Meeting Abstract
Aside from being able to move backwards with ease and retract their heads in a startle response, many elongate fishes are known to make terrestrial excursions. During swimming, highly elongate fishes propel themselves using sinusoidal waves, which pass along their bodies, better known as anguilliform locomotion. When highly elongate fishes cross from an aquatic to terrestrial environment, the wave amplitude is greater. More recently, we showed that when provided with vertical substrate in the form of wooden pegs, elongate fishes contact pegs presumably to make forward movements. We have also shown that differences in axial elongation can affect peg use in the aquatic and terrestrial environment. In this study, we provide a more detailed analysis of the different regions of the axial skeleton when ropefish (Erpetoichthys calabaricus) move in water and on land through differently spaced peg arrays. We tracked five distinct regions along the axial skeleton. Similar to previous work, we show that distance ratios in the head region were significantly different between environments. The head exhibits more lateral excursion on land compared to in the water suggesting less forward propulsion on land. Linear velocity differed between aquatic and terrestrial trials across the five body regions. We found that in the terrestrial environment, ropefish are moving slower and with more control. Ropefish tended to cover greater distance in a shorter time in water than on land. The spacing of pegs also had an effect on the movement patterns during terrestrial locomotion; fish moved more quickly in more widely spaced peg arrays. This work demonstrates how elongate fishes may be utilizing aspects of their environment for forward propulsion similar to what has been previously seen in limbless tetrapods.
