Meeting Abstract

P2.39  Saturday, Jan. 5  The axial motor pattern and kinematics of terrestrial locomotion of the African lungfish, Protopterus annectens HORNER, AM*; JAYNE, BC; Brown University; Univ. of Cincinnati angela_horner@brown.edu

Transitions between water and land have occurred numerous times in the evolution of vertebrates, but these transitions also occur frequently in the ontogeny and daily behavior of many taxa. Primarily aquatic organisms such as lungfish occasionally move on land to escape unfavorable conditions. Although the African lungfish has diminutive paired fins that aid in slow, benthic locomotion, most aquatic locomotion is powered by axial musculature during lateral undulatory swimming. Previous studies of lateral undulatory swimming in many diverse elongate vertebrates found that axial muscle activity propagates posteriorly and alternates between left and right sides, with onset tending to precede muscle shortening. Eels, snakes , and ropefish also use lateral undulation to move in both terrestrial and aquatic environments, with some adjustments to the timing of muscle activity. We hypothesized that lungfish would similarly exhibit posteriorly propagated alternating waves of unilateral muscle activity during terrestrial lateral undulation on a mud surface. We determined the kinematics and axial muscle activity of terrestrial locomotion in the African lungfish (Protopterus annectens) and found that 1) lungfish do not use the path-following terrestrial undulations common to snakes, eels, and ropefish but rather pivot with their heads; and 2) muscle activity in the trunk is nearly synchronous rather than showing a clear posterior propagation. Thus, rather than resembling the terrestrial locomotion of other elongate limbless vertebrates, the standing wave of axial muscle activity observed here is more similar to walking salamanders.