Camel mating call
That sac is the inner lining of his jaw, this is a male camel trying to impress the females.
September 04, 08: There was barely anyone at the zoo today. Most of the animals were more active than i've seen them in recent weeks.
If you enjoyed this, check out my other animal photos here --> www.flickr.com/photos/fpat/collections/72157606769846171/