Transfer of food from the plants (producers) through a series of organisms with repeated eating and being eaten is called a food chain. A food chain consists of
Producers or Autotrophs
Primary consumers or Herbivores
Secondary consumers or Carnivores
Decomposers make up the final trophic level in a food chain. Decomposers are the organisms that feed on dead organic matter called detritus of all the trophic levels and help in recycling the nutrients. Examples of decomposers are bacteria, fungi, mites, millipedes, earthworms, nematodes, slugs, crabs and molluscs.