Meeting Abstract

4.7  Saturday, Jan. 4 09:15  How moles destroy your lawn: the “lateral stroke” of Eastern moles (Scalopus aquaticus) LIN, Y.F.*; HORNER, A.M. ; EKSTROM, L. J. ; ROBERTS, T. J. ; DUMONT, E.R. ; University of Massachusetts at Amherst, MA; California State University, San Bernardino, CA; Wheaton College, Norton, MA; Brown University, Providence, RI; University of Massachusetts at Amherst, MA yifenlinOEB@gmail.com

Animal locomotion on land, water and air has been studied comprehensively during the past one hundred years. However, we know very little about how animals move through the earth. Burrowing is an energetically costly form of locomotion that involves loosening and removing soil as an animal tunnels. Moles are an excellent system for studying the mechanics of burrowing because their unique “lateral strokes” generate powerful forces that efficiently loosen and remove soil in a single movement. In this study, we measured the forces generated by moles when they were allowed to burrow in the tunnels of different widths. The maximum lateral force was generated when the distance between the sides of the tunnel (hand span) was 70% of body width. Lateral forces decreased when tunnel was narrower or wider. We also examined a dorso-ventral x-ray video of a burrowing mole and calculated the angles of the wrist (palm-ulna), elbow (ulna-humerus) and shoulder (humerus-scapula) joints throughout the lateral stroke cycle. We plotted these angles against relative hand span to estimate the position of the joints at the point of maximum lateral force production (70% hand span). We found that shoulder abduction, which has been suggested to be the main driver of the powerful lateral stroke, occurred before 70% relative hand span. At 70% relative hand span, the angles of wrist and elbow joints were at their maximum. These findings differ from earlier descriptions of burrowing and set the stage for future analyses using substrates of different densities and alternative force plate configurations.