Meeting Abstract

P3.40  Tuesday, Jan. 6  Directionally Mediated Escape Swimming in the Scallop BROWN, J.W.; University of Illinois at Urbana-Champaign jwbrown4@uiuc.edu

Despite the copious literature available and robust dynamic modeling on the ability of scallops to employ jet propulsion, no investigation has been undertaken to assess scallops’ ability to control their directionality during an escape swimming event. Twenty specimens of the Pacific Northwestern species Chlamys hastata were provoked using a severed arm from the sea star Pycnopodia helianthoides, a common predator, in order to elicit the escape swim response. A significant correlation was shown to exist between the anterior-posterior laterality–but not absolute position along the scallop’s mantle–of predatory stimulus and the ensuing direction of rotation; namely, stimuli applied to the anterior mantle consistently effected a counterclockwise rotation (when viewed from above the animal) during the initial escape swim, while posterior stimulation resulted in a clockwise rotation. Stimulation at the ventral end of the dorsal-ventral axis demonstrated a strong counterclockwise bias, suggesting a possible morphological or neurological asymmetry underlying this response. To these ends, visualization of the two dorsal jets and an additional diffuse ventral jet at the onset of swimming revealed the ability to fire the anterior or posterior dorsal jets exclusively in accordance with the preferred direction of rotation. Rudimentary modeling of this phenomenon is explored.