Meeting Abstract
Mola mola (Ocean Sunfish) fish are recognizable by their distinct morphological characteristics, including large lobate dorsal and anal fins which fuse in place of a non-existent caudal fin. Mola mola swim using synchronous flapping of the dorsal and anal fins, which generates lift-based thrust similar to the swimming of penguins and manta rays. The Ocean Sunfish is able to dive to depths of 600 meters and cruise at a speed of 3.2 km/h. Recent work on M. mola anatomy shows extremely disproportionately sized muscles inserting into the relatively equal aspect ratio dorsal and anal fins. This raises the question: how do Mola generate equal forces through synchronous flapping if the muscle mass powering the dorsal fin is nearly twice that of the anal fin? To elucidate the locomotor biomechanics of this large species, we microCT scanned two M. mola specimens and dissected two M. mola to measure muscle mass, muscle fiber angles, and physiological cross-sectional area (PCSA) to estimate maximum force production. Here, we present the results of our myological investigation and our biomechanical model explaining locomotor force generation in M. mola. This work will directly inform the design and actuation of our bioinspired Molabot, which we will use to empirically test the relationship between fin muscle force production and swimming thrust in these unique swimmers.
