Morphology and mechanics of tongue movement in the african pig-nosed frog Hemisus marmoratum: a muscular hydrostatic model

• DOI: 10.1242/jeb.202.7.771
• Publication Date: 2021-04-25T05:24:43Z
• Authors: Kiisa C. Nishikawa; William M. Kier; Kathleen K. Smith
• Keywords: Genioglossus; Hydrostatic pressure

ABSTRACT The goal of this study was to investigate morphological adaptations associated with hydrostatic elongation the tongue during feeding in African pig-nosed frog Hemisus marmoratum. Whereas previous studies had suggested that H. marmoratum elongates hydraulically, anatomical observations reported here favour a muscular mechanism elongation. possesses previously undescribed compartment m. genioglossus (m. dorsoventralis), which is intrinsic and whose muscle fibres are oriented perpendicular long axis tongue. On basis arrangement orientation hyoglossus, we propose model movement contraction dorsoventralis, together unfolding musculature tongue, results doubling length. Electron micrographs sarcomeres from resting elongated tongues show no special necessary accommodate observed length feeding. Rather, longitudinalis strikingly similar those anuran limb muscles. ability elongate hydrostatically, conferred by presence appearance several novel aspects behaviour These include protract slowly, thereby increasing capture success, aim azimuth elevation relative head. Compared other frogs, system allows more precise, localized diverse movements. This may explain why composed larger number motor units than frogs.