What does it mean to be biotic? The word biotic means relating to, prodcued by, or caused by living organisms. This means that anything that is living, or was once living, or was produced by a living organism within an ecosystem would be considered a biotic factor. The interactions of living organisms are also considered biotic factors.
Predation is the act of one organism hunting and eating another. This could be the frog catching the fly, the tiger catching the gazelle, or anywhere in between. Predation happens at every level of the trophic pyramid except within the decomposers and the producers.
Parasitism is the act of an organism using another organism as a host. In this symbiotic relationship the parasite usually causes harm to its host, although it will usually not kill it, or it will kill it fairly slowly. They are usually highly adapted, and can adapt quickly to new situations. Parasites include worms, ticks, bacteria, viruses, etc...
Competition is an interaction between species that are competing for the same resources. Typically this refers to food sources (both eat the same things) or water sources, although it may also refer to shelter. We will talk more about competition in the competition section of this website.
The organisms of an ecosystem are all of the living things within the ecosystem. This includes all plant life, bacteria, animals, fungi, algae, etc...
All living organisms create waste. This is due to the digestion process in which organisms take what they need (nutrients, water, etc...) from the things that they eat, and then they expell what's left (what they don't need.) Waste can have a great effect on a ecosystem if it is not be broken down properly by the decomposers of the system.
Animal homes are a large part of an ecosystem as well. This includes homes built in trees, in the grass, in the ground, etc... A good example of how these homes may have an effect on their ecosystem would be prairie dog holes. These holes are big enough, and hidden enough, that larger species, like deer and elk, may step into them and break their legs. Thus effecting the population of certain species within an ecosystem.