(Inia Geoffrensis)

INFORMATION AND CHARACTERISTICS.

Other common names of this dolphin are Boto, bufeo and pink river dolphin. Among the river dolphins, this species is the largest, best known, most researched and with the largest population. There are three subspecies of Amazon river dolphin:
– Inia geoffrensis geoffrensis.*
– Inia geoffrensis humboldtiana.
– Inia geoffrensis boliviensis.

* Recently (2014) this subspecies was split from Inia geoffrensis and defined as an independent species with the name Araguaian River dolphin as mitochondrial studies determined that they are indeed different species.

HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.

Morphology.
It is a robust dolphin with a very long snout easily distinguishable. It has a bulbous forehead due to a pronounced melon, chubby cheeks, small eyes and a remarkably flexible neck since its vertebrae are not fused. The pectoral flippers are large and have a triangle shape. He has a heterodont denture since his teeth are conical in the front of the jaw while the back pieces have a flange.

Order: Cetacea
Superfamily: Inioidea
Family: Iniidae
Genus: Inia

Weight and size.
Adults are between 1.53 and 2.4 meters in length, but this depends on the subspecies in question. The largest individual recorded was a female, weighing 98.5 kilograms.

Skin Coloration.
The most distinctive feature of this dolphin is the pink color that it acquires with age. The lower part of the body is usually clearer, and some individuals have gray patches.

Distinctive characteristic.
It is the only species of cetacean with heterodont dentition, and its dorsal fin is so small that it rather looks like a triangular crest.

Amazon River Dolphin – Inia Geoffrensis.

WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.

The Amazon River dolphin inhabits only the freshwater systems of South America. Its distribution includes the basins of the Amazon and Orinoco rivers and the tributaries of these rivers in Bolivia, Colombia, Brazil, Ecuador, Peru, and Venezuela. However, each subspecies lives in defined areas: I. g. Geoffrensis thrives in the Amazon and Araguaia river basins except for the upper Teotonio rapids in the Madeira river basin in Bolivia. I.g. Boliviensis inhabits above the Teotonio rapids in the basin of the Amazon River and, I. g. Humboldtiana dwells in the basin of the Orinoco River.

The Amazon River dolphin can live in areas of slow movement, in deep water channels, in flooded forests, in confluences where clear waters and sewage mix, in narrow channels and possibly under waterfalls and rapids.

WHAT DO THEY EAT? DIET AND EATING HABITS.

The Amazon pink dolphin consumes a variety of prey more diverse than other species of dolphins. Fish, crabs and small turtles are part of the diet of this cetacean that regularly hunts alone and consumes 2.5 percent of its total weight each day.

The diet of these dolphins includes 43 species of fish. Their favorite fish belong to the families Sciaenidae, Cichlidae, and the one of the feared piranhas, Serrasalmidae.

It is a natural hunter. Mostly active during the day, it knows that under the waterfalls or at the mouths of the rivers, it is easier to catch the fish that pass through the currents. Sometimes it looks for food at the riverbed. The hard shells of turtles do not deter this dolphin from eating these reptiles because for such prey it has a potent and long “snout” that helps break the hard parts.

Sometimes it associates with the giant otter (Pteronura brasiliensis) or the tucuxi (Sotalia fluviatilis) to hunt in a coordinated way and share the food.

HOW DO THEY BEHAVE? BEHAVIOR

Observations concluded that the Amazon River dolphin moves slowly. Its speed while swimming is only 1.5 to 3.2 kilometers per hour, but it has occasional bursts reaching up to 14 to 22 kilometers per hour.

It is not as sociable as the oceanic dolphins since it usually travels in groups of 2 or 3 individuals, mostly mothers with a calf. It is, therefore, a lone dolphin. The larger groups, with 12 to 15 members, are temporal associations with the purpose of feeding or mating.

It is somewhat shy with humans, but sometimes it shows curiosity. It is also very playful, and it has been seen pulling the aquatic grass and throwing pieces of wood. Curiously, at times its food is also its friend: it usually plays with fish and turtles.

It uses echolocation to perceive what is in its environment and capture prey. The “clicks” are the basis of their communication and reach from 16 to 170 kilohertz.

HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.

