UNIT 3 : FOOD CHAIN AND FOOD WEB

At the end of this unit, we will learn :•To classify animals according to the food they eat.•To construct food chain and food web of different habitats.•To identify producers and consumers in a food chain and food web.•The importance of organisms in a food web.

LESSON 1 : WHO EAT WHO?Animals can be classified into three categories according to the food they eat.

•These animals eat plants. They are herbivores.

• Carnivores eat animals.

• Omnivores eat plants and other animals.

• Cow eat grass. The grass provides energy to the cow. The energy comes from the sun. Plants use the energy from the sun to make their own food. They are called producers. The statement “cow eat grass” can be represented as below:

An arrow means ‘it is eaten by’.

If the cow is eaten by a tiger, the relationship can be represent as:

This relationship is called a food chain. The cow and the tiger in this food chain are called consumers because they get their food by eating other animals or plants.

LESSON 2 : TANGLED UP!• The relationship between organisms in food chain looks

very simple, but in reality it is more complex. For example, in an oil palm plantation, there are rats, owls, squirrels, snakes and eagles. The possible food chains in this habitat are:

When these food chains are linked together, we get:

This relation ship is called a food web. Thus, a food web consists of two or more food chains linked together.