Indus river dolphin
| Indus river dolphin | |
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| Size compared to an average human | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Infraorder: | Cetacea |
| Family: | Platanistidae |
| Genus: | Platanista |
| Species: | P. gangetica |
| Subspecies: | P. g. minor |
| Trinomial name | |
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Platanista gangetica minor |
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| Ranges of the Ganges River dolphin and of the Indus River dolphin | |
The Indus river dolphin (Platanista gangetica minor) is a subspecies of freshwater river dolphin found in the Indus river (and its Beas and Sutlej tributaries) of India and Pakistan. This dolphin was the first discovered side-swimming cetacean. It is patchily distributed in five small, sub-populations that are separated by irrigation barrages. The Indus dolphin does not form easily defined groups who interact. Instead, they're typically found in loose aggregations. From the 1970s until 1998, the Ganges River dolphin and the Indus dolphin were regarded as separate species; however, in 1998, their classification was changed from two separate species to subspecies of a single species (see taxonomy below). It has been named as the national mammal of Pakistan.
The species was described by two separate authors Lebeck and Roxburgh in the year 1801 and it is unclear to whom the original description should be ascribed. Until the 1970s the Indus and Ganges river dolphins were regarded as a single species. The two populations are geographically separate and have not interbred for many hundreds if not thousands of years. Based on differences in skull structure, vertebrae and lipid composition scientists declared the two populations as separate species in the early 1970s. In 1998 the results of these studies were questioned and the classification reverted to the pre-1970 consensus of a single species containing two subspecies until the taxonomy could be resolved using modern techniques such as molecular sequencing. The latest analyses of mitochondrial DNA of the two subspecies did not display the variances needed to support their classification as separate species. Thus, at present, there are two subspecies recognized in the genus Platanista: Platanista gangetica minor (the Indus dolphin) and Platanista gangetica gangetica (the Ganges river dolphin).
The Indus River Dolphin only occurs in the Indus River system. These dolphins occupied about 3,400 km of the Indus River and the tributaries attached to it in the past. But today, its only found in one fifth of this previous range. Its effective range today has declined by 80% since 1870. It no longer exists throughout the tributaries, and its home range is only 690 km of the river. This dolphin prefers a freshwater habitat with a water depth greater than 1 meter and that have more than 700 meters squared of cross-sectional area. Today this species can only be found in the Indus River's main stem.
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