What is a food chain and examples

The trophic chain or food chain of an ecosystem is a scheme in which the linear relationships between the species of organisms consumed and consumers are represented. In other words, arrows show how energy is transferred from an organism, belonging to a lower trophic level, to another organism, which occupies a higher trophic level.

Some of the main characteristics of food chains are:

• The transfer of energy occurs from simple organisms to more complex organisms.
• Arrows indicate the direction of energy transfer (unidirectional).
• The links in the food chain or trophic levels are each represented by a species.
• Key species are capable of modifying food chains, since their presence / absence controls the abundance of other species by their position in the food web.

The amount of energy at each trophic level in the chain can be represented in trophic or ecological pyramids . At the base, with a greater accumulation of energy, are the primary producers (autotrophs). In the next level, the triangle that represents the energy used and accumulated is smaller (representing 10% of all the energy of the previous level), and so on. The available energy decreases rapidly, so these pyramids are not very long. Here you can learn more about what is a trophic pyramid and its types

There are several types of trophic chains , depending on the organisms that initiate them or are located at the base of them:

• Predator food chains or herbivore-based chains (primary producers -> primary consumers -> secondary consumers -> tertiary consumers -> quaternary consumers ).
• Trophic chains of parasites: in them parasites can be the food base for other parasites; Or, they feed on very large animals, serving as food for smaller animals (such as birds).
• Decomposer trophic chains (debris -> decomposers -> secondary consumers ): Micro-organisms decompose dead organic matter.

As examples of the terrestrial trophic chain we indicate some of those that occur in the Mediterranean forest :

• Broom (primary producer) -> aphids (primary consumer) -> blue tit (secondary consumer) -> imperial eagle (super predator)
• Rosemary (primary producer) -> rabbit (primary consumer) -> lynx (super predator)
• Cork oak (primary producer) -> grasshopper (primary consumer) -> wild boar (secondary consumer) -> lynx (super predator)

In aquatic ecosystems, food chains are longer. As examples of aquatic food chain we indicate some marine trophic chain and some of fresh water.

Examples of marine food chains

• Green algae (primary producer) -> mollusks (primary consumer) -> Cottus cognatus (secondary consumer) -> king salmon ( tertiary consumer ).
• Phytoplankton (primary producer) -> zooplankton (primary consumer) -> sardine (secondary consumer) -> tuna (super predator).
• Diatoms (primary producer) -> Krill (primary consumer) -> blue whale (secondary consumer) -> killer whale (super predator).

Examples of freshwater aquatic food chains

• Algae (primary producer) -> Water fleas (primary consumer) -> Barbel (secondary consumer) -> Herons (tertiary consumer).
• Aeneas (primary producer) -> Grasshopper (primary consumer) -> Frog (secondary consumer) -> Gray heron (tertiary consumer).

The main difference between web and food chain is that chains are isolated relationships of the food web. In other words, the food web describes the set of food chains present in a given ecosystem.

For this reason the networks offer a more realistic representation of the nutritional relationships that occur in a community; however, they are more complex and difficult to represent and, therefore, it is often easier to study food chains separately. Here we tell you more about what are food webs and examples .