How Nature Works in Harmony | Class 8 Science Notes

Who Eats Whom?

This section explains feeding relationships among organisms in an ecosystem through the concepts of food chains and food webs. It begins with an activity involving a grassland ecosystem with organisms like grass, frog, hare, grasshopper, snake, and eagle. Students are encouraged to draw feeding relationships by linking who eats whom. A food chain is a linear sequence showing the flow of energy and nutrients from producers to consumers. For example, grass (producer) is eaten by hare (herbivore), which is eaten by leopard (carnivore). Another food chain example is grass → grasshopper → frog → snake → eagle. The section introduces trophic levels, which are the positions organisms occupy in a food chain: producers at the first level, herbivores at the second, small carnivores at the third, and large carnivores at higher levels. The section also discusses food webs, which are interconnected food chains showing complex feeding relationships. Organisms may be part of multiple food chains, forming a network that maintains ecosystem stability. The section highlights the importance of decomposers like fungi and bacteria that break down dead matter, recycling nutrients back into the soil, ensuring nothing is wasted in nature.

📊 Diagram: Figure 12.8 illustrates a food chain with grass eaten by hare, which is eaten by leopard. Figure 12.9 shows another food chain in a grassland ecosystem. Figure 12.12 shows mushrooms growing on dead organic matter, representing decomposers.

🧪 Activity: Activity 12.6: Students draw feeding relationships among given organisms in a grassland ecosystem. Activity 12.7: Students count organisms in a crop field food chain and represent it as a pyramid showing trophic levels.

🔗 Connection: This section leads to understanding how changes in one part of an ecosystem can affect others and the importance of maintaining balance.