Meeting Abstract

104.2  Wednesday, Jan. 7  Visualizing internal structural movements during soft-bodied crawling using phase-contrast X-ray microvideography SIMON, M.A.*; SMITH, D.; TRIMMER, B.A.; Tufts University, Medford, MA; Tufts University, Medford, MA; Tufts University, Medford, MA michael.simon@tufts.edu

In soft-bodied animals, the movements of internal tissues cannot be isolated from those of muscles involved in locomotion. Furthermore, internal tissue movements may contribute to the kinematics and dynamics of locomotion. In the caterpillar Manduca sexta, the gut is anchored at the mouth and anus and is also loosely tethered throughout the abdomen by an extensive array of trachea. Using phase-contrast X-ray microvideography of crawling 5th-instar larvae, we have found that the gut moves asynchronously and in advance of the anteriograde wave of segmental contractions during crawling. We observed similar internal movements using transmitted visible light to illuminate semitransparent hatchlings, which are less than one-thousandth the mass of fifth-instar larvae. Therefore, we conclude that such internal tissue movements are coupled to locomotion throughout the larval stages. One consequence of this motion is that an animal’s body mass will shift forward in its anterior abdominal segments even during those segments’ proleg stance phase. Given this information, we are now exploring the potential mechanical role of the gut in storing or dissipating energy during locomotion.