We have a truncated vision of the living world. The plants, animals, and insects that we see or know represent in reality only an infinitesimal part of life on Earth. The bulk of it is concealed underground. More than 50 billion microscopic organisms teem in a tablespoon of forest soil, and more than 1,000 species of invertebrates can be recorded over a square meter. It is the earth that harbors almost 80% of the continental biomass (weight of living matter) of our planet, a large part of it consisting of earth worms, which aerate and fertilize the soilóa fact that led Darwin, in 1881, to compare them to mankindís invention of the plow.
A whole array of creaturesóworms, centipedes, ants, mites, algae, molds, and bacteriaóare busily engaged in the task of recycling living matter: decomposing dead plants and animals and transforming them into humus, from which the roots of new plants draw their nutrients in order to create fresh living matter.
Another location where bacterial life is abundant is the human intestine. The human body contains ten times more bacteria than it does cells. We do not see these bacteria and rarely give them a thought, and yet they directly influence our health, aiding our digestion and helping us to fight against invading germs.
The animals we tend to feel most drawn to are large mammals whose appeal lies in their expressiveness or their beauty. The giant panda, the Asian tiger, and the polar bear are no more important than earth worms or mites. Their popular?ity, however, promotes an awareness that is crucial in safeguarding the great pageant of biodiversity, which includes not only the large and the beautiful, but also the minuscule, invisible, repugnant, and fearsome, together with all those other elusive species not yet recorded or described by science.