Yes. You are going to want to get her to the doctor immediately. If it is a brown recluse, it can cause a lot of damage if left untreated. Even if it isn't a brown recluse, it is as rayoflight says, it could be something exotic from one of the zoo animals.
If the infection is left untreated, it is possible that a piece of it can break off. If this happens it could travel to the heart, and even cause death. TAKE HER NOW!
This sounds like a brown recluse bite to me. I have had one. Since your daughter is young and more vulnerable to the toxins, I really think you need to take her to the hospital or Dr. As soon as possible. Different people react differently with these bites, and it can not be determined at first how much damage that will be done. I would take my daughter to a Hospital, since they probably have more of the kind of treatments used for toxic bites and venomous bites and could treat her more quickly, thus minimalizing the amt. Of damage done!
This can be insect bite. I advise you to visit a doctor and get differential diagnosis and proper treatment. In the zoo there are many parasites insects on the animals which can affect human as well. Some insects are parasites on animals and carry infections from the host and can transfer to human.
My son many many years ago got bit by a brown recluse spider and all I can say is take your daughter to the doctor immediately. Even if it isn't a b.r. Spider bite, don't take a chance, if it is, she needs to be seen asap.