A simple food chain in a broadleaf forest is described. The giant panda is discussed as an example of an animal that relies on a single food source. It has now become endangered due to humans destroying its food source. A coastal food chain is used to exemplify how population changes are interconnected through food webs, but in theory are self-balancing.

First broadcast:
25 March 2003

The clip shows students how food chains can be combined to form food webs and also shows how different species are interconnected through feeding relationships. The class could choose a local ecosystem and construct a food web for it. One by one, students could model what would happen if numbers of an organism were to drop or rise significantly. They could express this through a slide show, animation or generalised graphs. Extend the activity to predict what would happen if an organism were removed from the ecosystem, or if a new species invaded.