
Meeting Abstract
Several gobiid stream fishes climb waterfalls as juveniles during their amphidromous life cycle. Previous research identified two climbing styles: powerbursting and inching. Powerburst climbers use pectoral fin adduction and bursts of axial undulation to propel themselves upwards between periods of attachment to the substrate with a pelvic sucking disc. Inching climbers sequentially detach and reattach both pelvic and oral sucking discs to climb, with little axial movement. Powerburst movements represent the ancestral style of climbing in gobies, providing more time for their kinematics to diversify. As a result, we expect to observe higher kinematic variation between powerburst species than between inching species. To test this prediction, we compared previously collected, high-speed video data on climbing kinematics from juveniles of powerburst (Awaous stamineus, Lentipes concolor) and inching (Sicyopterus stimpsoni) species from the Island of Hawai’i, to new data from powerburst (Cotylopus acutipinnis) and inching (Sicyopterus lagocephalus) species from the Indian Ocean Island of Réunion. Powerburst climbers showed notable variation in climbing kinematics across species, with divergent ranges of maximum amplitudes and velocities of body segments, and the angles of segments to the direction of travel. In contrast, inching kinematics were similar across species with regard to oral sucker expansion and timing of head and pelvic sucking disk advancement. These patterns suggest that limited evolutionary time, and potentially constrained mechanics of the oral sucking disk, may limit the diversification of inching movements.