Beware the jumping cholla, Cylindropuntia fulgida. This shrubby, branching cactus will – if provoked by touching – anchor its splayed spines in the flesh of the offender. The barbed spines grip so tightly that a segment of cactus often breaks off with them, leaving the victim with a prickly problem.

This is one of six species of cactus subjected to careful testing by University of Illinois postdoctoral researcher Stephanie Crofts and animal biology professor Philip Anderson. The researchers, who study the biomechanics of puncturing plants and animals, wanted to know how spine structure influences its performance.