Cute Cat Taking A Bath

Senses
Cats have excellent night vision and can see at only one-sixth the light level required for human vision. This is partly the result of cat eyes having a tapetum lucidum, which reflects any light that passes through the retina back into the eye, thereby increasing the eye's sensitivity to dim light. Another adaptation to dim light is the large pupils of cats' eyes. Unlike some big cats, such as tigers, domestic cats have slit pupils. These slit pupils can focus bright light without chromatic aberration, and are needed since the domestic cat's pupils are much larger, relative to their eyes, than the pupils of the big cats. Indeed, at low light levels a cat's pupils will expand to cover most of the exposed surface of its eyes. However, domestic cats have rather poor color vision and can only see two colors: blue and green, and are less able to distinguish between red and green, although they can achieve this in some conditions.
Cats have excellent hearing and can detect an extremely broad range of frequencies. They can hear higher-pitched sounds than either dogs or humans, detecting frequencies from 55 Hz up to 79 kHz, a range of 10.5 octaves; while humans can only hear from 31 Hz up to 18 kHz, and dogs hear from 67 Hz to 44 kHz, which are both ranges of about 9 octaves. Cats do not use this ability to hear ultrasound for communication but it is probably important in hunting, since many species of rodents make ultrasonic calls. Cats' hearing is also extremely sensitive and is among the best of any mammal, being most acute in the range of 500 Hz to 32 kHz. This sensitivity is further enhanced by the cat's large movable outer ears (their pinnae), which both amplify sounds and help a cat sense the direction from which a noise is coming.
Cats have an acute sense of smell, which is due in part to their well-developed olfactory bulb and also to a large surface of olfactory mucosa, in cats this mucosa is about 5.8 cm2 in area, which is about twice that of humans and only 1.7-fold less than the average dog. Cats are very sensitive to pheromones such as 3-mercapto-3-methylbutan-1-ol, which they use to communicate through urine spraying and marking with scent glands. Cats also respond strongly to plants such as catnip which contains nepetalactone, as they can detect this substance at less than one part per billion. This response is also produced by other plants, such as Silver Vine and valerian, and may be caused by the smell of these plants mimicking a pheromone and stimulating cats' social or sexual behaviors.