A world scaled to the gaps in soil
Soil is not a solid block. It is a maze of mineral grains, decaying plant matter, and narrow pores that can hold thin films of water. Nematodes—slender, usually microscopic roundworms—can move through these watery passages, where larger animals may not fit. Their small size lets many individuals occupy a patch of ground without needing the space or food supply a larger animal would require.
Many meals, many niches
Nematodes do not all eat the same thing. Depending on the kind, they feed on bacteria, fungi, plant roots, or other small organisms. That variety spreads them across different food sources and positions in the soil food web. Some help regulate populations of microbes; others become food for mites, insects, and larger soil animals.
Their numbers also depend on conditions that can change over short distances. A damp pocket rich in decaying material may support a different crowd from a dry or nutrient-poor patch nearby. The soil’s tiny compartments make it possible for large populations to persist in places that look, from above, like ordinary dirt.
Abundance is not the same as bulk
A count of nematodes can be astonishing even when their combined mass is modest: each animal is so small that a huge number can fit into a relatively little space. That distinction matters when comparing them with conspicuous wildlife. Their ecological influence comes not from being individually powerful, but from being numerous and continually interacting with microbes, plants, and other animals beneath our feet.
