Suborder Odontoceti - Toothed Whales
With the exception of the sperm whale (males of which can reach lengths of at least 18 m), odontocetes are small to medium-sized cetaceans. Sexual dimorphism is the rule. Toothed whales are characterized by the presence of teeth throughout life (although teeth are buried in the gum or jawbone in some species, worn or lost in others, and take peculiar shapes in still others), a single blowhole, an asymmetrical skull with a concave profile, a sternum with 3 or more parts, a complex system of nasal sacs, and a fatty organ in the forehead area called the melon. All are hypothesized to be capable of echolocation (i.e., producing specialized sounds, and receiving and processing the echoes from these sounds to navigate, find food, and avoid predators), although this ability has been experimentally verified for only a handful of species held successfully in captivity. Odontocetes take individual prey, which consists largely of fishes and squids.