This article is about how living things interact with each other.
Ecosystem, Population, Community
Ecosystem is basically a habitat which has a variety of species of animals. Population is the total number of a specific specie. A community is made of various species.
You will know about food chain. Food chain is basically a chain of organisms involved in feeding. Now how this works is that the first organism in the food chain will always be a plant and will be called a producer. This is because the plant absorbs almost 2% of light for photosynthesis, meaning it has the energy required by an organism. Now when a herbivore, which is the primary consumer, is hungry it will feed on the plant. The energy in the plant is transferred to the herbivore. The next animal which feeds on the primary consumer, being a carnivore, it is called a secondary consumer. The next organism feeding on the secondary consumer is called a tertiary consumer. The cycle of food chain is continuous, this because energy cannot be recycled or stored. The energy that we obtain from feeding on a plant or an animal is lost in the surroundings as heat.
When you create a food chain you would always make an arrow pointing towards right, this shows that energy is transferred to the next animal.
Pyramid of Numbers and The Pyramid of Biomass
Pyramid of numbers shows the number of organisms involved in a food chain. The pyramid of numbers first starts with the producer at the bottom and works its way up the pyramid with the consumers in order. Usually a pyramid formed is like a normal pyramid but sometimes the structure might be inverted. For example; in the case of a tree food chain the tree has a large number of leaves which can feed the whole aphid population. In this case only one tree is involved compared to the aphid number, this inverts the pyramid of numbers.
Pyramid of Biomass is more accurate than a pyramid of numbers. Biomass is total mass of organism multiplied by the number of organism in a specific trophic level (stage of food chain). The structure formed is commonly a pyramid because as the biomass travels from organism to organism it decreases in number just like energy. The plants already have less than 10% of biomass which decreases from organism to organism. In some cases the pyramid of biomass is also inverted.
Now you will learn the importance of a vegetarian diet. The energy in the plant is already low due to low amount of light absorbed by the plant. When an organism feeds on the plant it will receive a low amount of energy but just enough to survive. This happens at every trophic level of the food chain. Now the top carnivore which is in the top of the food chain will always receive a very low amount of energy proving that the longer the food chain the lower energy we obtain. So a food chain with 2 or 3 trophic level is highly beneficial for us as it will provide a high amount of energy.
When 2 or more food chains combine they form a food web.
Decomposers in Food Chain
Food chain is incomplete unless there is a decomposer involved in it. This is because an organism eventually dies and produces dead organic matter containing nutrients in it. The nutrients are useless to us but they are useful for the decomposers and the detritivores. These digest the dead organic matter by either saprotrophic nutrition (releasing enzymes to soften and digest material) or by directly eating it. Therefore the decomposers end up at the top of the food chain by decomposing the dead matter for nutrients and energy.
Energy flow Diagram
As you have learned in the previous paragraph the energy collected from feeding is eventually lost as heat. This is because the energy is already low. There is 10% energy in plant biomass which further reduces in each trophic level.
The reason for low amount of energy is :
- Energy is lost in form of urea in excretion.
- Energy is lost in egestion in the form of feces.
- Herbivores do not feed on the whole plant resulting in low energy. It leaves some parts of the plant like the root.
- Energy is lost in the form of heat.
The loss of energy can be shown by energy flow diagram as such;
The consumers in the diagram mean all of the consumers involved in a food chain. As you can see in the diagram that when the decomposers die the nutrients they collected is spread across the soil which is beneficial for the plants. The plants then use these nutrients to survive.