the south asian river dolphin has the long, pointed nose characteristic of all river dolphins. their teeth are visible in both the upper and lower jaws even when the mouth is closed. the teeth of young animals are almost an inch long, thin and curved; however, as animals age, the teeth undergo considerable changes and in mature adults become square, bony, flat disks. the snout thickens towards its end. navigation and hunting are carried out using echolocation. they are unique among cetaceans in that they swim on their sides. the body is a brownish color and stocky at the middle. the species has only a small, triangular lump in the place of a dorsal fin. the flippers and tail are thin and large in relation to the body size, which is about 2-2.2 meters in males and 2.4-2.6 m in females. the oldest recorded animal was a 28-year-old male, 199 cm in length. mature females are larger than males. sexual dimorphism is expressed after females reach about ; the female rostrum continues to grow after the male rostrum stops growing, eventually reaching approximately longer.