Animal
Amazon river dolphin
The Amazon river dolphin is a pink dolphin that lives in rivers, not the sea. It swims between the trees of flooded forests to catch fish.
The Amazon river dolphin, or boto, is the largest river dolphin. Many adults are pink. It lives only in fresh water, in the Amazon and Orinoco river basins of South America, and its bendy neck and big flippers let it twist between tree trunks in flooded forests as it hunts fish using sound.
Inia geoffrensis, the boto, is the largest river dolphin and one of the most sexually dimorphic cetaceans, with males far larger than females. A flexible, slow-swimming echolocator of South American rivers and flooded forests, it is listed by the IUCN as Endangered, threatened by fisheries, dams and mercury pollution.
Photo: Dennis Otten, CC BY-SA 3.0, via Wikimedia Commons
Meet the boto
The Amazon river dolphin lives in rivers.
Young ones are gray. Many grown-ups turn pink! It has a long thin nose and a bump on its forehead.
The Amazon river dolphin, also called the boto or pink river dolphin, is the biggest of all the river dolphins. Large males can be about 2.5 meters long and weigh over 200 kilograms. Males are much bigger than females, which is unusual: in most river dolphins the females are bigger.
Babies are dark gray, but adults turn pink, either all over or in blotches, and males are usually pinker than females. A boto has a long, thin beak with stiff bristles on top and a soft, rounded forehead.
Inia geoffrensis is the largest river dolphin. Males reach 2.55 meters and 207 kilograms (averaging 2.32 meters and 154 kilograms), while females reach 2.18 meters and 154 kilograms, making it one of the most sexually dimorphic cetaceans and unusual among river dolphins, where females are generally larger.
Calves are dark gray, and adults are solid or blotched pink, males significantly pinker; coloration may vary with water temperature, clarity and location. Diagnostic features include stiff vibrissae on the rostrum, heterodont teeth (conical at the front, flanged at the back) and a long, low dorsal keel of 30 to 61 centimeters instead of a triangular fin. Boto is its internationally recognized common name.
Quick facts
- Group
- Mammal
- Length
- 2 to 2.55 m
- Weight
- 100 to 207 kg
- Top speed
- up to 22 km/h
Rivers and flooded forests
Botos live in the Amazon and Orinoco rivers in South America.
When the rivers flood, the water spreads into the forest. Then botos swim between the trees!
Botos live only in fresh water, in the Amazon and Orinoco river basins of Bolivia, Brazil, Colombia, Ecuador, Peru and Venezuela. They swim in big rivers, small channels, lakes and river mouths, and even just below waterfalls.
Their homes change with the seasons. In the dry season, when small channels get too shallow, botos gather in the main rivers. In the wet season, the rivers flood the forest, and botos swim into the flooded forest between the tree trunks.
The IUCN lists the boto in Bolivia, Brazil, Colombia, Ecuador, Peru and Venezuela, across the Amazon and Orinoco basins, an area of about 7 million square kilometers bounded by the sea, impassable rapids, waterfalls and very shallow water. Three subspecies are recognized: I. g. geoffrensis in the central Amazon, I. g. humboldtiana in the Orinoco basin and I. g. boliviensis in the upper Madeira, isolated by rapids.
The flood cycle shapes habitat use. In the dry season botos concentrate in main channels where prey gathers along the margins; in the wet season they enter tributaries, floodplains and flooded forest. Males return to the main channels while water is still rising, while females and calves stay farther inland in calmer water.
Continent
Its habitats
Where can you find this animal?
- Lives here naturally · Countries and seas named by a scientific source
- Sightings recorded · Records of wild sightings (GBIF)
Lives here naturally · Countries and seas named by a scientific source
Rivers, lakes and flooded forests of the Amazon and Orinoco river basins in South America. Botos live only in these rivers, not across whole countries.
Places: Bolivia, Brazil, Colombia, Ecuador, Peru and Venezuela.
Source: iucn-red-list · checked October 2026
Sightings recorded · Records of wild sightings (GBIF)
Counts of GBIF records of wild observations (human and machine) and preserved specimens. Records include introduced populations, vagrants, escaped or released animals and misidentifications, so a country with records is not necessarily part of the native range.
Wild sightings have been recorded in Colombia, Ecuador, Brazil, Peru, Bolivia, Venezuela, United States, Mexico and 1 more places.
Source: gbif · checked October 2026
Range maps show where scientists say an animal lives, often country by country. An animal may live in only part of a country shown, and sightings records can include animals that wandered far from home.
A fish-catching expert
Botos eat fish, and lots of different kinds!
They eat piranhas, catfish and other fish. They can even crunch up crabs and river turtles.
