The Amazon river dolphin (Inia geoffrensis), commonly called the pink dolphin, belongs to the order Cetacea, suborder Odontoceti, and the family Iniidae. It inhabits the freshwater systems of the Amazon and Orinoco basins, ranging across Brazil, Peru, Colombia, Ecuador, Bolivia, and Venezuela. Preferred habitats include main river channels, tributaries, floodplain lakes, and seasonally flooded forests where water depth can vary from a few centimeters to over 30 meters. Adults display a distinctive pink hue that intensifies with age and activity, a long beak, and a flexible neck that allows 90-degree head turns—unusual among cetaceans. Their skin is smooth and thick, adapted to warm tropical waters, and they possess a sophisticated echolocation system for navigation in turbid environments. The species is listed as Endangered by the IUCN due to habitat degradation, accidental capture, and pollution, with an estimated wild population of 30,000‑50,000 individuals. Conservation programs focus on habitat protection, sustainable fisheries, and community education to mitigate human‑dolphin conflict.

Amazon river dolphins are highly social and often travel in loose groups of 2‑10 individuals, though solitary sightings are common in deeper channels. They are crepuscular, showing peak activity at dawn and dusk, but can be active throughout the day depending on prey availability. Home ranges are fluid, overlapping with those of other riverine species, and individuals may travel up to 100 km during seasonal flood cycles to follow fish migrations. Communication relies on a repertoire of clicks, whistles, and burst‑pulse sounds used for echolocation, social bonding, and mother‑calf interaction. Playful behavior, such as surfacing together and leaping, is frequently observed, especially among juveniles. Territoriality is low; instead, dolphins exhibit a tolerance for conspecifics and even occasional interactions with humans, though they can become wary in heavily trafficked waterways.

Amazon river dolphins are opportunistic carnivores, feeding primarily on a diverse assemblage of freshwater fish such as piranhas (Serrasalmus spp.), catfish (Pseudoplatystoma spp.), and characins, as well as occasional crustaceans, turtles, and small mammals that enter the water. Daily intake can reach up to 5% of body weight, roughly 7‑9 kg for an adult. They employ active pursuit and echolocation to locate prey in turbid waters, often exploiting flooded forest habitats where fish are concentrated. Seasonal flood pulses expand their foraging grounds, allowing access to fish spawning aggregations. In low‑water periods, dolphins may focus on deeper channels and prey that seek refuge among submerged vegetation. Their diet reflects the high biodiversity of the Amazon basin, and they play a key role in regulating fish populations.

Females reach sexual maturity at 5‑7 years, while males mature slightly later at 6‑8 years. Breeding is not strictly seasonal, but peaks during the high‑water period (December‑May) when prey is abundant. Gestation lasts approximately 11‑12 months, after which a single calf is born, weighing 15‑20 kg. Calves are nursed for 12‑18 months, during which the mother provides exclusive care and protection. Weaning coincides with the onset of the low‑water season, encouraging calves to develop independent foraging skills. Interbirth intervals average 2‑3 years, reflecting the energetic demands of raising a calf in a fluctuating river environment. Calf mortality can reach 20‑30% in areas with high boat traffic or pollution, underscoring the importance of safe nursery habitats.

The IUCN classifies the Amazon river dolphin as Endangered, with an estimated decline of 30% over the past three generations. Primary threats include habitat loss from dam construction, which fragments river connectivity and alters flood regimes essential for feeding and breeding. Bycatch in gillnets and seine nets kills an estimated 1,000‑2,000 individuals annually, while intentional hunting for meat and live capture for tourism persists in remote communities. Pollution from mining (mercury) and oil extraction contaminates prey species, leading to bioaccumulation of toxins. Climate change exacerbates flood variability, further stressing populations. Conservation actions involve establishing protected river sections, promoting net‑free fishing zones, and community outreach programs that provide alternative livelihoods. Population surveys using acoustic monitoring suggest current numbers may be as low as 30,000 mature individuals, highlighting the urgency of coordinated protection measures.

• The pink coloration intensifies with age, activity, and blood flow, making older males the most vividly colored.
• They possess a flexible neck with 10 cervical vertebrae, allowing 90-degree head turns unlike most cetaceans.
• Amazon dolphins can navigate and hunt in near‑total darkness using sophisticated echolocation clicks up to 150 kHz.
• They have been observed cooperating with humans, guiding fishermen to schools of fish in exchange for discarded catches.
• Fossil records indicate the Iniidae family has existed for at least 5 million years, making them ancient inhabitants of South American rivers.