Bat Tongues and Foraging: Linking Morphology to Hunting Strategies

On their dorsal surface, bat tongues show a raised muscular structure called mediodorsal lobe (MDL) or lingual prominence. It exhibits different mechanical papillae across species, which we hypothesized are linked to foraging strategies. We predicted that tall MDLs and prominent papillae pointing frontward would effectively trap prey items caught on the wing by aerial hawkers. We examined 904 high-resolution, close-up images of 239 individual bats from 24 European species, focusing on MDL height and morphology and arrangement of MDL papillae. Aerial hawkers such as Tadarida teniotis, Nyctalus lasiopterus, Miniopterus schreibersii, and pipistrelles displayed prominent forward-pointing papillae and taller MDLs, adaptations suited to high-speed aerial foraging. These traits may be part of a broader "ecomorphological syndrome", facilitating efficient prey capture in open-space foragers. In contrast, gleaning and trawling species lacked these specializations, exhibiting flatter MDLs and less prominent papillae. Phylogenetic analysis indicated evolutionary convergence in MDL morphology among aerial hawkers, with M. schreibersii showing similarities to vespertilionids despite its phylogenetic distance. This convergence highlights the influence of evolutionary pressures arising from foraging requirements on tongue morphology. Although possessing tall MDLs, rhinolophids are outliers, possibly reflecting their unique perch-hunting strategy or echolocation. If the patterns we found are confirmed for a larger number of species, MDL morphology could predict foraging style across bat species and be included in future descriptions of foraging guilds.