Aartee Mishra is teaching live on Unacademy Plus
Environment Book Summary Presented B Aartee Mishra
CHAPTER 2 FUNCTIONS OF AN ECOSYSTEM (Part-1)
FOOD CHAIN Organisms in the ecosystem are related to each other through feeding mechanism or trophic levels, i.e. one organism becomes food for the other. A sequence of organisms that feed on one another, form a food chain. Grazing Food Chain Food Chain Types of Food Chains In nature, two main types of food Prim ry chains have been distinguished: Producer Consumer Secondary Consumer Tertiary Consumer Grazing food chain . The consumers which start the food chain, utilising the plant or plant part as their food, constitute the grazing food chain. Decomposers
This food chain begins from green plants at the base and the primary consumer is herbivore. For example, In terrestrial ecosystem, grass is eaten up by caterpillar, which is eaten by lizard and lizard is eaten by snake In Aquatic ecosystem phytoplanktons (primary producers) is eaten by zoo planktons which is eaten by fishes and fishes are eaten by pelicans Detritus food chain The food chain starts from dead organic matter of decaying animals and plant bodies to the microorganism and then to detritus feeding organisnm called detrivores or decomposer and to other predators. LITTER-EAR WORMS-CHICKEN-HAWK Detritus food chain
chalnstritus food chain is the . The two food chains are linked. The initial A Food Web energy source for detritus food chain is the waste materials and dead organic matter from the grazing food chain FOOD WEB Eagle ython An ecosystem may consist of several Wolf interrelated food chains. More typically, the same food resource is part of more than one chain, especially when that resource is at the lower trophic levels Dr Thrush Frog Butterfly Fruit Fly "A food web illustrates, all possible transfers Grasshoppe of energy and nutrients among the organisms in an ecosystem, whereas a food chain traces only one pathway of the food". Corn
If any of the intermediate food chain is removed the succeeding links of the chain will be affected largely. ECOLOGICAL PYRAMIDS .The steps of trophic levels expressed in a diagrammatic way are referred as ecological pyramids. The food producer forms the base of the pyramid and the top carnivore forms the tip. The ecological pyramids are of three categories. Pyramid of numbers, Pyramid of biomass, and Pyramid of energy or productivity.