Jan. 5, 2005 — Researchers have identified a jumping spider that does a double impersonation. It not only mimics an ant, but it also pretends to be an ant that is hauling a heavy parcel.

The discovery marks the first time that scientists have ever observed such compound mimicry in an animal or insect. Humans can flap their arms while whistling like a bird, or they can get on all fours and bark like a dog, but such play acting is temporary and is usually done in jest for fun. It also requires a fair amount of effort.

For male jumping spiders within the genus Myrmarachne, the trickery is full-time, serious business that comes naturally.

"The male has to do nothing except behave like an ant, as all Myrmarachne do — walking in short, erratic bursts, holding their first pair of legs above the ground in a simulation of ant antennae and unlike their family name, almost never jumping," said Ximena Nelson, who co-authored the research with colleague Robert Jackson.

Nelson, a scientist at Macquarie University in Australia, explained to Animal Planet News that this spider resembles an ant, which can be a good thing since many predators avoid ants because they can be feisty and difficult to chew.

"(Ants) are typically social and can mount solid defenses when threatened," she said. "They can either inflict a painful, or lethal to a spider, bite, or can sting. They also have a hard exoskeleton, which might make them difficult prey to bite into."

Male Myrmarachne, however, possess huge chelicerae, jointed, jaw-like appendages near the mouth that are used for feeding and possibly for fighting off other males who want to steal their female mates. Nelson likens them to deer antlers.

The chelicerae take away from the spider's ant look, but Nelson and Jackson theorized the spider might actually be mimicking an ant that is hauling a parcel.

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