Biodiversité

Source: McKay, George (Éd.). (2004). The Encyclopedia of Animals: A Complete Visual Guide (1ère éd.). California: University of California Press.

Scientists have described in the region of 1.75 million species of life-forms on Earth, but that is thought to be only a small proportion of the true figure. Estimates place this at between 5 and 100 million species. Even the figures for the number of known species are hard to pin down because new species are being discovered all the time. Vertebrates [...] are the best-described group but make up only about 5 percent of animal species. There are about 1 million known species of insects but the true number could be more in the region of 30 million. (p. 15)