producer consumers and decomposers

The green plant in the ecosystem are called producers. In a terrestrial
ecosystem, major producers are herbaceous and woody plants. Likewise,
producers in an aquatic ecosystem are various species like phytoplankton,
algae and higher plants. Starting from the plants (or producers) food chains or rather webs are
formed such that an animal feeds on a plant or on another animal and in
turn is food for another. The chain or web is formed because of this
interdependency. No energy that is trapped into an organism remains in
it for ever. The energy trapped by the producer, hence, is either passed on
to a consumer or the organism dies. Death of organism is the beginning
of the detritus food chain/web.


           All animals depend on plants (directly or indirectly) for their food needs.
They are hence called consumers and also heterotrophs. If they feed on
the producers, the plants, they are called primary consumers, and if the
animals eat other animals which in turn eat the plants (or their produce)
they are called secondary consumers. Likewise, you could have tertiary
consumers too. Obviously the primary consumers will be herbivores.
Some common herbivores are insects, birds and mammals in terrestrial
ecosystem and molluscs in aquatic ecosystem.The consumers that feed on these herbivores are carnivores, or more correctly primary carnivores (though secondary consumers). Those
animals that depend on the primary carnivores for food are labelled
secondary carnivores.
 

             The detritus food chain (DFC) begins with dead organic matter. It is
made up of decomposers which are heterotrophic organisms, mainly
fungi and bacteria. They meet their energy and nutrient requirements by
degrading dead organic matter or detritus. These are also known as
saprotrophs (sapro: to decompose). Decomposers secrete digestive
enzymes that breakdown dead and waste materials into simple, inorganic
materials, which are subsequently absorbed by them.