In this lesson, we will review what a food chain is, what herbivores and carnivores are, and why they are important in the food chain. We will also look at what a food chain would be like with only producers and decomposers.
What Is a Food Chain?
Picture the African savanna. Grazing animals, like zebra and antelope, roam in herds. Lions and hyenas hunt them down, stalking their prey from the bushes. Although they might seem like enemies, these beautiful animals are all interconnected through a food chain and each is essential for the survival of the other. A food chain is a type of diagram that shows who eats who in an ecosystem. The food chain shows connections between animals that are predators, doing the hunting, and their prey, the hunted. There are different levels on the food chain, and today, we're going to look at the importance of two, the herbivores and the carnivores.
What Are Herbivores and Carnivores?
To get into herbivores and carnivores, let's start at the bottom of the food chain. Producers are organisms that make their own food and supply energy for the rest of the food chain. These organisms are usually green plants. Herbivores are vegetarians. They eat the producers. Next in our food chain comes the carnivores. Carnivores only eat meat. They control the population of the herbivores and prevent them from eating all the producers.
Carnivores need herbivores to survive, but herbivores also need carnivores to keep their population in check. So, although carnivores might seem like the mortal enemy of herbivores, the whole food chain would collapse without them. But, could the other organisms in the food chain survive without both herbivores and carnivores? Let's look at what could happen if we removed these two types of organisms.
A Food Chain Without Herbivores and Carnivores
There are a few different organisms in the food chain. The producers, usually plants, we have already talked about, and then there are the herbivores and carnivores. There are also decomposers, which break down dead organisms. Decomposers can be fungi or bacteria. They grow on both plants and animals, recycling their bodies back to the soil for new growth.
So what would happen if we removed the herbivores and carnivores? The carnivores' job is to keep the populations of other carnivores and herbivores in check. But, in this scenario there are no herbivores, so the carnivores aren't really needed. Without the herbivores, the producers would be free to grow. Producers don't need the herbivores or carnivores to make their own food and energy. They are self-sustaining, and they can't exhaust their food source. When the producers die, decomposers would break them down and recycle the nutrients to the soil for new growth.
However, the skills needed to survive might change for the producers. Plants that have adaptations to prevent organisms from eating them, such as poison or spikes, would no longer be needed. They might evolve into something new or become extinct. Either way, the distribution and types of plant species, or biodiversity, would change without the herbivores and carnivores. Let's look at an example to see what might happen.
Example: Deciduous Forest
A familiar example we can use is the deciduous forest. This type of forest is common in the Northern United States, Europe and Asia. Broad leaf trees, grass, shrubs, moss and lichen are the producers here. Herbivores include grazing animals like deer, as well as small rodents like mice or rabbits. The carnivores, like foxes, weasels, coyotes and mountain lions, control the herbivore population.
Now let's remove the carnivores and the herbivores. Carcasses left from the carnivores would no longer exist, so there might be a decrease in the diversity of decomposers since they only have plant species to grow on. However, the producers could flourish. There would be no more animals grazing on the grass. The grass could grow larger and thicker in the meadows. Acorns and berries would no longer be gathered by squirrels, mice and rabbits, allowing for additional trees and shrubs to germinate. The forest would shift towards a producer heavy environment.
So, in answer to our question, although there would be drastic changes in biodiversity of an ecosystem, the food chain would survive without herbivores and carnivores. However, the reverse is not true. Producers are essential to the ecosystem, providing food for everyone else. Without producers, there would be no food chain.
In summary, a food chain shows who eats who in an ecosystem. The herbivores feed on producers only, and carnivores only eat meat from other carnivores or herbivores. The carnivores keep the population of herbivores in check, and the producers provide energy for the herbivores. If the herbivores and carnivores were removed, there would be changes to the biodiversity of the producers, but they would still survive. The food chain would be limited to these producers and decomposers, which break down dead organisms. The food chain would be intact, but would be mainly made of producers.