Are Tarantulas Dangerous and Other Interesting Tarantula Facts

Are tarantulas dangerous? Are tarantulas poisonous? Do tarantulas bite? These questions, and more continue to vex many people.

The easy answer to the questions is no, no and yes. All things being equal, tarantulas are neither dangerous nor poisonous. However, like all spiders, when they fear for their lives, they will bite.

It comes as little surprise that New World tarantulas rank among the most popular and least understood spiders in the United States. They are simultaneously in large demand for the spider pet trade and creators of large amounts of fear in the general population due to their large size.

Understanding tarantulas starts by defining them as the group of tarantulas (Theraphosidae) indigenous to North, South and Central America.

Generally they prefer warm habitats, with different species adapted to either life on the ground or life in the trees. Tree tarantulas tend to be smaller in size than their terrestrial counterparts, and as the article New World Arboreal Tarantulas points out:

New World arboreal tarantula species vary in size from several small Avicularia and Tapinauchenius species, which may only attain leg spans of 7.5 cm (3") to several members of the genera Avicularia and Psalmopoeus, which may attain leg spans of 17.5 cm (7") or slightly larger. Most species will average in size from 10 cm (4") to 12.5 cm (5") in leg span and are less robust in body size than comparatively sized terrestrial species. Most are colourful (Avicularia, Iridopelma and Tapinauchenius) or patterned (Psalmopoeus) and many are coloured in bright metallic hues of bronze, pink, green, blue, purple or gold on the carapace, trochanters and femurs of the legs (several species within the various genera).

Types of Tarantulas

The following sketch of four types of tarantulas provides insight into their relative danger as pets and in the wild.

Starting with the larger terrestrial spiders, the goliath birdeater (Theraphosa leblondi) of South America (second picture in the collage on the right), commonly receives credit for being the world's largest spider, having a leg span that approaches one foot in length. Typed as ground spiders, they inhabit the tropical rain forests floors in Northern South America, where they aggressively hunt small animals and birds that wander into their territory.

Their status as world's largest makes them a target for the pet trade. It should be noted that their aggressiveness extends to life as a pet. They bite and shoot uriticating hairs from their legs as defensive measures.

Of course not all new world tarantula species grow as large as dinner plates. Most of the fifty or so native North American species, for example, measure less than six inches long with their legs extended.

The lack of aggressiveness in the large, colorful and hairy terrestrial species captured the imagination of a segment of the population, resulting in increased demand for these species as pets.

Species in the Brachypelma genus, new world tarantulas found from Mexico, south through Central America, fit those criteria. The top picture in the collage on the right shows the Mexican redknee tarantula (Brachypelma smithi) (first picture in the collage), one of the initial high demand pet species.

Eventually the increased demand threatened their existence in the wild, and in 1994 member states of CITES voted to restrict the Brachypelma trade.

Concerns about wild tarantula populations also led to increased study of the spiders in their native habitat.

A recent survey covering the Distribution and Natural History of Mexican Species of Brachypelma and Brachypelmides, for example, documents tarantula habitat. However, it does not address current population trends.

Tarantula populations in the United States remain limited to areas west of the Mississippi River and south of Missouri.

The Desert Tarantula (Aphonopelma chalcodes), also called the Desert Blonde Tarantula, hunts the insects and small lizards of the desert southwest. During daylight hours, they retreat to their burrows. The late summer mating season brings males out of their burrows for extended periods of time. Like all spiders, they do bite. However their venom is not particularly toxic to humans.

The large and colorful Greenbottle Blue Tarantula (Chromatopelma cyaneopubescens) inhabits the dry forest floors of Venezuela. Growing up to six inches in length, they survive on an insect diet. Popular in the tarantula pet trade, they get characterized as somewhat aggressive, biting and sending off urticating hairs.

© 2008-2014 Patricia A. Michaels