Brachypelma klaasi

Geographic Range

Mexican pink tarantulas, Brachypelma klaasi, are found in North and Central Americas. Brachypelma klaasi inhabits many habitat types including humid, arid, deciduous forest zones. It is found at elevations of 300 to 1,400 m above sea level. The known range of this species extends from Tepic, Nayarit in the north to Chamela, Jalisco in the South. This is mainly the southern Pacific coast of Mexico. The largest known population of B. klaasi can be found at the biological reserve at Chamela, Jalisco. (Arnett, 1986)


This tarantula lives in tropical deciduous forest at elevations between 300 and 1,400 m above sea level. The soil is sandy, neutral, and sparse in organic matter.

The climate is highly seasonal, with pronounced wet and dry seasons. The annual rainfall (707 mm) occurs almost exclusively between June and December, when hurricanes are not uncommon. The mean temperature in the wet season is 32 C. The mean temperature in the dry season is 29 C. (Yanez and Floater, 2000; Arnett, 1986)

  • Range elevation
    300 to 1,400 m
    984.25 to ft

Physical Description

Brachypelma klaasi is sexually dimorphic, with females being larger and heavier than males. Female B. klaasi body size ranges from 50 to 75 mm, and weigh between 19.7 and 50 grams. Male weight ranges from 10 to 45 grams. (Arnett, 1986)

These spiders are colorful, by our standards. Brachypelma klaasi has a black carapace, tarsi, femora, and coxae, and orange-yellow metatarsi, tibias, and patellas. The hairs on the opistosoma are also orange-yellow in color. Although this sounds flashy, these spiders are actually well camoflauged in their natural environment, and are quite difficult to see on natural substrates. (Locht, et al., 1999)

  • Sexual Dimorphism
  • female larger
  • Range mass
    10 to 50 g
    0.35 to 1.76 oz


Mating in this species occurs after a period of courtship behavior shown by a male. Males approach a female to initiate mating. Males apparently use some tactile or chemical cues from the silk the female deposits near her burrow to identify her as a potential mate. Once in contact with the female's silk, the male begins drumming his legs on it. This drumming alerts the female to the presence of a male. (Yanez, et al., 1999)

Following this drumming either the male approaches the female, or the female may approach the male. The male may then box the female with his pedipalps. Mating typically takes place outside of the female's burrow. The actual physical contact between male and female may last between 67 and 196 seconds. Longer contact was observed in a pair where the female was most receptive, shorter contact occured in pairs where females were more aggressive. In two of three observed matings in this species, the female attacked the male after mating occured, and might have killed him if observers had not intervened. Although sexual cannabalism is not common in the Theraphosidae, this may be because of specially adapted male holds that prevent females from eating them. (Yanez, et al., 1999)

After mating, females retreat into the burrow to produce an egg sac. They are often sealed in with leaves and silk. (Yanez, et al., 1999)

Male B. klaasi sometimes show an interesting post-mating behavior. After copulating, males may deposit silk around the silk at the entrance to the female's burrow. In a cage, a second male introduced into the female's cage was unable to locate her burrow. This deposition of silk by males may inhibit other males from mating with a female, and may be a means of competition between males. (Yanez, et al., 1999; Yanez, et al., 1999)

Although in the three matings reported by Yanez et al. 1999, only one male mated with each female, not enough matings have been studied to determine the precise mating system. If females routinely kill their mates, then males may be monogamous. However, there is no telling whether females may attract additional males after mating with the first. If females do not kill their mates, males may then move on to mate with other females. Further research into this area of behavior would be helpful. (Yanez, et al., 1999)

The female B. klaasi lays a single egg sac containing 400 to 800 eggs in her burrow in April to May, immediately before the first rains of the season. The female guards the egg sac for two to three months before the spiderlings emerge in June to July. The spiderlings remain in the burrow for three more weeks before dispersing in July or August. Females become reproductively mature between 7 and 9 years of age, and can live for as many as 30 years. It is likely that they produce many eggs sacs durin their lives. Males mature more quickly, becoming capable of reporoduction at 4 to 6 years of age. (Locht, et al., 1999; Milne, 1980)

  • Breeding interval
    Breeding may occur annually for mature animals.
  • Breeding season
    Breeding takes place in April and May.
  • Range number of offspring
    400 to 800
  • Range gestation period
    2 to 3 months
  • Average time to independence
    3 weeks
  • Range age at sexual or reproductive maturity (female)
    7 to 9 minutes
  • Range age at sexual or reproductive maturity (male)
    4 to 6 minutes

Females invest in their young by provisioning their eggs with nutrients. They also construct egg sacs to keep the eggs safe until hatching. The young remain in their mother's burrow for about three weeks after hatching, and the mother presumably protects them during this time. (Yanez, et al., 1999)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female


Females may live up to 30 years. Male lifespan may be less, especially because males tend to wander, and so are more likely to be victims of predation. There is also some evidence that females may cannabalize their mates, further reducing the life expectancy of males. (Yanez, et al., 1999)

  • Range lifespan
    Status: wild
    30 (high) years


Brachypelma klaasi is diurnal and is most active in the early morning and early evening. It is also the most colorful species of the genus. This is thought to be related to its diurnal habits. This spiders' burrow ranges from .15 to meters deep. The burrow consist of a horizontal tunnel leading from the entrance to a primary chamber, and an inclined tunnel that connects the primary chamber to a larger, secondary chamber where the spider rests at night and prey is consumed. A survey was held and twenty-eight individuals of B. klaasi (13 females, 7 males, 9 juveniles, and 2 spiderlings) were found. Thirteen individuals were found in burrows, and fifteen individuals were found outside their burrows. The majority of the burrows contained females (69%), whereas three burrows held juveniles (23%), and one burrow contained a male (7%). Of the tarantulas found outside of the burrows: 40% were males, 7% females, 40% juveniles, and 13% spiderlings. (Yanez and Floater, 2000)

