Story: Soils

Microbes help to bind soil particles together, either as sticky strands (A) and (B), or by trapping clay on their sticky surfaces (C). Other micro-organisms such as protozoa (including amoeba and soil nematodes) are small animals, like the armour-plated protozoan (D), which feeds on bacteria. A spoonful of soil has about 100 billion bacteria, and contains about 15 kilometres of fungal threads.