You may remember in 2012 the curious revelation of the Peruvian rainforest spider that uses debris to sculpt counterfeit spiders in its web, either as a defensive strategy to confuse predators, or as a lure. Entomologist Phil Torres, who discovered what seems to be a species of Cyclosa, dismissed the innovation (in Wired):
“Considering that spiders can already make really impressive geometric designs with their webs, it’s no surprise that they can take that leap to make an impressive design with debris and other things,” he said.
“No surprise”! I commented on this at the time (“Ho Hum. Another Day, Another Startlingly Lifelike Decoy Expertly Sculpted by a…Spider“). Now it turns out there’s another spider that does the same thing, some 11,000 miles distant on a different continent — this one on the Philippine island of Negros. It’s also reported in Wired, which speculates
that similar predation pressures have driven an example of convergent evolution, in which both species independently found it beneficial to construct grand, spidery illusions.
So we have not one but two spiders that appear, in evolutionary terms, to have converged on this remarkable solution to the problem of…well that’s not clear. Avoiding predation? Being a more effective predator? Neither? Perhaps it’s just an enjoyable if seemingly narcissistic pastime.
They even get the number of legs right.
The discoverer of the new decoy-building spider with its “crazy constructions,” Lary Reeves, also takes it in stride: “I don’t think it’s surprising that this is happening.”
If it was unsurprising when there was one, it must be even more unsurprising to find there are two. On other hand, if it remarkable to find one, then it seems even more so to find two, so far apart yet otherwise so similar, pursuing a “benefit” no one can quite pin down.
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