Assassins at Macquarie University
Recently, Livescience ran an article about a paper in the Journal of Ethology by Anne Wignall and one of her colleagues here at Macquarie University (I say “here” because I’ve been a guest of Macquarie for the last week or so, and will be here for the next couple of weeks) about some very cool critters.
Assassin bugs (Stenolemus bituberus) take advantage of the fact that spiders use vibrations on their webs to detect when a prey item has become caught. Struggling insects generate vibrations on the threads, and spiders use these vibrations to locate and close on their prey.
Assassin bugs take advantage of this, producing vibrations that mimic those made by an insect caught in the web. This attracts the spider, and then the assassin bug does what its name suggests, having lured the unsuspecting spider in.
A few notes.
First, that’s just really cool. Check out the video.
Second, according to the paper, assassin bugs don’t always lure the spiders in. Sometimes they stalk them, moving around the spiders’ web without alerting the spider to their presence.
Third, the vibrations are so well designed, that they mimic struggling prey, but not other vibrations to which the spider might react differently, such as those made by a courting male spider.
And, lastly, an exercise for the reader. A few posts ago, I discussed the signal/cue distinction. When the assassin bug generates the vibrations on the spider’s web, would Maynard Smith want to call that a signal, or a cue?
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