The Amazon's pink dolphins get their colour from scrapes, not from their diet
Amazon river dolphins are born dark grey and only turn pink as adults, as years of abrasion wear their skin. Males, which fight more, end up pinker and scarred. They can turn their heads sideways, weave through flooded forest, and court females by carrying branches or balls of hardened clay in their mouths.
The boto is the largest river dolphin: adult males can reach 2.55 metres and 185 kilograms, while females top out around 2.15 metres and 150 kilograms. That size gap is unusual, since in other river dolphins females tend to be bigger. Males carry bite damage on their fins and blowhole plus rake marks from rivals' teeth, a sign of fierce competition for mates; scientists once assumed the species was monogamous.
Its body suits a maze of submerged trees. Unlike ocean dolphins, its neck vertebrae are not fused, so the head can swing 90 degrees, and long paddle-like flippers let it turn in tight circles. It is a slow swimmer, usually cruising at 1.5 to 3.2 kilometres per hour. Its long snout holds 25 to 28 pairs of teeth on each side of both jaws, some for gripping and others for crushing, and its diet is among the broadest of any toothed whale, with up to 53 kinds of fish, including piranhas, as well as river turtles, frogs and crabs.
Wild botos have been seen holding fishermen's oars, rubbing against boats and playing with sticks, turtles and even snakes. Most travel alone or in pairs, though up to 35 may cooperate when hunting. The species spans the Amazon and Orinoco basins and Bolivia's upper Madeira, and scientists still argue over how many subspecies it contains.
Captivity has gone badly. The dolphins proved hard to train, and a 1986 study found an average lifespan of only 33 months in the United States, though one male, Baby, lived at least 46 years at Germany's Duisburg Zoo. In 2018 the IUCN listed the species as endangered, threatened by fishing lines, hunting for bait, dams and pollution.
Source: Amazon river dolphin
