Meeting Abstract

 

32-6  Friday, Jan. 4 14:45 – 15:00  The effect of cactus spine surface structure on puncture and anchoring performance CROFTS, S. B.*; ANDERSON, P.S.L.; University of Illinois at Urbana-Champaign; University of Illinois at Urbana-Champaign scrofts@illinois.edu

Although primarily thought of as defensive in nature, cactus spines have a wide range of other uses: shading, climbing, and dispersal to name a few. Similarly, there is a wide range surface ornamentation like barbs or tubercles. Despite this diversity, the mechanics of cactus spine function has yet to be fully characterized. Here we study the puncturing and withdrawing ability of six species of cactus, including both barbed and non-barbed spines. We found that barbed spines use less work to puncture biological and artificial targets than non-barbed spines. Barbed spines also require more work than non-barbed spines to withdraw from biological materials, due to their barbs engaging with tissue fibers. The variation in performance of barbed versus non-barbed spines, as well as between barbed spines from different species, is likely tied to the diversity of ecological functions for which cactus spines are used. In particular, the ability of barbed spines to anchor in to fibrous materials will aid dispersal of vegetative propagules. Finally, the relative performance of barbed cactus spines is similar to that of porcupine quills, implying some degree of biomechanical convergence across phyla.