gs besides grass, and foxes eat many things besides rabbits and other things also eat grass and rabbits. When talking about the real world, it is more common to think of food webs.
             Food chains are still an important concept to understand. In the 1960s, a pesticide called DDT became popular for its effectiveness in killing insect pests. It was sprayed in small concentrations, so as not to affect larger animals, but it never went away once it was sprayed. Eventually, rain washed it into rivers and lakes, where the concentration was still very small, but this is where the food chain took effect. DDT was taken up by plankton in the water, and accumulated in them. They were eaten by small fish, so each
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