Platanista gangetica minor, Indus River Dolphin [+]
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Cetacea
Family Platanistidae
Genus Platanista
species: Platanista gangetica minor [+ITIS +WoRMS]
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Description & Behavior
Indus river dolphins, Platanista gangetica minor (Roxburgh, 1801), (aka blind river dolphin or bhulan) are a subspecies of Ganges river dolphins. With the exception of slightly different tail lengths, the 2 species are physically very similar; however the differ by the rivers they inhabit, which qualifies the Indus river dolphin as a subspecies. They are similar in color to the brown-gray water they inhabit on the dorsal side, paler on the ventral side. The have a distinctive, extremely long beak that swells at the tip. The dorsal fin is smaller than those of other river dolphins. They have large flippers and flukes. Like other river dolphin species, their necks are flexible. Their external ears are located beneath the small poorly sighted eyes. Like other river dolphins that live in muddy waters with poor visibility, the Indus river dolphin is not equipped with strong eyesight. Females are generally larger than males.
The Indus river dolphin is generally a solitary species; however groups of up to 30 dolphins have been observed. These dolphins are able to swim on their sides, which enables them to swim in very shallow water if necessary, although they are not known to be an acrobatic dolphin species. They are highly vocal and depend on echolocation to perceive their environment and to navigate because their eyesight is poor. They rarely use their ability to make sounds to communicate. The sounds they do emit are described as intermittent pulses.
World Range & Habitat
Indus river dolphins, P. gangetica minor, are found in the Indus River in Pakistan. Their range has decreased significantly by human created barriers and changes to the rainfall pattern. They are found above the Kotri Barrage and below the Chasma, Trimmu, Sidhnai, and Islam Barrages.
Some paleontologists believe that river dolphins may have have evolved during the Miocene era from marine-dwelling that eventually moved to estuaries and rivers with the rise and fall of sea levels. They appear to migrate seasonally along the river.
Feeding Behavior (Ecology)
Indus river dolphins, P. gangetica minor, use their echolocation abilities combined with their highly toothed, long snouts to forage for many bottom-dwelling animals including fish and invertebrates.P. gangetica minor has been known to eat some species of catfish, herring, carp, gobies, mahseers, prawns, and clams. Captive individuals reportedly consume about a 1 kg of food each day. Has few, if any, natural predators, however, they are often hunted by local people.
Life History
Indus river dolphins, P. gangetica minor, reach sexual maturity at about 10 years, and are thought to mate year round as calves are born throughout the year.Platanista gangetica minor has gestation period of 8-11 months after which calves are born measuring about 1 m, which is about half the size of the mother's body. Calves nurse for about a year. The exact lifespan of P. gangetica minor has not been documented; however it is thought to be long considering their latent sexual maturity.
Conservation Status/Additional Comments
Indus river dolphins, P. gangetica minor, are becoming increasingly rare for several reasons such as hunting, building of dams and barrages in the Indus river, and changing rainfall patterns. They have been classified as endangered since the 1970s. Their current population is estimated at only several hundred dolphins, a number unlikely to sustain the species, and one that will create genetic problems.
References & Further Research
BioOne ~ CITES ~ Discover Life ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList ~ MarineBio Network ~ NCBI ~ SCIRIS ~ SIRIS ~ Tree of Life Web Project ~ Wikipedia
Jefferson, T.A., S. Leatherwood, and M.A. Webber, FAO species identification guide, Marine mammals of the world, Rome, FAO. 1993. 320 p. 587 figs.
Whale and Dolphin Conservation Society (WDCS)
Ganges and Indus River Dolphin From Wikipedia
Biswas, S., S. Boruah. 2000. Ecology of the River Dolphin (Platanista gangetica) in the Upper Brahmaputra. Hydrobiologia, 430: 97-111.
Hamilton, H., S. Caballers, A. Collins, R. Brownell. 2001. Evolution of river dolphins. Proc. R. Soc. Lond., 268: 549-558.
Moreno, P. 2004. Ganges and Indus dolphins (Platanistidae). Pp. 13-17 in M. Hutchins, D. Kleiman, V. Geist, M. McDade, eds. Grzimek's Animal Life Encyclopedia, Vol. Volume 15: Mammals IV, Second Edition Edition. Detroit: Thompson Gale.
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