Cat senses roof of their mouths called the vomeronasal (or Jacobson's) organ. When a cat wrinkles its muzzle, lowers its chin, and lets its tongue hang a bit, it is opening the passage to the vomeronasal. This is called "gaping", "sneering", "snake mouth", or "flehming". Gaping is the equivalent of the Flehmen response in other animals, such as dogs, horses and big cats. A cat has about twenty-four movable vibrissae ("whiskers"), in four sets on each upper lip on either side of its nose (some cats may have more). There are also a few on each cheek, tufts over the eyes, bristles
Whiskers them understand how biological whiskers work and as a tactile sense for robots. These efforts range from the abstract, through feature-specific models, to attempts to reproduce complete whiskered animals in robot form (ScratchBot and ShrewBot, both robots by Bristol Robotics Laboratory). A range of non-mammalian animals possess structures which resemble or function similarly to mammalian whiskers. Some birds possess specialized hair-like feathers called rictal bristles around the base of the beak which are sometimes referred to as whiskers. The whiskered auklet ("Aethia pygmaea") has striking, stiff white feathers protruding from above and below the eyes of the otherwise slate-grey bird,