As someone who has always been embarrassingly weak, it's nice to know that sometimes all that's required to win is the right attitude. At least this is the case for the female jumping spider, Phidippus clarus.

Various species of female spiders are notorious for their viciousness against males. And female jumping spiders also fight aggressively with each other, sometimes to the death.   

Interestingly, in fights between female jumping spiders, winning isn't dependent on size or strength, but on how badly the female wants to win, according to scientists at the University of California at Berkeley and Dr. Maydianne Andrade, who we profiled on NOVA scienceNOW last year. Their work appears in this week's Behavioral Ecology.

Wait a minute. Why are battles between female jumping spiders so cutthroat? How is simply wanting to win an effective fight plan? Lead author Dr. Damian Elias said that to understand these behaviors we have to think about what's at stake for these animals.

The main reason male spiders fight is to defend females. A male will set up a nest next door to his sweetheart's, right around the time she's about to reach reproductive maturity. The idea being that if he fights off any suitors that come by he can increase his chances of reproductive success.

However, if he ends up losing a scuffle to his bigger or stronger opponent, the male spider will have to swallow his pride, pick up his broken dignity, and find another honey. It's really no big deal.

For female spiders, it's more complicated. They mature more slowly. The molting process (where they shed an old exoskeleton and grow into a new one) takes longer. And during this long maturation process they are more vulnerable. Female jumping spiders really need to find a good nesting site and stake their claim.

Good spots are hard to come by. Nests need to be well hidden, have plenty of food nearby and offer protection from the elements, so that females can get through that long molting period in peace.

Unlike their male counterparts, when female jumping spiders fight, it's a matter of life or death. In fact, when Elias and his team collected female spiders from the field and watched them battle it out in an arena constructed out of nylon fabric, they found that females would fight viciously, sometimes to the point of death.

The more tenacious female, who was usually closer to molting and needs the nest site more, consistently came out on top, regardless of whether she was larger than her opponent. 

It's really about how badly she wants to win.

The loser, if she's not dead or too badly injured, will have to pick herself up and go shopping for another spot.

"If a female loses a fight to another female, she's essentially losing the territory that she's going to develop in and lay eggs in.  That is a much bigger deal," Elias said when I spoke to him on the phone earlier this week. "So you'd expect in those circumstances that females won't give up and will fight as hard as they can."

Meanwhile, back at the NOVA intern desks, we've been fighting amongst ourselves for the "good" set of headphones. Fellow interns, watch out. I have a strategy.

Intern Rebecca Cheung is a Master of Journalism student at the University of British Columbia.

User Comments:

It’s Battle Royale – spider edition

Know why these spiders are found near computers? Because there's access to good web sites!

Interesting study and wrap up.....I would remind the interns to be careful that when studying berhavior of others, you do not adopt the behavior. Careful with the headphones.

I wondered how the researchers determined how much a spider wants to win? Questionnaire? hehe Oh, it's a GUESS based on how close to molting the female is... deduced from the urgency of its need for a nest. Well, it's still a guess and the article should have pointed that out. As it stands, total anthropomorphizing... Oh, and back off from my latte! :D

Interesting article Rebecca. Well done.

It's obvious that Mr and Ms Smith would be a much better cinematic reference. Actually, the perfect movie would "pitt" Angelina against Jennifer and, if it's as bad as Mr and Ms Smith, I would regret watching it.

I'd pay to see that movie. I used to be on Team Jolie, but now I'm with Team Aniston.

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