Definission: A rare species is a group of organisms that are very uncommon, scarce, or infrequently encountered. This designation may be applied to either a plant or animal taxon, and is distinct from the term endangered or threatened. Designation of a rare species may be made by an official body, such as a national government, state, or province. The term more commonly appears without reference to specific criteria. Rarity rests on a specific species being represented by a small number of organisms worldwide, usually fewer than 10,000. However, a species having a very narrow endemic range or fragmented habitat also influences the concept. Almost 75% of known species can be classified as rare.
Definission: A habitat that is in or on a sea or ocean containing high concentrations of dissolved salts and other total dissolved solids (typically >35 grams dissolved salts per litre).
Definission: Component found in mineralized skeletal tissue, (a specialized form of biogenic tissue in which the extracellular matrix is mineralized, and which functions in mechanical and structural support.)
Definission: 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)
