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Food Chain


All the tropic levels in an ecosystem are connected by the transfer of food or energy from one tropic level to the next tropic level and are called food chain or it is described as the feeding relationship between species within an ecosystem (Figure 10.2).

Characteristics of Food Chain

  • Producer based: All sustainable food chains are producer based.
  • Energy: Producers obtain energy from sun. All others obtain energy from food originally built up by producers. There is unidirectional flow of energy.
  • Biogenetic nutrients: Inorganic nutrients must keep on circulating with the help of decomposers. Otherwise, food chains cannot be sustained.
  • Straight: Unless linked with another, food chains run straight.
  • Size: Food chains are generally short with three to five trophic levels.
  • Populations: The size of populations decreases with the rise in the trophic level. Top carnivores are always very few.
  • Operation at different trophic levels: An organism can operate at more than one trophic level. For example, a snake feeds on an herbivorous rat as well as a carnivorous frog.


The food chain is of three types, namely grazing (predator) food chain, parasitic food chain and detritus food chain.

  1. The grazing food chain extends from producers through herbivores to carnivores.
    For example,
  • Algae  Insect larvae  Fishes  Birds
  • Grass  Grasshopper  Frog  Snake
  1. Parasitic food chains: If in the food chain, the primary and other levels of consumers are parasitic, then the food chain is described as parasitic food chain.
    For example,
  • Tree  Birds  Bird lice  Protozoan
  1. Detritus food chain begins with dead organic matter and passes through detritus feeding organisms in soil to the organisms which feed on detritus feeders.
    For example,
  • Fallen litter  Earthworms  Birds

Importance of Food Chains

  1. Food chains provide pathways for the passage of food and its energy in the ecosystem.
  2. They provide information about the living components of the ecosystem.
  3. Food chains indicate the interactions and interdependence among the different organisms.
  4. The effect of reduction or increase in the population at a trophic level can be known. The mechanism of biological control of populations is also known.
  5. Biomagnification: A non-degradable chemical, if happens to enter a food chain, will undergo increase in concentration with rise in trophic level.

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