Pink dolphins, also known as Amazon River dolphins or boto, are unique freshwater cetaceans found exclusively in South America. These distinctive aquatic mammals are recognized by their varying shades of pink coloration, which deepens with age, though they are born gray. Their flexible necks, unlike those of many marine dolphins, contribute to their remarkable agility.
The Amazon and Orinoco Basins
Pink dolphins primarily inhabit the vast freshwater systems of the Amazon and Orinoco river basins. The Amazon Basin represents the largest tropical wilderness and freshwater system globally, spanning approximately 6.9 to 7 million square kilometers. Similarly, the Orinoco Basin, covering about 1 million square kilometers, is also rich in biodiversity. These interconnected river systems provide the extensive freshwater habitats necessary for the dolphins’ survival. A natural waterway, the Casiquiare canal, forms a unique link between the Orinoco and Amazon basins, allowing for continuous aquatic connectivity. The sheer scale and intricate network of these basins offer diverse environments that support the dolphins’ specialized needs.
Aquatic Environments They Inhabit
Within the Amazon and Orinoco basins, pink dolphins utilize a variety of specific aquatic environments. They are not confined solely to the main river channels but also frequent tributaries, flooded forests, and oxbow lakes. During the wet season, when river levels rise, these dolphins can disperse into seasonally inundated areas, including the vast flooded forests known as várzea.
This ability to navigate through submerged trees is aided by their unfused neck vertebrae, allowing them to turn their heads up to 90 degrees. This maneuverability, along with their large pectoral fins, enables them to effectively hunt prey. Pink dolphins rely heavily on echolocation to navigate and locate food in the often murky waters. Their diverse diet includes over 50 species of fish, as well as river turtles and freshwater crabs.
Countries of Presence
The distribution of pink dolphins extends across several South American nations, reflecting the vastness of the Amazon and Orinoco river systems. These freshwater dolphins are found in Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela. Their presence in these countries underscores the interconnectedness of the regional waterways. Within this extensive range, specific subspecies inhabit particular geographical areas; for instance, Inia geoffrensis boliviensis is found in the upper Madeira River in Bolivia, while Inia geoffrensis humboldtiana resides in the Orinoco basin.