Grazing food chain                                                                                 Detritus food chain

1

In this food chain, energy is derived from the Sun.

1

In this food chain, energy comes from organic matter (or detritus) generated in trophic levels of the grazing food chain.

2

It begins with producers, present at the first trophic level. The plant biomass is then eaten by herbivores, which in turn are consumed by a variety of carnivores.

2

It begins with detritus such as dead bodies of animals or fallen leaves, which are then eaten by decomposers or detritivores. These detritivores are in turn consumed by their predators.

3

This food chain is usually large.

3

It is usually smaller as compared to the grazing food chain.

Production                                                                                        Decomposition

1

It is the rate of producing organic matter (food) by producers.

1

It is the process of breaking down of complex organic matter or biomass from the body of dead plants and animals with the help of decomposers into organic raw material such as $C{O}_2,H_{2}O$, and other nutrients.

2

It depends on the photosynthetic capacity of the producers.

2

It occurs with the help of decomposers.

3

Sunlight is required by plants for primary production.

3

Sunlight is not required for decomposition by decomposers

              Upright pyramid                                                                          Inverted pyramid

1

The pyramid of energy is always upright.

1

The pyramid of biomass and the pyramid of numbers can be inverted.

2

In the upright pyramid, the number and biomass of organisms in the producer level of an ecosystem is the highest, which keeps on decreasing at each trophic level in a food chain.

2

In an inverted pyramid, the number and biomass of organisms in the producer level of an ecosystem is the lowest, which keeps on increasing at each tropic level.

                           Food chain                                                           Food web

1

It is a single linear sequence of organisms.

1

It contains a number of interconnected food chains.

2

Members present at higher trophic levels feed on single types of organisms.

2

One organism has alternate food sources.

                            Litter                                                                        Detritus

1

Litter contains all kinds of wastes generated above the ground.

1

Detritus is composed of the remains of dead plants and animals.

2

Litter contains both biodegradable and non-biodegradable matter.

2

Detritus contains only biodegradable matter.

               Primary productivity                                                                     Secondary productivity

1

It is defined as the amount of organic matter produced by producers per unit area over a period of time.

1

It is defined as the rate of production of organic matter by consumers over a period of time.