P12-8 Sat Jan 2 The role of cranial mechanical linkages in gill ventilation of dorso-ventrally and laterally compressed fishes Stephens, S*; Gabriel, AN; Kaczmarek, E; Brainerd, EL; Olsen, A; Hernandez, LP; Camp, A; Farina, SC; Howard University; Howard University; Brown University; Brown University; Brown University; The George Washington University; The University of Liverpool; Howard University sydney.stephens@bison.howard.edu
Teleost fishes pump water over their gills by cyclically expanding and compressing the buccal and gill chambers. These chambers are typically modeled as coordinated but operating as independent components of the pumping process. The chambers are mechanically linked, however, and these linkages play an underappreciated role in ventilatory mechanics. Our goal is to quantify the extent to which these linkages impact ventilatory kinematics. In this study, we focus on the suspensorium-opercle linkage, by which abduction of the suspensorium (buccal chamber) contributes to abduction of the opercle (gill chamber). We calculated these values from XROMM (X-ray Reconstruction of Moving Morphology) animations of catfish (Ictalurus punctatus) and knifefish (Chitala blanci) ventilatory sequences. In the catfish, we found that abduction of the suspensorium contributes 46-70% to the abduction of the operculum during gill ventilation. However, in the knifefish, we found that abduction of the suspensorium contributed much less, only 30-33%, of abduction of the operculum. The catfish skull is dorso-ventrally compressed, and the knifefish skull is laterally compressed, representing two extremes of fish skull shape. While suspensorium abduction contributes to opercular abduction in both fishes, the relative extent of that contribution may be linked to head shape.
