ABSTRACT
Trophic pyramids and trophic levels are a familiar topic for most students of ecology. The intent of this chapter is to provide a foundation for the sophisticated concepts and techniques to follow in this book. We will review trophic levels and provide many examples of the diversity within them, showing that many of the trophic interactions occurring in ecosystems today were likely occurring up to 400 million years ago. The trophic pyramid concept and trophic levels may be somewhat misleading and oversimplistic, but processes of natural selection and self-organization do result in constructs that lead to meaningful groupings within ecosystems. It is in this context that important exceptions such as omnivory and ecosystem subsidies can be better understood and explored.
