What is a Decomposer? – Function, and Example?

What is a Decomposer?

A decomposer is an organism that decomposes or breaks down organic material such as the remains of dead organisms. Bacteria and fungi are decomposers. These organisms carry out the decomposition process that all living organisms go through after death. Decomposition is an important process as it allows organic material to be recycled in an ecosystem.

Mushrooms, like the one in the picture below, are a type of fungus and play a role in its decomposition.

type of fungus and play a role in its decomposition

Function of Decomposers

Decomposers play an important role in every ecosystem. Without decomposers, dead organisms would not be broken down and returned to other living matter. The reason decomposers decompose is simply because they have to survive.

Decomposers are heterotropic, which means that they get their energy from the uptake of organic material. A dead organism provides nutrients that decomposers such as bacteria and fungi can use to grow and reproduce and their own species to multiply.

The side effect of this basic need for survival is that organic matter and nutrients are circulated throughout the ecosystem while other organisms consume the bacteria and fungi.

Detritivores as a Decomposers

Some organisms perform a similar function as decomposers, and are sometimes called decomposers, but are technically detritivores. The difference lies in the way decomposers and detritivores break down organic material.

Detritivores must digest organic material within their bodies in order to break it down and gain nutrients from it. Decomposers do not need to digest organic material internally in order to break it down; instead, they can break down matter through biochemical reactions. Organisms that are detritivores include invertebrates such as earthworms, woodlice, sea stars, slugs, and fiddler crabs.

Scavengers as a Decomposers

Scavengers are the first to get hold of the remains of a dead organism, and they directly eat the dead plant and animal material. Once the scavengers are done with the remains, decomposers and detritivors take over the pieces that the scavengers left behind and use them up.

Many predators will eat occasionally; Examples of these occasional scavengers are lions, jackals, wolves, raccoons, and possums. Vultures are obligate scavengers, which means that it is from scavenging that they get all of their food. They are the only members of the animal kingdom who need to eat in order to eat.

Stages of Decomposition

When an organism dies and decomposers do the decomposition work, the remains of the organism go through five stages of decomposition: fresh, bloated, active decay, advanced decay, and dry / staying.

There are two main processes that go on in a decomposing organism: autolysis and putrefaction. Autolysis is when cellular enzymes in the body of the dead organism break down cells and tissues, while putrefaction is when microbes grow and multiply throughout the body after death.

Here is a quick summary of the five stages:

  1. Fresh: This phase begins as soon as the heart of an organism stops beating. When oxygen stops getting into the body and carbon dioxide builds up, autolysis begins. Putrefaction also begins.
  2. Bloat: The putrefaction leads to an accumulation of gases and the remains of the organism appear bloated in the so-called bloating stage. Some gases and liquids are removed from the body.
  3. Active Decay: The remains lose mass, and liquefaction and disintegration of tissues begins to occur. Bacteria produce chemicals such as ammonia, hydrogen sulfide, and methane, which cause strong odors.
  4. Advanced Decay: The organism has lost a lot of mass, so that there is not much left to decompose. If the organism is on or in the soil, the surrounding soil shows an increase in nitrogen, an important nutrient for plants.
  5. Dry/Remains: At this stage, only dry skin, cartilage, and bones are left. Plant growth can occur around the remains due to the increased nutrient levels in the soil. Ultimately, only the bones of the organism remain.

Examples of Decomposers


Bacteria are microscopic, unicellular organisms that can be found almost everywhere on earth, including in the human body. When an organism dies, it provides many nutrients for bacteria to grow and multiply, and they become numerous during the putrefaction process as it breaks down.

Bacteria are themselves a cause of disease and even death when they infect organisms. Serious and often fatal diseases such as typhoid, tuberculosis, and cholera are caused by bacterial infections. Bacteria killing their hosts inadvertently supply nutrients for other bacteria during decomposition.


Fungi are the main decomposers in many environments. Some examples of Fungi are yeast, molds, and mushrooms. Fungi have hyphae, which are branched filaments, and these hyphae can invade organic matter, making fungi effective decomposers.

Wood decay fungi have specific enzymes that digest compounds in wood and are the main decomposers in forests. In fact, wood decay fungi are the only producers of these enzymes, so they play a very important role in the decomposition process.

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