The main purpose of a food web, which can be a diagram or graphical model, is to show the network of interrelated food chains that occur within a particular ecosystem. A food chain depicts the path in which energy moves through an ecosystem as living organisms feed on one another, notes National Geographic.
By using a graphical model with arrows or lines to show specific links, food webs can show the relations between species in an ecosystems. As an example, tadpoles and water beetles can feed on algae in a freshwater ecosystem, tadpoles may be a food source for fish and frogs can eat water beetles. A kingfisher can prey on both fish and frogs. In a graphical model, these interconnected relationships or links can be depicted with arrows.
Food webs consist of food chains with different organisms, such as producers, consumers and decomposers, which are on different trophic levels of a food web, states the Duckster website. The producers, which are plants, are at the bottom trophic level. Consumers are animals, such as herbivores and carnivores, which are primary and secondary consumers, respectively. Some food chains can also consist of tertiary and quaternary consumers. Top predators are at the top of the food chain in a food web. Additionally, decomposers, such as worms and bacteria, are important organisms in an ecosystem because they break down decaying matter, which provides nutrients for the soil and plant life.