Find out about food chains and webs in this KS3 Science quiz. A food chain shows the dependency of organisms on other organisms as a source of food. It shows how energy is transferred in a habitat. A food web is just a lot of food chains linked together - it gives a more complete picture of what eats what in a natural habitat. All food chains begin with producers e.g. plants or algae. They produce their own food by the process of photosynthesis and are the source of energy for the entire food chain. Animals in a food chain are called consumers as they need to eat plants and other animals.
An animal that eats only plants is a herbivore and can be referred to as a primary consumer. Animals that eat other animals are either carnivores (only eat other animals, never eat plants) or omnivores (eat both animals and plants). A secondary consumer is an animal that eats herbivores and a tertiary consumer is an animal that eats secondary consumers. As you go up a food chain, there is less and less energy available which is why there are fewer tertiary consumers than secondary consumers.