Brachypelma hamorii

The *Brachypelma hamorii* is a large, terrestrial tarantula native to Mexico.

It is commonly known as the Mexican redknee tarantula. This species is considered vulnerable in the wild. It plays an important role in its ecosystem. These spiders live on the ground rather than in trees. They are found in the hilly, deciduous tropical forests of Mexico. This includes the western faces of the Sierra Madre Occidental and Sierra Madre del Sur mountain ranges. They live specifically in the states of Colima, Jalisco, and Michoacán.

To grow, this tarantula must undergo a process called molting. Because it is an arthropod, it possesses a hard exoskeleton. This outer shell cannot stretch as the animal grows. To increase in size, the spider must shed its old skin. Before molting, the spider becomes sluggish and stops eating. This helps it conserve energy for the difficult task ahead. The abdomen often darkens as the new exoskeleton forms underneath. The spider typically turns onto its back to molt. It wiggles its limbs to loosen the old shell. This process can take several hours. After molting, the spider may not eat for up to a month. This is because its fangs are part of the exoskeleton and remain soft until they harden.

For many years, scientists struggled to distinguish *B. hamorii* from a similar species called *B. smithi*. In 1897, *B. smithi* was first described, but the original specimens were later found to be immature males. In 1994, A. M. Smith redescribed *B. smithi* using two adult specimens. However, those specimens were actually *B. hamorii*. In 1997, Marc Tesmoingt, Frédéric Cleton, and Jean Verdez officially described *B. hamorii*. They noted differences in the female spermathecae, which are internal reproductive organs. The confusion persisted until 2017. That year, J. Mendoza and O. Francke clarified the distinction between the two species. They used DNA barcoding to prove they were unique. This method examines about 650 base pairs of the mitochondrial gene cytochrome oxidase I.

There are several physical ways to tell these spiders apart. When viewed from above, the chelicerae of *B. hamorii* often show two brownish-pink bands. *B. smithi* lacks these specific bands. In mature males, the palpal bulb is a key identifier. The palpal bulb of *B. hamorii* is narrower and less straight than the spoon-shaped bulb of *B. smithi*. In mature females, the shape of the spermathecae also differs. The baseplate of the *B. hamorii* spermatheca is elliptical. In contrast, the *B. smithi* version is divided and subtriangular. The ventral face of the *B. hamorii* spermatheca is also smooth rather than striated.

Physical dimensions and lifespans vary between the sexes. Adult females typically have a body length between 4.5 and 5.5 centimeters. Adult males are generally smaller in body length. However, males possess much longer legs than females. The fourth leg is the longest limb on the spider. The legs and palps are black or reddish-black. They feature three distinct colored rings. These include deep orange on the patellae and pale orange-yellow on the tibiae. The metatarsi end in a yellowish-white color. Longevity is also quite different for each sex. Females can live up to 30 years. Males usually live for only about 5 years.

In the wild, these spiders rely on complex burrows for survival.

They build or extend burrows under rocks, logs, or tree roots. These burrows protect them from predators like the white-nosed coati. A typical burrow has a single entrance and a tunnel. The tunnel is usually about three times the length of the spider's leg span. It leads to a chamber large enough for molting. A second, larger chamber is used for resting and eating. The entrance is only slightly larger than the spider's body. When the spider needs privacy to lay eggs or molt, it seals the entrance with silk, soil, and leaves.

Conservation efforts are vital for the survival of *B. hamorii*. The species faces threats from both the pet trade and local human activity. In 1985, *B. smithi* was placed on CITES Appendix II to regulate trade. Many Mexican redknee tarantulas are still smuggled out of the country. It was reported that at least 3,000 specimens were sent to the United States or Europe around 2017. Additionally, some local people kill the spiders due to myths and fear. They may use pesticides or gasoline in the burrows. While the species has been successfully bred in captivity, protecting their natural habitat remains a major challenge.