Jacobson's Organ and the Flehman Response

Cats (along with snakes and a few other mammals) have a magnificent organ called the vomeronasal organ, most oftenly known as the Jacobson's Organ. It is located inside the mouth, just behind the front teeth, and connects to the nasal cavity. Opening his mouth slightly enables the Jacobson's Organ to open up the ducts connecting to the nasal cavity. The appearance of the cat as he brings air into the Jacobson's Organ has sometimes been likened to a "smile," other times to a grimace. The Jacobson's Organ seems to play a large part in the sense of smell of a cat, judging by its frequency of use around my house.

According to Valeriy ILYICHEV, Doctor of Biology, in this article, there are three hypotheses on the exact function of the Jacobson's Organ. The first is to perceive the smell of food; the second, as a "sixth sense" to help predict unusual occurrences, e.g., earthquake, volcanic eruption; and the third is for perception of sexual odors - pheromones. If I got a vote, I'd choose all three, judging by the behavior of my own cats.
The Nose Knows
From Franny Syufy,
Your Guide to Cats.

http://cats.about.com/cs/felineanatomy/a/catsnose_scent.htm

Teaching Bio this year, I think we mentioned it to the kids when talking about reptiles and snakes, but not with cats. I will ask one of my Bio teacher friends... I hate to tell this group what his Anatomy and Physiology class are dissecting right now.....