Soil is home to thousands of living organisms, including moles, earthworms, centipedes, millipedes and grubs. Snails, beetles, ants, mushrooms and fungi also live in soil. Most of these organisms play a fundamental role breaking down remains of plants and animals, transforming them into nutrients to support growth of new plants.
Many species of organisms live in soil, such as bacteria, protozoa, fungi and algae. Other organisms include plants and small vertebrates. Whereas some living organisms spend only part of their life in soil, others spend their entire life underground.
Different types of soil are habitats for different kinds of organisms. The soil texture determines its content. For example, water and air are abundant in soil with spaces or pores between solid soil particles. Plant roots and soil organisms require water and air. In a quarter teaspoon of fertile soil, there are approximately 50 nematodes, 62,000 algae, 72,000 amoeba, 2.9 million actinomycetes and 25.2 million bacteria.
Soil organisms play a vital role in ensuring a continuous rotting of organic matter. Earthworms burrow through soil, loosening it and allowing in air. They eat plant materials and excrete worm castings, which are used as food for other organisms, including birds and beetles. Ants live in bulky colonies, and also burrow in soil.