Every 5 to 10 days
Prey: Small to medium crickets, roaches, or appropriately sized mealworms
Guidelines: Prey should be no larger than the tarantula’s body length
Post-molt: Wait 3 to 7 days before feeding

Juveniles are often excellent eaters, but uneaten prey should still be removed within 24 hours. Never leave live feeders roaming in the enclosure if the tarantula is in premolt or has recently molted.

Adults

Frequency: Every 10 to 14 days, or every 2 to 3 weeks depending on abdomen size
Prey: Large crickets, roaches, or other appropriate feeder insects
Guidelines: Adjust feeding based on body condition, not enthusiasm for food
Post-molt: Wait 7 to 14 days before feeding

Adults can take down large prey, but that does not mean they need oversized feeders. Reasonable prey items are safer, easier to digest, and less likely to injure the tarantula. Avoid the temptation to feed your tarantula vertebrates like mice or feeder lizards, because you needlessly run the risk of your tarantula being hurt.

Supplements

Tarantulas don’t require vitamin or calcium supplements. You should gutload your feeder insects with fresh fruits and vegetables for at least 24 hours before feeding. This is how you make sure your tarantula is getting all the nutrients they need to thrive.

A hungry Acanthoscurria geniculata will probably eat almost anything that moves, but that does not mean all feeders are equal. Healthy, gutloaded feeders make much better meals

Behavior & Handling

The Brazilian White Knee is bold, active, and usually very food-motivated. That makes them a fantastic display tarantula, but it also means you need to pay attention when opening the enclosure.

This species can be quick to react to movement, especially if they think food is involved. They may pounce on prey, strike at water being poured into the enclosure, or grab tongs if they mistake them for a feeder. That feeding response is impressive, but it is also a reminder to use tools and stay aware.

They are not usually a species I would describe as fragile or overly sensitive, but they can be defensive. When disturbed, they may kick urticating hairs, raise the front legs, slap the ground, or retreat. Some individuals are calmer than others, but this is not a tarantula I would recommend handling.

Handling is usually more dangerous for the tarantula than the keeper. They are heavy-bodied, and a fall from even a short distance can cause them serious injury. Their urticating hairs are also something you should take seriously, especially around your eyes and face.

Enjoy them as a display animal and use tools during maintenance. Move slowly. Respect the spider, and the enclosure will be a lot easier to manage.

Maintenance & Bioactive Considerations

A naturalistic or bioactive setup can work very well for this species, especially because they appreciate moisture, cover, and deep substrate.

Keep the water dish clean and full
Spot clean waste and boluses as needed
Remove uneaten prey within 24 hours
Keep leaf litter topped off
Maintain a damp lower substrate layer
Use springtails to help process organic waste
Monitor for mold, mites, or stagnant air

Because this species is large and powerful, don’t get emotionally attached to your plants. These tarantulas may dig up plants, drag moss around, bury leaf litter, move cork bark, and remodel their enclosure in ways you may not approve.

Hardy tropical plants, cork bark, and deep Terra Aranea substrate give the enclosure a better chance of holding together in the face of this bulldozing spider. The goal is a functional enclosure that can handle a large terrestrial tarantula behaving like a large terrestrial tarantula.

Common Issues

Overfeeding: This species has a huge feeding response and can become overweight if fed too heavily
Dry Conditions: Bone-dry substrate can lead to dehydration and bad molts
Poor Ventilation: Moist setups still need airflow to prevent stagnant air and mold
Too Much Height: Falls are dangerous for heavy-bodied terrestrial tarantulas
Urticating Hairs: This species can kick irritating hairs when disturbed
Mistaken Hunger: A strong feeding response does not always mean the spider needs more food
Plant Destruction: Adults may dig up plants or rearrange the enclosure

Final Thoughts

Acanthoscurria geniculata is big, bold, beautiful, fast-growing, and usually very visible compared to more secretive species. When they hit prey, they do so with the kind of commitment that makes feeding day feel like a main-stage event.

But that feeding response is also where a lot of keepers can get into trouble; just because they will eat does not mean that they should eat. This is a species that will try to convince you they are starving five minutes after finishing a meal. Watch the abdomen, not the attitude or pouty eyes.

With deep Terra Aranea substrate, stable moisture, good ventilation, a secure hide, and enough floor space, the Brazilian White Knee can be an incredible pet tarantula. They don’t have complicated care, but they do need an enclosure designed around what they actually are: a massive, terrestrial, moisture-loving New World tarantula with a serious appetite and enough personality to keep things interesting.

They are beginner-friendly, but they’re no pet rock. They’re powerful, reactive, and sometimes a little defensive. Give them respect, give them space, and give them a setup that lets them dig, hide, hunt, and settle in naturally. If you do all that, Acanthoscurria geniculata is one of the most rewarding large terrestrial tarantulas you can keep as a pet!

Written by Richard Stewart of Tarantula Collective 6/2/2026

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