S8-4 Wed Jan 6 11:30 – 12:00 Viscid spider silk shows robust adhesion on varied natural surfaces Blackledge, TA*; Alicea, A; Onyak, A; Htut, K; Singla, S; Dhinojwala, A; The University of Akron email@example.com https://www.blackledgelab.com/
The viscid capture threads produced by most of the world’s orb-weaving spiders are both a key innovation in spider diversification and an attractive model for synthetic adhesives. The sticky aggregate silk glue in capture threads maximizes adhesion through a beads-on-a-string morphology that by allows multiple glue droplets to simultaneously resist pull-off. These glue droplets are suspended in a cocktail of low molecular mass compounds (LMMC), which modulates glue viscosity to optimize the contributions of spreading and bulk cohesion to adhesion. Recent research suggests that LMMC mediated variation in viscosity helps to specialize spider species for foraging in different microhabitats by improving adhesion up to 10x at specific humidity. However, most of this research is conducted on smooth, hydrophilic glass. In contrast, orb spiders are largely generalists, capturing insects whose cuticles vary from smooth to rough and hair-covered, and which range from hydrophilic to hydrophobic. Here, we present evidence that aggregate silk glue functions as a remarkably robust adhesive across both varied surface roughness and a broad range of hydrophobicity through small changes in spreading and pull-off behavior. This robust performance is important for the generalist predatory strategy of orb spiders and may reduce the probability of insects evolving cuticular defenses against sticking to spider orb webs.