• The transfer of solar energy from the source i.e. green plants through a series of organisms by eating and being eaten constitutes a food chain.
• There are 4 parts in a food chain: producers (plants), primary consumers (herbivores), secondary/tertiary & further consumers (carnivores) & decomposers (eat dead or decaying matter).
• At each transfer, a large proportion of energy is lost in the form of heat.
• Also at each stage, a major part of the energy from the food is lost for daily activities.

• Each chain usually has only four to five such links. However a single species may be linked to a large number of species.

   

Example 1:

GRASS → GRASSHOPPER → FROG → SNAKE → EAGLE

Example 2:

WHALE → SEALS → SMALL FISH → PLANKTON