NSF Postdoctoral Fellowship in Biology FY 2019: Rough skin: microstructural and fluid dynamic studies of elasmobranch skin to understand how denticle morphology affects locomotion

Gabler Molly K, Wilmington NC

Investigators

Abstract

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2019, Research Using Biological Collections. The fellowship supports research and training of the fellow that will utilize biological collections in innovative ways. This research focuses on the morphology of fish skin, specifically, the microscopic scales called denticles on sharks and rays. Denticles have many proposed functions, including protection from predators, abrasion reduction, and alteration of water flow over the body. Shape characteristics of denticles are known to differ among species as well as along different positions of the body within an individual. Denticle shape is thought to alter water flow along the body of fish, by decreasing hydrodynamic drag. The functional significance of these scales is of particular interest because sharks and rays use many different ways of swimming, and there are many different denticle sizes and shapes. By comparing skin form with function, the fellow will answer questions about fish biology, including evolution, locomotion, and habitat. The Fellow will gain understanding of fish functional morphology by learning new techniques, including robotic testing of 3D printed skin. The results will also be important for learning about underwater locomotion for human use. The Fellow will work closely with the Atlantic White Shark Conservancy to develop a hands-on teaching seminar for young girls interested in shark research. The fellow will use elasmobranch specimens from the Harvard Museum of Comparative Zoology to conduct a large-scale comparative analysis of denticle shape. The Fellow will be trained in multiple three-dimensional (3D) imaging techniques to examine denticle morphology of species that employ various locomotor modes (i.e. axial-undulatory and pectoral-fin propulsors). The Fellow will use gel-based profilometry, which determines surface metrology variables (i.e. denticle roughness) together with micro-computed tomography, to create 3D models of individual denticles along various parts of an animal's body. These models will be used in a high-resolution 3D printer to produce a flexible material for quantitative hydrodynamic testing to investigate the fine-scale fluid dynamics produced by the skin denticles. Understanding how the morphology of the denticles contributes to hydrodynamic function and the ecology of elasmobranchs is important for understanding the structural and functional evolution of elasmobranchs and to design more efficient biomimetic materials for underwater locomotion for human use. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.