Mammals
Amazon River Dolphin
Inia geoffrensis · also called pink river dolphin, boto
Moving silently through flooded forest during the Amazon’s high-water season, a pink-tinged river dolphin navigates between submerged tree trunks almost entirely by sound, the largest river dolphin species on Earth at home in some of the murkiest water any dolphin is known to inhabit.
Overview
The Amazon river dolphin, Inia geoffrensis, is the largest river dolphin species in the world, native to freshwater river and flooded forest habitat across the Amazon and Orinoco river basins of South America. Its distinctive pink colouration, unusually flexible neck, and near-total reliance on echolocation for navigation make it one of the more physically and behaviourally distinctive freshwater cetaceans found anywhere on Earth.
A dolphin built for a flooded forest
Rather than relying on sight in the Amazon’s often murky, sediment-choked water, this species has instead built its entire navigational system around sound, allowing it to move confidently through submerged forest that would leave a sight-dependent hunter completely lost.
Status
Endangered and decreasing, present across much of its historical range within the Amazon and Orinoco river basins, with declines linked to habitat degradation, dam construction, and fishing gear entanglement.
Amazon River Dolphin: common questions
Why does the Amazon river dolphin turn pink?
This species can develop a distinctive pink colouration as it matures, with the exact shade varying considerably between individuals, though the precise biological reasons behind the colour change and its variation are still not completely understood by researchers.
How does the Amazon river dolphin find its way through murky water?
This species relies heavily on echolocation to navigate and hunt within the murky, sediment-filled water typical of the Amazon basin, using sound rather than sight to detect prey and obstacles in conditions where visibility is often extremely limited.
Why does the Amazon river dolphin have such a flexible neck?
This species has unfused neck vertebrae, giving it unusually flexible head movement compared with most ocean-dwelling dolphin species, an adaptation that helps it manoeuvre carefully through submerged forest and vegetation during the flooded season.
Why is the Amazon river dolphin considered Endangered?
This species has declined in parts of its range due to habitat degradation, dam construction, entanglement in fishing gear, and pollution, pressures that together have kept the species classified as Endangered despite remaining present across much of its historical range within the Amazon and Orinoco basins.