Physical Facts... A rat's sense of smell is excellent, even exceeding that of a dogs. Rats have extreme hearing capabilities, even in the ultrasonic ranges. Rats can exert the same jaw pressure as an adult crocodile. Which is why they can chew through lead pipes. Rats communicate much of their language on a sound frequency that the human ear cannot hear. Rats are poorly nearsighted. Rats do not see three dimensionally, thus having no depth perception. Rats are color blind. A rat's vision is geared for spotting movement. Pink eyed rats have much poorer vision than black eyed rats. Their four front incisors (teeth) grow at about four to five inches per year. A rat's tail helps them keep their balance. Rats molt throughout their lives, loosing old hair, and gaining new hair. While they are molting they will have patches of lighter, softer hair throughout their bodies. This is more noticeable in babies. If they have a hairless gene in their background, or if they are a rex, they may even develop bald patches while molting.