The cardiac ventricles of a baleen whale (Balaenoptera acutorostrata: Minke whale) and a toothed whale (Hyperoodon ampullatus: Bottlenose whale)

Fifteen minke whale (Balaenoptera acutorostrata: Mysticeti) and three bottlenose whale (Hyperoodon ampullatus: Odontoceti) hearts were obtained from Norway. Only the ventricular mass and the base of the great arteries were available for study. The shape of the heart, the double apex, the narrowness of the interventricular septum in the dorsiventral plane, the side-to-side position of the ventricles, the relative thickness of the wall of the right ventricle, and the heavy trabeculation agree with other, brief reports of whale heart morphology. Coronary artery tortuosity, which has been described in sperm whales by others, was found in the bottlenose but not in the minke whales. It is suggested that the shape of the heart is associated with depth and duration of dives and that the pattern of trabeculation may be related to the size of the animal.