Page 33 - Science Coursebook

2.5 Decomposers

The importance of decomposers
Many people feel a little bit sick when they see decomposers feeding. Have you ever
seen maggots (fly larvae) on a piece of rotten meat? It’s good to feel repulsed by them,
because it stops us eating something that could make us ill.

But decomposers are really important. Imagine what would happen if there were
none. All the dead bodies and waste material – including animal faeces – would just
pile up on the Earth. They would never disappear.

When decomposers break down dead bodies and waste, they make it possible for the
atoms in them to be reused by other organisms. For example, the worms in a compost
heap break down dead leaves. Molecules and atoms released from the dead leaves
can be used by new plants growing in the compost. The worms themselves get energy
from the dead leaves. Birds or other animals can eat the worms, and get energy
themselves, as part of a food chain. So nothing is wasted.

Activity 2.5
Decomposing fruit

Put a piece of fruit, such as an apple,
orange, or half a mango, on a plate or
dish. Label it with your name and the
date. Do not cover it. Leave it in the
laboratory or another warm place.
Look at your fruit every two or three
days. Note any changes that you
can see. You could make labelled
drawings on some days, or take digital
photographs. If you position the
camera in exactly the same place each
day, you might be able to make a very
short time-lapse sequence to show how
the fruit changes over time.
What sort of decomposers are growing on this orange?

Summary
• Decomposers are organisms that get their energy from dead
organisms or their waste products.
• Decomposers help to recycle substances from dead organisms and
waste, so that other living organisms can use them.

2 Living things in their environment 31