IDENTIFYING PYGMY AND DWARF SPERM WHALES (GENUS KOGIA) USING ELECTROSPRAY IONIZATION MASS SPECTROMETRY OF MYOGLOBIN AND HEMOGLOBIN

The differentiation of pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales has been problematic due to the morphological similarities between the two species. We report here a quick, efficient, and robust method for distinguishing the two species, based on differences in the molecular weights of their myoglobin and hemoglobin alpha-chain molecules. This approach can be used to verify field identification of stranded pygmy and dwarf sperm whales worldwide, and it also makes it possible to retroactively identify or confirm species assignment for previous strandings where photographs and measurements were not available or assignment was questionable, but voucher specimens (muscle or blood) have been collected and archived.