Animals do not generally eat just one thing, nor are they eaten by only one thing. This means that each organism, through feeding , is interconnected to may other organisms. This interconnection is called a feed web. It is important to stress here the difference between a food web and a food chain. But each of these members of this chain also eats other organisms, and so a food web is made up of may food chains.
All autotrophs are primary producers.
Small crustaceans, such as copepods, eat these microscopic algae and are called primary consumers, because they consume the primary producers. Small fish in turn eat these copepods and are referred to as secondary consumers. Larger consumers which eat the small fish are termed tertiary consumers, and so on. When a food we is written out on a piece of paper, an arrow is drawn from the prey, to the predator.