>>5051112
Deer can also see ultraviolet.
"The results regarding the UV capabilities of deer were equally fascinating. Our results confirmed that, unlike humans, deer lack a UV filter in their eye. In humans, this filter blocks about 99 percent of damaging UV light from entering the eye. It also functions much like a pair of yellow shooting glasses and allows us to focus more sharply on fine detail. The trade-off is a loss of sensitivity to short wavelength colors, especially in the UV spectrum. Because deer do not have a UV filter, they see much better in the UV spectrum but lack the ability to see fine detail. This helps explain why deer often move their head from side to side when they encounter a hunter."
https://deerassociation.com/hunters-guide-deer-vision/
Humans can see UV too when the lens of the eye is removed. But because we live far longer than deer we evolved a lens that blocks UV from entering the eye. Otherwise we would all be going blind in our early 20's.
"Subjects with aphakia are missing a lens, so UVA light can reach the retina and excite the visual opsins; this expands the visible range and may also lead to cyanopsia."
https://en.wikipedia.org/wiki/Visible_spectrum
