166. MICROSTRUCTURAL CHARACTERIZATION OF THE BONY PLATED ARMOR IN THE PREHENSILE TAIL OF SEAHORSES

Department: Mechanical & Aerospace Engineering
Research Institute Affiliation: Graduate Program in Materials Science and Engineering
Faculty Advisor(s): Joanna Mckittrick | Marc A. Meyers

Primary Student
Name: Michael Martin Porter
Email: m1porter@ucsd.edu
Phone: 757-615-3929
Grad Year: 2014

Abstract
The bony plated armor in the prehensile tail of the seahorse (Hippocampus kuda) is a multifunctional material that provides the seahorse structural support, protection, and even the ability to bend in a strict spiral and grasp objects. The bony plates are arranged in rings of four overlapping plates per tail segment, with approximately 35 segments spanning the length of the tail. The bony plated armor in seahorses was characterized with 3D optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and micro-hardness testing. When compared to bovine femur bone (~67 wt% mineral; ~500 MPa Vicker's hardness), the bony plates in the seahorse tail have a much lower mineral content (45 wt%) and average hardness (270 MPa). The distribution of hardness across a single bony plate, however, seems to be tailored to specific tasks - harder on the outer surface for protection, and softer at the overlapping joints for mobility. The structural hierarchy of the mineral and protein constituents, along with the distinct hardness distribution and overlapping nature of the bony plates, gives the prehensile tail its exceptional toughness and flexibility required to perform specific functions.

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