定义：A taxon is Endangered when the best available evidence indicates that it meets any of the \r\ncriteria A to E for Endangered, and it is therefore considered to be facing a very high risk of extinction in the wild.
定义：A habitat that is in or on a body of water containing low concentrations of dissolved salts and other total dissolved solids (<0.5 grams dissolved salts per litre).
定义：A group of species that exploit the same food resources, and/or use the same feeding or foraging methods. http://en.wikipedia.org/wiki/Guild_(ecology)
