for National Geographic News
The arrival of a jumping spider sends most moths into a flutter trying to escape the predator's lethal pounce.
Not so for metalmark moths in the genus Brenthia. These moths stand their ground with hind wings flared and forewings held above the body at a slight angle.
In that pose the moth looks like a jumping spider, said Jadranka Rota, a graduate biology student at the University of Connecticut.
"That will actually save [the moth's] life," she said.
"The spider needs to act pretty quickly. Deciding whether the moth is potential prey or another jumping spider could take enough time to offer an advantage, in comparison to other moths."
The trickery usually buys the metalmark moth time for a safe escape.
Sometimes the sight triggers territorial postures—raising and waving of the forelegs—from the spider (watch video of a spider encountering a mimic moth in the lab [video © 2006 Rota, Wagner; courtesy PLoS ONE]).
Occasionally the spider even backs off.
Rota and her advisor David Wagner described the metalmark moths' behavior last December in the Public Library of Science's interactive online journal PLoS ONE.
Mimicry is a well-known trick in the animal kingdom. Many creatures are known to adopt the looks and postures of undesirable prey species to evade their predators.
(Related news: "Poison Frog Uses Less-Toxic Looks to Survive, Study Finds" [March 8, 2006].)
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