Strange silk: Why rappelling spiders don't spin out of control

July 7, 2017

The last time you watched a spider drop from the ceiling on a line of silk, it likely descended gracefully on its dragline instead of spiraling uncontrollably, because spider silk has an unusual ability to resist twisting forces.

In a new paper appearing this week in Applied Physics Letters, researchers from China and the U.K. showed that unlike human hair, metal wires or synthetic fibers, spider silk partially yields when twisted. This property quickly dissipates the energy that would otherwise send an excited spider spinning on the end of its silk.

"Spider silk is very different from other, more conventional materials," said Dabiao Liu of Huazhong University of Science and Technology. "We find that the dragline from the web hardly twists, so we want to know why."

A greater understanding of how spider silk resists spinning could lead to biomimetic fibers that mimic these properties for multiple potential uses such as in violin strings, helicopter rescue ladders and parachute cords. "If we understood how spider silk achieves this, then maybe we could incorporate the properties into our own synthetic ropes," said David Dunstan of Queen Mary University of London.

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Specialized Leg Organs Help Spiders Glean Information From Their Silk

June 3, 2014

Brett Smith for redOrbit.com – Your Universe Online

A spider’s web is more than just a home or trap for unsuspecting prey, it’s also a communications network capable of telling a spider information about prey, mates, and its own structural integrity.

According to a new report in the journal Advanced Materials, spider silk can be tuned to a wide range of harmonics and these various frequencies provide a wealth of information to spiders, which sense the frequencies using leg organs called slit sensillae.

“Most spiders have poor eyesight and rely almost exclusively on the vibration of the silk in their web for sensory information,” said study author Beth Mortimer, a biologist at the Oxford Silk Group at Oxford University. “The sound of silk can tell them what type of meal is entangled in their net and about the intentions and quality of a prospective mate. By plucking the silk like a guitar string and listening to the ‘echoes’ the spider can also assess the condition of its web.”

This aspect is utilized by the spider through the “tuning” of silk to pick up sensory information. To examine the sonic qualities of silk, the scientists used ultra-high-speed cameras to capture the threads as they reacted to the impact of bullets. Specialized lasers were used to pick up the silk’s smallest vibrations.

“The fact that spiders can receive these nanometer vibrations with organs on each of their legs, called slit sensillae, really exemplifies the impact of our research about silk properties found in our study,” said study author Shira Gordon, a researcher at the University of Strathclyde.

“These findings further demonstrate the outstanding properties of many spider silks that are able to combine exceptional toughness with the ability to transfer delicate information,” added study author Fritz Vollrath, an ecology professor in the Oxford Silk Group. “These are traits that would be very useful in light-weight engineering and might lead to novel, built-in ‘intelligent’ sensors and actuators.”

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Spider Silk Inspires A More Efficient, Stronger Commercial And Biomedical Adhesive

May 17, 2014

April Flowers for redOrbit.com – Your Universe Online

Whether you think they are creepy and scary, or useful and beautiful, one has to admit that spiders are also fascinating. And it isn’t just Hollywood that finds spiders irresistible – research scientists find them equally alluring.

A group of researchers from the University of Akron (UA), for example, have just released a new study demonstrating a more efficient and stronger commercial and biomedical adhesive inspired by spider silk. This adhesive, described in the Journal of Polymer Physics, could potentially attach tendons to bones or bind fractures.

Dr. Ali Dhinojwala, UA’s H.A. Morton professor of polymer science, led the team that created synthetic duplicates of the super-sticky, silk “attachment discs” that spiders use to attach their webs to surfaces. Working like stitches or staples, Dhinojwala explained in a statement that the discs are created when spiders pin down one thread under additional threads. A very strong attachment force is created using the “staple-pin” geometry of the discs, with very little material outlay.

The research team used a process called electrospinning to draw very fine fibers from liquid polyurethane using electrical charges. This allowed them to imitate the efficient staple-pin design by pinning down a nylon thread with the electrospun fibers.

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Mysteries of Spider Silk Strength Unraveled

Jan. 27, 2013 — Scientists at ASU are celebrating their recent success on the path to understanding what makes the fiber that spiders spin -- weight for weight -- at least five times as strong as piano wire. They have found a way to obtain a wide variety of elastic properties of the silk of several intact spiders' webs using a sophisticated but non-invasive laser light scattering technique.

"Spider silk has a unique combination of mechanical strength and elasticity that make it one of the toughest materials we know," said Professor Jeffery Yarger of ASU's Department of Chemistry and Biochemistry, and lead researcher of the study. "This work represents the most complete understanding we have of the underlying mechanical properties of spider silks."

Spider silk is an exceptional biological polymer, related to collagen (the stuff of skin and bones) but much more complex in its structure. The ASU team of chemists is studying its molecular structure in an effort to produce materials ranging from bulletproof vests to artificial tendons.

The extensive array of elastic and mechanical properties of spider silks in situ, obtained by the ASU team, is the first of its kind and will greatly facilitate future modeling efforts aimed at understanding the interplay of the mechanical properties and the molecular structure of silk used to produce spider webs.

Continued:  http://www.sciencedaily.com/releases/2013/01/130128104741.htm

Do Tarantulas Shoot Spidey Silk? Scientists Debate

Tarantulas, like all spiders, extrude silk fromso-called spinnerets on their abdomens, and scientists recently found evidence suggesting the arachnids also shoot silk from their feet, Spider-Man style. Butthese powers were fleeting, it seems, with new research showing tarantulas are not so like the famed superhero, after all.

The tips of their eight legs don't shoot out Spidey silk.

"The history of science has plenty of examples which teach us that our present truths are provisional," Fernando Pérez-Miles, an entomologist at the University of the Republic in Uruguay, told LiveScience in an email. "But in my opinion the present evidence shows that tarantulas do not produce silk by their feet."

To hold on to vertical surfaces, spiders rely on molecular forces generated by thousands of microscopic hairs on their feet. Additionally, tiny foot claws allow themto cling to rough surfaces.In 2006, a study led by biologist Stanislav Gorb suggested that the zebra tarantula uses silk fibers — presumably produced by the nozzlelike spigots on their feet — to help them climb up a vertical glass wall.

Continued:  http://www.livescience.com/20364-tarantulas-shoot-spidey-silk-debate.html

Spider silk spun into violin strings

A Japanese researcher has used thousands of strands of spider silk to spin a set of violin strings.

The strings are said to have a "soft and profound timbre" relative to traditional gut or steel strings.

That may arise from the way the strings are twisted, resulting in a "packing structure" that leaves practically no space between any of the strands.

The strings will be described in a forthcoming edition of the journal Physical Review Letters.

Shigeyoshi Osaki of Japan's Nara Medical University has been interested in the mechanical properties of spider silk for a number of years.

In particular, he has studied the "dragline" silk that spiders dangle from, quantifying its strength in a 2007 paper in Polymer Journal

Read more:  http://www.bbc.co.uk/news/science-environment-17232058