Spiders lay down two types of webbing, says U of T zoology professor Darryl Gwynne: sticky and non-sticky. In fact, some spiders do get stuck in their own sticky webs, mainly by accident. But most are able to bypass the sticky strands and follow the safe trail of non-sticky webs laid down first for their own convenience.
Gwynne, who teaches at the University of Toronto at Mississauga, says web-building has several phases. A spider begins by attaching a single strand of silk horizontally between two supports, such as twigs or branches. It then builds an outside rim — almost like a bicycle wheel — and attaches spokes and a spiral from the centre to the outside of the web. These parts of the web are all composed of non sticky silk. With this frame — the foundation for a decent web — firmly in place, the spider adds the sticky strands, once again in a spiral pattern. This spiral is connected to the non-sticky spokes. "So, when a spider runs across from the centre of the web to grab a prey, it tends to go along a spoke, stepping on the bits that aren't sticky," Gwynne says. "And this essentially is the reason that spiders don't get stuck to their webs."
River-Spanning Spider Web
Photograph courtesy Matjaz Kuntner
A river-spanning spider web dwarfs a park ranger in Madagascar in 2008. Made of the world's strongest known biological material, the web is the product of a new species, the Darwin's bark spider, which makes the world's largest webs of any single spider, new studies say.
Zoologist Ingi Agnarsson and colleagues have found Darwin's bark spider webs as wide as 82 feet (25 meters)—about as long as two city buses.
Dew on a Spiders web
Wire Spider web
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