The Amazon River Dolphin

Inia Geoffrensis

Classification Order

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Cetacea

Family: Iniidae

Genus: Inia

Species: Inia Geoffrensis

(most closely related to the long finned and short finned pilot whales)


There are four other types of river dolphin: Indus, Ganges, Baiji, and Indian.

What and How the River Dolphin Eats

The Amazon river dolphin finds food (tetrads, carp, catfish, characins, piranhas, and other fish) using echolocation* and eats using its sharp teeth to grab the fish, and swallows it whole. They are capable of crushing "armored" prey also, such as the river turtle or crab. Almost 2.5% of their body weight* is consumed every day. Sharing food is often observed.


*echolocation: location of objects as reflected by a sound emitted by animals which are able, such as dolphins or bats.

*average body weight: in females the average weight is 154 kg, and in males the average weight is 100 kg.

Physical Features & Movement

Color: pale pink or grey

Flexible neck, unlike other dolphins

Longer rostrum than other species of dolphins (both freshwater & saltwater)

Unlike other dolphins, they do not have dorsal fins; instead they have a dorsal ridge.


Moves by shifting tail vertically

Max. speed in water: 18 mph

Size:

  • 2 - 3 meters in length (72 - 98 inches or 6 - 8 feet)


Weight: 220 - 440 lbs

Life span: 12 - 18 years

Poor vision; relies on echolocation to maneuver in the water and to locate meals, prey, and predators.

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Behavior & Social Life

The amazon river dolphin lives most of its live in a group of no more than four; however, congregations related to feeding or mating* season, or family groups of 5-8 individuals lead by the dominant male, are not rare. Very few are found in solitude.


River dolphins reproduce in a period of time that extends from the end of October to the beginning of November, and are pregnant from nine to twelve months.


Families become very attached to each other in these pods.


Social politics are visible in these large groups, but this order is not determined by violent acts. Violence, as it is observed in captivity, mainly occurs when there is a situation resulting the showing of the dolphins' more protective side for a mate or injured family member.


They are active at both day and night and have been observed in somewhat of an alliance with the gray river (tucuxi) dolphin and giant otters while in pursuit of their next meal. In the wild, they are curious animals, however difficult to train in captivity and more reserved than other species of dolphin.


The amazon river dolphin is sedentary and does not move themselves, or their pod, very far throughout 1-2 years unless necessity is shown at any time other than during migration season, which are small lapses of time that occur throughout the year. Territory battles are not regular, so home ranges are assumed to be large and to overlap each other throughout the lake.


To attract a mate, male river dolphins will wave a tree branch above the surface or strike rocks or chunks of clay against the river bottom, both while making noise.


*Mating: river dolphins do not mate for life, only for a season, however sometimes will travel with their families in a pod.

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Suggested Reading

Mama River Dolphin carrying her baby's dead body on and just below the surface in a tragic and touching service, much like a funeral parade (here).
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Habitat and Environment

The Amazon river dolphin lives in mainly fast-flowing, freshwater rivers, mainly in the Amazon and river basins of Bolivia, Colombia, Ecuador, Peru, and Venezuela.

In Literature:

River dolphins are featured in Amazonian myths as encantados*, in which they lure working women; The Hungry Tide, by Amitov Ghash, as the subject of study of a character working in Bangladesh; and the animated movie, Rio.


*Traditional Amazonian myths make the river dolphin out to be an animal that can morph into a handsome human wearing a hat (for the purpose of hiding its blowhole), seduce and impregnate young women, and then return to the water as a river dolphin again. They are also said to capture some of the women or children and take them back to the other encantados. Eye sight with one is supposed to curse a human with nightmares for the rest of their lives.

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Conservation

Dam-building, fishing net entanglement, boat traffic, and pollution contribute to the constant decline in population.


As the fishing economy improves, the amazon river dolphin population declines. The river dolphin appendix is considered a delicacy, however to prevent further danger of the animal, international trade of it has been prohibited by CITES, along with ASCOBANS, CMS and these animals are protected under the Indian Wildlife Act.
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