Jun 8, 2010, 18:00 PM by Clark Pest Control San Diego Office

If you thought women's pro wrestling was a cutthroat business, jumping spiders may have them beat.

In most animals the bigger, better fighter usually wins. But a new study of the jumping spider Phidippus clarus suggests that size and skill aren't everything - what matters for Phidippus females is how badly they want to win.

Found in fields throughout North America, nickel-sized Phidippus clarus is a feisty spider prone to picking fights. In battles between males, the bigger, heavier spider usually wins. Males perform an elaborate dance before doing battle to size up the competition. "They push each other back and forth like sumo wrestlers," said lead author Damian Elias of the University of California at Berkeley.

This fancy footwork allows males to gauge how closely matched they are before escalating into a full-blown fight. "Males rarely get to the point where they solve things by fighting," said co-author Carlos Botero of the National Evolutionary Synthesis Center in Durham, NC. "Before the actual fight there's a lot of displaying. This allows them to resolve things without injuring themselves."

But when the researchers watched female fights, they found that females fight by different rules. They skip the preliminaries and go straight for the kill. "Males have a more gentlemanly form of combat, whereas in females it's an all-out fight," said Elias. "At the drop of a hat they start bashing and biting each other."

And unlike male combat, female feuds were often fatal. "They don't give up, even when their opponent is beating them to a pulp," said Botero. "They keep going until one of them is dead, or severely injured."

The researchers were unable to predict which female would win based on size or strength. "Nothing we could measure predicted which one would come out on top. That was really unexpected," said Elias.

At first, the researchers wondered if victory went not to the bigger fighter, but to the owner of the battlefield. "In a lot of animals one of the things that determines whether they win a fight is whether they're on their own territory," Elias said.

Phidippus clarus spiders live in nests they build from silk and rolled up leaves. While males are nomads, wandering from nest to nest in search of mates, females generally stick to one nest and guard it against intruders.

Originally published on: https://www.redorbit.com/news/science/1875603/desperate_female_spiders_fight_by_different_rules/

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