Web Absorbs Impacts

Biological Strategy

AskNature Team

Image: Mike Bitzenhofer /

Manage Impact

An impact is a high force or mechanical shock that happens over a short period of time, such as a hammer hitting a nail rather than a hand pushing slowly against a wall. Because of their speed and force, impacts don’t allow materials to slowly adjust to the force, which can lead to cracks, ruptures, and complete breakage. Therefore, living systems have strategies that can absorb, dissipate, or otherwise survive that force without the need to add large amounts of material. For example, the Toco toucan’s large beak is very lightweight, yet can withstand impacts because it’s made of a composite material with rigid foam inside and layers of a hard, fibrous material outside.

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Arachnids

Class Arachnida (“spider”): Spiders, mites, ticks, scorpions

Arachnids get a bad reputation, but they play an important role in the ecosystem by controlling insect populations. Almost half of the species in the class are spiders, and most live in terrestrial environments. Unlike insects, most arachnids have two body sections: the cephalothorax, which is the head and thorax fused together, and the abdomen. Mites and ticks, on the other hand, have only one body section that is relatively flat. This body shape comes in handy for the species that are parasitic, because it makes it harder for their hosts to bite or scratch them off.

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Webs of araneid spiders absorb impacts via microscopic engineering.

“…spider webs owe their superior performance not just to the ultimate strength of the silk thread, but also from its nonlinear response to stress and its alignment within the geometry of the web. The silk nanocrystals are a stacked arrangement with each layer dialed in a different direction. They are held together by weak hydrogen bonds that act together in the stack to resist external force.” (Zygote Quarterly)

Learn more about hierarchical structures in spider webs, as well as other organisms, in Tom McKeag’s case study, “Little Things Multiply Up: Hierarchical Structures” on page 26 of Zygote Quarterly: