The mutual relation between the living organisms and non- living things of a particular area is known as the ecosystem. In every ecosystem, every organism has a definite habitat and a definite life pattern. It is the main characteristics of an ecosystem.
A pond is a self-sufficient and an ideal example of the ecosystem. In a pond, the intimate relation between the inhabiting living and non-living components is well understood. The non-living objects are various types of organic and inorganic substances such as water, sun rays, CO2, oxygen, calcium, phosphorus, humic acid etc. The living components are producers, primary consumers, secondary consumers, tertiary consumers and various types of decomposers.
Producers: Various types of photosynthetic algae and shallow water plants living in the pond are the producers. The floating organisms are called plankton. The minute plants of plankton type are known as phytoplankton. Green aquatic algae and other aquatic plants can live by producing food by the process of the photosynthesis, so they are called producers.
Primary consumers: These are various types of floating minute insects, larvae of mosquito and other microscopic animals like zooplankton etc. Floating minute animals are called zooplankton. These consumers cannot manufacture their own food and they live on by eating the producers directly.
Secondary consumers: Small fishes, some aquatic insects, prawns, frog etc. are secondary consumers. They can neither manufacture their own food nor accept the producers as food. They live on by eating the primary consumers.
Tertiary consumers: Small fishes, prawn and all other animals that feed, upon the secondary consumers are known as tertiary consumers. Large fishes like shoal, boal, vetki, stork and heron are the tertiary or highest consumers.
Decomposer: In pond water, various types of fungi and bacteria live as, saprophytes which are- known as a decomposer. These decomposers can live by floating on water or live at the bottom clay. They attack living or dead consumers and help to rot. As a result, organic and inorganic chemical substances usable by the producers have formed again. The producer community of the pond use these decomposed elements. The flowchart gives an idea about the components of the pond ecosystem.