The term .ecosystem . was coined by sir Arthur Tansely (1935).It is functional unit of nature , where living organisms interact among themselves and also with their physical enviroment.
Energy flow (FOOD CHAIN) : The primary source of energy for all living organisms in ecosystem is sunlght.The only living organisms capable of coverting light energy into molecules are green plants, hence the are called producers (P). It is for the food energy that the producers are eaten by all types of consumers. The process of flow of food energy from producers through a series of consumers by repeated eating and being eaten is called food chain. The steps of links involved in food chain are called trophic levels [T].
Trophi level: Trophic level is describe as the nutritional level of an individual in a food chain that indicates the specific food habit .e.g: Caterpilar, grass hopper, rabbits, and elephants, are grouped under same the trophic lecel since all of them are herbivores , they feed directly on plantsas food source.
The green plants (producres ) occupy first trophic level` (T_1) `,while the animals of `C_(1)`,` C_(2)` and` C_(3)` ocuupy successive tophic levels namely T2,T3,T4 respectively in a food chain. At each trophic level food energy id used up for metabolic activities and only 10% of its available for the next trophic level. Thus energy level decrases considerably at successive trophic levels, Hence smaller the food chain or less the number of trophic levels greater will be its available energy.
Types of food chains: There are 3 main types of food chains in nature namely .
Predatory food chain : It starts with green plants (producers) and proceeds from smaller animals (canvivorous) .Since it involves grazing of plants by herbivores it is also called grazing food chain . It explain predatory to prey relations . IT inculdes the following examples. Poad fiid chain :
Phytoplanktons (T1) `to` Zooplaktons(T2) `to` Small fish (T3) `to` Large fish (T4)
Forest food chain :
1 Green plants `to` Deer`to`Tiger
2 Green plants `to` Rabbit`to` Wolf `to`Tiger.
Grass land food chain: Grass (T1)`to`Grass hoper (T2) `to`Frog (T3) `to`Snake(T4) `to` Hawk (T5)
Marsh land food chain :
Flower plant (T1) `to`Butterfly (T2)`to` Dragon fly (T3)`to` Frog (T4) `to` Hawk (T5)
Parasitic food chains: It starts with produces and passes from large animals (hosts) to small animals (parasite ). it explain host - parastie relationship .Examples:
1 Green plants `to`Man (Host) `to` Interstinal round worms(endoparisites)
2 Grass `to` Sheep(host)`to` Live fluke (endoparasite).
3 Fruit tree(T1) `to` Fruit eating birds (T2) `to` Ecto parasites(Tick fleas(T3)) `to` hyperparasite (Bacteria & fungi( T4))
4 Grass `to`Horse `to` Roundworm (Ectoparasite)
Saprophytic food chain (Detritus food chain) : It starts with dead bodies and proceeds further from decomposers to detrivores which explain the recycling of matter. e.g Dead bodies.
1 Dead bodies `to ` Decomposers `to`Detriveres.
(Detritus trees T1 (Bacteria &Fungi ) T2(Millipedes and earthworms)T3.
2 Mangroove trees `to` Dried leaves `to`Ocean `to` Bacteria and fungi `to` Crabs amd Snails. FOOD WEB : Food chains remain inter connected at various levels. The web like inter locking system of several food chains is a communly is called food web. This maintains ecological homeostasis . It allows an organism to feed on two or more organisms of the lower trophic level and provides for survival of orgainsms.
