Microfauna

Definition

Microscopic animals and animal-like heterotrophic eukaryotes, typically smaller than 0.1 mm, inhabiting soil, water, or sediment systems. In terrestrial ecology, microfauna comprises nematodes, rotifers, tardigrades, and protozoans that consume bacteria, fungi, or detritus, forming a critical trophic link between microbial production and larger soil mesofauna and macrofauna. The term distinguishes these minute consumers from microflora (autotrophic microbes) and from larger size classes of soil fauna.

Etymology

From Greek mikros (small) + Latin fauna (animals)

Example

Soil microfauna such as bacterial-feeding nematodes and testate amoebae regulate microbial biomass and nutrient mineralization rates, indirectly influencing the food resources available to springtails (Collembola) and mites (Acari) in the litter layer.

Related Terms

• mesofauna
• macrofauna
• microflora
• soil food web
• Nematode
• rotifer
• tardigrade
• meiofauna

Usage Notes

Size thresholds vary slightly by discipline; soil ecology typically uses <0.1 mm, while marine contexts sometimes extend to <0.5 mm. Contrast with meiofauna, which overlaps in size but is habitat-specific to interstitial water films. Not a taxonomic group—encompasses multiple phyla and kingdoms united by size and heterotrophy.