Food Chain

Food Chain

Food Chain


  • The transfer of food energy from green plants (producers) through a series of organisms with repeated eating and being eaten links is called a food chain. For example, Grasses → Grasshopper → Frog → Snake → Hawk/Eagle.
  • Each step in the food chain is called the trophic level.
  • A food chain starts with producers and ends with top carnivores.
  • The trophic level of an organism is the position it occupies in a food chain.
  • Types of Food Chains: 1) Grazing food chain and 2) Detritus food chain

Grazing Food Chain

  • The consumers who start the food chain, utilizing the plant or plant part as their food, constitute the grazing food chain.
  • For example, in a terrestrial ecosystem, the grass is eaten by a caterpillar, which is eaten by a lizard, and the lizard is eaten by a snake.
  • In Aquatic ecosystem phytoplankton (primary producers) are eaten by zooplanktons which are eaten by fishes and fishes are eaten by pelicans.
Grazing Food Chain

Detritus Food Chain

  • This type of food chain starts from the organic matter of dead and decaying animals and plant bodies from the grazing food chain.
  • Dead organic matter or detritus-feeding organisms are called detrivores or decomposers.
  • The detrivores are eaten by predators.
  • In an aquatic ecosystem, the grazing food chain is the major conduit for energy flow.
  • As against this, in a terrestrial ecosystem, a much larger fraction of energy flows through the detritus food chain than through the grazing food chain.
Detritus Food Chain
  • Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called catabolism.
  • Humification and mineralization occur during decomposition in the soil.
  • Humification leads to accumulation of a dark-coloured amorphous (formless) substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate.
  • Being colloidal in nature, humus serves as a reservoir of nutrients.
  • The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as mineralisation.
  • Warm and moist environments favor decomposition, whereas low temperature and anaerobiosis inhibit decomposition, resulting in a buildup of organic materials (soils become acidic, like in taiga).

Food Web

  • Multiple interlinked food chains make a food web.
  • The food Web represents all the possible paths of energy flow in an ecosystem.
  • If any of the intermediate food chains is removed, the succeeding links of the chain will be affected largely.
  • The food web provides more than one alternative for food to most of the organisms in an ecosystem and therefore increases their chance of survival.
Food Web

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