Different shape but the same topographical complexity—The lingual gross anatomy of the Saimaa ( Pusa saimensis ) and Baltic ringed seals ( Pusa hispida botnica )

Despite the distinctly different shapes of their tongues, the tongue gross anatomy of Saimaa ringed seal closely resembled that of Baltic ringed seal. There were no differences in the extrinsic and intrinsic tongue muscles or their associated vascularization and innervation between Saimaa and Baltic ringed seals. Only the apex of the tongue had a median sulcus separating it into two lateral parts and the amount and organization of the pigmented areas on the dorsal surface of the tongue showed individual variation. The bilateral intermolar elevations previously reported in the tongue of adult Saimaa ringed seals occurred in subadults with a body weight approaching 40 kg but not in any of the younger individuals. The macroscopic and microscopic anatomy of the gustatory lingual papillae found on the dorsal side of the tongue was similar in all studied individuals. The dome-like fungiform papillae were scattered among the filiform papillae. In the root of the tongue, five to eight vallate papillae surrounded by a circular groove were arranged in a semicircle. Apparently, the oral food processing or dietary differences of Saimaa and Baltic ringed seals were not substantial enough to affect the topographical complexity of their lingual surfaces.