定義： A feature shaped by the dissolution of a soluble layer or layers of bedrock, usually carbonate rock such as limestone or dolomite. These landscapes display distinctive surface features and underground drainages, and in some examples there may be little or no surface drainage.
定義： the method used by some animals (e.g. bats, dolphins and some whales) to determine the location of something by measuring the time it takes for an echo to return from it. These animals emit sound waves and listen for the echo, calculating the distance to the object from the time lapse between sound emission and the echo returning.
定義： Description of the relationships among individuals within a population of organisms, including reproductive relationships (mating system), relationships within each sex, adult – young interactions, helpers and cooperation (group living).
定義： 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)
