The food chain in nature plays an important role in the survival of species. Every organism depends upon some organism for food. This chain is very easy to understand. So, let’s move on to something scientific, the pyramid of numbers. The pyramid or numbers represents species in a form that can be easily understandable. There are mainly three types of pyramids and the inverted pyramid of numbers is a very interesting one. So, let’s learn about it here.
1. What are the Three Types of Pyramids?
The three types of pyramids in ecology are:
- Pyramid of Numbers: The pyramid of numbers is where the number of consumers at each successive level is taken into consideration. The pyramid formed can be upright, partly upright, or inverted based on the type of ecosystem it represents.
- Pyramid of Biomass: The pyramid of biomass is where the total living biomass or organic matter at each trophic level in an ecosystem is represented. In an ecosystem, the mass of living organisms present at each trophic level is the biomass of that level. The biomass is represented as dry weight in grams or calories per unit area.
- Pyramid of Energy: The pyramid of energy represents the energy found at each trophic level of the ecosystem. It is a graphical representation of energy. It also shows the flow of energy from one trophic level to another in an ecosystem. The bottom level contains the largest amount of energy. The energy is measured in kilocalories (kcal).
2. What is Meant by Pyramid of Numbers?
The pyramid of numbers is a graphical representation that represents the number of organisms at each trophic level. In this pyramid, the total number of organisms at each level is taken into consideration. This pyramid is upright in the fact that in an ecosystem, the number of producers is always more than at other trophic levels. This pyramid is a result of the huge difference in the number of organisms that are involved in each level of the food chain.
The trophic structure has succeeding links that get reduced rapidly in number until there is a very small number of carnivores left at the top. This has got a pyramid shape because there should always be enough plants to produce food at the bottom of the structure, otherwise, the entire food chain will collapse. Neither the pyramid considers the biomass of organisms nor does it indicate the energy transmitted or utilized by the organisms involved. This pyramid is helpful in tracking the changes in the ecosystem over the years. (See What are Scavengers in a Food Web?)
3. How many Different Pyramids of Numbers are there?
There are three different pyramids of numbers. They are:
- Upright pyramid of numbers: The upright pyramid of numbers can be seen in the grassland ecosystem. The grassland ecosystem is characterized by a large number of autotrophs that are there to support the lesser herbivores and in turn, herbivores support a smaller number of carnivores. This pyramid is upright because, with every trophic level, the number of organisms decreases.
- Partly upright pyramid of numbers: The partly upright pyramid of numbers can be found in the forest ecosystem. Here, the producers are mainly large-sized trees. They sit at the bottom of the pyramid of numbers. The primary consumers are the elephants and fruit-eating birds, which are herbivores and they are more in number compared to the producers. After this level, the number of individual organisms reduces at each successive trophic level, so the pyramid gets upright from here on.
- Inverted pyramid of numbers: The inverted pyramid of numbers works just opposite to the upright pyramid of numbers. Here, the number of organisms increases at each successive level, unlike the upright pyramid where the number of organisms decreases. This type of pyramid is found in the parasitic food chains, where there is normally one producer that supports numerous parasites. In turn, these parasites support more hyperparasites. So, the pyramid becomes inverted as it succeeds to the top levels.
4. How do you Draw a Pyramid of Numbers?
A pyramid of numbers is mainly drawn by keeping the level and consumers in mind. The consumers that are highest in numbers have to be kept at the bottom followed by the organism that is lesser in number and so on. The least number of consumers comes at the top of the pyramid, occupying the least space. (See What is a Tropical Rainforest Food Web?)
5. Why is Pyramid Inverted?
The Pyramid becomes inverted when the number of consumers is more at the top levels while at the bottom levels, they are less. So, when the top levels have more organisms and the bottom levels have fewer, then the pyramid becomes inverted.
6. Could a Number Pyramid be inverted?
Yes, a number pyramid could be inverted. This depends upon the nature of the food chain. An inverted pyramid of numbers is present in an ecosystem where the community contains a few producers at the bottom levels that support a larger number of consumers at the top levels. For example, parasites. (See What are Few Examples of Producers Consumers and Decomposers?)
7. What is Inverted Pyramid of Numbers?
The inverted pyramid of numbers is where the number of consumers is lesser at the bottom and more at the top, so it takes the shape of an inverted pyramid. The pyramid of numbers shows the number of organisms at each trophic level and the inverted pyramid of numbers indicates that the number of organisms increases at every successive level, unlike the regular pyramid where the number of organisms decreases at every successive level.
8. What is an Example of Inverted Pyramid of Number?
An example of an inverted pyramid of numbers is the tree’s ecosystem. Let us consider the pyramid of numbers for trees. Here, the trees are the base-level producers. The trees produce their food through the process of photosynthesis. After the base level, the successive level is for herbivores which includes some animals and birds. The consumers at this level are known as first-order consumers. After this level, comes the parasites which consist of insects like lice. They are smaller in size but greater in numbers. Then, lastly, comes the hyperparasites. They are parasites too and their host is also a parasite.
So, in this food chain, we can see that as we go from base-level producers to top-level consumers, the number of organisms increases. This leads to the inverted shape of the pyramid with fewer organisms at the base and more at the top. Check out What is the Difference between Autotrophic and Heterotrophic Nutrition?
9. Which Ecosystem shows an Inverted Pyramid of Numbers?
The ecosystems that show an inverted pyramid of numbers are:
- Marine or sea ecosystem
- Tree ecosystem
10. Why Pyramid of Number is inverted in Tree Ecosystem?
The pyramid of number is inverted in the tree ecosystem because the base-level producers are fewer in number compared to the top-level ones.
- The tree ecosystem consists of trees at the base level which produces their food through the process of photosynthesis.
- Next comes the herbivores like birds.
- The next level consists of parasites like lice. Though they are small in size, they are massive in numbers.
- And lastly, comes the hyperparasites which are parasites that feed on other parasites. They are extremely huge in numbers.
So, this ecosystem has consumers that increase at each successive level. Hence, it has an inverted shape. (Also read What is the Role of Decomposers?)