Anatomy of the laryngeal apparatus of the pygmy right whale, Caperea marginata (Gray 1846)

The laryngeal apparatus of Caperea marginata is described for the first tim e and proves to be significantly different from that of any mysticete previ ously described. This difference is especially noticeable in the position o f the laryngeal sac, which is separate from the tracheal rings and lies to the right of the animal. Massive ontogenetic development of the sac in adul t males is demonstrated, far greater than that seen in most other mysticete s. Histological analysis of the laryngeal sac shows the walls to be very mu scular, abundantly innervated, and vascularized, indicating an active organ . Coiled blood vessels and nerves support the hypothesis that the sac under goes extensive expansion and contraction. A possible association with the u nique thoracic development of the species is suggested. The roles of the la ryngeal sac and arytenoid cartilages in mysticete sound production are also discussed.(C) 1999 Wiley-Liss, Inc.