River dolphin

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River dolphins
Ganges River Dolphin Photographer:Brian D. Smith
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Cetacea Suborder: Odontoceti Superfamily: Platanistoidea
Families
See text

River dolphins are four species of dolphin which reside in freshwater rivers and estuaries. They are classed in the Platanistoidea superfamily of cetaceans. Three species live in fresh water rivers. The fourth species, the La Plata Dolphin, lives in saltwater estuaries and the ocean. However it is scientifically classed in the river dolphin family rather than the oceanic dolphin family.

[edit] Ecology

River dolphins are some of the most endangered of all the world's cetaceans. Due to habitat loss, hunting by humans, and naturally low numbers, they are extremely vulnerable to extinction. Also, many river dolphins also possess very poor eyesight — some are considered blind — which can lead to unfortunate encounters with humans or manmade objects (boats or fishing nets for example).

Some dolphin species can live in marine or riverine environments. The Tucuxi, for example, is equally at home in both ecotypes. However these are not classified in the Platanistoidea superfamily and are therefore not regarded as true river dolphins.

[edit] Taxonomy

In the most recent classification (Rice, 1998) there are currently four extant families that make up the river dolphins - however it is almost certain that by the end of the decade the Lipotidae will have perished. Platanistidae is listed as the only extant family of the Platanistoidea superfamily. The previously accepted classification treated all four families as belonging to this superfamily and treated the Ganges and Indus River Dolphins as separate species.

[edit] Classification by Rice (1998)

• Superfamily Platanistoidea
  • Family Platanistidae
    • Ganges and Indus River Dolphin Platanista gangetica
  • 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

[edit] Previous classification

• Superfamily Platanistoidea
  • Family Platanistidae
    • Ganges River Dolphin Platanista gangetica
    • Indus River Dolphin Platanista minor
  • 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

[edit] References

• Rice, Dale W. (1998). Marine mammals of the world: systematics and distribution. Society of Marine Mammalogy Special Publication Number 4. 231 pp.

Cetaceans (Dolphins, Whales, and Porpoises)
Suborder Mysticeti (baleen whales): Eschrichtiidae (gray whales) - Balaenopteridae (rorquals) - Balaenidae (right whales) - Neobalaenidae (pygmy right whale)
Suborder Odontoceti (toothed whales): Platanistoidea (river dolphins) - Delphinidae (oceanic dolphins) - Phocoenidae (porpoises) - Monodontidae (beluga and narwhal) - Physeteridae (sperm whales) - Kogiidae (pygmy and dwarf sperm whales) - Ziphiidae (beaked whales)