Meeting Abstract

P2-112    Bending Mechanics of Sea Urchin Spines Saville, B.T*; Crofts , S.B; Akinrinade, A.O; College of the Holy Cross; College of the Holy Cross; University of Washington Bothell btsavi22@g.holycross.edu

Sea urchins employ their spines for a wide variety of tasks, and the forces exerted on urchin spines during the execution of these tasks will vary greatly. Forces generated during a puncturing defense, occurring along the long axis of the spine, will be very different from more lateral, bending-type forces experienced during burrowing or anchoring behaviors. In this study we look at how three species of urchin, all common in the Salish Sea, differ in regional spine morphology and structural resistance to bending. We collected and analyzed CT data to determine the second moment of area along the length of spines from three regions of the sea urchin body (oral, lateral, aboral), collecting data from 8 individuals per species and 5 spines per region. Purple urchin (S. purpuratus) spines had higher second moment of area values than those of the pale (S. pallidus) and green urchins (S. droebachiensis), while pale and green urchin spines yielded similar values. Higher second moment of area values indicate a higher flexural stiffness, and a greater resistance to bending. Variation in these parameters among species points to differences in function and ecological niche.