Small Animals

Mexican Redknee Tarantula

Mexican Redknee Tarantula (Brachypelma smithi) Care Sheet - Information

(Brachypelma smithi)

  • Kingdom:
  • Animalia
  • Phylum:
  • Arthropoda
  • Class:
  • Arachnida
  • Order:
  • Araneae
  • Family:
  • Theraphosidae
  • Genus:
  • Brachypelma
  • Species:
  • smithi

Mexican Redknee Tarantula
(Brachypelma smithi)

Mexican Redknee Tarantula (Brachypelma smithi)

Mexican Redknee Tarantula

The Mexican Redknee Tarantula (Brachypelma smithi) is a popular pet choice for hobbyists because of its large size, beautiful coloration and docile demeanor. The redknee is an attractive tarantula and has a dark brown body and legs. The joints on the legs are a dark red-orange color, which is where there name has been derived. The contrast between the colors makes for a visually appealing tarantula. Though not especially known for their bite, these tarantulas are in fact venomous. They have hollow fanged chelicerae that is connected to their venom glands. Their bite isn't fatal but can cause pain equivalent to that of a bee or wasp sting.

These tarantulas are known to be docile, making them a good choice for those looking into keeping tarantulas. Like other tarantulas, these arachnids will defend themselves if they feel threatened. If your tarantula felt agitated or threatened it could flick urticating hairs (small barbed hairs) from its abdomen and back legs. The hairs will cause skin irritation and itching. It can also result in a small rash. If it were inclined, it could also bite you. Unless you are allergic, you won't die from the bite but you are going to know that it bit you. If you respect the tarantula, it will respect you.


Redknee tarantulas are equipped with 8 eyes that allow them to see forward and backward. The hairs found on the legs can sense vibration and have pedipalps on the end of their legs that allow them to taste, smell, and feel. Each foot has 2 small claws that enables them to climb and grip different surfaces.

Enclosure - Housing

This species is easy to house and does well in a 10 gallon aquarium. The general rule is that the housing should be around 3 times the length of the legs long and 2 times the length of their legs tall.


These arachnids are terrestrial burrowers. To allow them to burrow, your substrate should be 6-8" or deeper. The substrate can be slightly damp sand and peat moss or coconut husk. A 50/50 ratio works well.


These arachnids are burrowers and will appreciate and utilize a hide above the entrance to their burrow. The hide, which could be a flower pot cut in half, a coconut shell hide ,cork bark or a commercially available hide will help keep the burrow dark and the spider feeling secure. Prior to placing your redknee in the enclosure, place the hide to one side of the enclosure and dig a depression beneath it. This will offer your tarantula a starting point for their burrow and will encourage its use.


The ambient air temperatures within the redknees enclosure should range from 78° - 84°F. They can be housed at these temperatures from first instar to adult.

You may be required to provide a heat source to maintain these temperatures. Some owners prefer under tank heaters and others prefer to heat from above using a low-watt light. Both methods can work and both come with risks and warnings.

Under Tank Heaters
Under Tank heaters (UTH) are used by many enthusiasts for heating their tarantulas. A UTH should be affixed to either the bottom of the enclosure, away from the spiders burrow, or to the side of the enclosure. The size of the UTH will be depicted by the size of the housing that you are providing. Keep in mind that this species likes to burrow. If you place the heat pad beneath their burrow, it could dry out the burrow and could even slowly cook your tarantula, turning fatal.

Overhead Lighting
Overhead lighting can be used to heat the enclosure. You will want to use a low-watt light and will need to experiment with the wattage you use to reach the desired temperatures. Lights that are too warm can quickly overheat smaller enclosures and will zap whatever humidity it can evaporate. The light can be placed slightly off from being over the spiders burrow entrance. (The hide you provide should help keep the burrow dark.) This will allow the tarantula the ability to bask under the light at the entrance of their burrow, which they have been known to do. You can also keep it to one side away from the burrow too. Your tarantulas personality and preferences will depict where the lighting remains.

Digital thermometers and heat guns are perfect for monitoring the temperatures within your tarantulas enclosure.

Digital Thermometers
The best digital thermometers are those that read both the indoor and outdoor temperatures at the same time. These units have an external probe that is designed to be placed out of a window while the base unit remains inside. From the comfort of the indoors, you can see the temperature of both the room you are in, as well as the temperature outside. This type of digital thermometer can be purchased at varying retail stores such as Target and Wal-Mart. Unbelievably, these can actually be bought for under $15.00 and sometimes as low as $10.00. The investment in this single unit will allow you to place the base of the unit over on the cool end of the enclosure and have the probe resting on the warm end. With this single unit you will be capable of monitoring both ends of the enclosure at the same time, and with great accuracy. This is the best solution for monitoring the temperatures.

