Trophic Level | Definition , Types & Examples

By | October 27, 2019

Trophic Level

Trophic Level Definition:

What is Trophic Level: In an ecosystem, a Trophic Level is a group of organisms that occupies the same level in the food chain. There are main five trophic levels in a food chain in which each is different in the nutritional relationship with the primary energy source.

Trophic Level definition Biology : 

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Why is a diagram of energy flow from trophic level to trophic level shaped like a pyramid?

  1. The primary source of energy is the Sun in any ecosystem. The radiations of Sun gives the input of energy used by primary producers, which is also called ‘Autotrophs’.
  2. The rest trophic levels are composed of Consumers, which is also known as Heterotrophs. The heterotrophs cannot create their own food, so they consume another organism to gain nutrition.
  3. The second trophic level is containing Herbivores. These organisms acquire energy by eating primary producers and also known as Primary Consumers.
  4. The third tropic level contains Carnivores and Omnivores that eat herbivores. These are known as ‘Secondary Consumers’.
  5. The tropic level four also consists of Carnivores and Omnivores, which survive by eat secondary consumers and known as ‘Tertiary Consumers’.
  6. The fifth tropic level contains Apex Predators. Apex predators are those animals that have no natural predators and because of this, it lies at the top of the food chain.

The Detritivores or decomposers are the organisms that consume dead animals and plant material. They convert it into energy and nutrients. Decomposers or detritivores including fungi, bacteria, earthworms, etc. do not fill the independent trophic level, but an important part of ecosystem function.

The organisms in trophic levels of the natural ecosystem do not often create a uniform chain, while many animals may have multiple predators and multiple prey.

Examples of Trophic Level:

Some examples of trophic level are given below:

  • Primary Producers:

Primary producers are also known as ‘autotrophs’. These organisms produce biomass from inorganic compounds. In simple words, these are Photosynthesizing organisms that convert energy from the sun radiations and use carbon dioxide and water in the glucose.

Almost all these producers come from the vascular plants including trees, ferns, and flowering plants, in the terrestrial ecosystem. While in the marine ecosystem, the primary productions are algae and seaweed.

There are also many primary producers present in deep-sea which perform oxidization of chemical inorganic compounds instead of the use of photosynthesis, these organisms are known as ‘chemoautotrophs’.

  • Primary Consumers:

The primary consumers are the herbivores which adapter to consuming and digesting algae and plants. Usually, there are two kinds of herbivores; the Grazers and the Browsers. Grazers are those animals whose diet contains at least 90% of grass, such as cows, rabbits, and sheep. While the browsers are those animals whose diet contains at least 90% of trees leaves or twigs, such as goat and deer.

The primary consumers can also consume many other kinds of plant material. Like many birds, bats, and monkeys eat fruits; birds, bats, insects, and arachnids eat nectar; and beetles and termites eat wood.

In the marine ecosystem, the category of primary consumers is zooplankton, and tiny crustaceans that feed off photosynthesizing algae called ‘phytoplankton’.

  • Secondary Consumers:

Secondary consumers are lying on the third trophic stage, which involves the carnivores and omnivores. These organisms gain nutrients from the tissues of herbivores.

The secondary consumers are often small animals, birds and fish like frogs, snakes, and weasels. It also exists in the second trophic level, which involves larger apex predators such as eagles and lion which may consume herbivores.

In the marine ecosystem, secondary consumers are those animals that consume zooplankton. This ranges from the jellyfish to the small fish like sardines and larger crustaceans like lobsters and crabs, and all organisms as the whale that filter feed and basking sharks.

  • Tertiary Consumers:

Tertiary consumers gain energy from eating carnivores but can also is preyed upon. The example of tertiary consumers is owls as they fed off mice and other of herbivores, and also eat secondary consumers as stoats.

  • Apex Predators:

The apex predators lie on the top of the food chain. These are the organisms which have not any natural predators. The apex predators usually have particular adaptions that make them highly efficient hunters like sharp teeth and claws, speed and stealth.

The apex predators perform important functions in the ecosystem as through predation they control the population of lower tropic levels. If apex predators are removed from the ecosystem, the organism including grazing herbivores can over-populated. While if there are fewer plant resources available, the organism which depends on plants will suffer and in turn, may affect the trophic level in an ecosystem. This disturbance in an ecosystem is known as ‘top-down trophic cascade’. It may be lead to ecosystem collapse.

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