Trophic Level: Definition, Food Chain, & Examples

Trophic Level Definition

A collection of species in an ecosystem are classified according to their trophic level.  A trophic level defines a place in the food chain.

  • Based on their eating habits, organisms are categorized into several food chains.
  • The trophic level is a stage in the nutritive chain of food chains, which in some circumstances, may create an intricate network known as a food web.
  • The distance an organism has traveled throughout the food chain is measured as its trophic level.
  • The nutritional connection between the organism and the main source of energy is determined in part by the trophic level. With the exception of some deep-sea habitats, the sun is the main source of energy for any food chain.
  • One of the earliest ideas in ecology that helped us understand how energy moves through and is regulated within food webs was the idea of the trophic level.
  • Based on the research of August Thienemann, who also developed the phrases “producer,” “consumer,” and “reducers,” Raymond Lindeman first proposed the idea in 1942.
  • The trophic levels are expressed as discrete integer numbers, such as grazers or predators.
  • An organism’s trophic level can be determined only within a certain ecosystem, depending on how it interacts with the main energy source.
  • The knowledge of the relationships between various creatures existing within a level is also made possible by determining trophic levels.
  • A trophic level depends on the trophic level beneath it because it consumes and absorbs energy from the lower trophic level.
Trophic Level
Image Credit: CK12-Foundation

What is a Food Chain?

The direction of the flow of energy or biomass within an ecosystem is determined by the food chain, a linear channel inside a food web.

  • A food chain can assist in identifying the relationships between various organisms based on how they eat.
  • The trophic levels that make up the food chain are determined by the energy sources used by the species that belong to each level.
  • Although less complex than a food web, the food chain is a component of it. A specific animal’s straight-line journey is followed by the chains.
  • The food chains of various species may be measured based on chain length. The number of connections between the organism and the chain’s base is known as the chain length.
  • Only 10% of the total energy of a level is transmitted to the next, while the remaining 90% is used by the organism at that level, meaning that the quantity of energy moved from one link to another diminishes as the length of the food chain shrinks.
  • Most species depend on the movement of energy and biomass via a food chain to survive, and removing a food chain link can lead to the extinction of an entire species.
  • All food chains are built on producers who use the major energy source—the sun or chemical reactions—to create food that can be consumed by living things.
  • To carry out diverse ecotoxicological research, food chains are frequently built as an ecological modeling technique. The food chain aids in identifying the ecological paths taken by different environmental pollutants.
  • Depending on the energy source, food chains may be roughly divided into two categories: grazing food chains and detrital food chains.
  • The energy and nutrients from green plants are the starting point of the grazing food chain, which subsequently progresses to higher-level creatures like herbivores, carnivores, and omnivores.
  • The detrital food chain starts with decomposers using energy from decaying organic materials, which then passes to detritivores and carnivores.
Food Chain Diagram
Image Credit: khanacademy.org

What is Food Web?

The natural interaction between various food chains in an ecological community is known as the “food web,” and it is frequently shown in the form of a graphical representation.

  • Food webs are sometimes referred to as consumer-resource systems since they show how various creatures feed depending on their supply.
  • In 1927, the idea of the food web was first introduced as “food cycles,” but in a later publication, the term was modified to “food web.”
  • Food webs are simulations of actual ecosystems in which various living things are grouped into trophic levels to form relationships.
  • Ecological interactions are investigated using simplified mathematical models to characterise the energy flow and balance of an ecosystem.
  • A much-simplified version of the food web has been used as a conceptual tool to illustrate the eating patterns of various species in a community, their interconnections, and community structure.
  • Based on the various influences between species, Robert Paine divided food webs into three categories.
  • The web of connections reveals the link between species in terms of nutrition.
  • Energy flux connections are represented by an energy flow web.
  • Functional webs show how population density affects other populations’ growth rates.
  • Additionally, food webs may be arranged based on the kind of habitat and the species that live there.
  • Numerous ecologists have used food webs to gather information on the trophic level to establish parameters and investigate trends and traits common to multiple ecosystems.
  • The number of species present in an environment and their relationships influences how complicated a food web is.
  • Food chains, also known as unique linear chains or food webs, are found in food webs and show the direct relationships between two or more species. The complexity of the food web rises along with the number of food chains.

Definition of Food Chain Energy Flow

The process of transferring energy within a food chain or ecological unit from one trophic level or point to another is known as food chain energy flow.

