Mexican Red-Kneed Tarantula

Mexican Red-kneed Tarantula

The red-kneed tarantula is found in Mexico, south-western United States and Panama.
They are found in dry areas with sparse vegetation. Burrows are found at the bases of cacti or similar plants or at the base of rocky areas, etc.
When mature, this tarantula has a dark-colored body with orange patches on the joints of its legs. The second element of the legs is orange-red. It is a very stocky species of tarantula with a tan and black carapace. Following molting, the colors are more pronounced. The dark portion is very black while the orange-red portions will be far more on the reddish side.
Mexican Red-kneed Tarantula

It carves deep burrows into soil banks to keep it protected from predators and enables it to ambush passing prey. The burrow is typically located in or not far from vegetation. It has a single entrance with a tunnel leading to one or two chambers.

The entrance is just slightly larger than the body size of the spider. The tunnel, usually about three times the tarantula’s leg span in length, leads to a chamber which is large enough for the spider to safely molt in. Further down the burrow, via a shorter tunnel is a larger chamber located where the spider will rest and eat its prey. When the tarantula needs privacy, (when molting or laying eggs), the entrance is sealed with silk that is sometimes covered with soil and leaves. The females spend the majority of their lives in their burrows.

Although usually peaceful, when threatened, this tarantula species will rear up to display its fangs and the bristles on its abdomen. By rubbing its back legs, hair can be flipped as a defense. These ”urticating” hairs are barbed and in contact with soft tissue they dig in and cause an irritation. It is not venomous to humans and is considered extremely docile, though, as with all tarantulas, allergies may intensify with any bite. It is nocturnal and solitary.

Two claws on each foot enable the spider to grip and climb up slippery surfaces. Palps – a pair of sensory appendages – on the end of the legs allow the spider to smell, taste, and feel. Eight eyes positioned around the head enable it to see both forward and backwards. However, it does not have great vision and instead relies on its leg hairs for guidance.

Spiders do not have ears for hearing, but instead have a very well-developed ability to sense vibrations, both airborne and those transmitted through the surface on which they are standing. This sensory ability is sited in a number of different receptors on their body, but especially on the legs.


During courtship, the male approaches a female shelter cautiously, tapping and vibrating his legs. This lures the female out of her burrow. Once out, the male lunges forward to using his hooks to hold the females chelicerae and pushes her into an almost upright position. Before copulation the male takes up into his palps sperm that he has deposited on a specially spun sperm web. The sperm is then implanted in the female’s storage organs and may remain there for some time.

Females lay several hundred eggs which she covers with a sticky liquid containing the sperm. The eggs are wrapped in silk and carried between the mother’s fangs. Eggs hatch between one and a half and two and a half months. Spiderlings are guarded for several weeks. Typically, the male will die within weeks of mating.

This species of tarantula grows very slowly and matures relatively late. Males reach sexual maturity at an age of four to five years. Females mature two to three years later than males, a factor which would prevent inbreeding in the wild. In captivity, with optimal conditions, these spiders may mature at a younger age than their wild counterparts.

Interesting Facts:
  • Tarantulas molt usually once a year. Molting of the old exoskeleton allows the spider to grow larger, gives it a completely new set of undamaged sensory and protective hairs and also gets rid of any parasite or fungus that might have started to grow on its exterior. Lost or damaged appendages are regenerated gradually with each succeeding molt, even during the adult phase.
  • Once they detect their prey, Mexican red-knee tarantulas rush out to bite prey and return to the burrow. They hold down their pray with their front legs and inject their venom to paralyze and liquefy their victims. They consume the juices of their prey, leaving behind undigested body parts. These are typically wrapped up in a web and transported to another area of the burrow.
Habitat destruction and the pet trade are of concern for these spiders. Tarantulas are valuable predators as they help stabilize and regulate insect populations.
Did YOU Know?    
Female red-kneed tarantulas are thought to be one of the most long lived tarantulas.
Mexican Red-kneed Tarantula
Class: spiders
Order: Theraphosidae
Family: Brachypelma
Genus: Brachypelma
Species: smithi
Length: Up to 5.5 inches long
Weight: 0.5 ounces
Average Lifespan: Females 30 years; Males 5-6 years
Wild Diet: Small invertebrates such as crickets, roaches, grasshoppers and small rodents
Predators: Birds, moths, lizards, and other insect eaters.
Where at the Zoo? Small Animal Building

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