Sticky Secrets Of Spiders’ Glue | Chemical & Engineering News
Volume 93 Issue 44 | p. 26 | Concentrates
Issue Date: November 9, 2015

Sticky Secrets Of Spiders’ Glue

Critter chemistry: High speed imaging reveals the stickiness of spiders’ glue is specific to their native habitats
Department: Science & Technology
News Channels: Materials SCENE, Biological SCENE
Keywords: spider, glue, adhesive, viscosity
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A spider’s capture thread is peeled from glass, under low (bottom), medium (middle), and high (top) humidity. The glue’s viscosity drops as humidity increases, and it achieves maximum adhesion at medium humidity.
Credit: Gaurav Amarpuri
Three photos of spider capture thread that show how adhesion varies with humidity.
 
A spider’s capture thread is peeled from glass, under low (bottom), medium (middle), and high (top) humidity. The glue’s viscosity drops as humidity increases, and it achieves maximum adhesion at medium humidity.
Credit: Gaurav Amarpuri

To learn how to make glues that work well even in humid environments, where most adhesives tend to lose their stickiness, scientists are gathering clues from spider glue. Spiders rely on sticky drops of glue dotted along their webs to snare insect prey. If a spider wants to eat regularly, that glue has to work well regardless of humidity. Researchers led by the University of Akron’s Ali Dhinojwala studied five spider species, each of which lives in an area with a different humidity. They found that each spider’s glue achieved its maximum stickiness in the humidity of its native environment (ACS Nano 2015, DOI: 10.1021/acsnano.5b05658). High-speed photography revealed that the spiders achieved maximum stickiness by modulating the glue’s viscosity. As humidity increases, the glue’s viscosity decreases. There is a sweet spot for each spider where its glue has just the right viscosity for catching prey. The spiders use different types and amounts of hygroscopic organic salts to achieve the best glue viscosity for the humidity of their habitat.

 
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