The most commonly known definition of trophic level is the position of an organism in the food web. The trophic level of any organism depends on their feeding behavior. In other words, the trophic level indicates how many steps away an organism is from its original source of energy (producers like plants).
All green plants that make their own food constitute the first trophic level. All organisms that obtain their food by consuming green plants form the second trophic level.
Similarly, the third trophic level is formed by secondary consumers who depend on the primary consumer for food.
Each trophic level describes
- the group of organisms that have a similar feeding mode.
- The number of steps an organism is away from the source of energy that is producer like green plants.
In an ecosystem, energy always flows from lower to higher trophic levels. For example, plants make their food using solar energy. Rabbits consume some of this energy, and eagles eat rabbits. Furthermore energy is lost as heat at each trophic level. Typically, there are four to five trophic levels. Let’s look at each of them in detail.
Examples of Trophic levels
Producers ( first trophic level)
Producers are those organisms which make their own food using sunlight, water, and carbon dioxide. They are also called autotrophs. This food is utilized by primary consumer (herbivores) and then by secondary consumer, tertiary consumer and so on. Some examples of autotrophs are,
- autotrophic bacteria
Consumers are those organisms who cannot make their own food. They largely depend on autotrophs (producers) and some of them eat other small consumers.
Organisms who eat only autotrophs are called a Primary consumers or herbivores. Organisms that eat this herbivore are called secondary consumers. Furthermore, consumers are classified into primary, secondary, and tertiary consumers.
1. Primary consumer ( trophic level 2)
The primary consumers are also called herbivores. They only eat plants. The following are some examples of primary consumer:
- most caterpillars
2. Secondary consumer (trophic level 3)
The secondary consumers eat only primary consumers such as rabbit, sheep, and grasshopper. They are also referred to as primary carnivores. The following are some examples of secondary consumers,
3. Tertiary consumer (trophic level 4)
Tertiary consumers are sometimes referred to as secondary carnivores. They feed on secondary carnivores. However, apex predators may prey on tertiary consumers. The following are some examples of tertiary consumers,
4. Apex predators ( trophic level 5)
Apex Predators are also called quaternary consumers or top carnivores. They occupy Fifth(top) trophic level in the food chain. Apex Predator only eats meat and has no predators of its own. The examples of Apex predators are,
omnivorous are organisms that feed on both producer and consumers. In other words, they obtain their food from different trophic levels. Therefore, it is difficult for the omnivorous to choose any one trophic level. Some examples of omnivorous are,