There are many animal species that completely blind, and they lead a normal life without the need of eyes because they are adapted to their surroundings. Typically, these animals live in an environment where eyes are not necessary such as caves or environments of total darkness where they have adapted to the life of darkness, although some may have eyes with poor vision.
Primates and humans possess unique dichromatic color vision which enables them to differentiate between colors such as violet, green, and yellow-green, which are the short wave, medium wave, and long wave respectively. On the other hand, other animals that are not primates possess two receptor color perception systems which allow them for a dichromatic color vision. While other mammals, for instance, the Marine mammals are monochromats. Animals such as birds and tropical fish possess a more complex color vision system than humans because ultraviolet light plays a role in their color perception. Evidence suggests that birds such as pigeons are Pentagromats and some species of butterflies are believed to have tetrachromatic color vision, although they have six photoreceptors. The most intricate color vision structure in the animal kingdom are found among the stomatopods which have twelve different optical receptors which are thought to work in multiples of dichromatic units.
The animals that live in caves are known as troglobites, and they are similar to those living in the deep seas which live in perpetual darkness and are therefore blind without the need of eyes, and they have other specialized senses that compensate for the lack of eyes.
Star-nosed mole (Condylura cristata) refers to small moles inhabiting wet habitats, particularly in North America. They are characterized by the 22 pink fleshy appendages around its snout used for touching. The organ has more than 25,000 tiny touch receptors called Eimer’s organ, and the animal uses to feel its way around. With the help of the organ, the mole can perfectly detect vibrations of seismic waves. Other mole species have the organ as well, but it is not specialized compared to that of the Star-nosed mole. The mole is typically blind, and the organ had all along been suspected to be used by the mole to detect its environment. The mole lives in total darkness, and therefore, it remains heavily reliant on the information processed by the specialized organ to identify and find their prey without using sight. The organ has a high reaction speed and high sensitivity, and in about eight milliseconds the mole will have decided whether the prey is edible or not, and this is among the fastest response to stimuli found in the kingdom Animalia. The mole has earned itself a title in the Guinness book as the fastest foraging animal in the world.
Sinopoda scurion refers to the spider which was discovered in 2012 in Laos, and it is the first huntsman spider without eyes. The spider has legs which measure about 2.4 inches and the body length of about 0.47 inches. The huntsman spiders have more than 1,000 species, and most of these species have eyes. The Sinopoda scurion does not have eyes because they live permanently in dark caves where eyes are not required for any purpose like hunting. The spider gets its name from Scurion, which is a Swiss company making headlines used by cavers.
Thaumastochelidae refers to a family of deep-sea lobsters which is made up of five different species. The species was discovered during the 10-year census of marine life which was a worldwide network of researchers for more than 80 different countries working to explain and assess the diversity, abundance, and distribution of marine life in all the oceans around the world. The family of thaumastochelidae is recognized because of their peculiar shape which has a large cheliped with elongated fingers which are typically four times as long as the palm. They are also characterized by the slender, with alternating small and large teeth. The eyes are completely absent in the family of thaumastochelidae.
The blind cave fish is also referred by several other names such as the Mexican tetra among others, and it is a freshwater fish which is common in parts of eastern and central Mexican regions. The fish can grow to 4.7 inches long. The blind cavefish do not have eyes, and its color is pinkish white, and it resembles an albino. The fish is popular with aquarists. In its native habitat, the fish spends most of its time in the sandy or rocky bottoms in their natural habitats. These fish types are found in the tropical climate, and they prefer waters with a pH of between 6.5 and 8.0 and temperatures lying between 68 and 77 degrees Fahrenheit. During winter, most of the fish migrate to warm waters, and they prey on insects, crustaceans, and annelids, while those in captivity are omnivorous. These fish can find their way around using their lateral lines, which are highly sensitive to fluctuation in water pressure.
Olms (Proteus anguinus) refers to an aquatic salamander which belongs to the Proteidae family, and they live exclusively in caves. This species breed, sleep and eat underwater, and they are endemic to water that flows underground particularly southeastern part of Europe such as in Southern Slovenia, Croatia, Bosnia and Herzegovina, and parts of Italy. The cave salamander has adapted to the life of complete darkness in the underground habitats. Their eyes are undeveloped, and they are blind, while other senses such as hearing and smell are highly developed. The fish lacks pigmentation in their skin and has three toes on its forelimbs, while the hind feet have two toes.
Almost all animals are born blind to prevent the young ones from wandering off from their parents. The phrase that certain animals are born blind could refer to them being born having their eyes closed, and their eyelids are fused together, although they open later. For instance, rabbits and humans are born with the eyelids fused together but shortly after they open up. This phenomenon is different from animals which are truly blind throughout their lives.