Did you know that this funny looking expression is actually very important to a cat. As a matter of fact, all cats "flehm". To flehm is to communicate via olfactory means or more simply by smell. As most of you know, most cats lead solitary lives in the wild and yet they are part of a sophisticated social system that relies on various signaling systems. Smelling signals from others is a major piece of the puzzle at making their social system so effective.
For instance, a domestic cat approaches a urine mark of another , sniffs and then raises its head with his mouth half open. In small cats, the upper lip is slightly withdrawn, while in larger cats, the upper lip is withdrawn so that the cat appears to be grimacing; the cat seems immobilized, staring off and breathing slowly. The cat could be smelling urine, the anogenital region of another cat, birth fluids or any strange odor.
What is the function of this behavior? When a cat flehms, it uses its tongue to bring droplets of the substance in question in contact with a secondary olfactory system called the vomeronasal organ. This organ is also known as the Jacobson's organ. This organ allows the animal to examine message loaded molecules called pheromones that are otherwise too heavy to be inhaled and smelled in the conventional sense. This VNO allows its owner to get a second or closer look at signposts left by others.
In cats, the vomeronasal organ is located on the roof of the mouth right behind a cat's front teeth. Two tiny holes are visible within a slightly raised area. These organs can actually be seen on your cat companion. One of the most common uses of this organ is to test the urine of females. In effect, the male is trying to determine whether or not the female cat is in estrus. (ready to mate)
Cats use vocal, visual, and chemical signals to communicate with one another. Some vocal signals can be heard over great distances while other vocal signals are used in close contact situations and are combined many times with visual signals. Vocal and visual signals do not persist in the environment while chemical signals ( smell related) on the other hand can be read for some time after the depositor has left his location. These chemical signals are well suited to the spatially and temporally dispersed lifestyles of felids.
Scent marking is widely used among the cats and hence, the importance of "flehman".
Thanks to Sam for modeling the Flehmen behavior