Millipedes (class Diplopoda) are multi-legged arthropods found globally in damp, dark environments like forests, gardens, and lawns. Their role is primarily that of a decomposer, consuming dead organic matter on the forest floor. By feeding on this material, millipedes play a fundamental part in nutrient recycling and decomposition in terrestrial ecosystems.
The Primary Diet of Decaying Plant Matter
The majority of a millipede’s diet consists of detritus, or non-living organic material, making them detritivores. Their main food source is decaying plant matter, such as fallen leaves, rotting wood, and bark. Millipedes prefer materials already softened by moisture and the action of microbes like fungi and bacteria.
Microbial colonization breaks down the complex cellulose and lignin in plant matter, making nutrients more accessible to the millipede’s digestive system. Millipedes prefer certain types of leaf litter, consuming broadleaf species more readily than tougher pine needles. They actively seek out these moist, semi-decomposed materials, frequently locating them beneath rocks, in mulch piles, or in thick leaf litter.
Consuming this decaying matter is a slow process, reflecting the low nutrient density of their food. Millipedes must process large quantities of litter to extract sufficient energy and nutrients. This helps break down large pieces of debris into smaller fragments on the forest floor. Their preference for moist food sources is tied to their biology, as they are susceptible to desiccation and must maintain high internal moisture levels.
Supplemental Food Sources and Soil Consumption
While detritus forms the bulk of their diet, millipedes supplement their meals with other sources that provide specific nutrients. Fungi and molds growing on decaying plant matter are readily consumed, as they are rich in protein and easier to digest than fibrous plant material.
Millipedes also consume animal feces and occasionally feed on the remains of small, dead animals like insects. These items offer concentrated sources of nitrogen and minerals less prevalent in plant litter. When food is scarce or conditions are dry, certain species may opportunistically feed on soft or damaged living plant tissues, such as seedlings or soft fruits.
The consumption of soil is part of the feeding habits for some species. Millipedes eat soil not purely for mineral content, but for the fine organic particles, microorganisms, and minerals embedded within it. This behavior, known as geophagy, ensures they ingest necessary micronutrients, like calcium, which is required for building their hard exoskeleton. Some species even consume their own shed exoskeletons after molting to recover lost calcium.
Feeding Mechanics and Ecological Impact
Millipedes are equipped with simple, sturdy mouthparts designed for grinding and scraping soft materials. Their mandibles shear and chew pre-softened detritus into fine particles that are easily ingested. This mechanical breakdown converts large pieces of leaf litter into a form that can be processed by the soil ecosystem.
After ingestion, the material passes through a digestive system that efficiently processes the low-nutrient food. The millipede’s gut extracts nutrients before the remaining material is excreted as fecal pellets, which are deposited back into the soil.
This feeding process has a profound ecological impact by accelerating nutrient cycling. By converting coarse leaf litter into fecal pellets, millipedes increase the surface area available for microbial action. This speeds up the decomposition rate, releasing elements like carbon and nitrogen back into the soil, which supports plant growth. Millipedes are recognized as ecosystem engineers for improving soil health and facilitating nutrient flow.