Natural Resources, School of


Date of this Version

January 2006


Published in Journal of Zoology 269 (2006), pp. 51–56. © 2006 The Authors. Journal compilation © 2006 The Zoological Society of London. Used by permission. Published by Blackwell Publishing. “The definitive version is available at”


Idealized edged and non-edged indenters, mimicking canine teeth, were used to puncture thin materials and thick materials. Less force was needed for the edged (triangular in cross section) indenter to penetrate thin Mylar, paper, leather, beetle elytra and turkey skin than the non-edged (circular in cross-section) indenter. Oak, grass and magnolia leaves responded equally to both indenters. In thick materials, the edged indenter punctured beetles, shrimp, bananas, and chicken flesh more easily than the non-edged indenter. Apple, tomato and avocado were punctured equally well. The edged indenter directs cracks at the corners so that the material can fold away in the direction of puncture, whereas cracks form unpredictably with the non-edged indenter. Edged indenters have the advantage in many of the materials tested.