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:4/28/2016)... Sweden , April 28, 2016 First ... M (139.9), up 966% compared with the first quarter of 2015 ... profit totaled SEK 589.1 M (loss: 18.8) and the operating margin ... 7.12 (loss: 0.32) Cash flow from operations was SEK ... The 2016 revenue guidance is unchanged, SEK 7,000-8,500 M. ...
(Date:4/19/2016)... -- The new GEZE SecuLogic access control ... system solution for all door components. It can be ... interface with integration authorization management system, and thus fulfills ... dimensions of the access control and the optimum integration ... considerable freedom of design with regard to the doors. ...
(Date:4/14/2016)... BioCatch ™, the global ... the appointment of Eyal Goldwerger as CEO. ... Goldwerger,s leadership appointment comes at a time of significant ... of its platform at several of the world,s largest ... unique cognitive and physiological factors, is a winner of ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... 27, 2016  Sequenom, Inc. (NASDAQ: SQNM ... lives through the development of innovative products and services, ... the United States denied its petition to ... of Sequenom,s U.S. Patent No. 6,258,540 (",540 Patent") are ... by the Supreme Court,s Mayo Collaborative Services v. Prometheus ...
(Date:6/27/2016)... , ... June 27, 2016 , ... ... bring innovative medical technologies, services and solutions to the healthcare market. The company's ... of various distribution, manufacturing, sales and marketing strategies that are necessary to help ...
(Date:6/27/2016)... , June 27, 2016   Ginkgo Bioworks ... to industrial engineering, was today awarded as one ... selection of the world,s most innovative companies. Ginkgo ... scale for the real world in the nutrition, ... engineers work directly with customers including Fortune 500 ...
(Date:6/24/2016)... ... June 24, 2016 , ... While the majority of commercial ... Cary 5000 and the 6000i models are higher end machines that use the more ... the spectrophotometer’s light beam from the bottom of the cuvette holder. , FireflySci ...
Breaking Biology Technology: