Cats are known for having excellent night vision. Their ability to see in low light conditions far surpasses that of humans. But does this mean cats can see the color black in total darkness? The answer is a bit more complex than a simple yes or no. In this article, we will explore how cat eyes work, how they see in the dark, and whether they can discern the color black when there is no light available.
How Cat Eyes Work
Cats, like many other predators, have eyes that are specialized for hunting. Their eyes have a larger cornea and pupil size relative to their retina. This allows more light to enter the eye and illuminates their vision in dark environments. Cats also have a reflective layer behind the retina called the tapetum lucidum. This layer acts like a mirror, reflecting light back through the retina a second time, giving cats a “second chance” to register visual information.
Other adaptations include:
More rods than cones
The feline retina contains a high concentration of rod photoreceptor cells and relatively few cone cells. Rods detect shades of gray and are more sensitive to dim light. Cones detect color and require more intense light to function. With more rods, cats can pick up more details in near-darkness.
Vertical slit pupils
Cats have vertical slit shaped pupils that can open very wide to let in additional light. The shape and versatility of the pupil optimize light capture.
Increased density of rods
Cats not only have more rods in their retina but the rods they do have are packed more densely and have a different structure. This further boosts their ability to capture light photons.
Thanks to these specialized adaptations, cats have excellent night vision and can see well in light levels 6 times lower than the threshold of human vision. But seeing well in the dark and seeing color in total darkness are two different things.
How Cats See Color
Cats do have some limited color vision, thanks to the presence of cone cells. However, they have far fewer cones compared to humans. Humans have 3 different types of cones, allowing us to see red, green and blue light. Cats only have 2 types of cones, responsive to blue and green light. This means cats can distinguish between blue/green and yellow/red but see fewer shades than we do.
Essentially cats have a form of red-green color blindness. Their world consists of mainly blues, grays and yellows. To see any colors at all, cats need ample bright light. In low light, cone cells don’t receive enough activation to detect color. Rod cells take over, providing black, white and gray images.
So while cats can see some color, they need decent illumination. In darkness, color vision disappears.
Do Cats See Black in the Dark?
Based on the structure of feline eyes and how they process color, it’s clear cats cannot truly distinguish the color black when there is no light available. In pitch blackness, cat eyes function using rod cells alone. Rods cannot discern colors, only shades of brightness and contrast.
So theoretically, cats would not see true “black” in complete darkness. They rely on very dim light reflections to create visual contrasts in monochrome. The darker shapes and figures cats make out in the dark are more akin to very dark gray. Their vision would consist only of a range of gray tones in the absence of light.
However, some experiments on cats and color perception suggest cats may retain some very basic color discrimination even in low light. While they cannot see full spectrum color, they seem to register familiar objects as having consistent color.
For example, cats may see their food bowl as blue and their bed as red, even in near darkness when humans would see everything in gray tones. This rudimentary chromatic sense likely helps cats recognize important objects and environments when lighting conditions change dramatically.
So cats may maintain a primitive color map based on memory and association that functions below the threshold of actual color vision. In this sense, cats can discern a black object as subjectively “black” by remembering it has that color, even when only seeing it in grayscale.
Why Can Humans See Some Colors in the Dark?
Humans also lose color vision in low light. Cones stop working, and rods provide black and white vision. Yet some humans report still seeing traces of reds and oranges, even in nearly pitch-black conditions. Why is that?
The reason may be the Purkinje effect. This phenomenon, named after the Czech anatomist who studied it in the 1800s, refers to how the eye changes spectral sensitivity from photopic (well-lit) vision to scotopic (low-light) vision.
When transitioning from photopic to scotopic vision, the peak light wavelength we are most sensitive to shifts from green (around 555 nm) to blue (around 507 nm). Our eyes become much more sensitive to shorter wavelengths.
This means that when light levels are very low, the rods are predominantly detecting blue hues. Reds and oranges, being longer wavelengths, fade out first. The extra sensitivity to blue is likely what creates the perceived loss of reds and oranges in dark environments.
Cats would experience a similar Purkinje shift. But given their limited color vision to begin with, it simply translates to a loss of color perception altogether.
Do Cats Rely on Senses Other Than Vision in the Dark?
Cats definitely take advantage of their excellent night vision when hunting and navigating in low light. But they also utilize other senses to maximize their awareness when vision becomes limited. Their key supplemental senses are:
Hearing
Cat ears contain 32 muscles to control their position and sensitivity. By swiveling their ears in different directions, cats can pinpoint the source of faint sounds very accurately. Large movable ears give cats superb directional hearing.
Smell
Cats have an extremely advanced sense of smell. They have around 200 million odor-sensitive cells in their nose, versus only 5 million in humans. Their sense of smell likely becomes more important for close range identification when vision is obscured.
Whiskers (Vibrissae)
Cat whiskers are specialized, sensitive tactile hairs that provide spatial, navigational and textural information. Whisking helps cats avoid obstacles and gauge openings in low light. The whisker tips have numerous nerve endings that detect even minute vibrations in the air.
Touch
Cats have very sensitive paws that help them tread silently. The paws may also supplement vision by perceiving textures and surfaces, much like whiskers do.
So while cats may not distinctly see “black” per se, their total sensory integration allows them to adeptly perceive their surroundings even in pitch darkness. They seem to manage just fine without literally seeing the color black.
Do Cat Eyes Glow in the Dark?
One iconic trait of cats is the eerie glow of their eyes at night. This shining effect is another visual adaptation that improves their ability to see in the dark.
In daylight, the slit pupil closes to a thin vertical line and the tapetum lucidum membrane is not visible. But in dark environments, the pupil dilates fully, exposing the reflective tapetum lucidum behind it.
When a direct light source like a flashlight shines into the cat’s eye, the light reflects off the tapetum lucidum, creating a bright flash. This is the “glowing eyes” effect. It serves to improve the ability of rod and cone cells to absorb weak light signals under low light conditions.
So cats do not generate their own glow. The eyes simply reflect back a brilliant flash thanks to the mirror-like membrane. This helps compensate for cats not being able to see bright color when it’s dark.
Conclusion
To summarize, cats are not capable of seeing the true color black when there is no light available to stimulate their vision. In total darkness, they rely on rods to deliver a grayscale view of the world. However, they may retain some rudimentary chromatic perception through memory and association with familiar objects.
While unable to see black, their well-adapted eyes allow cats to visualize shapes, textures and movement exquisitely well in the dark. With the added input from their other finely-tuned senses, cats can hunt and navigate perfectly well in the absence of light. So not being able to distinguish the actual color black does not handicap cats in the least in terms of their ability to perform in low light environments.