科学美国人60秒:Spider's Scat Disguise May Be Its Salvation

Ever look in the mirror first thing in the morning and say, I look like crap! Well, for some spiders, looking like poop can actually be a lifesaver. Because masquerading as a bird turd appears to protect certain arachnids from getting eaten by wasps. That’s according to a study in the journal Nature Scientific Reports. [Min-Hui Liu et al, Evidence of bird dropping masquerading by a spider to avoid predators]
 
Researchers were marveling over the plentiful bird doo they were seeing in a forest in Taiwan. Then they realized that some of those droppings were in fact speckled spiders sitting atop silky white discs at the center of their webs.
 
Sure, this scatological costume might fool a bunch of PhDs. But do the predatory wasps fall for it?  
 
To find out, the researchers used a spectrometer to confirm that the spider in its web is spectrally indistinguishable from bird splat. Then they changed the coloring of some webs by dusting them with carbon powder. And they found that spiders that rested on the artificially blackened silk were much more likely to get eaten.
 
Now, these results don’t prove that wasps buy the whole poop act. Maybe spiders against the white background are just harder to spot. To be more confident that looking like poop is key, researchers might test the wasps to find out if they’re just glad they didn’t step in it.
 
—Karen Hopkin