CAREER: Tuning fish: mechanics of biomaterials change with changing demands of locomotion

Florida Atlantic University, Boca Raton FL

Investigators

Abstract

How do animals tune, or dynamically adjust, their movements using their skin and skeletons? This research investigates the contributions of the shark cartilaginous vertebral column, skin, and animal movements that tune the body during swimming. Shark vertebrae work as springs, which store and return energy based on the species-specific arrangement of mineral in the cartilage. Shark skin contains mineralized teeth, which make the skin feel like sandpaper and are hypothesized to resist stretching. During swimming, the movements of both the body and the tail can vary among different species. By studying these three levels of organization individually, the influence of hard and soft tissues on overall body performance can be modeled and understood in sharks swimming at different speeds. The results of this research will provide information about swimming, and inspiration for both stiff and stretchy synthetic materials. The research will be conducted at Florida Atlantic University, a Hispanic Serving Institution that is considered to have one of the most diverse student populations in the United States. The project will support advancement of a female assistant professor, whose laboratory draws diverse graduate, undergraduate, and dual-enrolled high-school researchers from a student population in which 26% of STEM majors are Hispanic. The principal investigator will teach an Animal Locomotion course in which students develop active-learning-focused content that is shared in open-access education journals and then disseminated locally at nature centers and museums. This work facilitates collaboration with researchers studying machine learning and ocean and mechanical engineering. Stiffness imparted from the vertebral column and skin, which tune an animal’s body, can impact swimming speed and style. This research links the contributions of both mineralized (cartilaginous vertebrae) and soft (skin) biological materials to animal movement. The mineral amount and arrangement impact mechanical properties like stiffness in cartilage and skin, but there are complex interspecific morphological variations that are not understood. The vertebral column contains repeating centra that yield, or permanently deform at high stresses, creating a mechanical space wherein the cartilage can operate without permanent damage, and the impacts of body tuning can be explored. Similarly, this research will examine the tiny mineral inclusions (dermal denticles) that have been shown to impact stiffness of the skin and potentially the whole body. Mechanical properties and mineralization patterns of cartilage and skin from several shark species will be quantified using material testing and CT scanning. Preliminary video data show that some species of shark can swim using a double oscillating system, where frequency of movement varies in the anterior to posterior direction, and these mechanics may be facilitated by passive stiffness from the vertebrae and skin. The work facilitates collaboration with researchers through university programs and partnerships including the university lab school. The PI will impact the larger scientific community in South Florida by organizing a seminar series on campus, in which graduate students interact and network with marine scientist speakers from educational, industry, and non-profit organizations. Research findings will be shared with the general public, including K-12 students, at local nature centers and science museums. 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.