Producers

What are Food chains and Explain their Characteristics

Food chain is a sequence of organisms in a biotic community through which food passes with members of a step becoming food of the members of the next step of the sequence. In other words, it is a list of who eats whom in a biotic community. A food chain usually consists of producers, various levels of consumers and decomposers. Each step or division in food chain which is characterized by a particular method of obtaining food is called trophic level.

Producers :
They constitute the base or beginning of a food chain. They constitute the first trophic level (T₁) of a food chain.

Herbivores or first order consumers (Primary consumers) :
They are animals which feed on plants or plant products. e.g., Grasshopper, Rabbit, Deer Elephant. Herbivores constitute second trophic level (T₂).

First order (Primary) carnivores or second order consumers (secondary consumers) :
They are animals which prey upon herbivores, e.g., Frog, Wild Cat, Fox. These animals form the third trophic level (T₃).

Characteristics of Food chain:

1. Producers based :
   All sustainable food chains are producer based.
2. Energy :
   Producers obtain energy from sun. All others (consumers) obtain the energy from food originally built up producers. There is unidirectional flow of energy.
3. Biogenetic Nutrients :
   Inorganic nutrients must keep on circulating with the help of decomposers. Otherwise, food chains cannot be sustained.
4. Straight :
   Unless linked with another, food chain runs straight.
5. Size :
   Food chains are generally short with 3-5 trophic levels.
6. Populations :
   Size of populations decreases with the rise in trophic level. Top carnivores are always very few.
7. Operation at different trophic levels :
   An organism can operate at more than one trophic level, e.g., snake feeds on herbivorous rat as well as carnivorous frog.