According to researchers, spider fine tune the viscosity of their web glue on the basis of the humidity in their surroundings. They do so to maximize adhesion and prey capture. The researchers said out of the 45,000 known spider species, more than 16% species spin webs for catching their prey.

The researchers studied the structure of this capture silk, and discovered that it contains an axial fiber that is covered with ‘glue droplets’ at regular intervals.

In the study published in Journal of Rheology, the researchers revealed that the glue in the web of spider was unique because its adhesion increases while responding to humidity. The increase is so much that the adhesion goes up to 100% relative humidity (RH).

It is quite contrary to all the synthetic glue that the researchers are aware of as they peel right off the moment they come in contact with sweat or water or severe humidity.

University of Akron, Virginia Polytechnic Institute team of researchers explored the properties of this glue and its humidity-responsive adhesion.

Gaurav Amarpuri of Akron said that the team measured the glue’s adhesion as a function of humidity. They used high-speed imaging for the calculation of the spreading rate of the spiders’ glue droplets. The same process was done for five different species of spider.

The team explained that a liquid droplet spread followed the ‘spreading power law’, wherein the low viscosity droplets spread faster in comparison to high viscosity droplets. The researchers used the spreading power law for the calculation of spider glue viscosity as a function of humidity. They found that the glue had maximum adhesion at the humidity levels wherein the spider generally forages.