Meeting Abstract

8.6  Saturday, Jan. 4 08:40  Modes of sustained terrestrial locomotion in osteichthyian fishes PACE, C.M.; GIBB, A.C.*; Northern Arizona University; Northern Arizona University alice.gibb@nau.edu

Sustained terrestrial movements by osteichthyian fishes can be categorized based on the contributions of the paired appendages and/or the axial body to forward propulsion. Elongate fishes with axial-based locomotion (e.g. the ropefish Erpetoichthyes calabaricus) generate an anterior-to-posterior wave of undulation that travels down the axial musculoskeletal system and pushes the body against the substrate at multiple points. Appendage-based locomotors, (e.g. the barred mudskipper Periophthalmus argentlineatus), produce no axial bending during sustained locomotion, but instead use repeated protraction/stance-retraction/swing cycles of the pectoral fins to elevate the center of mass (COM) and propel the entire body anteriorly. Fishes that use an axial-appendage-based mechanism (e.g. walking catfishes Clarias spp.) produce side-to-side, whole-body bending in coordination with protraction-retraction cycles of the pectoral fins; once the body is maximally bent to one side, the tail is pressed against the substrate and drawn back through the mid-sagittal plane, which elevates the COM and rotates it anteriorly about a fulcrum formed by the pectoral fin and the ground. Although appendage-based terrestrial locomotion appears to be rare in osteichthyian fishes, many divergent taxa have converged upon functionally similar axial-based and axial-appendage-based behaviors to move over land. Based on common forms observed across these divergent taxa, dorsoventral axial compression, axial elongation, and/or the presence of robust pectoral fins appear to facilitate the production of effective movements by fishes in the terrestrial realm.