Detritivores (scavengers) are an important part of the food chain. Detritivores shred and eat detritus that contains fungi, algae, and bacteria. The final link in the food chain are decomposers (bacteria and fungi). By breaking down dead tissues and cells, decomposers release nutrients for use by primary producers.
The levels of a food chain are called trophic levels. These trophic levels describe the passage of energy through a food chain. Any ecosystem includes a finite number of trophic levels. A limit is reached when consumers cannot consume enough energy to balance energy lost during normal physiological functions (growth, reproduction). Most ecosystems have about four to five trophic levels.
Food Pyramid
The food pyramid is a simple way to demonstrate biomass (weight of living matter) relative to the number of organisms and amount of energy found at each trophic level. Figure 4-12 illustrates