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The Q? Blog

Tarantula: Friend or Foe?

by Devin Reese -- Jul 14, 2014
Devin Reese, smiling

Devin is the lead digital science writer for the Q?rius website. She writes and gathers media for the Smithsonian Science How? webcast series,...

The massive Goliath birdeater tarantula (Theraphosa blondi). Smithsonian photo by Rosa Pineda
The massive Goliath birdeater tarantula (Theraphosa blondi). Smithsonian photo by Rosa Pineda

How can you tell whether to trust a tarantula or not? Most tarantula defenses, such as trying to look big, hissing, or running away, are harmless to humans. It’s the rare but harmful defense -- the bite -- that we tend to focus on.

In Q?rius, at the National Museum of Natural History, I saw a specimen of a Goliath birdeater tarantula. These are the heaviest spiders in the world (the largest known weighing in at more than a quarter pound) and boast ¾-inch fangs. They feed by injecting venom into insects, frogs, and other small animals. However, even this frightening tarantula has a bark worse than its bite. It does not often eat birds, and if you were unlucky enough to get bitten, you’d suffer about what you’d suffer from a wasp sting.

Honduran curlyhair tarantulaIn his Smithsonian Science How webcast, Arthropod Adaptations - Inside the Insect Zoo, Dan Babbitt (former Director of Smithsonian’s Insect Zoo) brought out live tarantulas to talk about the ways they defend themselves. Tarantulas don’t usually bite unless they are cornered or getting a meal. But many tarantulas resort to other painful, physical defenses if pestered. Like many tarantulas, the Honduran curlyhair (photo at right) uses its hind legs to fling barbed abdomen hairs into a predator’s eyes. While we are luckier than the would-be predators who suffer the blinding hairs, we can end up with a skin rash.

So, tarantulas are naturally defensive but otherwise not especially dangerous to humans. You could even feel sorry for them. As fearsome as they seem, tarantulas are eaten by many other animals. The Mexican red-knee tarantula is preyed on by birds, moths, and other insect-eating animals. It dodges predators by skulking around at night and ambushing its own meals of small insects and mice.

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