The Amazon river dolphin (Inia geoffrensis), often called the boto, is a large freshwater dolphin adapted to the Amazon and Orinoco river systems. Its long beak, flexible neck and broad flippers help it forage in complex floodplain habitat. Adults vary from gray to mottled pink, but the familiar claim that every boto simply “turns pink with age” leaves out important individual and sex differences.
Key takeaways
- Amazon river dolphins are born gray, but adults range from gray to strongly pink-mottled.
- Accumulated scarring is strongly associated with pink coloration in adult males; a single universal cause for every pink patch has not been established.
- Unlike many oceanic dolphins, botos have unfused cervical vertebrae and a highly mobile neck, but “exactly 90 degrees” is not a dependable species-wide measurement.
- The IUCN assessed Inia geoffrensis as Endangered in 2018.
- Fishing mortality, dams, habitat degradation, boat traffic, drought and mercury contamination all compound the risk.
What is an Amazon pink river dolphin?
The boto is a toothed whale found in freshwater rivers, channels, lakes and seasonally flooded forests across much of the Amazon and Orinoco basins. “Pink river dolphin” is a useful common name, but it can imply that all animals are uniformly bubble-gum pink. In reality, coloration varies greatly.
Its body is stockier than that of many marine dolphins. A rounded forehead, a long narrow rostrum, large paddle-like flippers and a low dorsal ridge suit slow, controlled movement in cluttered water. Adult males can exceed females in length and mass, so descriptions of the boto as the largest river dolphin should be understood as a general comparison, not a fixed size for every individual.
Why are Amazon river dolphins pink?
Calves and young animals are generally dark gray. As botos mature, some become paler or develop extensive pink areas. A study of sexual dimorphism and body scarring found that mature males were much more heavily scarred than females and proposed that intense male-to-male aggression explains much of their conspicuous pink appearance. Older, large males can therefore look far pinker than females or younger dolphins.
Scarring is an important part of the answer, but it should not be turned into a rule that every boto follows. Blood flow near the skin may make color appear stronger during activity, and background pigmentation varies between individuals. Evidence does not support presenting genetics, capillary flow, age and scarring as four equally proven causes of a predictable transformation.
How does a flexible neck help in flooded forest?
Many fast-swimming oceanic dolphins have neck vertebrae that are partly fused, creating a relatively rigid connection between head and torso. In the boto, the cervical vertebrae are not fused in the same way. This gives the animal unusual head and neck mobility for a cetacean.
That flexibility is useful when water rises into forests and floodplains. A boto can angle its head around roots, branches and submerged trunks while probing for fish. Its broad flippers and low dorsal ridge also favor maneuverability over sustained high-speed travel. Popular accounts often assign the neck an exact 90-degree rotation, but anatomy supports the broader point—greater mobility—more securely than that precise number.
What do botos eat?
Amazon river dolphins eat a varied fish diet and may also take crustaceans and turtles. Their conical front teeth help seize prey, while broader rear teeth can crush tougher items. Echolocation is essential in sediment-rich water where vision is limited, although their small eyes are functional.
Calling the boto an “apex predator” can be useful shorthand, but river food webs are dynamic. Likewise, dolphins can act as sentinels of river health because long-lived predators accumulate contaminants from prey. Their presence alone does not prove an ecosystem is healthy; abundance, reproduction, survival, contaminant loads and prey conditions must be measured.
Why is the Amazon river dolphin endangered?
The IUCN Cetacean Specialist Group lists the Amazon river dolphin among threatened cetaceans, and the species has been assessed as Endangered since 2018. Long-term research indicates serious declines in monitored areas, but no precise basin-wide population total is known.
- Gillnets and deliberate killing: dolphins can drown after entanglement, and some have been killed for bait or because of perceived competition with fisheries.
- Dams: barriers fragment connected river habitat, alter flow and sediment, and can isolate dolphin populations.
- Mercury: gold mining and disturbed soils release mercury into waterways. It moves through fish and accumulates in dolphins.
- Habitat and climate stress: boat traffic, overfishing, deforestation, unusually severe drought and high water temperatures can interact rather than acting alone.
In September 2025, scientists in Colombia conducted health checks to measure mercury exposure. The Associated Press reported that researchers use dolphins as sentinels for river contamination while cautioning that proving a direct cause of individual deaths requires further study.
How can Amazon river dolphins be protected?
Effective conservation has to work at river-basin scale. Priorities include reducing gillnet deaths, enforcing bans on deliberate killing, keeping migration and habitat corridors connected, controlling mercury use and discharge, protecting fish stocks, and monitoring dolphins consistently across national borders. Dam planning also needs cumulative-impact assessment, because several barriers can divide a population more severely than one project considered alone.
Responsible tourism helps when boats keep their distance and operators do not feed or chase dolphins. Feeding can condition wild animals to approach people and vessels, changing natural behavior and increasing injury risk.
Frequently asked questions
Are all Amazon river dolphins pink?
No. Individuals range from gray to pale or strongly pink-mottled. Adult males are often pinker and more heavily scarred, but color varies.
Can a boto turn its head 90 degrees?
Botos have unusually flexible necks because their cervical vertebrae are not fused like those of many marine dolphins. The often-repeated 90-degree figure should be treated as an illustration, not a standardized measurement.
Is the Amazon river dolphin extinct?
No. It still occurs across a large river-basin range, but the IUCN classifies it as Endangered and monitored populations have declined.