Botos eat a huge variety of fish: scientists have found at least 43 different kinds in their diet, from 5 to 80 centimeters long. Favorites include croakers, cichlids, tetras and piranhas. Their teeth can crush crabs and even river turtles.
Botos usually hunt alone, mostly in the early morning and late afternoon. They like to wait near waterfalls and river mouths, where the current scatters schools of fish. Sometimes they hunt alongside giant otters and another dolphin, the tucuxi.
The boto has an unusually broad diet: at least 43 fish species in 19 families, from 5 to 80 centimeters (average 20), with drums and croakers, cichlids, characins and piranhas preferred. Its heterodont dentition lets it crush armored prey such as river turtles and crabs. A boto eats about 2.5 percent of its body weight a day.
It is usually a solitary feeder, most active between about 6 and 9 a.m. and 3 and 4 p.m. It exploits places where currents break up shoals, such as waterfalls and river mouths, and even disturbances made by canoes. Loose, coordinated hunting groups with tucuxis and giant otters have been observed, with little competition because each prefers different fish.
Did you know?
Many grown-up botos are pink.
Boto calves are dark gray, but adults turn pink, and males are usually pinker than females.
Adults are solid or blotched pink, males significantly pinker; coloration may vary with water temperature, clarity and location.
A bendy, flexible body
A boto can turn its head from side to side.
Its big flippers help it swim around trees. It finds fish by making clicks and listening for echoes.
A boto can turn its head in all directions, because the bones in its neck are not joined together. Its wide flippers can move in a circle, so it can steer around branches and tree trunks in the flooded forest. The trade-off is speed: botos usually swim slowly, though they can put on bursts of up to about 22 kilometers per hour.
Botos have small eyes but seem to see well, both above and under the water. They also use echolocation: they make clicking sounds and listen for the echoes to find fish and find their way.
None of the boto's cervical vertebrae are fused, so it can move its head in all directions. Broad flippers on long humeri can move in a circular motion, giving exceptional maneuverability among submerged vegetation but limiting top speed: normal swimming is about 1.5 to 3.2 kilometers per hour, with bursts of 14 to 22.
The eyes are small but vision appears good above and below water. A small, flexible melon on the forehead can be reshaped by muscles during echolocation. Clicks range from 16 to 170 kilohertz, with a dominant frequency around 45 kilohertz, and are used for hunting, navigation and communication; captive botos have been recorded making 10 distinct calls.
Growing up
A boto mother has one baby at a time.
The baby is born when the rivers are high. Mom helps it up to the surface to breathe. They stay together for a long time.
A boto mother is pregnant for about 11 months. Her single calf is born between May and July, when the rivers are at their highest. Right after it is born, the mother helps her calf up to the surface to take its first breath. A newborn is about 80 centimeters long.
The mother feeds her calf milk for more than a year, and calves stay with their mothers for two to three years. Most pairs of botos you see in the wild are a mother and her calf.
Births are seasonal, from May to July, coinciding with peak water levels; as the water falls, prey becomes concentrated in flooded areas, providing food for nursing females. Gestation is about 11 months, and mothers help newborn calves, about 0.8 meters long, to the surface to breathe.
Lactation lasts well over a year, some females are pregnant and nursing at once, and the interval between births is estimated at 15 to 36 months. Calves stay with their mothers for two to three years, a long period that may allow for learning. Maturity is reached at about 2.0 meters in males and 1.6 to 1.75 meters in females, and wild lifespan is not known.
Curious and playful
Botos are curious and playful.
They rub against canoes and grab paddles. They play with sticks, logs and grass in the water.
Botos usually live alone or in pairs, and the pairs are mostly mothers with calves. Sometimes loose groups gather to feed or mate. They are active in both the day and the night.
Botos are playful and curious. In the wild they have been seen rubbing against canoes, grabbing fishers' paddles, pulling grass under the water and throwing sticks. When they come up to breathe, the tip of the beak, the forehead and the low ridge on the back all appear at the same time.
Botos are mostly solitary and rarely form tight groups of more than three, though loose aggregations form for feeding or mating. They are active by day and night, fairly sedentary, and make only small seasonal movements with water level and fish abundance. Males carry more scars, bite wounds and damaged fins from tooth-raking, which suggests intense competition between males for females.
They are curious and playful, rubbing against canoes, grasping paddles, pulling grass, throwing sticks and playing with logs. They seldom raise their flukes when diving; at the surface the rostrum tip, melon and dorsal keel break the water together. No natural predator has been recorded, though black caimans, bull sharks, anacondas and jaguars could potentially take them.
Protecting river dolphins
Botos are in danger, and people are trying to help.
Some get caught in fishing nets. Some rivers are dirty. People count botos and work to keep their rivers clean.
The Amazon river dolphin is endangered. Many botos get tangled in fishing nets by accident. Some are hurt or killed by people who see them as rivals for fish, and in parts of Brazil and Colombia they are killed to use as bait for catching catfish.
Dams split rivers into separate pieces, and mercury from gold mining and chemicals from farms pollute the water. Conservation groups such as WWF support counts of river dolphins, research on how dams affect them and work to protect the rivers where they live.
The IUCN's 2018 global assessment lists Inia geoffrensis as Endangered with a decreasing population. Bycatch has grown as fishing technology has improved, and botos are harpooned, shot or poisoned for taking fish from nets. WWF reports that in the Brazilian and Colombian Amazon they are deliberately killed for bait in the 'mota' catfish fishery.
Hydroelectric dams block fish migrations, lower oxygen downstream and fragment dolphin populations into smaller, less genetically diverse groups. Floodplain deforestation removes the fruits and seeds that feed their prey, and rivers carry pesticides and mercury from gold mining, which reaches dolphins through the fish they eat. WWF supports population surveys and studies of how dams affect dolphin numbers and movement.
IUCN Red List
How is the amazon river dolphin doing in the wild?
- Least Concern
- Near Threatened
- Vulnerable
- Endangered (this animal)
- Critically Endangered
- Extinct in the Wild
- Extinct
Endangered
At very high risk of disappearing from the wild.
See the IUCN Red List assessment · The IUCN Red List of Threatened Species 2022.2
Amazing facts
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Botos can turn their heads.
A boto can turn its head from side to side, because the bones in its neck are not joined together.
None of the boto's cervical vertebrae are fused, allowing head movement in all directions.
-
Many grown-up botos are pink.
Boto calves are dark gray, but adults turn pink, and males are usually pinker than females.
Adults are solid or blotched pink, males significantly pinker; coloration may vary with water temperature, clarity and location.
-
Botos sometimes grab fishers' paddles.
Curious botos have been seen rubbing against canoes, grabbing paddles and throwing sticks.
Wild botos rub against canoes, grasp paddles, pull grass underwater and play with logs, sticks and other animals.
-
Botos eat lots of kinds of fish.
Scientists have found at least 43 kinds of fish in the boto's diet.
At least 43 fish species in 19 families have been recorded in the diet, an unusually broad range for a dolphin.
Words to know
- echolocation
- finding things by making sounds and listening for the echoes
- flooded forest
- a forest that is under water for part of the year
- melon
- the rounded forehead of a dolphin, used in echolocation
- fresh water
- water that is not salty, like in rivers and lakes
- bycatch
- animals caught by accident in fishing gear
- calf
- a baby dolphin
Discovery challenge
-
Where do Amazon river dolphins live?
What kind of water do Amazon river dolphins live in?
Which habitat does Inia geoffrensis occupy?
- Fresh water in rivers
- The salty open ocean
- Frozen Arctic seas
Show the answer
Fresh water in rivers
They live in rivers.
They live only in fresh water, in rivers, lakes and flooded forests.
Freshwater rivers, lakes and floodplain forests of the Amazon and Orinoco basins.
-
What color are many grown-up botos?
What color do many adult botos turn?
How does boto coloration typically change with age?
- Pink
- Bright green
- Black and white stripes
Show the answer
Pink
Many grown-up botos are pink!
Calves are gray, and many adults turn pink, especially males.
Dark gray calves become solid or blotched pink adults, males usually pinker.
-
How do botos find fish?
How do botos find their way and catch fish in the river?
What method do botos use to locate prey and navigate?
- Making clicks and listening for echoes
- Smelling with their tails
- Seeing in the dark like owls
Show the answer
Making clicks and listening for echoes
They click and listen for the echoes.
They use echolocation: clicks bounce off fish and come back as echoes.
Echolocation clicks of about 16 to 170 kilohertz.
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Why can a boto turn its head?
What lets a boto turn its head in all directions?
Which skeletal feature gives the boto its head mobility?
- Its neck bones are not joined together
- It has a long tail
- It has no teeth
Show the answer
Its neck bones are not joined together
It can turn its head, because its neck bones are not stuck together.
None of the bones in its neck are joined, so it can turn its head.
Its cervical vertebrae are unfused.
Places where you might see it
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Watch
Country
Brazil
Brazil covers about half of South America and is the fifth-largest country in the world. It holds most of the Amazon River basin and much of the world's largest rainforest, and about 214 million people lived there in 2026, most of them near the Atlantic coast.
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Watch
Country
Peru
Peru is a country on the Pacific coast of South America. It has a dry desert coast, the high Andes mountains and the Amazon rainforest, and about 34 million people lived there in 2025, many of them in the capital, Lima.
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Watch
Natural wonder
Amazon rainforest
The Amazon rainforest covers about 6 million square kilometers around the Amazon River and its branches in northern South America, and about 60 percent of it is in Brazil. Britannica calls it the world's richest and most varied home for living things, with millions of kinds of insects, plants and animals.
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Watch
Life around the world
River boats from Manaus, Brazil
Manaus, a city of about 2.3 million people, sits where the dark Rio Negro meets the muddy Solimões. Rivers are the main way to reach most towns in Amazonas state. Big wooden boats called recreios carry passengers and cargo for a day or more, with hooks for hammocks, while fast boats called expressos cut the time.
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Watch
Natural wonder
Amazon River
The Amazon River flows from tiny streams in the Andes Mountains of Peru across Colombia and Brazil to the Atlantic Ocean. NASA calls it the largest river in the world: about 219,000 cubic meters of water pour into the ocean every second, nearly a fifth of all the water that rivers carry to the oceans.
Explore next
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Watch
Country
Brazil
Brazil covers about half of South America and is the fifth-largest country in the world. It holds most of the Amazon River basin and much of the world's largest rainforest, and about 214 million people lived there in 2026, most of them near the Atlantic coast.
-
Watch
Country
Peru
Peru is a country on the Pacific coast of South America. It has a dry desert coast, the high Andes mountains and the Amazon rainforest, and about 34 million people lived there in 2025, many of them in the capital, Lima.
-
Watch
Animal
Giant otter
The giant otter is the longest otter in the world, up to about 1.8 meters from nose to tail. It lives in the rivers and lakes of South America in noisy family groups that hunt fish together by day. It is endangered, and people are working to protect it.
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Watch
Animal
Red-bellied piranha
The red-bellied piranha is a silver fish with a red belly that lives in rivers, creeks and floodplain ponds of South America. It has a famous reputation, but experts say the danger to people is greatly exaggerated: piranhas mostly eat fish, insects, snails and plants.
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Watch
3D
Animal
Common bottlenose dolphin
The common bottlenose dolphin is a fast, clever ocean mammal named for its short, thick snout. It finds fish with echoes, talks with whistles and clicks, and lives in warm and mild seas all around the world.
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Watch
Natural wonder
Amazon rainforest
The Amazon rainforest covers about 6 million square kilometers around the Amazon River and its branches in northern South America, and about 60 percent of it is in Brazil. Britannica calls it the world's richest and most varied home for living things, with millions of kinds of insects, plants and animals.
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Watch
Animal
Hoatzin
The hoatzin is a strange and wonderful bird of the Amazon and Orinoco rivers. It eats mostly leaves and digests them slowly with the help of bacteria, a bit like a cow. Its chicks have claws on their wings that help them climb back up through the branches.
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Watch
Life around the world
River boats from Manaus, Brazil
Manaus, a city of about 2.3 million people, sits where the dark Rio Negro meets the muddy Solimões. Rivers are the main way to reach most towns in Amazonas state. Big wooden boats called recreios carry passengers and cargo for a day or more, with hooks for hammocks, while fast boats called expressos cut the time.
For parents & teachers
What children will learn
- Describe how the boto's body is adapted to rivers and flooded forests.
- Explain how echolocation helps animals find food.
- Describe how seasonal floods change where botos live and feed.
- Understand why the boto is endangered and what threatens rivers.
Recommended ages: 3 to 17 · About 12 minutes
Talk about it
- Why might a bendy neck and big flippers be more useful than speed in a flooded forest?
- How could pollution from a mine far upstream reach a river dolphin?
- Why might fishers and dolphins come into conflict, and how could both be helped?
Try at home or in class
- Clap in a large room and then in a small one, and listen to how the echoes change, like a boto using echolocation.
- Set up an obstacle course of chairs and try to steer a toy boat or yourself through it, first quickly and then slowly with careful turns.
Key vocabulary: echolocation, flooded forest, melon, fresh water, bycatch, calf
Where these facts come from
- The IUCN Red List of Threatened Species , International Union for Conservation of Nature (IUCN terms of use (no redistribution of Red List data or range maps))
- GBIF Backbone Taxonomy and GBIF Occurrence Search , Global Biodiversity Information Facility (CC0 1.0 (backbone); occurrence counts are facts derived from records under CC0, CC BY and CC BY-NC)
- Inia geoffrensis (Amazon River dolphin) , Animal Diversity Web, University of Michigan Museum of Zoology
- Amazon river dolphin , World Wildlife Fund
- Inia geoffrensis (Amazon River Dolphin), 2018 global assessment , IUCN Red List of Threatened Species
- Wikidata , Wikimedia Foundation (CC0 1.0)
- Wikimedia Commons , Wikimedia Foundation (Per file: Public domain, CC0, CC BY or CC BY-SA only (credited on each page))
Checked, not yet human-reviewed. Last updated October 24, 2026. Spotted a mistake? Tell us.