Meeting Abstract
Mola mola (Ocean Sunfish; Tetraodontiformes: Molidae) are recognizable by their distinct morphological characteristics, including large lobate dorsal and anal fins which fuse to form a clavus in place of a non-existent caudal fin. Adult mola lack axial musculature, but by synchronous flapping of the dorsal and anal fins they are able to dive to depths of 600 meters and cruise at a speed of 3.2 km/h. Larval mola more closely resemble sister species of pufferfish, but early in ontogeny undergo rapid morphological changes. Previous work examined some of the skeletal changes in mola ontogeny using cleared and stained specimens, with particular focus on the formation of the clavus, however, no studies to date have looked at the myological changes that occur as a result of the body shape and skeletal transformations that take place. Using computed microtomography (microCT) scanning, we were able to produce high-resolution three-dimensional skeletons of three stages of mola fry and an adult mola for ontogenetic comparison. Phosphotungstic acid (PTA) staining and re-scanning of mola fry generated images of soft tissue morphology, allowing us to compare muscle volume, position, and fiber angle through ontogeny with measurements from dissections of adult mola. Herein we discuss the functional implications of drastic morphological modeling and changes in body size during ontogeny on the locomotor performance of Mola mola.
