About
- 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:Â 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](https://launchpadeducation.in/wp-content/uploads/2024/07/image-2.png)
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](https://launchpadeducation.in/wp-content/uploads/2024/07/image-3.png)
- 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](https://launchpadeducation.in/wp-content/uploads/2024/07/image-4.png)