Energy in an Ecosystem
Organisms get their enery they need to survive by eating plants or other living things to get their energy. Energy enters and moves through an ecosystem by a food chain. This food chain has levels that are in order. The 1st one would be producers (plants), 2nd the primary consumer, 3rd the secondary consumer, 4th the tertiary consumer, and so on.
A food web is a model that shows the complex network of feeding relationships and the flow of energy within and sometimes beyond an ecosystem.
Trophic levels is levels of nourishment ina food chain. Energy flows up the food chain from the lowest trophic level(Producers) to the highest, level by level. Majority of the energy consumed bythe organims is lost into the enviromemnt. The rest is stored within them.
A trophic pyramid is the basic structure of interaction in all biological communities characterized by the manner in which food energy is passed from one trophic level to the next one along the chain. The trophic pyramid represents the trophic levels. A biomass pyramid is graphical representation to show the relative amounts of biomass at each trophic level.This represents the amount of potential food available for each trophic level in an ecosystem. 
A pyramid of numbers shows the relative number of organisms at each stage of a food chain. In this case a pyramid of biomass is a better diagram to use. A pyramid of numbers represents the number of individuals at each trophic level in the food chain.
