Amazon River Dolphin

Inia geoffrensis

Puerto Arturo Guaviare Colombia

Quick Facts

Endemic Migratory
  • Scientific Name: Inia geoffrensis
  • Spanish Name: DelfĂ­n rosado
  • Family: Iniidae
  • Known Nicknames: Boto, Boto Cor de Rosa, Pink River Dolphin, Bufeo
  • Average Length: 200–250 cm / 79–98 in
  • Average Weight: 100–160 kg / 220–352 lb
  • Wingspan: N/A
  • Key Feature: Distinctive pink skin coloration and unfused neck vertebrae allowing for 90-degree head rotation
  • Primary Diet: Carnivore (Piscivore)
  • Range: Amazon and Orinoco River basins of South America
  • Habitat: Freshwater rivers, tributaries, and seasonally flooded forests
  • Social Structure: Primarily solitary or in mother-calf pairs
  • Nesting/Breeding: Freshwater river systems and flooded forest areas
  • Conservation Status: Endangered (EN)
  • Population Trend: Decreasing

The Amazon River Dolphin, also known as the Boto, is a remarkable freshwater cetacean most famous for its striking pink coloration, which can intensify based on the dolphin's age and activity levels. Unlike its oceanic relatives, this intelligent mammal possesses the unique ability to turn its head 90 degrees thanks to unfused neck vertebrae, a vital adaptation for navigating through the complex roots of flooded rainforests. Its distinctive appearance is characterized by a bulbous forehead, small eyes, and an elongated, toothy snout perfectly suited for hunting in murky waters. Lacking a traditional dorsal fin, the Boto instead features a prominent hump on its back and exceptionally large, paddle-like flippers that provide incredible maneuverability. Relying on a sophisticated echolocation system to thrive in the Amazon and Orinoco basins, this "pink dolphin" remains one of the most enigmatic and evolutionarily specialized predators of the river world.

Fun Facts

Known for their striking bubblegum-pink hue, these dolphins possess unfused neck vertebrae that allow them to turn their heads 90 degrees, a rare trait among cetaceans that helps them navigate the tangled roots of flooded forests. They are also unique for having stiff sensory hairs on their snouts to help find prey in murky water and an unusual courtship behavior where males carry rocks, branches, or clumps of grass in their mouths to impress potential mates.

Habitats & Distribution

This species is widely distributed across the Amazon and Orinoco river basins, spanning several South American countries including Brazil, Peru, Colombia, Venezuela, and Bolivia. Its range encompasses a vast network of freshwater environments, from large, deep river channels to smaller tributaries and remote lakes. During the high-water season, it moves into seasonally flooded forests and grasslands, navigating through submerged vegetation to forage. In contrast, during the dry season, it typically retreats to the deeper sections of main rivers. It is particularly known for frequenting river confluences, where the mixing of different water types creates productive ecosystems rich in prey.

Behaviours & Reproduction

These dolphins are predominantly solitary or found in small, fluid groups, typically consisting of a mother and her calf. Unlike their marine relatives, they possess unfused neck vertebrae, allowing them to navigate the complex roots of flooded forests with exceptional agility. Their social structure is relatively loose, but during the mating season, males exhibit a unique and rare courtship behavior known as "object carrying." They brandish sticks, clumps of vegetation, or pieces of clay to attract females, a display that is often accompanied by aggressive physical competition between rival males to establish dominance. Reproduction is closely tied to the seasonal flooding of the Amazon basin, with mating usually occurring during the dry season. Following a gestation period of roughly 11 months, calves are born when water levels are high, providing a vast area of flooded forest rich in prey for the nursing mother. This timing is a critical reproductive strategy that maximizes the calf's chances of survival. Mothers provide intensive care for several years, teaching their offspring the specialized hunting techniques required to navigate the river's murky waters and dense vegetation.

Diet

The Amazon River Dolphin, also known as the Boto, possesses one of the most diverse diets among all cetaceans, consuming over 50 different species of fish including croakers, catfish, and even piranhas. Beyond fish, these dolphins frequently feed on crustaceans like crabs and small river turtles, utilizing their unique heterodont dentition—featuring both conical front teeth for grabbing and flatter back teeth for crushing—to break through hard shells. An interesting aspect of their feeding behavior is their reliance on their incredibly flexible necks, which lack fused vertebrae, allowing them to maneuver through the complex roots and branches of flooded forests to snatch prey. While they are often solitary hunters, they may occasionally coordinate in small groups to herd schools of fish, using sophisticated echolocation to pinpoint targets in the murky river waters.

Colors

Amazon River Dolphins are renowned for their unique pink coloration, which develops from a dark gray juvenile state as they age and accumulate scar tissue. This pink hue, caused by capillaries near the skin's surface, often appears mottled with gray or white patches. Their shifting tones and blotched patterns provide natural camouflage within the sediment-heavy, tea-colored waters of their riverine habitat.