Structure and material composition of oral disc structures in selected Anuran tadpoles (Amphibia)

This study investigates the material composition of the keratinous teeth and jaw sheaths of Anuran tadpoles, for the first time. Using scanning electron microscopy (SEM), confocal laser scanning microscopy (CSLM), and energy dispersive X-ray spectroscopy (EDX), the oral discs of eight species were analysed. SEM analysis revealed structural diversity, including different tooth microstructures, which may reflect functional adaptations to different mechanical loads. CSLM imagining documented consistent autofluorescence patterns across species, with notable interspecific differences in tooth composition. EDX analysis identified a wide variety of elemental compositions, suggesting possible correlations with ecological or/and dietary factors. This study is the first on the composition of tadpole mouth parts and provides a foundation for future research on the functional morphology and biomechanics of these structures and their interplay with feeding ecology. STATEMENT OF SIGNIFICANCE: This study marks the first detailed exploration of the material composition of keratinous teeth and jaw sheaths in Anuran tadpoles, unveiling significant structural and compositional diversity. Using SEM, CSLM, and EDX analyses, it highlights interspecific differences in microstructure, autofluorescence, and elemental composition, with potential links to ecological and dietary adaptations. Notably, SEM revealed multi-layered tooth structures likely reducing abrasion, while CSLM indicated species-specific autofluorescence variations possibly linked to element distribution. Elemental analysis identified differences in sulphur, aluminium, and silicon content across species. These findings provide a critical foundation for advancing research into the functional morphology, biomechanics, and ecological roles of tadpole oral structures, paving the way for deeper understanding of their evolution and adaptive mechanisms.