Montana Public Radio

Bug Bytes: Old World Vs. New World Tarantulas

Jun 15, 2020

With over 900 different species, there’s a lot of diversity in the tarantula world. They range from the size of your thumbnail to the size of a Frisbee.

But at the most basic level, tarantulas can be divided into two different groups – old world and new world.

Old World tarantulas come from the eastern hemisphere (the continents of Asia, Africa and Europe plus Australia). New World tarantulas come from the western Hemisphere (the continents of North and South America, including the Central America region).

While this division is geographic, this separation also speaks to some very real differences in how they’ve evolved.

Old World tarantulas are fast and much less hairy than their new world relatives. If provoked, some can also deliver an incredibly painful bite.

A Mexican red knee tarantula, a New World species.
Credit Brenna Shea / Missoula Butterfly House and Insectarium

By comparison, New World tarantulas are slow moving, hairy and typically have venom comparable to a bee sting. But what they lack for in speed and venom, they make up for with some special hairs.

New world tarantulas have tiny hairs covering their abdomens called urticating hairs. When threatened, they use their back legs to kick a cloud of hairs into the air. Like tiny, floating porcupine quills they can get into the eyes, nose or simply in contact with a potential predator’s skin, causing significant irritation.

Wondering what the temperament of a new world tarantula might be like? Check out its butt – tarantulas with hairy behinds tend to be more docile (thus keeping their defensive hairs), while individuals with bald butts show a more aggressive nature.

Small or large, New World or Old World, tarantulas are among the thousands of amazing spider species that play important roles in our world and deserve our respect.