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8.7. Trophic relationships: chains and networks

Trophic relationships

The trophic or food relationships are the relationships of food dependency that are established between the different trophic levels of an ecosystem.

Organisms at a trophic level obtain matter and energy from organisms at a lower trophic level.

Two types of trophic relationships are distinguished:

Trophic chains

The food chain describes the process of transfer of matter and energy between the organisms of an ecosystem. It is a linear sequence in which the direction of nutrients and energy from one organism to another is indicated by arrows.

Cadena trófica

Tomada de Wikipedia, de chris (through works of J. Patrick Fischer, C. Schuhmacher, Madprime, Luis Fernández García, Luis Miguel Bugallo Sánchez, chung-tung yeh, Susanne Heyer and Simon Andrews)

Interactive activity: Complete the food chains.

Interactive activity: Food chains.

Food webs

But as you might think, the food chain is a very simple representation, since a species does not feed exclusively on another species, but many different food chains are established. A species can be consumed by many types of organisms and feed on several different species. For this reason, more than chains, in nature there are trophic networks , a set of related trophic chains that express all the food relationships that occur between the organisms of an ecosystem.

Red trófica

By Matthew C. Perry [Public domain or Public domain], via Wikimedia Commons

Interactive activity: Food webs.


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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.