Though SF is generally tarantula-free due to its climate and topography, thousands of these massive spiders are currently on the move in the Bay Area.
Tarantulas are creatures that you either love or hate; there’s little room for ambivalence when one’s exoskeleton serves as inspiration for Halloween decor. But regardless of what feelings you hold for them, the California tarantula, which is the SF Bay Area’s only endemic tarantula, plays a major role in our region’s ecosystems.
Our Fuzzy, Eight-legged Friends are Looking for Love this Autumn!
The sexual cannibalism seen among other spiders is rare among Aphonopelma iodius (aka the Bay Area blond tarantula)🕷️🤎🕷️https://t.co/wfTLIpqPdy
✒️: Ralph Washington, Jr.
📷: Photo by Ben Witzke pic.twitter.com/TYcogxigqn
— Bay Nature magazine (@BayNature) October 15, 2022
Aside from being highly effective insectivores — they’re masters of eating hearty amounts of the crickets, grasshoppers, beetles, and caterpillars that could otherwise reproduce in overwhelming numbers — their burrows can serve as homes for other small creatures, once vacated. The tarantulas native to North America are largely terrestrial, and these spiders can serve as somewhat efficient pollinators for low-hanging flowering plants; during the mating season, male tarantulas regularly travel over a mile to find a mate.
In the San Francisco Bay Area, the region’s nearly 8 million residents are now being reminded that they share this slice of Northern California with large spiders… now that we’re in the thick of their mating season.
The California tarantula (Aphonopelma chalcodes), which is also commonly referred to as the desert tarantula, can be found throughout the SF Bay Area but is especially commonly on Mount Diablo and other regional environments that boast an arid microclimate and rocky outcrops. In fact, the spider that occupies our area was recently re-categorized into its own subspecies. From August to October, these usually solitary creatures — invertebrates capable of living over 30 years — exit their dens and seek out a reproductive mate.
And it’s a harrowing journey for many, particularly the male tarantulas. (Female spiders often stay relatively close to their home ranges and burrows, with the male spiders traversing long distances to reach them, the pheromones released by female tarantulas existing as their north stars.) It can take days, sometimes weeks for males to find an accepting mate; female spiders are much larger than their male counterparts — and they absolutely call the shots.
Their nocturnal nature means people often find them at night or dusk, crossing country roads and hiking trails. But that’s not to say early morning and midday hikers won’t come across them on their paths. Regardless, it’s imperative that we humans allow them to complete their crossings — and not pick them up. Though these animals are mostly harmless and not fatal (barring a severe allergic reaction to their urticating hairs, which they’ll sometimes fling off their abdomens when threatened), tarantulas are quite fragile. Even a short drop down from a person’s hand can cause their thorax to explode, killing them instantly.
For those keen on seeing these spiders IRL and learning more about them, the East Bay Regional Park District will offer its annual tarantula hiking tours in October — just in time for Spooky Szn.
Feature image: Courtesy of X via [at]MidpenOpenSpace