As species and habitat losses climb to the top of the planet's list of environmental threats, researchers worldwide are becoming more concerned about preserving biodiversity. But the word itself has become a buzzword in the last decade, and is frequently tossed around by environmental activists and political groups without much explanation of its actual meaning.

It would be virtually impossible for scientists to measure Earth's biodiversity by any numerical value. The number of species on the planet remains a mystery and ecologists disagree about borders distinguishing habitats.