Ganges Indian narrow-headed softshell turtle ("Chitra indica"), Indian softshell turtle ("Nilssonia gangetica"), Indian peacock softshell turtle ("N. hurum") and Cantor's giant softshell turtle ("Pelochelys cantorii"; only in the lowermost section of Ganges basin). Most of these are seriously threatened. The river's most famed fauna is the freshwater Ganges river dolphin ("Platanista gangetica gangetica"), which has been declared India's national aquatic animal. This dolphin used to exist in large schools near to urban centres in both the Ganges and Brahmaputra rivers, but is now seriously threatened by pollution and dam construction. Their numbers have now dwindled to a quarter of their numbers
Endangered species future. The introduction of non-indigenous species to an area can disrupt the ecosystem to such an extent that native species become endangered. Such introductions may be termed alien or invasive species. In some cases the invasive species compete with the native species for food or prey on the natives. In other cases a stable ecological balance may be upset by predation or other causes leading to unexpected species decline. New species may also carry diseases to which the native species have no resistance. Captive breeding is the process of breeding rare or endangered species in human controlled environments with restricted