Aquatic Mammals (1988)


(…) Tongues (Lingua) of dead harbour porpoises are much smaller than those of comparable terrestrial mammals (Boenninghaus, 1903). With the exception of a small area at the tip of the tongue, the entire margin (Margo linguae) is covered with papillae (Papillae fungiformis). A longitudinal section through the tongue shows differences when compared with the tongues of terrestrial mammals, their inner parts consist of muscles. The inner parts of harbour porpoise tongue and of their papillae consist of cavernous tissue (Corpus cavernosus) and muscles are very poorly developed. The corpus cavernosus is an extension of the venous vessel system and enable it to carry larger quantities of blood (Boenninghaus, 1903). The corpus cavernosus is covered by the integument (Integumentum commune). The boundary lines between different skin parts, the subcuticle (Tela subcutanae), corium (Corium) and the cuticle (Epidermis), are clearly recognized. The cuticle is covered with a squamous muscosa. This means that the integument of the tongue of the harbour porpoise is of the same structure as the integument of other terrestrial mammals. Some toothed whales possess taste buds, but mainly of a residual nature (Stadtmüller, 1938). The anatomy of odontocete brains shows that they are able to taste. It is also confirmed that toothed whales can use the tip and the margin of their tongues as organs of touch (Caldwell & Caldwell, 1972).

If the harbour porpoise is able to taste and to touch, its tongue must have nervous receptors. As the integument of the harbour porpoise tongue is similar to the one of other mammals, it was important to find out whether its nerves are comparable to the nerves of the tongues of terrestrial mammals, and how sensitive they are. (…)