Abstract
Previous studies have described two distinct vascular systems in cetacean fins. However, these studies have been limited to Delphinoidea species, with little information on their three-dimensional structures. In this study, the anatomical analysis of the caudal and dorsal fins of a dwarf sperm whale was conducted using X-ray computed tomography and gross dissection with staining, providing the first confirmation of the two vascular systems in the fins of the family Kogiidae. This finding suggested that these vascular systems are common across Odontoceti species. In addition, we observed unique three-dimensional structures in the superficial veins, which formed a reticulate pattern in both fins and converged at the centerline at the base of the dorsal fin, potentially influencing individual's heat reduction capabilities.