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A Boto at Duisburg Zoo.
A Boto at Duisburg Zoo.
Size comparison against an average human
Size comparison against an average human
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Eutheria
Order: Cetacea
Suborder: Odontoceti
Superfamily: Platanistoidea
Family: Iniidae
Gray, 1846
Genus: Inia
Species: I. geoffrensis
Binomial name
Inia geoffrensis
Blainville, 1817
Boto range
Boto range

The Boto, Boutu, Amazon River Dolphin or Pink River Dolphin[1] (Inia geoffrensis) is a freshwater river dolphin endemic to the Amazon River and Orinoco River systems. The largest of the river dolphins, this species is not to be confused with the Tucuxi (Sotalia fluviatilis), whose range overlaps that of the Boto but is not a true river dolphin.

The IUCN lists various other names to describe this species including Amazon Dolphin, Boto Vermelho, Boto Cor-de-Rosa, Bouto, Bufeo, Dauphin de l'Amazone, Inia, Pink Dolphin, Wee Quacker, Pink Freshwater Dolphin, Pink Porpoise, and Tonina.


[edit] Taxonomy

The first type specimen was described by Henri Marie Ducrotay de Blainville in 1817.

1998 classification lists a single species, I. geoffrensis, in the genus Inia, with three recognised subspecies:

  • I.g. geoffrensis - Amazon basin population (excluding Madeira river drainage area, above the Teotonio Rapids in Bolivia)
  • I.g. boliviensis - Amazon basin population in the Madeira drainage area
  • I.g. humboldtiana - Orinoco basin population

Some older classifications listed the boliviensis population as a separate species.

[edit] Physical Description

1883 drawing of Boto
1883 drawing of Boto

The boto can vary in color from a memorable bright pink color through to a murky brown, gray, blue-gray or creamy white.[2] When young, the dolphins are a light gray and develop in color later on. When they are excited or surprised, they become pinker - almost as if they are blushing. Adults are typically 2.5 metres (8 feet) in length and weigh 150 kilograms (330 pounds). The flippers are large compared with body size and are curved back. The Boto does not have a dorsal fin, though a bumpy raised ridge on the back shows the evolutionary remnants of one. It has a prominent, long, thin beak with 25-35 pairs of teeth in both the upper and lower jaws. The front teeth are peglike, whereas the rear teeth are flatter with cusps. The two tooth types serve different functions: seizing prey and crushing, respectively. Botos generally feed from the bottom of the river and their preferred diet consists of crabs and small fish. Small turtles are also occasionally eaten.

This species is not often seen in groups larger than 5, but in rare circumstances up to 20 may be seen together. Unlike other dolphins, the Boto's cervical (neck) vertebrae are not fused, allowing the head a wide range of movement. Though their eyes are small they can see quite well, except for their bulging cheeks hampering downward view. This, however, is overcome by swimming upside-down.

[edit] Conservation

By the precarious standards of the river dolphins, the Boto is the most secure species in the superfamily. Nevertheless, the 1994 and 2000 IUCN Red List of Threatened Species classified it as vulnerable. In contrast to the rapidly dwindling areas of population of the recently-extinct Baiji and the Ganges and Indus River Dolphin, the area populated by the Boto seems to have remained fairly steady over time. Although complete surveys have not been taken owing to the inaccessibility of the rainforests, it is estimated that the total population of Botos runs into tens of thousands.

Botos have never been directly hunted. However fishermen are known to have occasionally killed them to protect their catch and fishing gear. It is not known whether this practice is widespread enough to damage local sub-populations. Since 1988 this practice has been outlawed in Brazil and Bolivia and in protected areas of Ecuador, Peru, Venezuela and Colombia.

The rising human population in the Amazon and Orinoco basins gives scientists cause for concern. Several damming projects of the kind that have devastated the recently-extinct Baiji populations in Asia have been proposed for the region for which environmentalists are vigorously opposed.

Some Boto deaths occur to mercury poisoning of their environment. These deaths typically occur close to gold mines; mercury is widely used to separate gold from surrounding rock.

[edit] Mythology

In a traditional Amazon River myth, at night a Boto becomes a handsome young man who seduces girls,[3] impregnates them, then returns to the river in the morning to become a Boto again. This dolphin shapeshifter is called an encantado. It has been suggested that the myth arose partly because dolphin genitalia bear a resemblance to that of humans. In the local area, there are also tales that it is bad luck to kill a Boto. Legend also states that if a person makes eye contact with a Boto, that person will have nightmares for the rest of his or her life.

The botos at Duisburg Zoo in June 2006
The botos at Duisburg Zoo in June 2006

[edit] Food and diet

The Boto has peg-like front teeth for catching prey and it mainly eats crabs, shrimps, and sometimes even turtles and catfish.

[edit] Botos in captivity

There are only two institutions which keep Botos in captivity, the Acuario de Valencia (Venezuela) that has five and the Duisburg Zoo (Germany) where there is only one boto. In October 2006 at Duisburg Zoo, the oldest known Amazon River Dolphin died at over 40 years of age.

At The Pittsburgh Zoo & PPG Aquarium (Pittsburgh, Pennsylvania) there was an Amazon River Dolphin named Chuckles, who died on February 20, 2002. At approximately 34 years old, he held the longevity record for Amazon river dolphins in captivity in North America, having well outlived the species' life-span of 18 years in captivity. Coming to the zoo in 1970, he was the only Amazon river dolphin in North America. He was there for 32 years.[4]

[edit] References

  1. ^ Wildfacts: Boto. BBC. Retrieved on 2007-02-21.
  2. ^ Amazon River Dolphin description. Whale and Dolphin Conservation Society (WDCS). Retrieved on 2007-02-21.
  3. ^ "Whales and Dolphins" at
  4. ^ Pittsburgh Zoo & Aquarium Mourns Loss of Amazon River Dolphin].
General references
  • Cetacean Specialist Group (1996). Inia geoffrensis. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Database entry includes a lengthy justification of why this species is vulnerable.
  • Rice, Dale W. (1998). Marine mammals of the world: systematics and distribution. Society of Marine Mammalogy Special Publication Number 4. 231 pp.
  • Montgomery, Sy (2000). Journey of the pink dolphins : an Amazon quest. Simon & Schuster, 317 pages. 068484558X
  • Juliet Clutton-Brock (2000). Mammals, 381 pages.
  • Hilda. Pink Dolphin. Retrieved on 2007-09-08.

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