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Trophic Levels and the Food Chain

The author is a lover of nature and technology. He has been an online writer since 2009.

Algae and Phytoplancton

Trophic Levels in the Food Chain

Every animal on the planet is prone to be eaten by other animals, either because it is smaller or is not sufficiently strong. A creature is on a certain trophic leavel, depending on the position that one animal is in the food chain. So, for example, most small organisms are said to be in the first trophic level, whereas bigger organisms are said to occupy the next trophic level. The small organisms in the first trophic level (Algae and Phytoplancton, grass) are eaten by organisms on the next level, which in turn, will be eaten by the organisms on the next trophic level, and so on. Animals obtain their energy from the first trophic level, and in doing so, they become producers and consumers, that is to say, they will eat and be eaten. Producers represent the first level and consumers represent the the second and up levels. The animals at the very top of the thropic level are usually apex predators.

Herbivores Carnivores

Trophic levels

Trophic levels are usually categorized according to where an organism is placed along the food chain. Plants and algae form the first trophic level because they are the primary producers in the food chain. Primary consumers are the organisms that eat them, they’re called herbivores. Secondary consumers are the organisms that feed on herbivores, they’re known as carnivores; however, these carnivores can also eat plants; therefore, they can also be classified as omnivores. Tertiary consumers are the organisms that feed on other animals, they’re called carnivores. The organisms on the next trophic level may also be carnivores and the organisms at the top of the trophic level are usually apex (they don´t have predators of their own) predators.

Transfer of Energy

The Transferring of Energy Along the Food Chain

The primary producers in a food chain are most commonly plants and algae, which is found in water reservoirs (sea, river, streams, and lakes). They´re known as autotrophs. This is because they produce their own energy from the sun through the process of photosynthesis; however, recently it was discovered that some organisms can produce their nutrients, in the absence of sunlight, through a process called chemosynthesis. This occurs in hydrothermal vents in the bottom of the ocean, at the mid-ocean ridges. The energy obtained through the process of chemosynthesis and photosynthesis is transferred from one trophic level to the next, in which one organism eats other organisms. Through this process, small amounts of energy are lost due to dissipation of energy in the form of heat.

Food Chains

Food Chain

An Evident Food Chain

A plain example of a food chain starts with the grass in your garden, which obtains its energy from the sun through photosynthesis. The grass is a primary producer therefore, it occupies the first trophic level; the grass provides the energy to the organisms in the next trophic level, which are the rats. Rats are eaten by snakes, which occupy the next level and the snakes are eaten by hawks in the up level. This is a simple example of a food chain, but in a food chain, trophic levels usually comprise close to five levels. The remains of a hawk are broken down into nutrients by decomposers. The nutrients obtained through this process become good soil and may be utilized once more by primary producers (plants) in another cycle.

Food Web

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A Food Web

In the ecosystems of the planet, there is a complexity of food chains. Generally, organisms feed on more than one single source of food or are preyed and eaten by more than one type of predator. In this way, a food chain derives in a complex interconnection of feeding habits known as a food web. While a food chain follows a given feeding pathway in which one organism in a trophic level consumes the organism in the next lower level, in a food web, the organisms can consume one or two different living species obeying no level or linear pathway. Typically, decomposers break down the organic matter from death plants and animals, making it available in a food web. In this way, it can be used again by the primary producers.

Energy Pyramid

Energy Transfer

Normally, the energy that is transferred from one organism to another is depicted in an energy pyramid. The energy pyramid can also illustrate the amount of mass that is transferred to higher trophic levels from the biomass that is consumed at the lower trophic levels. The organisms at each level transform an approximate10% of energy, contained within food, which is stored in their tissue. Plants may store only 1% of sunlight energy, the amount of sun energy stored in the tissue of tertiary consumers is about 0.01%. The efficiency with which organisms the biomass is transferred from one trophic level to the next is called ecological efficiency.

Facts About Food Chains

According to, an increment in solar radiation can produce significant increases in the energy that is transferred from one organism to another

In the ecosystems of the world, there is more there is more than one food chain for most organisms, since most organisms are eaten and prey for more than one organism

Humans are both apex predators and omnivores.

Plants are situated at the bottom in a food chain

Herbivores occupy the second trophic level

Carnivores are situated above these two

Decomposers break down organisms and turn them into good nutrients for the soil

© 2015 Jose Juan Gutierrez

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