A comparative morphological study on the tongue and the lingual papillae of some marine mammals —Particularly of four species of odontoceti and zalophus—

Abstract

We observed the structure of the tongues of some aquatic mammals in four species of Odontoceti (Stenella coeruleoalba, Lagenorhynchus obliquidens, Tursiops truncatus andMesoplodon stejnegeri) andZalophus californianus californianus using light microscopy (LM) as well as scanning electron microscopy (SEM) and compared the characteristics of the tongue of each animal species. In the four species of Odontoceti, the dorsal surface of the anterior part of the tongues had a smooth surface. However, after removal of the epithelium, slender conical connective tissue cores (CTCs) were densely distributed. At the boundary between the lingual body and the root ofTursiops truncatus, several round vallate-like structures were observed and inLagenorhynchus obliquidens, they had a pair of V-shaped long fissures. In the shallow part of these fissures of both species, some taste buds were observed. Generally, the characteristics of the tongue of three species of dolphins were respectively more simple fromTursiops truncatus toLagenorhynchus obliquidens, toStenella coeruleoalba. InMesoplodon stejnegeri, the structure of the tongue showed further simplified characteristics. In the tongue ofZalophus californianus californianus, well-developed lingual papillae (e.g. filiform-, fungiform-, vallate papillae) were observed. Instead of foliate papillae, a series of finger-like long papillae were distributed. The tongue of theZalophus had typical lingual papillae similar to those of Carnivorae of land mammals.