The algae is the producer. It converts sunlight energy into glucose. The other creatures are producers, they get their energy from the sugars (glucose) made by consumers.
It is an example of a food chain because it is a simple linear series of connections between producers and consumers.
Producers: Organisms that obtain their energy from a primary source such as sunlight. Consumers: Organisms that obtain their energy from eating other organisms. Food Chain: A line of linkages between producers and consumers.
Tip: The arrows show where the energy is transferred to, so will be pointing up in food chains.
Food Webs
This is an example of a British woodland ecosystem food web.
A food web shows the connections between producers and consumers in a more detailed way, there is more than one producer unlike a food chain.
Notice that when any living element dies, it is broken down by the decomposer fungi. Other food webs might also have scavengers, which eat dead organisms. Scavengers and decomposers usually return the nutrients in the organisms to the soil, which is important to the nutrient cycle, as it means that the nutrients are available for the growth of organisms once again.
There are two main sources of nutrients in an ecosystem, rainwater washing chemicals out of the atmosphere, and weathered rock releasing nutrients into the soil.
Food Web: A diagram that shows all the linkages between producers and consumers in an ecosystem. Decomposers: Organisms such as bacteria that break down plant and animal material. Scavengers: Organisms that consume dead animals or plants. Nutrient Cycle: The recycling of nutrients between living organisms and the environment.
Tip: Again, remember that the arrowheads show the direction of energy transferal, so (apart from the decomposers) arrow heads should be pointing up.
The Impact of Change on an Ecosystem Change can be caused by natural factors such as environmental change (eg flood, fire, drought) or human-induced change (eg drainage, reclamation, fish stocking.) Food webs can be used to find out the impact of that change on other parts of the ecosystem.
For example in the woodland ecosystem, if a cull wiped out all the badgers then: - Increase in numbers of worms and beetles - Increase of bird population as they have more food - Increase in foxes as more prey - Decrease in oak leaves and trees as more worms and beetles eating them.