1. Animals and plants need each other for food:
The primary requirement of all animals and plants is food. Without food, they will die. We know that plants make their food through a process called photosynthesis. Photosynthesis is the process where plants make their food from carbon dioxide and water in the presence of sunlight and chlorophyll. Therefore, they are food producers. Most of this food is stored in them as sugar and starch. Some animals eat these plants and some eat other plant-eating animals. Therefore, they are food consumers.
The food chain begins with green plants as these plants make their own food. They are producers. Linked to them are the plant-eating animals or herbivores. They eat the food stored in the plant. They are also called the primary or first-order consumers, e.g., horse, goat and deer. Next in the chain are the flesh-eating animals or carnivores. They eat the first-order consumers or herbivores.
They are called secondary or second-order consumers, e.g., tiger, cheetah and fox. The next link in the chain are the flesh-eating animals which eat other carnivores, e.g., snakes eat frogs which, in turn, feed on plant-eating insects. The snake is a tertiary or third-order consumer. And the final link are the decomposers or creatures who feed on dead plants and animals, e.g., fungi. We write the food chain in this manner where the arrow stands for “is eaten by: :
Grass – Caterpillar – Hen - Wolf
It upsets the balance of nature if any member of the food chain disappears. For example, can you imagine what would happen if there were no plants? The herbivores would perish and only carnivores would be left. They would be eating each other. Gradually all animals will die. Therefore plants and animals need each other to survive.
2. Animals need plants for shelter:
Forests are the home to animals, birds and insects. Birds make nests in trees. Snakes, squirrels, ants, etc., live in holes made in the tree trunks. Cutting trees and destroying forests affects the natural habitat of many animals.
3. Plants need animals for keeping the balance of carbon dioxide in the air:
When animals breathe out, they exhale carbon dioxide gas. This carbon dioxide is then used by the plants to make their food through photosynthesis. In turn, the plants give out oxygen that is needed by animals to breathe. Without green plants, there would not be enough oxygen for men and animals to breathe and they would die.
4. Plants need animals for nourishment:
Cow-dung and other animal waste-matter is a good manure for the plants. The waste matter mixes with the soil and acts as fertilizer. It helps the plants to grow.