Meeting Abstract
One of the major morphological changes in the water to land transition is the development of limb-like fins. However, many extant species of fish lacking fins manage to move across a variety of terrestrial substrates. These species are generally described as highly elongate, relying on axial based locomotion to advance their bodies on land. Aquatic animals must overcome an elevation gradient which is inherent to the water to land transition. Echidna nebulosa, the snowflake moray, is an eel which occupies both coral reefs and intertidal reef flats. Snowflake morays are known to make terrestrial forays to feed on invertebrates such as crabs. For this study, we tested the hypothesis that incline has an effect on the kinematics of locomotion of E. nebulosa when moving across wet pebble substrate. We tested individual eels at two different inclines, 5 and 10 degrees. A level pebble substrate, 0 degrees served as our control. We measured two kinematic variables to determine terrestrial locomotion efficiency: distance ratio, and velocity. Wavelength and amplitude was measured for each wave along the body. Distance ratio and velocity were gathered by tracking three body points (head, center of mass, and tail). When faced with either incline, E. nebulosa demonstrated a consistent reduction in velocity and distance ratio while moving across a terrestrial substrate compared to a flat (0 degree) treatment. Differences in kinematic variables between the two incline treatments (5 and 10 degrees) were not significant. Our results show that movement on land for an elongate fish is possible but the real challenge is overcoming the incline to transition from water to land.
