Brachypelma smithi (common name the Mexican Red-kneed Tarantula), is a terrestrial tarantula native to the western faces of the Sierra Madre Occidental and Sierra Madre del Sur mountain ranges in Mexico. They are a large species, and are a popular choice for enthusiasts. Like most tarantulas, they live a very long life.
The mature Brachypelma Smithi has a dark-colored body with orange patches on the joints of its legs. The second element of the legs is orange-red. 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.
An adult female has a body roughly 4 inches long, with a leg span of 6 inches, and a mass of approximately 15 grams. Both sexes are similar in appearance, with the male having a smaller body, but longer legs. Though the male is of comparable size to the female, the male has a much smaller mass.