What do you Understand by Trophic Level

What do you understand by trophic levels?

The various links or steps in a food chain at which food and energy are transferred from one organism to another organism are called trophic levels or feeding levels. The amount of food and energy transfer reduces with each successive trophic level and therefore they are limited and generally do not exceeding the count of four or five comprising of the following:

• The first and the lowest trophic level consists of producers who manufacture food

• Plant eaters or the primary consumers occupy the next level

• Then the third one consists of small carnivores or the secondary consumers

• And lastly, It comprises of the large or tertiary consumers

Hence it can be said that each organism in the food chain represents a trophic level depending on its feeding behavior. Also, since the number of organisms decreases with upward movement in a food chain, it implies that at the lowest trophic level, the number of organisms will be maximum.

For Example,

Consider the below given food chain:

Phytoplankton → Zooplankton →    Fishes → Birds

In the above pond ecosystem, the phytoplankton who make their own food are the producers and they form the first trophic level. They are eaten by the primary consumers Zooplanktons who form the second trophic level. The small carnivores like fishes that eat the zooplankton are secondary consumers and form the third trophic level. Then largely the birds which eat fish, also called tertiary consumers form the fourth trophic level.

There are some food chains who have a smaller number of trophic levels as well. Like in case of forest ecosystem, there are only three trophic levels with no secondary consumer as presented below:

Plants → Deer → Lion