The backbone of any ecosystem is the food chain. Like in an ordinary chain, if any one link is missing, the chain (and the ecosystem) will fall apart. Depending on which link in the chain is taken, it may take more or less time for the ecosystem to implode on itself, but it will eventually happen.
But just the simple concept of needing to eat or else we will die is not enough to be able to understand this system of Magizoology as a whole. The complete food chain as we know it is made up of many different classifications, combinations, and all sorts of other this; all of which will be described in this section. The various different eating patterns and how they all fit together are all key things in understanding how the food chain is held together.
In order to understand the food chain, one must first understand the parts that make it up. An ecosystem can be made up of autotropes (self-feeders), herbivores (plant-eaters), carnivores (meat-eaters), omnivores (plant and meat eaters), and decomposers (bacteria and fungus). But to make it simpler, in order for an ecosystem to exist, it needs to be made up of at least two components: producers and decomposers.
A producer, by definition, is any plant or animal that uses energy. But once the creature dies, even though it is no longer using energy itself, it can still serve as a means of energy for others (e.g. the decomposer). Once a plant or animal does die, it is eventually devoured by fungus or bacteria (I’m sure you have all seen this process at some point in your lives) who break it down until the environment becomes a neutral state once again. An ecosystem can be simple or complicated as you like, but it must have these two components—producers and decomposers—if it hopes to last for very long. If the producers are missing, we lose the most basic point of the food chain, and when decomposers are lost, the environment becomes littered with the corpses of the dead.
So, as you can see, both of these very basic parts of the food chain are most essential.
However, many ecosystems are much more complicated, branching off the concept of producers and decomposers. To start with, there are autotropes, which are capable of creating their own food supply from the sun’s rays. The members that make up this group do not technically include magical creatures—photosynthetic plants, algae, and bacteria—but they do serve as a highly important food source for many of the magical creatures we study. For more studies in magical aspects of autotropes, I would highly suggest paying more attention in your Herbology classes.
Then we have herbivores, which live off of plants. I am sure that many creatures come to mind with this definition: Unicorns, Re’ems, and Winged Horses, as well as many other creatures associated with being ‘nice’ and ‘harmless’. A Magizoologist, when discovering a new creature, can usually tell pretty easily whether or not a creature is an herbivore. Herbivores have a very distinct set of teeth—flat and used for grinding—and sometimes have a very distinct digestive system (ones with more than one stomach) that allow them to break down plants and roots they normally wouldn’t be able to digest.
Because herbivores do not hunt or feed on meat, they are often considered not to be a threat to humans, but in most cases, this is not true in the least. Just because a creature does not feed on meat does not mean they do not see humans as a threat and that they are not capable of attacking in potentially deadly ways. As with any magical creature, common sense is key in their study, and it is prudent for all students in the subject of Care of Magical Creatures to, when a approaching an unknown creature, to afford as much caution as humanly possible.
The carnivores can be harder to distinguish. There are true carnivores, which eat only meat, and then there are creature with a primarily meat diet, but can also live off roots and berries, really making them omnivores. Creatures in the wizarding world that would be considered true carnivores are dragons and Acrmentullas.
Omnivores, as said before, can live off any combination of meat and plant life (humans fall into this category, in case this description sounds a bit familiar). Other magical creatures in this category include Gumberoos, Agripeltors, and Jersey Devils. If a discrepancy ever does occur in an ecosystem, omnivores will be the creatures that will survive the longest, simply because they are the least picky eaters.
In short, these are the main links on the food chain, and the ones that are most notably recognized in the study of magical creatures.
Creatures and plants are alike in the sense that they all consume some sort of stored energy in order to survive. Humans, as we all know, must eat and drink in order to survive. The calories in food are our stored energy and every time we move, speak, or do anything else, we use that energy, as do all creatures. This is one of the most basic information for life on earth.
Plants require stored energy in order to exist as well, but, most plants at least, can’t ‘eat’ in the same way creatures do. Instead, most plants get their energy by use of sunlight through a process called photosynthesis. They take in sunlight and produce simple sugars, it rids itself of waste through a process called Aerobic Respiration, breathing it out as oxygen that living creatures need to breathe.
Animals live off energy they get from plants and animals that eat plants. When creatures breathe in oxygen, they exhale the remains are carbon dioxide, which, ironically enough, is what plants need in order to breathe. Plants breathe in carbon dioxide and breathe out oxygen, and animals breathe out carbon dioxide. This shows the balance in which nature exists and how we all survive together.
What you have just read is a very simple explanation of the food chain as known to both wizards and Muggles. As you have probably already guessed, there is much more to know about creatures’ feeding patterns than what has been outlined in this one short chapter. It is, however, more than enough for a layperson to understand the basic constructs of the food chain and what makes it up.
More detailed explanations can be found in more advanced texts in Care of Magical Creatures, though make sure you understand what has been explained in this chapter first.