Wilderness First Aid Q&A

Are tarantulas dangerous?

tarantula-300x222Tarantulas have become increasingly popular pets within both the kid and adult worlds. Known for their massive size, hairy body and frequent cameos in horror movies everywhere, these creatures are actually much less menacing than they look.

Tarantulas are arachnids, which is a class of animals with eight legs and an external skeleton (also known as an exoskeleton). This is important to help distinguish spiders from other insects, which only have six legs. Within the class of arachnids there are many families of spiders; the large and hairy tarantulas we know come from the Theraphosidae family, which includes over 900 other specific species. They can range in size from as small as 2.5 cm (about the length of a fingernail) to as big as a foot-long sandwich!

The tarantulas’ name comes from an Italian town of Taranto where a different spider was initially found but the name traveled to North America and stuck like a fly in a web. Tarantulas can be found throughout the Americas, Africa and in parts of Asia. Overall, they prefer dry soils in deserts and grassland areas. In North America, many species prefer living in the ground, but rarely they can be found residing within trees.

Tarantulas mainly eat insects and other smaller spiders, but large tarantulas can kill lizards, mice, birds and even snakes! Before attacking their enemy or prey, tarantulas usually send a warning signal either by getting into a “threat posture” or making a hissing sound. The tarantula’s mouthparts, called chelicerae, contain the glands that produce the venom that drain through the fangs – like nature’s version of a hypodermic needle. Once prey has been envenomated, tarantulas secrete juices from their chelicerae that coat their captured prey and help to liquefy and digest it from the “outside-in” (the reverse of how our own stomachs work!) making it easier for the tarantulas to slurp up.

As horrifying as that sounds, most tarantulas are relatively harmless to humans. Only rarely does a tarantula bite cause serious harm or an allergic reaction that may actually become life-threatening to some.

Tarantulas do have another potentially more serious defensive trick up their sleeve – their hair! Other than giving tarantulas an instantaneously recognizable outfit, these hairs serve a secondary function of defense. Many of the North and South American tarantulas have barbed wire-like, 1-mm long hairs on their belly which, when attacked or threatened, tarantulas can fling at their attackers. These hairs may be extremely irritating to human eyes and mucous membranes (our nose and mouth) and can lead to intense itching and the formation of hives (urticaria). Because of this, any airborne fragments of a tarantula can lead to severe irritation and allergic reactions, some even requiring emergency medical treatment.

Comments about “Are tarantulas dangerous?”

  1. Yessenia says:

    This is good information. It has a lot of facts.

  2. squishy says:

    are tarantulas really dangerous?

  3. Ghost202 says:

    So do they make good pets?

  4. brad says:

    Tarantulas are very fast and it can poison with one bite.

  5. Spidey says:

    “This is important to help distinguish spiders from other insects”
    Spiders are not insects.

  6. hy 6yhuj says:


  7. CrystalAngel says:

    Are turantulas venomous?

  8. x says:

    how do tarantulas help humans

  9. spider man says:


  10. Spider Guy says:

    This was a great article. Thank you and keep this sort of information coming!

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  • Dr. Andrew C. Krakowski is the host of the boonDOCS Wilderness & Travel Medicine show on Outdoor Channel. He is the founder of the Johns Hopkins School of Medicine's wilderness medicine program and currently works in the field of pediatric dermatology at the Rady Children's Hospital in San Diego.

    Dr. K loves the outdoors and believes that knowledge, adaptability, and experience are essential for being prepared in the wilderness.