Mechanical properties of silk of the Australian golden orb weavers Nephila pilipes and Nephilaplumipes

Genevieve G Kerr; Helen F Nahrung; Aaron Wiegand; Joanna Kristoffersen; Peter Killen; Cameron Brown; Joanne Macdonald

doi:10.1242/bio.029249

Mechanical properties of silk of the Australian golden orb weavers Nephila pilipes and Nephilaplumipes

Biol Open. 2018 Feb 22;7(2):bio029249. doi: 10.1242/bio.029249.

Authors

Genevieve G Kerr¹, Helen F Nahrung¹, Aaron Wiegand¹, Joanna Kristoffersen¹, Peter Killen¹, Cameron Brown^{2

3}, Joanne Macdonald^{4

5}

Affiliations

¹ Genecology Research Centre and School of Science, Engineering and Education, University of the Sunshine Coast, Sippy Downs, Queensland 4556, Australia.
² Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, OX3 7LD, UK.
³ Institute of Health and Biomedical Innovation and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland 4000, Australia.
⁴ Genecology Research Centre and School of Science, Engineering and Education, University of the Sunshine Coast, Sippy Downs, Queensland 4556, Australia jmacdon1@usc.edu.au.
⁵ Division of Experimental Therapeutics, Columbia University, New York, NY 10032, USA.

Abstract

Silks from orb-weaving spiders are exceptionally tough, producing a model polymer for biomimetic fibre development. The mechanical properties of naturally spun silk threads from two species of Australian orb-weavers, Nephila pilipes and Nephilaplumipes, were examined here in relation to overall thread diameter, the size and number of fibres within threads, and spider size. N. pilipes, the larger of the two species, had significantly tougher silk with higher strain capacity than its smaller congener, producing threads with average toughness of 150 MJ m^-3, despite thread diameter, mean fibre diameter and number of fibres per thread not differing significantly between the two species. Within N. pilipes, smaller silk fibres were produced by larger spiders, yielding tougher threads. In contrast, while spider size was correlated with thread diameter in N. plumipes, there were no clear patterns relating to silk toughness, which suggests that the differences in properties between the silk of the two species arise through differing molecular structure. Our results support previous studies that found that the mechanical properties of silk differ between distantly related spider species, and extends on that work to show that the mechanical and physical properties of silk from more closely related species can also differ remarkably.

Keywords: Nephila sp; Spider silk; Stress-strain; Toughness.