Hungry spiders tune up web jiggliness.An Asian spider spins webs of different designs depending on how hungry it is, reports a Japanese researcher.
A well-fed Octonoba sybotides spider adds silk bands along web spokes, Takeshi Watanabe of the University of Kyoto has observed. When the spider gets hungry, however, it arranges the bands so that they spiral toward the web's hub.
The two web types responds differently to incoming prey, Watanabe argues in the March 22 PROCEEDINGS OF THE ROYAL SOCIETY Proceedings of the Royal Society is a scientific journal published by the Royal Society of London.
Today, the Royal Society publishes two proceeding series:
tr.v. sa·ti·at·ed, sa·ti·at·ing, sa·ti·ates
1. To satisfy (an appetite or desire) fully.
2. To satisfy to excess.
Filled to satisfaction. spiders tune down the sensitivity so webs vibrate only for a big prize.
The report joins a recent surge of research on an old question: Why do spiders decorate their webs? At least 78 species add scrawls of silk, perhaps bars or an X, that have no purpose clear to people. A description in 1889 called them stabilimenta, as if they added stability, notes George Uetz of the University of Cincinnati The University of Cincinnati is a coeducational public research university in Cincinnati, Ohio. Ranked as one of America’s top 25 public research universities and in the top 50 of all American research universities, . Since then, researchers have speculated that silk squiggles evolved as hiding spots, warnings for birds, lures for prey, devices to slow bee leaning, and even sun shields.
"It s like `Certs is a candy mint; Certs is a breath mint," Uetz says. "What's interesting about this paper is, here's yet another point of view."
Watanabe's suggestion echoes the original notion of a structural function, notes Marie Herberstein of the University of Melbourne
In 2006, Times Higher Education Supplement ranked the University of Melbourne 22nd in the world. Because of the drop in ranking, University of Melbourne is currently behind four Asian universities - Beijing University, in Australia. When she recently reviewed the literature on web decorations Web decorations, sometimes termed stabilimenta (the plural of stabilimentum), are conspicuous silk structures included in their webs by some species of orb-web spider. , she found little testing of their mechanical effects.
Now, however, Watanabe has analyzed web tension by comparing the straight-line distance between points to the length of the silk strand linking them. Webs with spiral stabiltmenta have tauter strands, he reports.
Watanabe's earlier work had established that when a spider in a laboratory case satiates itself with two fruit flies a day, it builds its daily web with linear instead of spiral decorations.
In the new tests, he moved spiders to webs that their neighbors had built. An underfed spider responds slowly to prey when placed on the looser web of a well-fed neighbor. Conversely, that well-fed spinner's hunting speeds up when it's on the hungry spider's taut web. Tautness, not hunger alone, sparks spiders' quickness, Watanabe argues.
Todd Blackledge Todd Alan Blackledge (February 25, 1961 in Canton, Ohio) was a three-year starter at Penn State, where he guided the Nittany Lions to 31-5 record including a national championship in 1982. Following the 1982 season, he won the Davey O'Brien Award for best quarterback in the nation. of Ohio State University Ohio State University, main campus at Columbus; land-grant and state supported; coeducational; chartered 1870, opened 1873 as Ohio Agricultural and Mechanical College, renamed 1878. There are also campuses at Lima, Mansfield, Marion, and Newark. in Columbus says that he's intrigued by Watanabe's demonstration that individual spiders adjust web sensitivity to detect prey of different sizes. It's the first evidence he's seen for that, he notes. Blackledge asks whether the spiral stabilimenta themselves tighten the web or just mark a taut structure.
The experiments also convinced Herberstein that spiders adjust their webs' tautness, she says. However, she adds, "I do not think spiders evolved stabilimenta to tune web tension."
The decorations evolved independently at least nine times, but only in diurnal diurnal /di·ur·nal/ (di-er´nal) pertaining to or occurring during the daytime, or period of light.
1. Having a 24-hour period or cycle; daily.
2. spiders, Herberstein notes. If tuning had driven the evolution, wouldn't nocturnal nocturnal /noc·tur·nal/ (nok-tur´n'l) pertaining to, occurring at, or active at night.
1. Of, relating to, or occurring in the night.
2. other purposes.