Food webs

• In an ecosystem plants and animals are connected by their feeding relationships. This is called a food web.
• A food web consists of:
• plants (producers) which produce food for themselves and animals;
• animals (consumers) which are herbivores, carnivores, omnivores;
• micro-organisms (decomposers) that break down dead plant and animal matter and return nutrients to the soil.
• A food web is made of many linked food chains. A food chain only follows one path as animals eat their food. A food web shows the many different connecting paths of plants and animals.

An example of a food web and a food chain:

• Ask the learners what they have learnt so far about ecosystems.

Answer: 

An ecosystem is an area where living and non-living things depend on each other (there are relationships between the living and non-living things in an ecosystem).

• Ask the learners if they think that the plants and animals are connected in an ecosystem.

Answer:  Yes, they are connected due to their feeding relationships.

• Tell learners that in this relationship, one group makes the food (producers) and the other group eats the food (consumers). Can they tell which is which?

Answer:  Plants are producers and animals are consumers.

• Ask learners if they know what a vegetarian is.

Answer:  A person who does not eat meat – only vegetables and fruit and sometimes animal products, such as eggs or milk.

• In the animal kingdom, we also find vegetarians. Do they know what these types of animals are called?

Answer:  Herbivores.

• Besides herbivores, there are other types of animal consumers too.
• Tell learners that they will find out more about these consumers a little later.
• Show VIDEO CLIP 6: Producers, Consumers and Decomposers (5:15 min.).
• In this video, the roles of producers, consumers and decomposers in a pond ecosystem are discussed.

• Learners complete WORKSHEET E.
• Guide the learners on how to undertake this activity by providing examples and explaining how this worksheet will be assessed.
• Remember to explain that the answers provided in the worksheet can be used more than once .

• Show VIDEO CLIP 7: Decomposers Song (3:20 min.) and let learners sing along.  This song can also be utilised for revision.

• Ask learners if they can remember from their Grade 5 lessons what a food chain is.
• Explain the food chain as follows:

• A food chain shows how each living thing gets food.
• A food chain shows how nutrients and energy are passed from plants to animals and from creature to creature.
• Food chains begin with plant-life, and end with animal-life. Some animals eat plants and some animals eat other animals.

Draw a simple food chain on the blackboard to show how a food chain could start with a leaf eaten by a caterpillar and continue until it ends with a snake being eaten by a large animal such as a mongoose.

• Have large pictures of plants and animals to form a simple food chain available.
• Place the pictures on the board in no particular order.
• Ask volunteer learners to come and place the pictures in the correct order to form a simple food chain.
• Once this has been done, ask learners to identify the following in this simple food chain:
  • Producers
  • Consumers
  • Decomposers
• Ask learners to draw a simple food chain in their exercise books.
• Guide the learners on how to undertake this drawing of a simple food chain by providing examples and explaining how this activity will be assessed.

• Tell the learners that when many different food chains are connected to each other, they form a food web.
• Present an overview of the different components of the food web by using PRESENTATION 3: Food Webs.
• Show VIDEO CLIP 8: Food Chains and Food Webs (3:02 min.).

Learn how some animals eat other plants and animals to survive, and create a food chain.

• Learners complete Worksheet F.

• SHOW VIDEO CLIP 9: Food Chains, Food Webs, Energy Pyramid (5:53 min.).

• Learners complete Worksheet G.
• Guide the learners on how to undertake this activity by providing examples and explaining how this worksheet will be assessed.

• Learners complete Worksheet H as a practical task.
• Guide the learners on how to undertake this activity by providing examples and explaining how this worksheet will be assessed.