The Complete Cat: The Whiskers

If you thought cats only had whiskers on the sides of their upper lip, look again. Those extra strong hairs are called vibrissae, or tactile hairs, and you'll see them above the eyebrows, way back on the cheeks, and shorter ones on the backs of the front legs. They are at least twice as thick as the cat's ordinary hair, with roots that go three times deeper, surrounded by nerves and blood vessels. Vibrissae should never be trimmed. They will fall out occasionally, just like regular hairs shed, but replacements will grow back in.

A cat's whiskers are so sensitive that they can feel the slightest whisper of a breeze. Their whiskers are invaluable in judging wind speed and direction, which helps, both for protecting a new litter of kittens from predators and (combined with the nose), in identifying the location of potential prey.

Whiskers are also used by cats as locators, by judging how wide an opening is before entering. A cat's whiskers are roughly as wide as his body, so they're a useful measuring tool. They are also used in keeping track of prey, such as a mouse kitty has just caught. You can also learn a lot about two cats' interaction by observing their whisker signals. If they are pushed forward, they usually indicate friendliness or inquisitiveness, as illustrated in the picture above. Pulled back, they signal defensive hostility or aggression.