Blindness in animals

In general, nocturnal or subterranean animals have less interest in the visual world, and depend on other sensory modalities.

Blindness in animals can be caused be the result of environmental adaptations over time, or due to various conditions of the eyes.

Some species are born without eyes such as the kauaʻi cave wolf spider, olm and the Mexican tetra.

[13] The most complex color vision system in animal kingdom has been found in stomatopods with up to 12 different spectral receptor types which are thought to work as multiple dichromatic units.

[14] Charles Darwin cites moles as an example of mammals that have organs that have become vestigial and are being phased out by natural selection:

The eyes of moles and of some burrowing rodents are rudimentary in size, and in some cases are quite covered by skin and fur.

In South America, a burrowing rodent, the tuco-tuco, or Ctenomys, is even more subterranean in its habits than the mole; and I was assured by a Spaniard, who had often caught them, that they were frequently blind.

(Charles Darwin, The Origin of Species[15])The blind forms of the Mexican tetra have proven popular subjects for scientists studying evolution: A recent study suggests that there are at least two distinct genetic lineages among the blind populations, arguing that these represent a case of convergent evolution.

)[17] [18] The evolution of trichromatic color vision in primates occurred as the ancestors of modern monkeys, apes, and humans switched to diurnal (daytime) activity and began consuming fruits and leaves from flowering plants.