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.
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.
After mating, females retreat into the burrow to produce an egg sac. They are often sealed in with leaves and silk.
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.
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.
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.
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.
Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; fertilization (External ); oviparous ; sperm-storing
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.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female)