Spiders have long inhabited the edges of humanity’s nightmares, and the larger the arachnid, the more fear they elicit. Ironically, the largest spiders tend to be the least harmful to humans and can be quite helpful. Aside from their usefulness in curbing insect populations, tarantula venom is being studied to help treat muscular dystrophy, incontinence, and atrial fibrillation.
Scientific & Common Names
Kingdom - Animalia
Phylum - Arthropoda
Class - Arachnida
Order - Araneae
Family - Theraphosidae
Genus – Brachypelma
Species –Brachypelma smithi
Common Names – Mexican Orange-kneed Tarantula, Orange-kneed Tarantula, Red Knee Tarantula, Red-kneed Tarantula
Tarantulas are long lived creatures and female orange-kneed tarantulas can live as long as 30 years, while the smaller males live only about 10. Their bodies are black or brown with some white markings and prominent orange or reddish-orange stripes on their legs and back. They range from 4-7 inches with the males lighter bodied with longer legs in proportion to their bodies. Since they have a hard exoskeleton, tarantulas must molt to grow. It is during molting that they begin to regrow lost limbs, a process that can take years. After molting, even a tarantula’s teeth are soft and they are unable to eat until they harden.
Orange-kneed tarantulas are territorial and solitary. They come together to breed, but the male puts himself at risk when doing so since the females have been known to eat them after mating. The females will mate within months of their yearly molt and the egg sacks will be produced weeks later, with the timing dependent on variables like temperature and the general health of the female. The eggs will hatch in a few weeks and nymphs will emerge. These are all white and will become full color spiderlings after their first molt, at which time they will leave the nest.
Orange-kneed tarantulas are burrowing spiders and live in arid regions like scrub land or semi-desert areas. They are carnivores and hunt for insects, small mammals, and reptiles. While they spend much of their life in burrows, these spiders can run in short spurt up to 18 mph, primarily when threatened and not when hunting. Females are more aggressive than males, which could account for their larger, more robust size and longer life span. Like all New World (North and South American) tarantulas, orange-kneed are able to flick the hairs from their abdomen when threatened. These hairs can cause skin irritation, eye problems, or, in extreme cases, even death in small mammals. This is their primary defense since their venom, aside from being physically expensive to create, is too weak to be an effective deterrent to larger predatory animals.
The over eight hundred species of tarantulas are found primarily in North and South America, Asia, and Africa with only a few species in Australia and Europe. They can be found in trees, deserts, grasslands, caves, and burrowing underground. The body type of spiders does not lend well to being fossilized and the few ancient specimens found were preserved in amber. Due to the lack of many fossilized specimens, it is impossible to know when modern tarantulas emerged, but there is evidence found in amber that dates back millions of years, with little change from today’s tarantulas.
Due to both the pet trade and habitat loss, the orange-kneed tarantula is now considered near threatened and they are protected in the wild.
Tarantulas Today by Andreas Tinter
University at Buffalo
Arachnids by Jan Beccaloni, Trudy Brannan
Encyclopedia of Spiders by James Jones
The Evolution of Mating Systems in Insects and Arachnids by Editors Jae C. Choe, Bernard J. Crespi