Food webs represent the complex entanglement of the species within an environment. It shows how different species sustain each other and is essential to understanding the environment itself. Different species can be divided into trophic levels such as producer, primary consumer, secondary consumer, tertiary consumer, scavenger and decomposer. These trophic levels determines where an organism would fit on a food chain based on what it eats and its predators. For example, in a forest an owl would be a tertiary consumer because it eats rodents and small birds, and has no predators. A producer creates its own food through photosynthesis, a consumer eats producers as well as other consumers lower on the food chain, a scavenger does not hunt other organisms, it only eats dead plant or animal material and a decomposer breaks down other organisms. Energy pyramids show the flow of energy that occurs within an ecosystem. When energy is transferred between trophic levels, it is transformed into a less useful form because 90% of that energy is lost in the form of heat. By the time the energy consumed from a producer reaches a tertiary consumer, there will be a very small percentage left, which means that the secondary and tertiary consumers must hunt more to gain the same amount of energy that a primary consumer can get straight from a producer or a producer can get through photosynthesis.
