Food webs are complex network of feeding interactions. Food webs may consist of food chains. In that sense, there are a lot of animals hunt for the same animal. Food webs can also be identified as numerous food chains combine together to form a single, but large feeding interaction.
Decomposers and detritivores can also be found in food webs. Decomposers are important in this food web because they convert dead materials to detritus, which will then be eaten by detritivores. Decomposers also release nutrients for the primary producers to use.
Food web and food chains contain steps which are called trophic levels. Primary producers, as always, make up the first tropic level. This order can be modeled in an ecological pyramid.
Apart from representing the trophic levels, ecological pyramid also show the relative amount pf energy and matter contained in each trophic level, in any given food web or food chain. To that extent, there are three types of ecological pyramids: pyramids of energy, pyramids of biomass, and pyramids of numbers.
Organisms transfer energy by eating or being eaten through a series of steps known as a food chain. Food chain can vary in length, depending on the complexity of the ecosystem. The primary producers are always the first organisms presented in a food chain.
Some aquatic food chains present a mixture of the primary producers called the phytoplankton. This organism is a mixture of a floating and an attached algae.
Pyramids of energy show the relative amount of energy available at each trophic level of a food chain or food web. Approximately 10% of the energy available in a trophic level is transferred to the next trophic level.
Pyramid of biomass illustrates the relative amount of living organic matter available at each trophic level in an ecosystem. Biomass, on the other hand, is the total amount of living tissue within a given trophic level.
A pyramid of numbers shows the relative number of individual organisms at each trophic level. Interestingly, consumers are much less in number than the organisms they feed upon.
Miller, Kenneth R., and Joseph S. Levine. "Chapter 3: The Biosphere." Miller & Levine Biology. Boston, MA: Pearson, 2010. N. pag. Print.