Meeting Abstract
Sicyopterus japonicus are a species of waterfall-climbing goby fish indigenous to Japan. While developing into adults from a post-larval stage, the fish migrates from the ocean to freshwater rivers and streams. During migration, the fish climbs waterfalls by using alternating motions of suctions by the mouth and fused pelvic fins (pelvic sucker) generating pressure differential that allows adhesion on the rock surface. This suction pressure was recorded by having S. japonicus individuals climbing on the artificial waterfall with a pressure transducer installed in its climbing surface. In addition, the suction force was calculated by taking the area of the pelvic fins into account. S. japonicus produced the force for adhesion up to 4.3 times greater than their body weight against gravity. During the experiment, some S. japonicus individuals showed gradual reduction in suction force for adhesion while staying stationary on the climbing surface, indicating the fish experiences some levels of muscle fatigue, although the absolute minimum force produced was still above the theoretical minimum force requirement. In addition, scaling patterns of the suction force as well as muscle fatigue in relation to body size of the fish indicate ontogenetic changes in functional performance of the locomotor muscles.
