have excellent night vision and can see at one sixth the light level required for human vision.[53]: 43 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.[68] Large pupils are an adaptation to dim light. The domestic cat has slit pupils, which allow it to focus bright light without chromatic aberration.[69] At low light, a cat's pupils expand to cover most of the exposed surface of its eyes.[70] The domestic cat has rather poor color vision and only two types of cone cells, optimized for sensitivity to blue and yellowish green; its ability to distinguish between red and green is limited.[71] A response to middle wavelengths from a system other than the rod cells might be due to a third type of cone. This appears to be an adaptation to low light levels rather than representing true trichromatic vision.[72] Cats have a nictitating membrane, allowing them to blink without hindering their vision.
The domestic cat's hearing is most acute in the range of 500 Hz to 32 kHz.[73] It can detect an extremely broad range of frequencies ranging from 55 Hz to 79 kHz, whereas humans can only detect frequencies between 20 Hz and 20 kHz. It can hear a range of 10.5 octaves, compared to about 9 octaves for humans and dogs.[74][75] Its hearing sensitivity is enhanced by its large movable outer ears, the pinnae, which amplify sounds and help detect the location of a noise. It can detect ultrasound, including ultrasonic calls from rodent prey.[76][77] Research has shown that cats have socio-spatial cognitive abilities to creat mental maps of familiar people's locations based on hearing their voices.
Cats have an acute sense of smell, due in part to their well-developed olfactory bulb and a large surface of olfactory mucosa, about 5.8 cm2 (0.90 in2) in area, which is about twice that of humans. [79] Cats and many other animals have a Jacobson's organ in their mouths that is used in the behavioral process of flehmening. It allows them to sense certain aromas in a way that humans cannot. Cats are sensitive to pheromones such as 3-mercapto-3-methylbutan-1-ol,[80] which they use to communicate through urine spraying and marking with scent glands.[81] Many cats also respond strongly to plants that contain nepetalactone, especially catnip, which they can detect at less than one part per billion. [82] About 70–80% of cats are affected by nepetalactone.[83] This response is also produced by other plants, such as silver vine (Actinidia polygama) and the herb valerian; it may be caused by the smell of these plants mimicking a pheromone and stimulating cats' social or sexual behaviors.[84]
There are 48 cat breeds