 When a horse is said to "grab the bit in its teeth" they actually mean that the horse tenses its lips and mouth against the bit to avoid the rider's commands (although some horses may actually learn to get the bit between their molars).Depending on the style of bit, pressure can be brought to bear on the bars, tongue, and roof of the mouth, as well as the lips, chin groove and poll.Bits offer varying degrees of control and communication between rider and horse depending upon their design and on the skill of the rider.