Earthworms are terrestrial invertebrates whose primary role involves the continuous processing of soil and organic matter. Moss is a non-vascular plant that lacks true roots and absorbs water and nutrients directly through its leaves. Earthworms are fundamentally detritivores, meaning they consume decomposing organic material. They do not actively seek out or primarily feed on live moss as a food source.
The Earthworm’s Primary Diet and Function
Earthworms are important detritivores in terrestrial ecosystems, meaning their diet consists mainly of detritus (decaying plant and animal matter). They ingest a wide variety of dead organic materials, including fallen leaves, dead roots, and other plant debris. The nutritional value comes primarily from the vast communities of bacteria, fungi, and other microorganisms that coat the detritus, not the dead plant material itself. This continuous processing is a core ecological function, as it physically breaks down material and helps cycle nutrients, such as nitrogen and phosphorus, back into the soil, significantly improving soil fertility.
Ecological Groups
Earthworms are categorized into different ecological groups based on their feeding habits and location in the soil profile. Epigeic species live in the surface litter and feed on freshly decaying organic matter. Anecic species pull surface detritus into their deep, vertical burrows. Endogeic worms consume large amounts of soil rich in organic matter throughout the mineral layers. The resulting material, called cast, is a processed version of the ingested soil and organic matter, making nutrients more available for plants.
Why Moss is Not a Preferred Food Source
Moss is unattractive to earthworms due to its structure and chemical composition, making it a poor energy source compared to other detritus. The physical structure of moss often contains high levels of lignin and cellulose, complex carbohydrates difficult for earthworms to digest efficiently. These components resist rapid breakdown, meaning the worm expends more energy to process the material than it gains. Moss also possesses low concentrations of protein and nitrogen, elements required for growth and reproduction. Furthermore, the sparse microbial community associated with live or recently dead moss makes it an inefficient meal. Peat moss, which is dead and partially decayed Sphagnum moss, is highly acidic, and acidic conditions are detrimental to earthworm health and activity.
The Indirect Interaction Between Worms and Moss
Although earthworms do not eat moss, their activity indirectly influences the moss’s habitat. Moss often thrives in compacted, damp, and acidic soils that lack the high nutrient content preferred by vascular plants. Earthworm tunneling and feeding activities drastically alter these soil characteristics. The movement of earthworms creates burrows that increase aeration and improve drainage, reducing the soil compaction and moisture levels moss favors. The deposition of nutrient-rich, pH-neutral casts shifts the soil’s chemistry and structure, making the environment more favorable for competing vascular plants and less optimal for dense moss carpets.