14-billion-years-later:

Spiders Are Bigger Than They SeemArachnophobia, or the irrational fear of spiders, is something that affects 50% of women and 10% of men. But it seems this isn’t the only thing blown out of proportion. A recent study has shown that people who are afraid of spiders actually rate spiders as much bigger than they really are, even trebling the length. The study was conducted by taking arachnophobes who have undergone therapy and getting them to interact with a range of spiders for a few minutes. After this session the human participants were made to fill out a questionnaire rating their level of distress and also asked to draw a line indicated how long they perceived the spider. The results showed a strong correlation between level of distress and exaggerated length of their 8 legged friend with on average the most fearful drawing lines 50% longer than those of the least fearful.Image

14-billion-years-later:

Spiders Are Bigger Than They Seem

Arachnophobia, or the irrational fear of spiders, is something that affects 50% of women and 10% of men. But it seems this isn’t the only thing blown out of proportion. A recent study has shown that people who are afraid of spiders actually rate spiders as much bigger than they really are, even trebling the length. The study was conducted by taking arachnophobes who have undergone therapy and getting them to interact with a range of spiders for a few minutes. After this session the human participants were made to fill out a questionnaire rating their level of distress and also asked to draw a line indicated how long they perceived the spider. The results showed a strong correlation between level of distress and exaggerated length of their 8 legged friend with on average the most fearful drawing lines 50% longer than those of the least fearful.

Image

myampgoesto11:

The Science Of Spider Webs

[credit: (top) Susan Ford Collins on Flickr/ (bottom) Zina Deretsky, National Science Foundation, in collaboration with S. Cranford, G. Bratzel and M.J. Buehler (all three from Massachusetts Institute of Technology, and Rihcard C. Yu and Andaluz Yu of Green Pacific Biologicals ]

From the National Science Foundation (Feb 1st, 2012):

View a video interview with Markus Buehler of MIT, an animationof a spider web under extremes stresses, and an animation of a spider web subjected to mechanical forces.

While researchers have long known of the incredible strength of spider silk, the robust nature of the tiny filaments cannot alone explain how webs survive multiple tears and winds that exceed hurricane strength.

Now, a study that combines experimental observations of spider webs with complex computer simulations shows that web durability depends not only on silk strength, but on how the overall web design compensates for damage and the response of individual strands to continuously varying stresses.

sagansense:

Spider That Builds Its Own Spider Decoys Discovered

image 1: A decoy spider hangs below its much smaller builder, suspected to be a new species in the genus Cyclosa. Photo: Phil Torres.
image 2: Photo: Phil Torres.

A spider that builds elaborate, fake spiders and hangs them in its web has been discovered in the Peruvian Amazon.

Believed to be a new species in the genus Cyclosa, the arachnid crafts the larger spider from leaves, debris and dead insects. Though Cyclosa includes other sculpting arachnids, this is the first one observed to build a replica with multiple, spidery legs.

Scientists suspect the fake spiders serve as decoys, part of a defense mechanism meant to confuse or distract predators. “It seems like a really well evolved and very specialized behavior,” said Phil Torres, who described the find in a blog entry written for Rainforest Expeditions. Torres, a biologist and science educator, divides his time between Southern California and Peru, where he’s involved in research and education projects.

“Considering that spiders can already make really impressive geometric designs with their webs, it’s no surprise that they can take that leap to make an impressive design with debris and other things,” he said.

In September, Torres was leading visitors into a floodplain surrounding Peru’s Tambopata Research Center, located near the western edge of the Amazon. From a distance, they saw what resembled a smallish, dead spider in a web. It looked kind of flaky, like the fungus-covered corpse of an arthropod.

But then the flaky spider started moving.

A closer look revealed the illusion. Above the 1-inch-long decoy sat a much smaller spider. Striped, and less than a quarter-inch long, the spider was shaking the web. It was unlike anything Torres had ever seen. “It blew my mind,” he said.

So Torres got in touch with arachnologist Linda Rayor Cornell University who confirmed the find was unusual. “The odds are that this [species] is unidentified,” she said, “and even if it has been named, that this behavior hasn’t previously been reported.” Rayor notes that while more observations are necessary to confirm a new species, decoys with legs — and the web-shaking behavior — aren’t common in known Cyclosa. “That’s really kind of cool,” she said.

Afterward, Torres returned to the trails near the research center. Only within a roughly 1-square-mile area near the floodplain did Torres find more spider-building spiders — about 25 of them. “They could be quite locally restricted,” he said. “But for all I know, there’s millions of them in the forest beyond.” The spiders’ webs were crafted around face-height, near the trail, and about the width of a stretched-out hand. Some of the decoys placed in the webs looked rather realistic. Others resembled something more like a cartoon octopus.

“I have never seen a structure just like this,” said William Eberhard, an entomologist at the Smithsonian Tropical Research Institute and University of Costa Rica who studies spiders and web-building.

Though Cyclosa are known for building decoys, most of the described spiders’ constructions are clumpy, made out of multiple little balls built from egg sacs, debris or prey, rather than something resembling an actual spider. “Known Cyclosa don’t have that spider-with-leg looking thing, which is why we think it’s a new species,” Torres said.

But without a permit to collect any organisms, anatomical confirmation of the new species is on hold. Torres is returning to the site in January, and will be able to collect some spiders then. Eberhard notes that identifying a new species based on the decoy-building behavior alone is probably not possible. “Species are distinguished on the basis of the structure of the male and female genitalia,” he said. “To a lesser extent, on the overall abdomen shape.”