THEfood chain, also called chaintrophic, can be defined as a linear sequence of matter and energy transfer on a ecosystem, in which it is possible to observe a sequence of organisms serving as food for others. This transfer always starts with a producer and ends in a decomposer, being this one-way transfer.
Next, we'll find out more about the food chain, we'll get to know its components, examples, we'll understand how the extinction can affect it and why it is not the best way to represent the feeding relationships in an ecosystem.
Components of the food chain
Food chains are composed of organisms that can be classified into three categories:
• Producers: Organisms capable of producing their food, that is, autotrophic beings. They are always found at the beginning of the trophic chain and are usually represented by photosynthetic organisms such as plants and the seaweed.
• Consumers: Organisms that need to feed on other organisms, that is, beings heterotrophs. Consumers can be classified into primary, secondary, tertiary etc. consumers. Primary consumers are those who feed on producers, while secondary ones feed on primary ones, tertiary ones feed on secondary ones, and so on.
• Decomposers: Organizations that perform decomposition, a process in which these beings extract the energy necessary for their survival from dead organic matter and return important substances to the environment. As an example of decomposing organisms we can cite fungi and bacteria. It is important to highlight that decomposing organisms act on all living beings in the chain and, therefore, are often not represented in the food chain.
We realize, therefore, that each of the components of the food chains are characterized by having organisms with common food needs. The producers of an ecosystem, for example, stand out for being autotrophic, while all primary consumers are characterized by feeding on the producers. Each group of organisms that have these similar needs is called trophic level.
Read too: Autotrophic and heterotrophic beings: what are their differences?
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Examples of food chains
Here are two examples of food chains: a terrestrial food chain and an aquatic food chain.
terrestrial food chain
In the example shown, we have a terrestrial food chain, in which it is possible to observe a plant, a mouse, a snake and a hawk. The plant is the producer of this food chain, as it is capable of producing its own food through the photosynthesis. It serves as food for the rat, which behaves, therefore, as a primary consumer. The snake, which feeds on the primary consumer, is a secondary consumer. The hawk behaves as a tertiary consumer. In this food chain, decomposers were not represented.
aquatic food chain
In this example, we have a aquatic food chain. Phytoplankton, which are made up of photosynthetic organisms, is the producer. Phytoplankton serve as food for krill, which behaves, therefore, as a primary consumer. Krill serves as food for the penguin, which can be classified as a secondary consumer. Finally, the seal feeds on the penguin, behaving like a tertiary consumer.
Read more: What is Phytoplankton?
Impacts of species extinction on the food chain
The food chain represents the food relationships existing in an ecosystem, that is, analyzing the food chain, we see which living being serves as food for another. Species extinction negatively affects the food chain, because that living being, which would serve as food for another, now no longer exists.
Let's imagine that, for example, the snake in the terrestrial food chain example mentioned earlier went into extinction. This would have a great impact on the chain, since rats would increase their population, causing the reduction of plants, and hawks, without food, would also have their population reduced. Over time, the rat population would cause an exaggerated decrease in the number of plants, which would cause a reduction in food, triggering a reduction in the rat population. We therefore realize that all living beings are important and its extinction negatively impacts the ecosystem.
Also access:Endangered animals: causes and consequences of this process
Is the food chain the best way to represent the ecosystem?
As stated earlier, food chains are linear, which does not show the true complexity of an ecosystem. This is due to the fact that in a given environment, an animal can be, for example, a tertiary consumer as well as a secondary one. Therefore, the most adequate representation to show the complexity of an ecosystem is the food web.
At food webs show multiple interconnected food chains and taking place at the same time. As such, it is more complex than the chain, showing the transfer of matter in different directions.
By Vanessa Sardinha dos Santos
Biology teacher