Food Chain: Definition, Meaning and Characteristics

In this article we will talk about the meaning, definition and characteristics of Food chain.

Food Chain Definition and Meaning

Food chains or trophic chains are the transfer path of energy and nutrients in an ecosystem .

Food chains are divided into a series of links or levels, each of which represents a way of obtaining food .

The idea of ​​a chain, as a linear structure, is a simplification that allows us to understand the transfer of substances from simpler organisms to more complex ones.

However, food relationships in an ecosystem can also be understood as networks in which there are multiple exchanges between one link and the next.

Characteristics of Food Chain

Here are the main characteristics of a food chain:

Autotrophs and heterotrophs

Every food chain begins with autotrophic organisms , which are those capable of producing organic substances from inorganic substances.

Autotrophic organisms in the food chain are called producers and are the beginning of the chain since they obtain food exclusively from inorganic substances.

On the contrary, heterotrophic organisms are those that obtain their food from other living beings . Through food , heterotrophic organisms obtain the energy to sustain their metabolism and growth, as well as the substances with which they build the structures of their organism.

Producers

Producers occupy the first link in the food chain . They are the organisms that are capable of converting inorganic substances (such as carbon dioxide ) into organic substances.

Organic substances are the food for all the other links in the food chain , meaning that the entire food chain depends on this link.

Producers can use energy from sunlight to produce organic substances , a process called photosynthesis . Almost all plants are photosynthetic producers.

On the other hand, there are organisms capable of producing organic substances without the intervention of light , using the energy contained in iron , sulfur and nitrogen .

This process is called chemosynthesis and it is carried out mainly by bacteria .

Primary consumers

Primary consumers eat plants, fruits and seeds. 

They are the animals called phytophagous and commonly known as herbivores . They take their energy and nutrients by consuming the producers.

Primary consumers can feed on various parts of plants , both their leaves, stems, flowers, fruits, roots or even seeds.

Bees are primary consumers that consume a substance made by the plant (nectar) without having to eat the plant itself.

There are many herbivorous animals, from small insects such as aphids or ants , to large mammals such as cows or horses .

Secondary consumers

They are carnivorous animals (also called zoophagi) that feed on herbivorous animals. They can be scavengers, that is, those that feed on dead animals such as vultures.

They can also be parasites : animals that feed on another animal without killing it, such as fleas. They can also be predators , like owls .

Tertiary consumers

Tertiary consumers are not preyed upon by any other species. 

They are the largest carnivores , feeding on both primary and secondary consumers.

Among them are marine animals such as sea lions and sharks , many mammals such as wolves and super predators, that is, those animals that are not preyed upon by any other species.

However, when tertiary consumers die, their organic matter is also used by degrading organisms , which break down organic matter into simpler substances that can be used by producers to restart the food chain.

Energy at trophic levels

The energy present in an ecosystem is transmitted from one trophic level or link to the next . However, by graphing each of the levels, a pyramid is formed since not all the energy at the producer level is available at the primary consumer level.

This is because primary consumers do not contain all the energy that they consumed in their own bodies as they used it to perform their metabolic tasks, and the energy used is dissipated in the form of heat or chemicals.

Therefore, secondary consumers have less energy available to consume . Energy is transmitted from producers to primary consumers to secondary consumers to tertiary consumers, but not in its entirety.

Biomass

Biomass is the amount of living tissue at each trophic level . The amount of biomass at each level in an ecosystem is also often represented as a pyramid, since the number of grams of producers is usually greater than the number of grams of primary consumers, and so on.

Read: Characteristics, Features and Types of Aquatic Ecosystems

This balance tends to be maintained naturally since if there are, for example, more secondary consumers than primary consumers, the shortage of food will have the consequence that the number of secondary consumers will decrease again.

Food web

In addition to the food chain, the food relationships between organisms in an ecosystem can be represented as a network.

This is because the same organism of one link can be food for several animals of the next link. For example, a mouse can be consumed by a snake and an owl.

In turn, a single animal from one of the links can feed on several from the previous link. For example, a hawk eats both pigeons and toads .

Omnivorous animals

Omnivores can adapt to a shortage of energy in one of the links.

Omnivorous animals, those that eat both animals and plants , occupy a fluctuating place in the food chain.

They are the animals that can most easily adapt to the lack of energy in one of the links.

Missing links

When a species ceases to exist in an ecosystem, all the trophic chains associated with that animal or plant are completely modified .

For example, if a mouse is completely eliminated from an ecosystem, the predators that fed on it may suffer a reduction in their number due to lack of food, or they may begin to feed more on other species of the same trophic level.

Read: Why Do We Need to Conserve Our Natural Resources

For example, in the absence of mice, hawks could eat more toads . Given the decline in toads, the population of mosquitoes and other species that the toads fed could significantly increase .

That is why it is so important to avoid the extinction of any species, since its absence affects the entire ecosystem in unpredictable ways.