Physical Decomposers - Larger Organisms

Besides the many types of bacteria and fungi that chemically break down the materials in a compost pile, there are a multitude of larger organisms that add diversity to the compost pile and assist with the mechanical breakdown of materials. Many of them feed on dead bacteria and their by-products as well as each other. The following is just a sampling of some of the more common organisms in this diverse group of physical decomposers:

nematodes
fermentation mites
springtails
wolf spiders
centipedes
sow bugs
ground beetles
red worms

ALSO SEE:
the decomposition process
chemical decomposers-microorganisms

Nematodes

Nematodes, or roundworms, are the most abundant invertebrates in the soil. Typically less than one millimeter in length, they prey on bacteria, protozoa, fungal spores, and each other. Though there are pest forms of nematodes, most of those found in soil and compost are beneficial.

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Fermentation Mites

Fermentation mites, also called mold mites, are transparent-bodied creatures that feed primarily on yeast in fermenting masses or organic debris. Literally thousands of these individuals can develop into a seething mass over a fermenting surface. As a result, they often become pest species in fermenting industries, such as wineries and cheese factories. They are not pests in the compost pile.

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Springtails

Springtails, or collembola, along with nematodes and mites, dominate in numbers among the soil invertebrates. They are a major factor in controlling fungi populations. They feed principally on fungi, but also on nematodes and small bits of organic detritus.

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Wolf Spiders

Wolf spiders are truly "wolves" of the soil and compost communities. They don't build webs, but run freely, hunting their prey. Depending on the size of the spider, their prey can include all sizes of arthropods- invertebrate animals with jointed legs and segmented bodies.

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Centipedes

Centipedes are frequently found in soil and in compost communities. They prey on almost any type of soil invertebrate near their size or slightly larger.

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Sow Bugs and Pill Bugs

Sow bugs and pill bugs feed on rotting woody materials and highly durable leaf tissues, such as the veins comprised of woody xylem tubes. Sow bugs that roll up like an armadillo are known as pill bugs or roly-polys.

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Ground Beetles

Ground beetles have many representatives lurking through litter and soil spaces. Most of them feed on other organisms, but some feed on seeds and other vegetable matter.

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Redworms and Earthworms

Redworms and earthworms play an important part in the break-down of organic materials and in forming finished compost. As worms process organic materials, they coat the material with a mucus film that binds small particles together into stable aggregates and helps to protect nutrients from being leached out by rain. These stable aggregates give soil a loose and well-draining structure.

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