Physical properties of Hydropsyche siltalai (Trichoptera) net silk

Brown, S. A., Ruxton, G. D. and Humphries, S. (2004) Physical properties of Hydropsyche siltalai (Trichoptera) net silk. Journal of the North American Benthological Society, 23 (4). pp. 771-779. ISSN 0887-3593

Abstract/Summary

Most suspension-feeding trichopterans spin a fine-silk capture net that is used to remove suspended matter from the water. The efficiency of these nets has previously been studied by considering the geometry of the web structure but the material from which the nets is constructed has received little attention. We report measurements of the tensile strength and extensibility of net silk from Hydropsyche siltalai. These measurements place caddisfly silk as one of the weakest natural silks so far reported, with a mean tensile strength of 221 +/- 22 megaNewtons (MN)/m(2). We also show that H. siltalai silk can more than double in length before catastrophic breakage, and that the silk is at least 2 orders of magnitude stronger than the maximum force estimated to act upon it in situ. Possible reasons for this disparity include constraints of evolutionary history and safety margins to prevent net failure or performance reduction.