Persistent stickiness of viscous capture threads produced by araneoid orb‐weaving spiders

Abstract

The most commonly encountered spider orb-webs rely on sticky, viscous capture threads to retain prey. These threads are composed of supporting fibers covered by a complex aqueous solution that forms a series of droplets, each with a glycoprotein granule that confers adhesion. This adhesive system normally functions for less than a day before being replaced. Despite their ephemeral nature, we found that the stickiness of viscous threads persists for much longer. When measured over the course of 7 days, small decreases in the adhesion of Larinioides cornutus threads were not statistically significant. Threads of Araneus marmoreus, Argiope trifasciata, and Metepeira labyrinthea were aged for 8-10 months and remeasured under environmental conditions similar to those under which initial measurements were made. When returned to humidity similar to that under which measurements were initially made, neither the droplet volumes nor the stickiness of aged threads differed significantly from those of newly spun threads. These observations indicate that when viscous threads are protected from contamination, the compounds responsible for their hydrophilic and adhesive properties do not degrade easily.