River dolphin
River dolphins are five species of dolphin which live in fresh water rivers and estuaries. Three species live in fresh water rivers. The La Plata Dolphin lives in salt water estuaries and the ocean.
- South Asian river dolphins (two sub-species)
- Ganges river dolphin, Platanista gangetica gangetica – Lives in Nepal, Republic of India and Bangladesh
- Indus river dolphin, Platanista indicus minor – Lives in Pakistan; National mammal of Pakistan.
- South American river dolphins (three species)
- Amazon river dolphin (or Boto), Inia geoffrensis – Largest of river dolphins, lives in Peru and Brazil.
- Araguaia river dolphin, Inia araguaiaensis – Recently discovered in the river basin in Brazil after which it is named. Identified as a separate species by genetic sequence analysis.[1]
- La Plata dolphin (or Franciscana), Pontoporia blainvillei – Lives in Argentina.
- Chinese river dolphin (or Baiji), Lipotes vexillifer – Lives in the Yangtze River in China (one of the most endangered of all dolphins and whales). Recent counts have come up with 17 remaining individuals.[2] Scientists now want to raise some dolphins in a lake.
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| Ganges River Dolphin Photographer:Brian D. Smith | |
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| Superfamily: | Platanistoidea
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Differences between marine and river dolphins
Both river dolphins and marine dolphins belong to a group of mammals called cetaceans. The snout of a river dolphin measures about 58 centimeters (2 ft) long, approximately four times as long as that of most marine dolphins. They use their long snout to search for fish on the muddy bottom of the river. River dolphins have smaller eyes than marine dolphins, and their vision is poorly developed because they live in dark, muddy water. River dolphins are less active than marine dolphins because they do not need to search so widely to find fish. Marine dolphins work in pods (packs) because when they find a shoal of fish then they work together to make the most of their find. River dolphins work mostly as individuals or small groups.[3]
Taxonomy
The following is the taxonomy of river dolphins, or how dolphins are classified: [3]
River dolphin classification
- Superfamily Platanistoidea
- Family Platanistidae
- South Asian river dolphin Platanista gangetica (two subspecies)
- Ganges river dolphin P. g. gangetica
- Indus dolphin P. g. minor
- South Asian river dolphin Platanista gangetica (two subspecies)
- Family Iniidae
- Amazon river dolphin (or Boto) Inia geoffrensis
- Family Lipotidae
- Chinese river dolphin (or Baiji) Lipotes vexillifer
- Family Pontoporiidae
- La Plata dolphin (or Franciscana) Pontoporia blainvillei
- Family Platanistidae
River Dolphin Media
Distribution map of known species and subspecies of the South American river dolphin genus Inia, following the recognition of Inia araguaiaensis as a separate species.*The original PLoS ONE image has been modified by conversion from tiff to jpeg format.
Cetacea range map South Asian river dolphin
Life reconstruction of Arktocara yakataga, an allodelphinid
Yangtze river dolphin is listed as critically endangered, likely extinct
Phylogeny of cetaceans based on cytochrome b gene sequences, showing the distant relationship between Platanista and other river dolphins.
Indus river dolphin skull
Animation of the echo-location of a dolphin.
River dolphins have very small eyes
Conservation areas for the baiji along the Yangtze River
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