Organisms have roles in ecosystems:
Producers - organisms that make their own food
using the energy of sunlight - plants.
Consumers - obtain their food by consuming other
creatures - if they consume a producer then they are
primary consumers or herbivores - if they consume
herbivores they are secondary consumers or
If they consume carnivores they are tertiary
consumers or carnivores. Some species eat both
producers and other consumers and they are called
omnivores. Some creatures eat dead producers or
consumers and are called detritivores.
Decomposers - Bacteria and fungi that break
down dead organic material. Decomposers have an
important role in ecosystems - they absorb
nutrients from dead organisms or waste materials
and return organic matter to the soil.
Food chains are simple ways of representing
feeding relationships among organisms.
Grass > insect > spider > bird
Food webs show the feeding relationship of all
organisms in a particular location (food web = many
food chains intertwined together).