My friend sent me this video randomly on Facebook and I thought it was cool enough to share. What stood out to me the most was how all the animals (except the elephant?) had a reaction to seeing themselves in the mirror. However, I don't think they understood that they were seeing reflections of themselves. The gorilla's reaction was the most entertaining, he saw his reflection as a threat more so than the other animals did. Also what I find interesting is that my pet cat doesn't have any reaction when she sees herself in the mirror, and she doesn't like other cats. I don't know how to explain that though. Do your pets notice themselves in the mirror?
Here's the video, I encourage you to watch it!