PUNCTURE PERFORMANCE OF THE CAUDAL SPINES FROM TWO COASTAL STINGRAYS, HYPANUS SAY AND HYPANUS SABINUS

A diagnostic characteristic of stingrays in the Family Dasyatidae is the presence of a defensive, partially-serrated spine located on the tail. The objective of this study is to assess the impacts of caudal spine morphology on puncture and withdrawal performance from two stingrays, Hypanus sabinus and Hypanus say. Spines have highly variable morphology. I used an Instron E1000 materials tester to quantify the puncture and withdraw forces from porcine skin, a model for human skin. I found no significant differences between puncture and withdraw or between the species. By incorporating micro-CT scanning to quantify mineralization density, I quantified more mineralization along the shaft of the spine. Equal puncture and withdraw forces and increased mineralization along the spine shaft may create a stiffer structure that can be a persistent predator deterrent.