The Atlanta Journal-Constitution
Spider’s hunting trick involves looking like bird droppings
It almost sounds like a playground taunt: You look like bird poop and smell like it too.
For the aptly named bird dung crab spiders residing in Southeast Asia’s tropical rainforests, such looks and smells are essential to survival in an eat-or-be-eaten world.
“All spiders are predators, but they also have their own predators,” said Daiqin Li, a biologist at the National University of Singapore.
The spiders’ glossy blackand-white patterning and foul odor are part of a mephitic masquerade that tricks predators that would otherwise seek to eat the spiders — after all, birds tend to avoid ingesting what they have already fully digested.
But the bird dung spiders’ mimicry serves yet another role.
According to a study published last month in Current Zoology, the spider’s fecal facade attracts prey at the same time it wards off predators — the first masquerading species described to use what researchers call aggressive mimicry to actively lure in its lunch.
“Many people would not be able to even distinguish a spider from a bird dropping,” said Stano Pekar, a zoologist at Masaryk University in the
Czech Republic who was not involved in the study and said its results were impressive. “I mean, they really have a very good masquerade.”
Other animals have also evolved to masquerade themselves as inedible or inanimate objects for predator protection: Larvae of early thorn moths appear like twigs, and dead-leaf butterflies look like, well, dead leaves. But researchers rarely investigate whether coloration tricks can serve multiple functions in the same species. That could change, Pekar said.
“I think in the future,” he said, “we will see many more cases where both the coloration or the pattern will be both defensive and offensive.”