River dolphin
There are five known species of river dolphins in the world. Unlike their relatives, the oceanic dolphins, river dolphins live in fresh water.
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2 Ecology |
Taxonomy
In the most recent classification (Rice 1998) there are four families that make up the river dolphins. The 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.
Rice's 1998 classification
Previous classification
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 not regarded therefore as true river dolphins.
For more information, see the articles on the individual species