Not everything in a food chain gets eaten. Many plants and animals die long before they become anyone else’s lunch. Also, trees shed their old leaves and animals leave droppings containing the indigestible parts of their food – such as plant fibres or bones.
All this dead stuff has run out of energy. It can’t grow any more. But it is still vital to life, because it contains chemicals that are the basic building blocks of all living things. These chemicals get recycled into the food web with the help of organisms called decomposers.
Decomposers are organisms that break down dead plants or animals into the substances that plants need for growth.
There are many kinds of decomposer. Each helps recycle food in its own way.
Fungi release chemicals to break down dead plants or animals into simple substances. They absorb some of these substances for growth, but others enter the soil.
Earthworms digest rotting plant and animal matter as they swallow soil. The waste that comes out of their bodies at the other end contains the important minerals, all ready for plants to take up again.
Bacteria are tiny, microscopic organisms. Some kinds live on other living things – for instance, there are millions inside your gut helping you to digest your food. Others live on dead things, and help break them down into the minerals in the soil.
Here’s how a woodland food chain looks when you add decomposers:
Earthworms are wiggly recyclers that break down rotting matter
View this page online at http://www.rspb.org.uk/youth/learn/foodchains/decomposers.asp