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Nature Notebook – Spider Venom

Once the initial terror of meeting a tarantula has passed, visitors are curious about how tarantulas behave in the wild. Interest in the hunting techniques is second only to questions about the toxicity of the venom.    The two topics are intricately connected as spiders use their venom to subdue and then predigest their food.

Tarantulas are ambush hunters. One will sit in or near its home burrow waiting for insects and other arthropods (including spiders) to walk by. Subdued prey may be crushed to hasten the liquefaction process begun by the injection of venom. Additional digestive enzymes are sprayed from the chelicerae (fangs) until the prey is a nice soupy consistency that can be sucked into the stomach.

A spider’s chelicerae are akin to a “pantry” in that the venom is stored there in parts. If it were premixed, the venom could dissolve the spider itself since it is designed to digest arthropod prey. Spiders use different “recipes” to produce different venoms for different jobs: defense, subduing prey, digesting prey.