Scientists believe that this species is monogamous, but after noticing the male’s aggressiveness during mating and the multiple scars on its body, they began considering the idea of polygamy because this is the evidence of a possible competition for females.

Males and females reach sexual maturity at about five years of age or when the former is already about 2 meters in length, and the latter is between 1.60 and 1.75 meters. When a male finds a receptive female, he communicates his mating intentions by biting the female’s flippers.

11 months after mating, a single offspring is born between May and July measuring about 0.8 meters long. The time between each birth can last up to 5 years.

WHAT IS THEIR CONSERVATION STATUS? THREATS AND CONSERVATION.

Conservation Status: Data Deficient.

The fact that the pink dolphin has a “Data Deficient” conservation status on the Red List of the International Union for the Conservation of Nature entails a danger not completely unknown, but that makes difficult to implement conservation strategies. It is evident that the species faces a serious problem for survival in its natural habitat and until 2011 had a classification as a vulnerable species.

Their principal anthropogenic threats are:

– Overfishing.
This practice reduces the availability of food for the species.

– Dam construction.
The development of hydroelectric dams in the river, alter the conditions of their habitat separating populations which reduce the availability of mating partners and the genetic diversity.

– Uncontrolled logging.
When logging for converting the forests into agricultural land, the number of animals consuming the products of the trees decreases, and the amount of food for the Boto reduces in consequence.

– River traffic.
Excessive boat traffic causes collisions with these dolphins where the propellers cause them serious injuries.

– Habitat pollution.
The increasing contamination of the river brings all kind of problems to these dolphins and reduces their chances to survival drastically.

In their natural habitat, alligators, jaguars, anacondas and Bull sharks (Carcharhinus leucas) are their major threats. In Brazil, Peru, Venezuela, Colombia and Bolivia, there are laws to protect this species. Since 1986, the Cetacean Specialist Group of the Species Survival Commission has been working to protect and design conservation strategies for all endangered river dolphins.

Amazon River Dolphin Infographic!

(Click for expand)

References

Annalisa Berta. Whales, Dolphins, and Porpoises: A Natural History and Species Guide. University of Chicago Press, 2015.

William F. Perrin, Bernd Würsig, J.G.M. ‘Hans’ Thewissen. Encyclopedia of Marine Mammals. Academic Press, 2009. Page 26

Sy Montgomery. Journey of the Pink Dolphins: An Amazon Quest. Chelsea Green Publishing, 2009.

http://www.iucnredlist.org/details/10831/0

http://ufdc.ufl.edu/UFE0046251/00001

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There are five species of dolphins that make their homes in rivers, being the most popular of them the Pink Dolphins also known as Boto, Boutu or Amazon River dolphins as it inhabits the Amazon River.

The scientific name of the Pink Dolphins from the Amazon is Inia Geoffrensis and they belong to the genus Inea, part of the family Platanistoidea, which is conformed by the five species of river dolphins.

Pink dolphins are not the same dolphins that you would see in the ocean; they have special adaptations to their habitat. In fact, river dolphins are only distantly related to sea dolphins.

They belong taxonomically speaking to different families. The oceanic dolphins belong to the family delphinidae while river dolphins belong to the family Platanistoidea as we said above.

Among the five species of river dolphins, Amazon pink dolphins are considered the most intelligent of them, with a brain capacity 40% larger than that of humans.

Pink dolphins inhabit the Amazon River, but they can also be found in the Orinoco basins and the upper Madeira River as well. While they are mostly pink, these dolphins have various colored skins, which can be light gray, pink, or brown.

The Amazon River pink dolphins conform the largest population of river dolphins in existence as the other four species are functionally extinct or close to extinction.

The river dolphins are among the most endangered species of all the world’s cetaceans. Pink dolphins have been listed by the International Union for the Conservation of Nature (IUCN) as a “vulnerable species-threatened” and recently was moved to “endangered species-threatened”

These friendly and social creatures have been living for centuries in the Amazon and its tributaries, but the accelerated destruction of the Amazon basin have put them in a every time more dangerous situation.

The raise in contaminant levels of mercury have caused and increased number of deaths among pink dolphins, especially near gold mines where mercury is used as part of the gold mining process.

The increase of traffic in the Amazon River, also threatens these creatures as they are curious by nature and they sometime approach to vessels where they are easily hurt by the sharp propellers.

