Definition: 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.
Definition: A linear shoaling landform feature within a body of water. Bars tend to be long and narrow (linear) and develop where a current (or waves) promote deposition of granular material, resulting in localized shallowing (shoaling) of the water. Bars can appear in the sea, in a lake, or in a river. They are typically composed of sand, although could be of any granular matter that the moving water has access to and is capable of shifting around (for example, soil, silt, gravel, cobble, shingle, or even boulders). The grain size of the material comprising a bar is related: to the size of the waves or the strength of the currents moving the material, but the availability of material to be worked by waves and currents is also important.
Comment: "Large" is ambiguous. For details on "Large rivers" (e.g. the Mekong river) see http://worldwildlife.org/biomes/large-river-ecosystems This class will be replaced with a less ambiguous class.
Definition: A shallow stretch of a river or stream, where the current is above the average stream velocity and where the water forms small rippled waves as a result. It often consists of a rocky bed of gravels or other small stones.
Definition: Gravel is an environmental material which is composed of pieces of rock that are at least two millimeters (2mm) in its largest dimension and no more than 75 millimeters.
Definition: National Museum of Natural History, Smithsonian Institution (USNM), Washington, District of Columbia, USA.\r\nNMNH and USNM both refer to the National Museum of Natural History. Collections are associated with one or the other acronym. US, the US National Herbarium, is a collection within the National Museum of Natural History. URL for main institutional website, http://www.mnh.si.edu/rc/\r\nURL for institutional specimen catalog, http://collections.mnh.si.edu/
