Frequently asked questions: can cats see in the dark?
- Before cats became our pets they hunted for their food, mostly during the dusk and dawn hours
- Cats can’t see in absolute darkness, but their night vision is much better than ours, scientists have found. Find out why
Don’t have a word of the day yet? Here’s one: “crepuscular”.
The zoological term classifies animals that are most active around dusk and dawn. Cats, for example, are crepuscular, which explains why you’ll hear them padding about just before morning rolls around, and lazing about for most of the day.
In line with their most active waking hours, cats’ eyes have evolved to suit twilight and its dimmer conditions. After all, it’s when they would have hunted for food for their survival before they were widely domesticated.
Having slit pupils allows cats to dilate their eyes 6mm (¼ inch) more than a human pupil, explains 2006 research from the Irish Veterinary Journal. The pupils in mammals’ eyes work a lot like windows, widening and narrowing in response to light conditions. Cats’ pupils let in more light by dilating 50 per cent more than ours do, hence their rumoured ability to “see in the dark”.
Other aspects of cats’ eyes help them see better in low light. They have large corneas, and there are more of the light-sensing rod cells in the back of cats’ eyes – their retinas – than in ours.
As the Carnegie Museum of Natural History explains, these photoreceptive cells trigger nerve impulses that pass through the optic nerve to the brain, where a visual image is formed. Cats can see better in dim light settings than humans, in part, simply because they have more rod cells, says the journal.
Still, there’s more to this than meets the (human) eye. Playing a big role in cats’ superior lowlight vision is the tapetum lucidum in theirs eyes. A Latin term meaning “shining layer”, the tapetum lucidum is a thin layer of tissue that receives light, converts the light to an electrical signal, and sends this signal to the brain to make sense of the final image.
Since this layer is made of reflective cells containing crystal rods, it doubles as a mirror, bouncing light right back through the retina – giving the eye a second chance to absorb light. Now that’s something that comes in handy when trying to see in the dark.
However, while cats enjoy enhanced vision under low light conditions, 2010 research from the University of Victoria shows they appear to have reduced vision in situations where light is abundant.
Behavioural studies further suggest that feline colour vision isn’t so great, the Irish journal reports.
