Anatomical investigation of the common minke whale fetal tongue reveals papillae marginales and glands

Abstract The tongue serves as a vital organ in mammals, facilitating crucial functions such as mastication, swallowing, vocalization, thermoregulation, and taste reception. Cetacean tongues have evolved under distinct selective pressures compared to those of terrestrial mammals, yet research on their tongues is limited, leading to controversy regarding their gustatory abilities. This study aims to elucidate the morphological characteristics of the fetal tongue of common minke whales through both gross and microscopic observations. Macroscopic examination revealed that the papillae marginales were the only lingual papillae that were obviously developed in all specimens, and these projections are hypothesized to aid in suckling during the nursing period. Lingual glands were exclusively found in the proximal region of the tongue, unlike in toothed whales, where they are distributed in rostral regions. The rudimentary mechanical papillae and the caudal location of the lingual glands are thought to be consistent with the lunge feeding strategy. Neither macroscopic nor microscopic observations detected taste buds or any structures which are responsible for taste reception. Hence, it is suggested that gustation is not a crucial sense for nutrition in this species. These morphological findings enhance our understanding of rorqual feeding habits and provide insights for the management of this unique mammalian lineage.