The correct option is C Phytoplankton → Clams → Salmon fish→ Shark
A food chain refers to the sequence of organisms where one living organism eats another, and later that organism is consumed by larger organisms. It also explains the feeding pattern or relationship between living organisms.
Different organisms occupy different levels in the chain and each level is referred to as trophic levels.
There are two types of food chains:
Phytoplankton → Clams → Salmon fish→ Shark
- Detritus food chain (DFC): It begins with dead and decaying organic material. It is composed of decomposers like bacteria and fungi (heterotrophic organisms) which meet their energy requirements by degrading dead organic matter (detritus).
- Grazing food chain (GFC): It begins with autotrophs like green plants, cyanobacteria, etc. that are able to synthesise their own food and pass on the energy to herbivores and further to carnivores.
The above mentioned food chain is an example of grazing food chain in aquatic ecosystems. It begins with producer phytoplankton which are eaten up by clams (primary consumers), which are further eaten up by salmon fish (secondary consumers) and later sharks (tertiary consumers).
Fruits → Rodents → Snake → Hawk
Plant → Deer → Tiger
Both of the above mentioned food chains are examples of grazing food chains in terrestrial ecosystems. As they are beginning with the terrestrial autotrophs i.e., plants or its products (fruits).
Dead organic matter → Decomposers → Detritivores → Carnivores
This food chain begins with dead and decaying organic material which are acted upon by decomposers. So, this is an example of DFC.