Symbiosis in Science Class

In science class, we are learning about symbiosis. The three types of symbiosis are mutualism, which is when two organisms interact and both benefit, commensalism, which is when two organisms interact and one organism benefits while the other is neutral, and parasitism, which is when two organisms interact and one organism benefits while the other is harmed. We also recieved an assignment. Each of us had to choose any symbiotic relationship taking place in our area, take a picture of it, and write a paragraph on how that specific relationship is important and what is happening to the two organisms involved. The symbiotic relationship I chose was between a horse and its intestinal bacteria. I did some research and I found out that this relationship could either be commensalism or parasitism, so I typed two paragraphs. It can be commensalism because the intestinal bacteria perform a number of functions useful for the horse. It can be parasitism because if the intestinal bacteria leave the gut, it can cause a fatal infection that might lead to death. I also found out that all animals (including humans) have them, but don't worry, you're not going to die anytime soon. At least, I don't think so.

For more information on symbiosis, check out this link:
http://en.wikipedia.org/wiki/Symbiosis

For more information on intestinal bacteria, check out this link (the website will call it "gut flora"):
http://en.wikipedia.org/wiki/Gut_flora