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Physical
Decomposers
Decomposers are organisms that break down dead plants and animals and release their nutrients back into the environment.
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The idea
Decomposers are organisms that break down dead plants and animals and return their nutrients to the environment. Plants depend on them, because plants cannot travel to find nutrients and most cannot digest other living things. Without decomposers, dead matter would pile up and its nutrients would stay locked away.
Decomposition works much like digestion: enzymes break large, complex molecules into smaller, simpler ones. Fungi and bacteria digest their food outside their bodies. They release enzymes onto dead matter, give the enzymes time to work, and then absorb the nutrients. Invertebrates such as earthworms, woodlice and sea cucumbers digest dead matter inside their bodies and return nutrients through their waste.
The word decomposer names a role in an ecosystem, not one particular kind of organism. Animals that eat dead matter are also called detritivores, and an organism can be both a detritivore and a decomposer. Weathering and ultraviolet light also help break dead matter down, but only living things count as decomposers. The nutrients that decomposers set free feed new plant growth, so the cycle of life in an ecosystem can keep going.
Check yourself
Question 1 of 2
What does the word decomposer describe?
Composition
what it's made of
- Fungi — Molds and mushrooms that release enzymes onto dead matter and absorb the nutrients.
- Bacteria — Microbes that also digest dead matter outside their cells.
- Invertebrates — Earthworms, woodlice and sea cucumbers that digest dead matter inside their bodies.
- Enzymes — Chemicals that break complex molecules into simpler ones.
- Released Nutrients — Nutrients freed from dead matter that plants can then absorb.
Connection
how it relates
Under Food Chains
Change
how and why it evolves
- Past
- People have always seen dead things rot, but only after the microscope was invented did scientists learn that bacteria and fungi do much of the work.
- Now
- Today people put decomposers to work in compost piles and in wastewater treatment, where microbes break down waste.
- Next
- As the climate warms, decomposers may break down soil matter faster, which could release more carbon into the air.