Additionally, the noise produced by engines and motors and the sound pollution caused by them, has been considered to produce a disorienting phenomenon in their navigations systems, causing the death of many pink dolphins.

What do Pink Dolphins Eat?

Pink dolphins eat crabs, catfish, small river fish and even small turtles.

As crabs and turtles have to be catch mainly at the bottom of the river, pink dolphins spend a lot of time while swimming looking at the bottom of the river for food.

The boto cervical vertebrae are not fused allowing them to move their head up to 180 degrees, which is a great help for hunting in shallow waters and floodplains.

Hunting fish require some techniques like herding, where they round a fish pod to concentrate fish and take turns for feeding. This procedure is largely used by their oceanic cousins.

Physical Description of Pink Dolphins

In the Amazon Region…There is a legend about the Boto or Pink Dolphin. According to the legend, the Boto turns from man to dolphin and backwards, changing shape at will.

The legend also states that when dolphins find young women on the shore, they changes shape and impregnate them.

This comes from the similarites between certain body parts of the Boto and humans.

There are several other superstitions about the Pink Dolphins in the Amazon River and around.

Pink dolphins can be found in pink, light gray or brown colors but there is not conclusive evidence of the reason why pink dolphins are pink.

It could be an adaptation to the river life or caused by the presence of capillaries near the surface of the skin what provide them such impressive color. Additionally, pink dolphins get pinker when they are excited or surprised, resembling blushing in humans.

The Amazon River dolphin is between six and eight feet long, and weighs between 185 and 355 pounds when it is fully grown.

River dolphins are typically smaller than sea dolphins but they have longer snouts, an adaptation provided by evolution, which is needed to hunt at the bottom of the river. River dolphins also tend to have more pointy teeth than sea dolphins.

Most species of river dolphins are almost blind, due to navigating muddy waters, but their brains are extremely large and well developed, however pink dolphins are considered to have a relatively good sight.

Unlike sea dolphins, river dolphins have what resembles fingers on the ends of their flippers, and their dorsal fins are much smaller than that of sea dolphins or even have humpbacks instead of dorsal fins like the pink river dolphin.

//www.youtube.com/watch?v=20h9Tg8BCYU

Behavior of Pink Dolphins

Pink dolphins appear to be the friendliest of all the river dolphins when approaching to humans and some stories of people being pushed to the shores by them are common among some tribes in the Amazon.

They swim up to 30 kilometers in one day, although they usually swim slowly looking for food at the bottom of the river.

“Amazon River Pink Dolphins are typically smaller than sea dolphins but they have longer snouts, an adaptation provided by evolution…”

How do Pink Dolphins Reproduce?

Males and Females mate to start a gestation period which is believed to last from nine to twelve months. Copulation is performed between males and females belly to belly.

Calves are born about 75 cm long and weighing a bit more than 1 Kg.

Pink dolphins deliver their babies when the Amazon River is at its high between the months of May and July.

Pink Dolphin Conservation

The World Conservation Union, also known as International Union for the conservation of Nature and Natural Resources (IUCN) is an international organization based in Gland, Switzerland, devoted to the conservation of natural resources.

It was founded in 1948 and groups 83 states, 108 governmental agencies and more than 10,000 scientists and experts from countries around the world.

The IUCN publishes a red list of threatened species which is a reference in the field and the base for conservation of species.

Union for the Conservation of Nature (IUCN)

Frequently Asked Questions about Pink Dolphins

How Do Pink River Dolphins Reproduce

Why Are Pink River Dolphins Endangered

Why Are Pink Dolphins Pink

Where Do Pink Dolphins Live

//www.youtube.com/watch?v=LoAqeOsJacA

//www.youtube.com/watch?v=rK2Kk4DpTVQ

//www.youtube.com/watch?v=20h9Tg8BCYU

The Amazon River dolphin, also known as Boto (Inia geoffrensis), is a freshwater dolphin that lives in the Amazon River and the Orinoco River systems which include several countries in South America.

These dolphins are Pink Dolphins move around these rivers to every place where they can reach without going to the ocean.

Other pink dolphins such as the Chinese white dolphin (Sousa chinensis) live in an area that covers the east and west coasts of northern Australia, eastern China, the Indo-Malayan archipelago, and the Bay of Bengal in the east of India.