Meeting Abstract
Many animals have venomous structures for defense against predators, such as bee stingers, male platypus spurs, and lionfish spines. A diagnostic characteristic of stingrays in the Family Dasyatidae is the presence of a barb located on the tail and used for defense. Stingray barbs are composed of mineralized collagen and are partially serrated. Barb cross-sectional shape, serrated length, and number of serrations vary across taxa and are correlated with ecology. The goal of this project was to determine the puncture performance of barbs from the Atlantic stingray, Hypanus sabinus and the Bluntnose stingray, Hypanus say. We used an Instron E1000 materials tester to quantify the puncture and withdraw forces from porcine skin, a common model for human skin. We hypothesized that withdraw force would be greater than puncture force for both species due to the presence of the recurved serrations. To quantify puncture forces (N), barbs were oriented orthogonal to the skin and advanced at 30 mm min-1 until 20% of the total barb length embedded in the tissue. The withdraw forces (N) were quantified by raising the barb at 30 mm min-1 until the tip was no longer embedded into the porcine skin. We also incorporated micro-CT scanning to quantify the morphology of the barb as well as mineralization density. Preliminary data suggest that forces required for withdraw are larger than those needed for puncture, supporting our hypothesis. By investigating the puncture and withdraw mechanics of stingray barbs from two common coastal species, we can quantify outcomes of an interaction between a stingrays and their accidental targets, humans.
