Why spiders' silk threads don't twist

Mar 30, 2006
Araneus diadematus spider dangling from its thread.
Araneus diadematus spider dangling from its thread.

Unlike a mountain climber swinging from a rope, a spider suspended from its silk thread hardly ever twists. Although the flexibility and strength of a spider’s dragline outperforms the best synthetic fibres, surprisingly little has been published on the twist properties of the thread. A new study however, by a research team from Oxford and Rennes Universities, published in Nature, reveals just how good the damping properties of spider silk are.

The researchers used a small plastic or copper rod to represent the weight of the spider, and tied it to a variety of threads. The 'spider' rod was twisted through 90 degrees, to make the rod turn back and forth many times around its original position, and a camera linked to a computer registered the responses of the different threads.

The research team first used a thread of Kevlar, a synthetic organic polymer used in the manufacture of racing cars, known for its strength when stretched. After the thread was twisted around from its equilibrium, it oscillated gently around its original position. The response was elastic with little energy wasted. They then examined a soft metallic copper thread, which twisted a few times in the same experiment, but after several trials became brittle. It displayed the high damping typical of high-energy dissipation. The researchers then used a dragline silk from an Araneus diadematus spider, where the oscillation was damped down after a few twists, and unlike the copper thread, the spider silk retained its twisting qualities through several cycles.

Professor Fritz Vollrath said: 'It seems that selection against twisting and swinging in the spider dragline thread has led to the evolution of a shape-memory material that does not need any external stimulus to give total recovery, even if it does take time. The twist properties add yet another beneficial quality to the famously strong silk, and this might have evolved so that an abseiling spider does not swing in a way that might attract predators.'

The researchers intend to carry out further research into this and other silk proteins to see whether sacrificial hydrogen bonds and their reconstruction may form the basis for the observed mechanical behaviour.

Source: University of Oxford

Explore further: When rulers can't understand the ruled

add to favorites email to friend print save as pdf

Related Stories

How spiders fix their webs

Aug 14, 2014

Spider silk is light and delicate, while incredibly resilient and tear-resistant. Understanding the structure and way of construction of these threads is a challenge taken up by a research team of Kiel University. ...

Silkworms spinning spider webs

Jan 03, 2012

(PhysOrg.com) -- A spiders silk is strong and more elastic and has a large range of possible medical applications. However, spiders have a history of being territorial and prone to cannibalism, so the idea ...

Spider silk glue inspires next-generation technology

Jul 22, 2011

(PhysOrg.com) -- Water affects orb spider web glue differently than cobweb glue. Orb web glue reacts to humidity, but cobweb glue resists it. These findings by a University of Akron research team inspire the ...

Spiders know the meaning of web music

Jun 03, 2014

Spider silk transmits vibrations across a wide range of frequencies so that, when plucked like a guitar string, its sound carries information about prey, mates, and even the structural integrity of a web.

Spiders spin possible solution to 'sticky' problems

May 16, 2014

Researchers at The University of Akron are again spinning inspiration from spider silk—this time to create more efficient and stronger commercial and biomedical adhesives that could, for example, potentially ...

Recommended for you

When rulers can't understand the ruled

13 hours ago

Johns Hopkins University political scientists wanted to know if America's unelected officials have enough in common with the people they govern to understand them.

When casualties increased, war coverage became more negative

17 hours ago

As the number of U.S. casualties rose in Afghanistan, reporters filed more stories about the conflict and those articles grew increasingly negative about both the war effort and the military, according to a Penn State researcher. ...

User comments : 0