Spider Webs Use Electrostatic Charge To Effectively Catch Insects

A study from biologists in University of California, Berkeley, shows that spider webs use the electrical charge in insects to help better capture them. The result of their findings is published in Scientific Reports.

The image on the left is that of a cross spider, Araneus diadematus, lying in wait in its web. The cross spider, just like most spiders, produces silk to create its web to capture its prey.

There are other researches done to study and analyze the structure of the spider web to discover what makes spider webs resilient and how these properties relate to the molecular structure of silk fibers. A key property of spider silk that helps make webs robust is that it can stretch and soften at first when pulled, and then stiffen again as the force of the pulling increases.

The UC Berkeley study states that the electrostatic charge generated by insects as they flap their wings help deform the silk web before capturing them; increasing the effectiveness of the spider web in capturing its prey.

UC Berkeley post-doctoral fellow Victor Manuel Ortega-Jimenez used electrically charged dead insects, a spider web, and high speed video cameras to test his hypothesis. Dropping the electrically dead flies into the web while filming it, showed that before the insects hit the web, the silk deforms and touches the insects; ensuring capture.

New Spider Family Trogloraptoridae Discovered In Oregon

This is a male Trogloraptor photographed in the lab.
Credit: Griswold CE, Audisio T, Ledford JM

The spider family Trogloraptoridae is a new species of spider discovered in the old growth forests of southern Oregon. To date, it only comprises a single species; Trogloraptor Marchingtoni.

The spider is named after amateur biologist, Neil Marchington, who helped in the discovery of the arachnid. Marchington is a Deschutes County deputy sheriff and led the team of scientists to caves where the Trogloraptor spiders were found. He is also an amateur biologist and local cave explorer. Neil is a member of the the Western Cave Conservancy.

The trogloraptor has been observed to spin primitive webs that comprises only a few strands. They hang beneath those webs from the cool, damp ceilings of the caves.

Spider version of Bigfoot emerges from caves in the Pacific Northwest

The forests of the coastal regions from California to British Columbia are renowned for their unique and ancient animals and plants, such as coast redwoods, tailed frogs, mountain beavers and the legendary Bigfoot (also known as Sasquatch). Whereas Bigfoot is probably just fiction, a huge, newly discovered spider is very real. Trogloraptor (or "cave robber") is named for its cave home and spectacular, elongate claws. It is a spider so evolutionarily special that it represents not only a new genus and species, but also a new family (Trogloraptoridae). Even for the species-rich insects and arachnids, to discover a new, previously unknown family is an historic moment. A study of the new family and its evolutionary and conservation significance was published in the open access journal Zookeys.

A team of citizen scientists from the Western Cave Conservancy and arachnologists from the California Academy of Sciences found these spiders living in caves in southwest Oregon. Colleagues from San Diego State University found more in old-growth redwood forests. Charles Griswold, Curator of Arachnology, Joel Ledford, postdoctoral researcher, and Tracy Audisio, graduate student, all at the California Academy of Sciences, collected, analyzed, and described the new family. Audisio's participation was supported by the Harriet Exline Frizzell Memorial Fund and by the Summer Systematics Institute at the Academy, which is funded by the National Science Foundation.

Credit: Joel Ledford, Calif Academy Of The Sciences / SF

Brown Widow Spiders Invade Southern California Displaces Black Widow Spiders

The Brown Widow Spider (Latrodectus Geometricus) is one of the widow spiders under the genus Latrodectus. It is related to the black widow spider (Latrodectus Mactans).

The Latrodectus genus is all under the family Theridiidae. It is a large family of spiders, also known as the tangle-web spiders, cobweb spiders and comb-footed spiders. The diverse family includes over 2200 species in over 100 genera).

The origin of the brown widow is uncertain as specimens have been independently discovered in both Africa and the Americas. In the US, they can be found in the southern half of the country. Other countries such as Australia, Afghanistan, Japan, Tanzania, South Africa and Cyprus have reported also presence of the arachnid.

The spider is lighter in color than the black widow. It ranges from tan to dark brown to black. Like the black widow, it also has an "hourglass" marking on the underside of the abdomen that is a vivid orange or a yellowish color.

