Orinoco river dolphin. A freshwater dolphin that lives in freshwater systems such as the Amazon, Orinoco, and Tocantins, found in Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela. It has very poor eyesight and senses its surroundings by echolocation and whisker-like vibrissae at the tip of the snout. Its cervical vertebrae are not fused, so it has a flexible neck and can swim while avoiding obstacles in shallow water and flooded forests. Its elongated beak bears heterodont teeth, and it preys not only on fish but also on crustaceans and turtles. It usually lives alone or in small groups, and breeding occurs during periods of low water levels. Population numbers are declining, and it is classified as Critically Endangered (IUCN Category I B).