OK, so it's like this:
Wikipedia wrote:Animals that are dichromats
It is more informative to use situations where less than the total visual system is operating when studying about vision. For example, a system by which cones are the sole visual receptors could be used. This is rare in humans but certain animals possess this trait and this proves useful in understanding the concept of dichromacy.[6]
While their Triassic ancestors were trichromatic,[7] placental mammals are as a rule dichromatic;[8] the ability to see long wavelengths (and thus separate green and red) was lost in the ancestor of placental mammals, though it is believed to have been retained in marsupials, where trichromatic vision is widespread.[9] Recent genetic and behavioral evidence suggests the South American marsupial Didelphis albiventris is dichromatic, with only two classes of cone opsins having been found within the genus Didelphis.[10] Dichromatic vision may improve an animal's ability to distinguish colours in dim light;[11] the basically nocturnal nature of mammals, therefore, may have led to the evolution of dichromacy as the basal mode of vision in placental animals.[12]
The exceptions to dichromatic vision in placental mammals are primates closely related to humans, which are usually trichromats, and sea mammals (both pinnipeds and cetaceans) which are cone monochromats.[13] New World Monkeys are a partial exception: in most species, males are dichromats, and about 60% of females are trichromats, but the owl monkeys are cone monochromats, and both sexes of howler monkeys are trichromats.[14][15][16][17]
[...]
Animals that are monochromats
It used to be confidently claimed that most mammals other than primates were monochromats. In the last half-century, however, evidence of at least dichromatic color vision in a number of mammalian orders has accumulated. While typical mammals are dichromats, with S and L cones, two of the orders of sea mammals, the pinnipeds (which includes the seal, sea lion, and walrus) and cetaceans (which includes dolphins and whales) clearly are cone monochromats, since the short-wavelength sensitive cone system is genetically disabled in these animals.[dubious – discuss] The same is true of the owl monkeys, genus Aotus.
Researchers Leo Peichl, Guenther Behrmann, and Ronald H. H. Kroeger report that of the many animal species studied, there are three carnivores that are cone monochromats: raccoon, crab-eating raccoon and kinkajou and a few rodents are cone monochromats because they are lacking the S-cone.[12] These researchers also report that the animal's living environment also plays a significant role in the animals' eye sight. They use the example of water depth and the smaller amount of sunlight that is visible as one continues to go down. They explain it as follows, "Depending on the type of water, the wavelengths penetrating deepest may be short (clear, blue ocean water) or long (turbid, brownish coastal or estuarine water.)" [12] Therefore, the variety of visible availability in some animals resulted in them losing their S-cone opsins.
Both rod and cone monochromacy occur as very rare forms of color blindness in humans. Rod monochromacy, or maskun, is the more common of the two. The majority of people described as color blind, however, are either dichromats or anomalous trichromats.
Also this is interesting:
If that's typical of carnivora, and it probably is, color TV looks pretty odd because it doesn't have an ultraviolet phosphor. But it will look different from black-and-white.
So, I guess I won't have Cinnamon say anything humorous about why it's called a black-and-white TV show.