Temperature Guns
Temperature guns are an accurate and swift method to check out the temperature of your cages and environments instantly, at any time. Using infrared technology, you simply aim the hand held device exactly at the point you are looking to get the temperature of, and you press a button. Within seconds, you get the exact temperature reading for that location.


Tarantulas spend the majority of their time in their burrows where it is dark. This doesn't mean they do not require a photoperiod though. A normal light cycle of 12 hours on and 12 hours off is typical. The light used should be of low-wattage to prevent stressing the spider. Your spider must be able to escape the lighting if it is inclined.

Some owners rely on the rooms ambient light to create their photoperiod. If your enclosure doesn't require additional heating from your lighting choices, this is a completely acceptable method since most tarantulas shun away from lighting. Dimly lit enclosures will allow you the best opportunity to observe your tarantulas natural behaviors.


This species doesn't require excessive humidity and does well when kept in the 50-60% range. A humidity of 55% is ideal. This may require light misting, away from the hide. The misting could agitate your spider, which could result in them flicking their hairs. Don't spray the tarantula directly. You can also overfill the spiders water dish every once in awhile and allow that water to evaporate. You will need to monitor the humidity or else the spider could have a hard time molting and this could turn fatal. Inexpensive hygrometers can be purchased for monitoring the humidity. You can also purchase a combination thermometer and hygrometer.

Dehydration can be dangerous. Many keepers try to replicate the dry, desert habitat these spiders come from and end up keeping them too dry. The burrows in the wild always have a higher ambient humidity than the outside air. Inadequate humidity will cause your tarantula to appear shriveled and will result in very poor molts. Bad molts can result in the death of tarantulas. If you notice that your tarantula is curling its tarsi inward and is lethargic, they could be dehydrated.

Mexican Redknee Tarantula (Brachypelma smithi) Anatomy

Anatomy Diagram

(1) - Jointed Legs
(2) - Cephalothorax
(3) - Abdomen


These spiders can be aggressive feeders and should be fed prey that is appropriate in size. Appropriate sized prey items would be something smaller than your spiders cephalothorax as described above. Crickets and roaches are typically used as primary food sources and should be offered several times a week. A good starting point is to offer 1-2 appropriately sized prey items every Monday, Wednesday, and Friday. You can adjust your feedings based on how often your tarantula feeds.

If your tarantula stops eating and you haven't changed any of its husbandry (heating, lighting, humidity, etc.), it is likely that your tarantula is preparing to molt. External changes or inadequate husbandry can cause stress and prevent your tarantula from eating. Undersized prey or feeding too infrequently can cause the abdomen to appear thin. If your tarantula appears thin and is consuming the prey you offer quickly, increase the frequency of your feedings or provide larger - more prey to be consumed at feedings.

Spiderlings can be started off on fruit flies and then properly sized crickets and roaches as they mature.


A shallow dish of water should be left in the enclosure. A rock should be placed inside the dish to prevent the tarantula from going in the water and to help drowning prey escape so they can still be eaten. The likelihood of your spider drinking from the dish is slim but the option should be made available at all times.


Redknees can be sexed as early as fifth instar if using a light microscope. The process is not simple and requires that you have a fresh molt. The shed exuvium (cast skin) needs to be gently separated and opened. You will be looking for the book lungs, which are four white patches. Between the pair of book lungs there may or may not be a small triangular flap called the epigastric furrow. The epigastric furrow is only present in females.

Unfortunately you will never be able to look at a Mexican Redknee Tarantula and sex it by visual inspection. To get a more comprehensive look at how to sex, read "How to Determine the Sex of Your Tarantula", by Mark R Hart. (Edited and Reviewed by Rick West, an Arachnologist.)


Molting is commonly considered the most dangerous time during your tarantula’s life-cycle. While your tarantula is molting it is susceptible to attack from its prey. If you notice your tarantula is preparing to molt, ensure that there are no prey items inside of the enclosure. Poor humidity can hinder a molt and that can lead to mangled limbs and can even be fatal.
When they begin to molt, your tarantula will lay on its back, with its legs facing up in the air and they may appear to be dead. Do not disturb your tarantula during this time.


Brachypelma smithi - © Jurgen E Haug [CC BY-SA 3.0]