Keshu

DECOMPOSERS

What are decomposers?

Decomposers are organisms that feed on dead and decaying plants, animals, and organic waste and break them down into simpler substances. These substances are returned to the environment and reused by plants.

They are also called nature’s recyclers.

3. Position of Decomposers in an Ecosystem

An ecosystem has:

• Producers (plants)

• Consumers (animals)

• Decomposers (bacteria & fungi)

Decomposers occupy the final trophic level of the food chain.They act on all trophic levels because every organism eventually dies.

➡️ This means decomposers connect living components with the non-living environment.

4. Types of Decomposers

A. Bacteria

• Microscopic, single-celled organisms

• Found everywhere: soil, water, air, dead bodies

• Decompose soft tissues like muscles and organs

• Important in nitrogen fixation and ammonification

Examples:

• Bacillus

• Pseudomonas

B. Fungi

• Multicellular organisms

• Grow on dead wood, leaves, food waste

• Secrete powerful digestive enzymes

• Break down hard substances like cellulose and lignin

Examples:

• Mushrooms

• Mold

• Yeast

C. Detritivores (Decomposer Helpers)

These are not true decomposers but assist decomposition.

• Earthworms

• Termites

• Millipedes

• Beetles

They:

• Physically break down dead matter

• Increase surface area for bacteria and fungi

5. Process of Decomposition (Step-by-Step)

Decomposition occurs in five major stages:

1. Fragmentation

• Dead matter is broken into smaller pieces

• Done by detritivores like earthworms

2. Leaching

• Water dissolves soluble nutrients

• Nutrients seep into soil

3. Catabolism

• Bacteria and fungi secrete enzymes

• Complex compounds → simpler compounds

4. Humification

• Dark-colored humus is formed

• Improves soil structure

5. Mineralization

• Nutrients like nitrogen, phosphorus released

• Ready to be absorbed by plants

6. Role of Decomposers in Nutrient Cycles

A. Carbon Cycle

• Dead organisms contain carbon

• Decomposers break them down

• Carbon released as CO₂ into atmosphere

B. Nitrogen Cycle

• Proteins broken into ammonia

• Ammonia → nitrates

• Plants absorb nitrates

C. Phosphorus Cycle

• Decomposers release phosphates

• Used by plants for ATP and DNA

7. Importance of Decomposers in Ecosystems

1. Nutrient Recycling

• Return essential minerals to soil

• Prevent nutrient loss

2. Soil Fertility

• Formation of humus

• Improves water retention and aeration

3. Environmental Cleanliness

• Remove dead bodies and waste

• Prevent spread of disease

4. Ecosystem Stability

• Maintain balance between producers and consumers

• Support food webs

8. Importance of Decomposers to Humans

• Compost production

• Sewage treatment plants

• Waste recycling

• Agriculture productivity

• Biodegradation of pollutants

9. Decomposers vs Other Organisms

Producers

• Make food

• Use sunlight

• Example: plants

Consumers

• Eat food

• Depend on others

• Example: animals

Decomposers

• Break down waste

• Recycle nutrients

• Example: bacteria