Brown Recluse Spins Studded Ribbons

Loxosceles laeta, the brown recluse spider, is feared for its venom, which can cause gangrenous lesions. But it is the unusual studded ribbons the spider spins from its silk that lured Fritz Vollrath of the University of Oxford and Hannes C. Schniepp and Sean R. Koebley of the College of William & Mary into its web (Adv. Mater. 2013, DOI: 10.1002/adma.201302740). Most spiders and silkworms spin smooth cylindrical filaments, but L. laeta instead makes 40–80-nm-thick, 6–9-μm-wide films dotted with nanosized bumps. When the team probed the mechanical properties of the film via atomic force microscopy, they found that despite their simple structure, the ribbons are as strong as the best silk filaments and are far superior to artificial silk films. The researchers propose that the studs make the silk stickier, and the easily deformable flat shape of the silk increases the area that comes in contact with other surfaces. They say the unusual webbing could help scientists better understand the structure of silks and allow them to design a new generation of silk-based materials.