  • An arrow with the arrowhead pointing in the direction of the energy flow may be used to indicate the flow of energy down a food chain.
  • A food chain’s unidirectional energy flow results in progressive energy loss as it ascends through the levels. The law of thermodynamics, which establishes the idea of energy transfer between systems, is followed throughout the whole process.
  • Before deciding on the direction of flow in an ecosystem, it’s critical to comprehend its supply of energy. Sunlight serves as the main energy source in the majority of ecosystems. Chemical processes could serve as a source of energy in deep-sea habitats.
  • The process of turning atmospheric carbon dioxide into glucose and oxygen in the presence of light is called photosynthesis, and it is the first stage of energy flow.
 Energy flow through ecosystems
Image Credit khanacademy.org
  • Green plants and algae are the generators of energy, which is subsequently transferred through the food chain to other creatures.
  • Primary production refers to the energy generated by producers, which subsequently flows up the food chain.
  • The biomass that consumers create through primary output is known as secondary productivity. In many ecosystems, consumers are present to varying degrees, with energy and biomass being the primary two.
  • Some energy is lost throughout the transfer process, which may be measured by the biomass or the efficiency of the energy flow in terms of how much energy reaches the next stage.
  • Only 10% of the energy is moved from one trophic level to another in a food chain, with the other 90% going toward the metabolic needs of the organisms. This is known as the ecological rule of 10%.

Trophic Level Pyramid

  • The transmission of food and energy from one trophic level to the next in a food chain represents interactions in biological communities in the form of the trophic level pyramid, also known as the ecological pyramid.
  • One of the three forms, the trophic pyramid, depicts the many relationships between various factors.
  • The movement of energy from one trophic level to another is illustrated by an energy pyramid. A biomass pyramid shows how much biomass—also known as living or organic matter—is present at each trophic level. The number of unique creatures found at various trophic levels is represented by a number pyramid.
  • The Pyramid of numbers was the first pyramid to be created, and it was inspired by the writings of Raymond Lindeman and G. Evelyn Hutchinson.
  • The producers are at the base of each of these pyramids, followed by other living things at various trophic levels. The summit of the food chain is represented by the pyramid’s highest trophic level.
  • The species that make up the base of the pyramid vary depending on the habitat; for example, green plants are found at the base of terrestrial ecosystems, whereas multicellular plants and green algae are found at the base of aquatic ecosystems.
  • Although the biomass pyramid exhibits inverted pyramids, the ecological pyramid of energy is always upright since the flow of energy in an ecosystem is unidirectional.
  • Because phytoplanktons have shorter individual lifetimes than zooplankton, their biomass in oceanic or pond environments is smaller than that of zooplanktons.
  • Although trophic-level pyramids are crucial for assessing the effectiveness of energy transfer and keeping track of the health of the ecosystem, they have certain drawbacks.
  • The link between the environment and seasons is not represented by the pyramids. There may be certain species that cannot be classified using the pyramids that exist at various levels.

You may also like to read: Phytoplankton Vs Zooplankton

Trophic Levels (with Examples)

A food web’s trophic levels start with producers, who occupy the first level, followed by a variety of consumers, and then apex predators.

A. 1st Trophic Level (Producers)

  • In all food webs, producers occupy the trophic level. The primary source of energy in all ecosystems, these producers are in charge of converting solar energy into useful energy.
  • Green plants in terrestrial and aquatic environments, as well as green algae in deep-sea ecosystems, are producers. Phytoplankton is another name for the photosynthetic algae that make up a marine environment.
  • Organic matter is produced by photosynthesis in both green plants and algae. But in other deep-sea microbes, chemical processes are used to produce energy.
  • Chemoautotrophs are creatures that make food through chemical processes, and photoautotrophs are organisms that produce energy when solar energy is present.

Example- Green Plants

  • Many ecosystems across the biosphere are produced by plants.
  • Green vascular plants are found at trophic level 1 and function as producers on land and in water.
  • These plants use specialized cells known as chloroplasts to absorb solar energy. Afterward, the energy is transferred through many substances to turn carbon dioxide into glucose and release oxygen.
  • The ecological food chain then moves the energy generated by the green plants to a higher trophic level.

