In every ecosystem, organisms are linked through feeding relationships. There are a great many feeding relationships in any ecosystem but energy always flows from primary producers to various consumers. These feeding relationships are represented by food chains and food webs.

Food chain is a series of steps in which organisms transfer energy by eating and being eaten.

Here is an example of a food chain from the animation you saw in section one of this resource.

This image shows a food chain starting with grass, that is eating by the zebra. The zebra is eaten by the hyena and the hyena is eaten by the lion Source: Grass, Zebra, Hyena, Lion, Ocal, Clker

Notice that the arrows point in the direction of the energy flow. The point of the arrow goes to who is doing the eating.

In most ecosystems, feeding relationships are much more complicated than the relationships shown in a food chain. The network of feeding interactions is called a food web. Look at the simple food web below. This shows a more realistic feeding pattern.

This image shows a food web in which a zebra and a gazelle eat grass. The Zebra and gazelle are eaten but the hyena, and lion. The hyena is also eaten by the lion. Source: Grass, Zebra, Hyena, Gazelle, Lion, Ocal, Clker

Now you try!

This activity might not be viewable on your mobile device.Interactive exercise. Assistance may be required. In this activity you will build a food web. Move the arrows from the predator and put it directly on what it eats. Make sure the arrow overlaps the food image.