Gangetic Dolphin

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The Gangetic and Indus river dolphins (Platanista gangetica) are the only ones, out of more than 40 different species in the planet's oceans and rivers that do not have a crystalline eye lens, thus making them effectively blind. They can probably detect the direction and intensity of light, but they navigate and find their food using a highly-evolved and sophisticated echolocation (sonar) system.

Though no one knows for sure why these dolphins are sightless, the scientific explanation is that their eyesight probably regressed in the course of the long process of evolution, on account of the high turbidity of the silt-laden river waters. The only other freshwater dolphins in the world, those in the Amazon and Yangtse river systems, while not completely blind, have extremely poor vision.

[edit] Why should I be aware of this?

Dolphins have probably lived in the Gangetic basin from time immemorial, perhaps since the origin of the river, and are mentioned in mythological literature and folklore, including the Mahabharata, which refers to them as the Vahana (carrier) of the legendary Ganga.

Years later, the Gangetic dolphin was also recorded in an illustration that formed part of the Babur namah, an indication of its prominence during the early 16th century A.D.

However, the status now is desperate as their total numbers have dwindled to less than 2000 in the entire range, which inludes Nepal and Bangladesh. This has led to its being declared a protected species under the Wildlife Protection Act of 1972.

  • The proposed Barh Thermal Power Project on the banks of the Ganges in the Tal wetlands will not only cause the reclamation of several hectares of these wetlands, which have been proposed as an Important Bird Area, but also necessitate the intake of large volumes of water from the river and their consequent discharge at higher temperatures. This is known to kill the fish and harm other aquatic life. In addition, the disposal of ash slurry, which contains heavy metals such as mercury, cadmium, and lead, as well as other substances such as sulphur, also poses a pollution threat to the Ganges.
  • The largest number of dolphins found dead has been at the Vikramshila Gangetic Dolphin Sanctuary in Bihar an eastern state in India.

[edit] CopperBytes

  • Gangetic dolphins are among the oldest creatures in the world along with crocodiles, sharks and some turtles.(This is not true as sharks and crockadilians go back long before mammals, and aquiatic mammals evolved from land mammals so are not even early mammals)
  • As top predators they are not eaten by anything else
  • Another 10 years could wipe out what has survived 100 million years.

[edit] See Also

[edit] Further Reading and Online Resources

  • Watch a youtube video of the Gangetic River Dolphin by David Attenborough
  • Documentary about dolphins of the Ganges river

[edit] News

  • 07 January 2006 Pollution kills off Gangetic river dolphin

[edit] References

  • Conserving Gangetic dolphins