Navigation Links
Bigger, scarier weapons help spiders get the girl
Date:12/12/2011

DURHAM, N.C. If you're a red-headed guy with eight bulging eyes and a unibrow, size does indeed matter for getting the girl.

More specifically, the bigger a male jumping spider's weapons appear to be, the more likely his rival will slink away without a fight, leaving the bigger guy a clear path to the waiting female.

Duke University graduate student Cynthia Tedore, working with her dissertation advisor, visual ecologist Snke Johnsen, wanted to know what visual signals matter most to magnolia green jumping spiders, which have an impressive array of eyes, including two giant green ones that face forward.

Vision is clearly important to these quarter-inch animals, which can be "very predaceous and aggressive," when love is in the air.

Tedore's lab in the basement of Duke's biological sciences building is lined with wire shelves covered with row after row of Lucite boxes, each holding an individual chartreuse jumping spider. Full-spectrum lights and squares of green paper mimic sunlight and leaves to keep the spiders calm between bouts. They're fed leftover fruit flies from other labs.

In pairs, 24 males squared off for 10 minutes in "the arena," a box festooned with female silk to put the males in a fighting frame of mind. Over the course of 68 of these cage matches, the male with the bigger chelicerae, heavy, bristling fangs hanging in front of their mouth parts, usually scared the other guy off without a fight.

"The males wave their forelegs at each other for a period, and then the smaller male runs off," Tedore said. "That's why we think they're using vision to size each other up. Most of the time, the smaller one will run away before it comes to blows."

On the rare occasion that a male with smaller weapons won, he tended to have chelicerae which were less red. That's the opposite of what Tedore expected, and she's not sure what the color differences are about. It may be that the spiders who invest fewer resources into making red fangs gain some agility or endurance as a tradeoff.

Seven of the matches were scored as ties. Seventeen of the contests turned into shoving matches, with the spiders butting chelicerae against each other. Occasionally one would flip an opponent on his back, then chase and pounce on him. Tedore had to break up a couple of contests before time expired so that nobody got hurt.

Tedore said her work provides another glimpse into how these creatures, which have tiny brains and never met their parents, manage to make decisions and navigate their world. "I don't really think of them as conscious, but they're following rules of some kind. I think of them more as robots."

In her next series of experiments, Tedore is pitting males against video images of other males that have artificially exaggerated chelicerae and altered colors.


'/>"/>

Contact: Karl Leif Bates
karl.bates@duke.edu
919-681-8054
Duke University
Source:Eurekalert

Related biology news :

1. Evolution drives many plants and animals to be bigger, faster
2. New materials capability to increase weapons explosive force demonstrated at Navy test range
3. Protein microarrays may reveal new weapons against malaria
4. Rutgers, UMDNJ receive $23 million to develop antidotes for chemical weapons attacks
5. Native ants use chemical weapons to turn back invading Argentine ants
6. Engineering new weapons in the fight against juvenile diabetes
7. Search for weapons of mass destruction expands to East Africa
8. Zooming in on the weapons of Salmonella
9. New medical weapons to protect against anthrax attacks
10. Multifunctional polymer neutralizes both biological and chemical weapons
11. Lombardi research: Monoclonal antibodies primed to become potent immune weapons against cancer
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/2/2016)... NEW YORK , Feb. 2, 2016 /PRNewswire/ ... Potentials of that Rising Market Are you ... new analysis forecasts revenues for checkpoint inhibitors. Visiongain,s ... world market, submarket, product and national level. ... Instead discover what progress, opportunities and revenues those ...
(Date:2/1/2016)... BURNABY, Canada , February 1, 2016 ... new technological advancements to drive global touchfree intuitive gesture ...   --> Rising sales of consumer electronics ... intuitive gesture control market size ... of consumer electronics coupled with new technological advancements to ...
(Date:1/27/2016)... 2016  Rite Track, Inc. a leading semiconductor equipment ... Chester, Ohio announced today the acquisition of PLUS ... in Austin, Texas , will significantly ... modifications, installations and technical support offerings for TEL Track ... commented, "PLUS has provided world class service including refurbishment, ...
Breaking Biology News(10 mins):
(Date:2/9/2016)... , Feb. 9, 2016 This market ... the current and future prospects of the market in ... report include companies engaged in the manufacture of microbiology ... executive summary with a market snapshot providing the overall ... of this report. This section also provides the overall ...
(Date:2/9/2016)... , February 9, 2016 Three-Year ... Enables Children to Take Part in Life-Changing Camp ... new initiative designed to positively affect the lives of children born ... care. --> SHPG ) is announcing a new initiative ... diseases, as well as the future of rare disease care. ...
(Date:2/9/2016)... LONDON , Feb. 9, 2016 /PRNewswire/ ... (PTP1B) Inhibitors-Pipeline Insights, 2016", report provides in ... their development activities around the Protein-Tyrosine Phosphatase ... the product profiles in various stages of ... Phase II, Phase III and Preregistration. Report ...
(Date:2/8/2016)... 2016 Should antibiotic bone cement products be ... prevent infection after standard total hip or knee replacement ... Institute have been fielding a lot lately. ... Line?" --> "Antibiotic Bone Cement: ... --> While there isn,t a simple answer, ...
Breaking Biology Technology: