Amazon River dolphin (Inia geoffrensis) is the world’s largest river dolphin with the length reaching at 225 cm. The males are significantly greater in size and heavier than the females. It is also called boto in Brazil, keep on reading these Amazon River Dolphin Facts to know more about these amazing dolphins. The amazon river dolphin is a freshwater species of amazon river in Brazil, Columbia, Peru, and Venezuela. This dolphin is known as Boto and it is the most widely distributed river dolphin.
Amazon River Dolphin Facts
Anatomy of Amazon River Dolphin
- The male averages 255 cm in length and weighs up to 207 kg while females reach a length of 225 cm with weight averaging 153 kg. The males are 55% heavier and 16% longer than the females.
- The amazon river dolphin or simply boto has large paddle-like flippers which are able to separate circular movements.
- The flukes are mainly broad and triangular along with the long dorsal fins. It’s true that all these features make it difficult for dolphin to swim fast however characteristics such as these does allow the dolphin not only to swim backward but also to go through the submerged vegetation in search of food.
- The amazon river dolphin is primarily recognized by its prominent long and robust rostrum.
- The boto (Amazon River dolphin) has a very good vision not only under water but also above it.
- The boto is not always pink as it varies with the age. The young dolphins are dark grey in color but as they come of age the skin become pinker. The males are relatively more pinkish than females.
Amazon River Dolphin Habitat and Distribution
- The boto is widely distributed in six countries of South America—Brazil, Ecuador, Columbia, Peru, Venezuela, and Bolivia. It is known to occupy an area of about 7 million square kilometers.
- The entire amazon river including its tributaries are home to boto. In Peru it also occurs in small lakes and rivers, including Maranon and Ucayali rivers of the country.
- The boto is also found in the Xingu and Tapajos rivers of Brazil.
- The isolated population of boto also occurs in the southern part of the Amazon Basin.
- It is known to live in the Orinoco River basin, except Canra Rivers or Caroni in Venezuela. Botos are often sighted in the Casiquiare canal which connects the Orinoco to the Amazon River Basins.
- During dry season, the amazon river dolphins prefer living in the main channels of the rivers. However during floods, the boto will migrate to igapo (the flooded forest) and varzea (river floodplains).
Amazon River Dolphin Behavior
- The boto lives a solitary life and is rarely seen in cohesive groups. Each group consists of 1 to 4 individuals. The group is composed of a mother with her calf pairs and a male.
- The boto is not a fast swimmer with the speed averages 1.5 – 3.2 km/h but in short bursts it is able to reach 14 – 22 km/h. The amazon river dolphins are capable of strong swimming for some length of time.
- Before a dive the boto rarely raises its tail out of the water.
- Studies show that botos are not only more aggressive than bottlenose dolphins but show less social contact. In captivity, they are observed playing with each other and also that botos are not afraid of strange objects. In the wild they do play with fisherman’s paddles, pull grass under water, play with turtles, fish, logs, and clay.
- Perhaps the captive botos do not show their true range of behaviors.
Feeding Ecology and Amazon River Dolphin Diet
- The boto is neither nocturnal nor diurnal as it remains active all day and night. The peak time during which the boto feeds on fish in between 0600 – 0900 and 1500 – 1600h.
- It is known to consume as many as 43 species of fish belonging to 19 different families. The amazon river dolphin often feeds on fish which is 20 cm (range 5 – 80 cm). The boto’s diet includes catfish, crustaceans, piranha, small turtles, shrimps, and crabs.
- In captivity botos also share their food with their fellow members.
- The amazon river dolphin eats 2.5% of their body weight each day.
Reproductive Biology of Amazon River dolphin
- The females reach the maturity age much earlier than the males. Males become mature at about 200 cm in length while females attain the maturity between 175 and 180 cm.
- The females become mature at around 6 to 7 years of age.
- The gestation period lasts 11 months. The birth occurs only at the peak of river’s flood seasons.
- The young are 80 cm long at birth.
- The female gives a second birth after an interval of 2 to 3 years.
- The calf sucks milk for about one year.