Zoo dreams are often similar to museum dreams. The actual content of the zoo may be true to life, or it may contain some nonsense inhabitants such as co-workers, past romantic interests or relatives. You may also be a display, rather than an observer.
If others are on display, you may feel as though these people need to be confined or that they draw too much attention to themselves. If you are on display, you may feel that your life is somehow "abnormal" and on display for others to observe and critique.
Do you feel as though others keep you "on-display" or "caged-in"? Perhaps you are uncomfortable with a particular sense of notoriety you have attained.
Still, a dream that takes place in a zoo may have to do with ecological concerns, memories of childhood or a sense of adventure.