In this lesson, you will learn what a food chain is and what composes one. You will also learn about different food chains that humans fit into, seeing many different examples.
You just sat down to dinner and start cutting into a juicy steak.
As you are savoring each delicious bite, you stop and think about your piece of meat. Where did it come from? What did it eat? Why are you eating it?These questions can be answered with a little understanding of food chains. These are diagrams that show what organisms eat what and how energy is passed through an ecosystem. An arrow indicates an organism consuming another one and obtaining energy from it.
For example, grass gets eaten by a grasshopper, which is eaten by a mouse, which gets consumed by an owl.Every food chain must start with a producer, or autotroph, an organism that makes its own energy through a process called photosynthesis. During photosynthesis, energy from the sun is used to turn carbon dioxide and water into glucose, which can be broken down for energy.
In this case, the grass is the producer at the bottom of the food chain.Producers are eaten by primary consumers, organisms that eat producers, usually plants. The primary consumer in the above example is the grasshopper, because it is eating the producer. The mouse is considered a secondary consumer because it eats the primary consumer. The owl is a tertiary consumer because it eats the secondary consumer – the mouse in this case.Food chains can sometimes be extended if there is another consumer that eats the tertiary consumer.
This consumer is called a quaternary consumer, but is rare because available energy decreases as a food chain is extended. Thus, quaternary consumers get the least amount of energy from their food and have to consume more of it to survive.So what happens to the owl? In this scenario, we would say that the owl sits at the top of the food chain and is an apex predator, a consumer that does not get hunted by other animals (predators).
But we all know that no organism can live forever. When the owl dies, it will get consumed by scavengers, animals that feed off of dead organisms, or decomposers, organisms that break down materials from dead organisms and return the nutrients back to the soil.
Human Food Chains
How does this play into your nice steak dinner? Well, steak is a meat that comes from cows, and cows rely mostly on grass for food. The grass is the producer, and the cow is the primary consumer. This makes you the secondary consumer!Let’s say you threw a nice salad into your meal; then you would be considered an omnivore, a type of consumer that eats both plants (producers) and animals (consumers).
On the other hand, the cow would be considered an herbivore because it is a consumer that only eats plants (producers). A carnivore, on the other hand, is a type of consumer that only eats other animals, like a jaguar or a wolf.
Humans have a wide variety of foods in their diets, which results in many different food chains! Not everyone eats steak for dinner every night; maybe you eat fish instead. So let’s see where humans fit on that food chain. In this case, algae, a water-living plant, would be the producer. The algae gets consumed by a small water-living organism, such as a shrimp, the primary consumer.
The shrimp gets eaten by a fish – let’s say a cod – who is now the secondary consumer. You then fry up that cod for dinner, and now you are the tertiary consumer!Let’s look at another common dinner item – chicken. Chickens are often fed grain by farmers.
This makes chicken a primary consumer and humans a secondary consumer. Now let’s say that chicken found some nice bugs to eat the night before. In this case, you would now be a tertiary consumer while the chicken would be the secondary consumer. The bugs would be the primary consumers, getting energy from a plant source such as leaves.What if you are a vegetarian? If you are a true vegetarian, meaning you only eat producers, that means you are an herbivore and therefore always a primary consumer. Your food chain will always be very short, only consisting of whatever producer you eat and yourself!
Humans are typically seen as being on the top of the food chain like the owl in our first example.
We are apex predators because we do not typically get consumed by other organisms; we have no natural predators. There are some occasions where humans do get attacked by animals, such as bears and lions, but this is not the norm.Humans are a bit different from the typical apex predator in that we eat at all different trophic levels, levels of a food chain such as primary and secondary consumer. Most apex predators will only eat higher trophic level organisms, but humans have much greater diversity in their diet. We eat anywhere from the producer to the tertiary consumer!Although we do not have natural predators to eat us, human bodies are decomposed after death by bacteria and fungi, which bring nutrients back to the soil for producers to use.
Humans can fill a variety of different roles in a food chain depending on which organisms they eat.
If a human decides to eat only plants, they are a primary consumer. If they eat an organism that eats the plant, they are a secondary consumer, and so on. Most humans are omnivores, filling the role of a primary consumer and secondary or tertiary consumer, based on what they decide to eat. Humans have a very wide variety of foods in their diet, which is why they can fill so many different roles!