The brown widow also has a black-and-white geometric pattern on the dorsal side of its abdomen. The Latin name comes from this pattern but the pattern can become obscured when the spider's coloring darkens over time.

Are brown widows displacing black widow spiders around southern California homes?

Brown widow spiders are relatively new to North America, where they were first documented in Florida in 1935, and even newer to southern California, where they were only recently discovered in 2003. However, in the last decade they have been so successful that they may be displacing native black widow spiders. If so, the overall danger to homeowners may decrease because brown widow spider bites are less toxic than those of native western black widow spiders.

In "The Prevalence of Brown Widow and Black Widow Spiders (Araneae: Theridiidae) in Urban Southern California," an article in the July issue of the Journal of Medical Entomology, the authors describe the results of their efforts to document the presence of brown widows in southern California by performing timed searches in various habitats, such as urban properties, agricultural lands, developed parks, and undeveloped natural areas. They also included the native western black widow spider to compare the abundance and habitat selection of the two species.

New Species of Trapdoor Spider Discovered: The Auburn Tiger Trapdoor Spider

Male specimen of Myrmekiaphila tigris
Credit: J. Bond

Trapdoor Spiders are cataloged under Family: Ctenizidae. In 1985, Robert Raven transferred species that are endemic to the southeastern USA to the genus Myrmekiaphila.

Trapdoor spiders do not build a web to capture prey, instead they burrow into the ground. They construct a trapdoor in the opening from which they spring from to capture their prey. These spiders usually wait for an unsuspecting prey to pass by and activate trip lines that the spider lay out around the trapdoor. These trip lines alert the spider by vibrating, sending out information as to where the prey is for the spider to jump out and grab.

The Auburn Tiger trapdoor spider: a new species discovered from a college town backyard

Researchers at Auburn University have reported the discovery a new trapdoor spider species from a well-developed housing subdivision in the heart of the city of Auburn, Alabama. Myrmekiaphila tigris, affectionately referred to as the Auburn Tiger Trapdoor spider, is named in honor of Auburn University's costumed Tiger mascot, Aubie.

The research team, directed by Biological Sciences professor Jason Bond, lead investigator and director of the Auburn University Museum of Natural History, and Charles Ray, a research fellow in the Department of Entomology & Plant Pathology, was excited at the prospect of such a remarkable find just underfoot. Bond and Ray actually live in the neighborhood where the new species was discovered. The study was published in the open access journal ZooKeys and is freely available under a Creative Commons Attribution license.

Kinds of Spiders and the Secret Behind The Strength of Their Webs

Spiders weave their own silk to build webs. It is this silk that is known to be one of the strongest materials to exists. On a pound per pound basis, spider silk is stronger than steel.

Researchers have studied and analyzed the structure of the spider web to discover what makes spider webs resilient and how these properties relate to the molecular structure of silk fibers. Research such as these may open up the possibility of synthesizing spider web for practical real world applications as well as apply the same knowledge to design principles that might apply to networked systems such as the Internet or the electric grid.

A key property of spider silk that helps make webs robust is something previously considered a weakness: the way it can stretch and soften at first when pulled, and then stiffen again as the force of the pulling increases.

This stiffening response is crucial to the way spider silk resists damage. Researchers at MIT analyzed how materials with different properties, arranged in the same web pattern, respond to localized stresses. They found that materials with other responses — those that either behave as a simple linear spring as they’re pulled, or start out stretchy and then become more “plastic” — perform much less effectively.

White-tailed spiders are vagrant hunters that live beneath bark, rocks, and in leaf litter and logs, and gardens, and are often seen in houses. Tufts of specialized scopulate hairs on the ends of their legs allow them to walk easily on smooth or sloping surfaces. They make temporary silk retreats and spin disc-shaped egg sacks, each containing up to 90 eggs.

Spider webs, it turns out, can take quite a beating without failing. Damage tends to be localized, affecting just a few threads — the place where a bug got caught in the web and flailed around, for example. This localized damage can simply be repaired, rather than replaced, or even left alone if the web continues to function as before. Markus Buehler, an associate professor of civil and environmental engineering (CEE) at MIT, says, "Even if it has a lot of defects, the web actually still functions mechanically virtually the same way. It’s a very flaw-tolerant system.”