Communication and Perception

Communication in this species, at least as pertains to reproduction, includes tactile, and chemical components. Because males drum on female silk, females are aware of their presence outside their burrows. However, it has not been shown whether females are responding to vibrations from the drumming or noise produced from the drumming. Although these spiders have eight eyes, they are reported to have poor vision. (Arnett, 1986; Yanez, et al., 1999)

Food Habits

The hunting strategies of B. klaasi include actively searching the forest floor close to its burrow, including searching up to two meters high in the surrounding vegetation. The tarantula also uses the "sit-and-wait" hunting method. Silk around the entrance to the burrow helps to transmit vibrations from prey movement to the tarantula. Typical prey include large insects such as Orthoptera and Blattodea as well as small lizards and frogs. After feeding in the burrow, prey remains are removed from the burrow and deposited near the entrance. (Milne, 1980)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods


The main predators of B. klaasi are armadillos, skunks, snakes, and tarantula wasps. (Biodiverstiy 1996) However, because of the venom and the hairs on the body of the spider, the rate of predation on adults is probably low. Although we find these tarantulas brightly colored, they blend in well with their environment, and so are somewhat cryptic in nature. (Yanez and Floater, 2000; Locht, et al., 1999)

  • Anti-predator Adaptations
  • cryptic
  • Known Predators
    • armadillos
    • skunks
    • snakes
    • tarantula wasps

Ecosystem Roles

These tarantulas probably have some impact on insect populations. To the extent that they are a prey species, they may have a positive impact on predator populations. Because they burrow, these spiders may also be seen as contributing to soil aeration. (Locht, et al., 1999; Locht, et al., 1999)

Economic Importance for Humans: Positive

The main populations of B. klaasi are located away from humans. Therefore there is not much human interaction. The most reaction with this tarantula occurs at zoos. This is an extremely beautiful species, and a favorite of those who love spiders. For this reason, these animals are illegally captured and used in the pet trade. (Yanez and Floater, 2000; Locht, et al., 1999; Yanez, et al., 1999)

Economic Importance for Humans: Negative

The species adversely affects humans by illegal pet trafficking. Because B. klaasi is rare, it has an extremely high value on the black market. This causes many people to be arrested trying to steal tarantulas. Also, when humans do encounter these spiders, there is always the possibility of being bitten, which can be painful.

  • Negative Impacts
  • injures humans
    • bites or stings

Conservation Status

The value placed on tarantulas in the pet trade has led to high rates of collection and trafficking from Mexico. For this reason, all species of the genus Brachypelma have been included in Appendix II of CITES. This is the only genus of spiders to be recognized as endangered by CITES. The extreme rarity of several species of Brachypelma, combined with potential threats of habitat degradation and illegal trafficking, has led to the need for captive breeding for future reintroduction. Brachypelma klaasi is the rarest and most threatened of Mexican tarantulas. It is a long living, slow growing species. With a high proportion of pre-adult mortality; less the .1% of individuals are estimated to survive from egg to adult in the field. (Yanez and Floater, 2000)

Other Comments

From June 1997 to August 1998, twelve intensive surveys were performed. These surveys where done at the Estaciòn de Biologìa, Camela, Mexico which is run by the Instituto de Biologìa (UNAM). If the scientist could not find an individual outside the burrow, a live grasshopper was placed inside the burrow to coax the tarantula out. If the grasshopper elicited no reaction, the burrow was excavated. In all cases excavation revealed no tarantula. If the grasshopper elicited a reaction, the tarantula was removed and marked with individual phosphorescent markings, and records were made of size, weight, maturity, and sex. During these surveys some of the tarantulas were removed for captive breeding. The results of these surveys account for almost all the knowledge that we have on B. klaasi.


Nancy Shefferly (editor), Animal Diversity Web.

Justin Hart (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.



living in the southern part of the New World. In other words, Central and South America.

World Map


uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


an animal that mainly eats meat


uses smells or other chemicals to communicate


having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

  1. active during the day, 2. lasting for one day.

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body


union of egg and spermatozoan


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


An animal that eats mainly insects or spiders.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

seasonal breeding

breeding is confined to a particular season


remains in the same area


reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in


lives alone


mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.


uses touch to communicate


Living on the ground.


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate

young precocial

young are relatively well-developed when born


Arnett, R. 1986. The Insect and Spider Colections of the World. Gainesville, Florida, USA: Brill/Flora and Flauna Publications.

Locht, A., M. Yanez, I. Vazquez. 1999. Distribution and natural history of Mexican species of Brachypelma and Brachypelmides (Theraphosidae, Theraphosinae) with morphological evidence for their synonomy. The Journal of Arachnology, 27: 196-200.

Milne, L. 1980. The Audobon Society Field Guide to North American Insects and Spiders. New York, New York, USA: Knopft.

Yanez, M., A. Locht, R. Macias-Ordonez. 1999. Courtship and mating behavior of Brachypelma klaasi (Aranea, Theraphosidae). The Journal of Arachnology, 27: 165-170.

Yanez, M., G. Floater. 2000. Spatial distribution and habitat preference of the endangered tarantula, Brachypelma klaasi (Araneae: Theraphosidae) in Mexico. Biodiversity and Conservation, 9/6: 795-810.