river dolphins are relatively small compared to other dolphins, having evolved to survive in warm, shallow water and strong river currents. they range in size from the long south asian river dolphin to the and amazon river dolphin. several species exhibit sexual dimorphism, in that the males are larger than the females. they have streamlined bodies and two limbs that are modified into flippers. river dolphins use their conical-shaped teeth and long beaks to capture fast-moving prey in murky water. they have well-developed hearing that is adapted for both air and water; they do not really rely on vision since the water they swim in is usually very muddy. these species are well-adapted to living in warm, shallow waters, and, unlike other cetaceans, have little to no blubber.