Amazon river dolphin (boto)

The Amazon river dolphin (Inia geoffrensis), also called the boto, bufeo or pink river dolphin, is the largest of all river dolphins. Many adult males reach about 185 kilograms and 2.5 metres in length. Adults become pink as they age, and the colour is stronger in males.

It lives in the rivers of the Amazon and Orinoco basins in South America. When the rains come, it swims into the flooded forest between the trees. Its neck bones are not fused, and its large fins let it twist and turn through tight spaces. The species is now listed as endangered, with fewer animals each year.

A dolphin in the treetops

In the rainy season, rivers rise and spill over into the forest. The Amazon river dolphin follows the water and weaves between tree trunks. Because its neck vertebrae are not fused, it can bend its head far more than most dolphins, and its big fins help it steer. Like other toothed whales, it has a rounded forehead called the melon, which it uses for echolocation, a kind of natural sonar.

Food and dangers

Boto eat up to 53 kinds of fish, including croakers, catfish, tetras and piranhas. They also eat river turtles, frogs and freshwater crabs. In 2018 the IUCN ranked them as endangered, with a falling population. Dangers include getting caught in fishing lines, being hunted for fishing bait, dams that block rivers, and pollution. Males are about 16 percent longer and 55 percent heavier than females.

On the globe

The model shows an Amazon river dolphin. Look for its pink colour and long snout.