The hypothetical disappearance of worms, primarily earthworms, would represent the sudden loss of one of the planet’s largest terrestrial animal biomasses. These organisms are universally distributed across nearly all soil types and function as perpetual soil engineers. Their collective activity drives fundamental ecological processes that sustain the surface world. Exploring this scenario means confronting the immediate, cascading collapse of soil function, agriculture, and the broader food webs that depend on these invertebrates. The global extinction of these organisms would trigger a rapid and irreversible decline in the health and productivity of the world’s terrestrial ecosystems.
Loss of Physical Soil Structure
The most immediate consequence of losing the global earthworm population would be the swift deterioration of physical soil quality. Earthworms are constant burrowers, and their movement creates extensive networks of vertical and horizontal tunnels known as macropores. These channels are fundamental to soil architecture, allowing for the efficient infiltration of water and the exchange of gases necessary for root respiration. Without this constant physical churning, the soil would quickly lose its porosity and become significantly more dense.
Increased soil density would lead to widespread compaction and a dramatic reduction in the soil’s ability to absorb rainfall. Rainwater would be unable to drain effectively, resulting in increased surface runoff and waterlogging during wet periods. During dry periods, the compacted soil structure would prevent plant roots from penetrating deeply to access moisture and nutrients.
The process of soil aggregation, which involves the formation of stable soil crumbs, would also cease. Earthworm excrement, or casts, are micro-structures stabilized by mucus and organic materials that act as the binding agents for larger soil aggregates. These stable aggregates resist erosion and maintain the necessary crumb structure for plant growth. Without the continuous production of these casts, the soil surface would become much more vulnerable to wind and water erosion, leading to the rapid degradation of topsoil layers globally.
The Halt of Nutrient Cycling and Waste Decomposition
The extinction of worms would halt a central engine of nutrient processing, leading to the rapid accumulation of organic debris on the soil surface. Earthworms are primary detritivores, consuming dead leaves, roots, and other organic waste that falls onto or into the soil. Their feeding habits mechanically fragment this detritus, increasing the surface area for microbial action and accelerating the entire decomposition process.
The constant passage of organic matter through the worm’s gut turns complex organic compounds into simpler, bioavailable nutrients. The casts they excrete are significantly richer in forms of nitrogen, phosphorus, and potassium that plants can readily absorb compared to the surrounding soil. This rapid conversion facilitates a quick turnover of nutrients, which is essential for sustaining plant growth.
Without the worms’ constant activity, organic matter would slowly decompose through microbial and fungal action alone, leading to a profound buildup of a thick, undecomposed litter layer. This layer would act as a barrier, physically separating plant roots from the nutrients locked within the debris. Anecic earthworms drag surface litter down into their burrows, incorporating this material into the mineral soil; their absence would effectively halt this critical burial and mixing process. The rate of nitrogen return to the soil would drop precipitously, fundamentally starving the world’s flora.
Collapse of Agricultural Yields and Food Security
The combined failure of soil structure and nutrient cycling would translate directly into a collapse of global agricultural productivity. Earthworms are recognized as a natural subsidy to crop production, contributing significantly to the yields of staple crops worldwide. Recent scientific estimates suggest that earthworms contribute to approximately 6.5% of global grain production and 2.3% of global legume production.
The loss of this contribution would instantly create a global food deficit. In regions where farmers have less access to synthetic fertilizers, such as Sub-Saharan Africa, the ecological services provided by earthworms are even more pronounced, accounting for up to 10% of annual grain yield.
Farming would become significantly more difficult, requiring unprecedented inputs to compensate for the compromised soil. To maintain current yield levels, farmers would need to apply massive increases of artificial fertilizers to replace the lost biological nitrogen and phosphorus cycling. Furthermore, the loss of natural aeration and drainage would necessitate increased mechanical tilling, which further destabilizes the fragile soil structure and accelerates erosion. The increased cost of inputs, coupled with reduced yields and the difficulty of cultivating compacted, waterlogged, or heavily eroded fields, would lead to soaring food prices and widespread economic instability and famine.
Disruption of Terrestrial Ecosystem Food Webs
Beyond the soil itself, the extinction of worms would trigger a trophic cascade, destabilizing terrestrial food webs that depend on them as a protein-rich prey base. Earthworms are a mid-level trophic group, serving as a primary link between decaying organic matter and a host of vertebrate and invertebrate predators. The sudden removal of this food source would lead to population crashes among dependent species.
Many common birds, such as American robins, blackbirds, and song thrushes, rely heavily on earthworms as a major component of their diet, particularly during the breeding season when high-protein food is needed for their young. The loss of this reliable food source would drastically reduce nesting success and overall population numbers for these and other ground-foraging birds.
Underground ecosystems would suffer the most direct impact, as small mammals such as moles and shrews are highly specialized earthworm predators. Amphibians like frogs and toads, along with many reptiles such as grass snakes, also include earthworms in their diets. The disappearance of this easily accessible, abundant prey would simplify these food webs, leading to reduced biodiversity and a shift in predator-prey dynamics across various habitats.