B. 2nd Trophic Level (Primary Consumers)

  • The heterotrophic category of creatures is known as primary consumers that eat producers. These creatures get all their biomass and energy from producers like plants and phytoplankton.
  • These are found in all ecosystems’ trophic level 2, where producers transmit 10% of their energy output. The trophic level’s biomass rises because these species consume producers.
  • Herbivores are classified as grazers and browsers at trophic level 2 in terrestrial habitats. Grazers mostly eat grass, whereas browsers eat the leaves and twigs of trees.
  • Zooplanktons are the main eaters of phytoplankton in aquatic habitats.

Example: Zooplankton

  • Animals that are heterotrophic and consume phytoplankton make up zooplankton (green algae).
  • Microscopic zooplanktons make up the majority of the population and are more in number than phytoplanktons.
  • Zooflagellates, radiolarians, dinoflagellates, and marine microbes are examples of common zooplanktons. For energy and nutrition, these creatures consume both green plants and green algae.
  • The trophic level 2 of primary consumers in the biomass pyramid is bigger than the producers because there are more zooplanktons than phytoplanktons.

C. 3rd Trophic Level (Secondary Consumers)

  • A class of animals known as secondary consumers eat prime consumers. In some habitats, these creatures are classified as trophic level 3 organisms.
  • Carnivores are examples of secondary consumers since they graze on herbivores and other animals to get their energy.
  • Because they devour food from other animals (their prey), secondary consumers are sometimes referred to as predators.
  • Frogs, fish, birds, and snakes are typical secondary consumers, but trophic level 3 may also contain apex predators like lions and eagles.
  • Animals that consume zooplankton in aquatic settings range in size from tiny fish to bigger crustaceans, and they are found at trophic level 3.

Example: Fish

  • In an aquatic ecosystem, fish are secondary consumers that consume zooplanktons like dinoflagellates and other tiny creatures.
  • The trophic level 3 includes all of the many types of fish that may be found in different habitats.
  • The principal consumers and the fish are in a predator-prey relationship.

D. 4th Trophic Level (Tertiary Consumers)

  • Animals that can eat both primary and secondary consumers are referred to as tertiary consumers.
  • Although all consumers are heterotrophic, only tertiary consumers have a purely carnivorous diet.
  • Tertiary consumers may be found at the top of ecological pyramids, but because they may also be consumed by other species, they are not the most important organisms in the ecosystem.
  • In the ecological pyramid, tertiary consumers are located above secondary consumers because they have less biomass and energy than lower trophic levels.

Example: Owl

  • Because it eats both herbivores like mice and carnivores like stoats, the owl is an example of a tertiary consumer in terrestrial environments.
  • However, other species, like eagles and hawks, may hunt and consume owls.

E. Apex Predators

  • Animals are known as apex predators, reside at the top of the food chain, and are unaffected by other predators.
  • These creatures have a unique adaptability to their lifestyle, which makes them extremely effective hunters. Vultures, eagles, lions, and tigers are a few of the often-occurring apex predators in terrestrial habitats.
  • To maximize their chances of successful hunting, they can either operate in groups or alone.
  • Despite the fact that most apex predators in terrestrial environments are ruthless hunters, this is not always the case.
  • Due to the lack of natural predators, certain species can occasionally act as apex predators.
  • Apex predators are crucial to maintaining environmental equilibrium. Since these species sustain lower trophic levels, apex predators are

For instance, whale sharks

  • The top predators in marine environments are whale sharks. These creatures consume phytoplankton as well as smaller, bigger, and fish of all sizes.
  • While not all whale sharks hunt, these animals are nonetheless regarded as apex predators since they lack other natural predators.
  • These creatures contribute to the maintenance of the population of creatures living in lower trophic levels because they consume creatures and plants from all trophic levels.

F. Decomposers or detritivores or transformers

  • Decomposers are living things that feed on decaying organic matter, such as dead plants and animals and turn it into nutrients and energy.
  • Plants can then absorb the nutrients and energy for efficient development.
  • Decomposers are creatures that recycle waste from all trophic levels, including bacteria, fungi, and some arthropods. They do not constitute an independent trophic level, however.
  • These are crucial to a healthy environment because they stop the loss of nutrients caused by the demise of many living things.

Example: Bacteria

  • Bacteria are saprophytic organisms that help break down complex organic materials into simpler chemicals that plants can use.
  • Depending on the sets of enzymes that the bacteria create, different species of bacteria feed on various kinds of organic materials.


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