Spiders' webs help them do more than just catch prey

If you’re a fan of E.B. White’s popular children’s novel “Charlotte’s Web,” or maybe the famed giant spiders of the wizarding world of Harry Potter, it's understandable why you may have the perception that all spiders spin large ornamental webs. But in reality, not all spiders even spin webs. What’s more, those that do, turn their silk in a variety of ways.

First off, scientists don’t know exactly how spiders spin silk, but they do have a basic idea of the spinning process. Spiders produce silk from glands located beneath the abdomen, according to Fritz Vollrath, an evolutionary zoologist at the University of Aarhus in Denmark and an expert on spider silk. The silk itself is a protein that initially comes out in liquid form and hardens as it leaves the glands. Some of it is used to make webs, while the rest goes toward wrapping up prey and creating sacs for eggs.

Vollrath classifies several types of spider webs.

Orb webs—the circular-type nets formed from a series of spirals—are probably the best-known, from photos, books and movies. These webs trap flying insects, which the spider then consumes.

Funnel webs, on the other hand, are used by burrowing and other types of spiders to move around and stalk prey. Unlike the orbs, they aren't sticky. That allows their creators to move quickly to attack and retreat. These webs are used to fortify their nests in the winter while they prey for food.

Cobwebs and meshwebs are less structured because they are attached to a variety of objects. These are the ones often found in grassy fields and under rocks, stones and dead leaves. Like orb webs, these webs are also used to trap flying insects, but they are strung to be adaptable to the environment.

However the silk is used, spider silk is stronger than any known natural or synthetic fiber. So these webs are built to serve spiders well, whatever the purpose. 

—Frank Graff

Frank Graff is a producer/reporter with UNC-TV, focusing on North Carolina Science Now, a weekly science series that airs Wednesdays, beginning in August 2013, as part of North Carolina Now on UNC-TV. In addition to producing these special segments, Frank will provide additional information related to his stories through this North Carolina Science Now Reporter's Blog! 

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