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 Act of 1973 habitat protection and recovery goals, requiring the identification and protection of all lands, water and air necessary to recover endangered species. To determine what exactly is critical habitat, the needs of open space for individual and population growth, food, water, light or other nutritional requirements, breeding sites, seed germination and dispersal needs, and lack of disturbances are considered. As habitat loss is the primary threat to most imperiled species, the Endangered Species Act of 1973 allowed the Fish and Wildlife Service (FWS) and National Marine Fisheries Service (NMFS) to designate specific areas as protected "critical habitat" zones. In 1978, Congress