Albinism

Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and reddish pink or blue eyes.

[3] It is a common misconception that all albino animals have characteristic pink or red eyes (resulting from the lack of pigment in the iris allowing the blood vessels of the retina to be visible); this is not the case for some forms of albinism.

[7][8][6] In plants, albinism is characterised by partial or complete loss of chlorophyll pigments and incomplete differentiation of chloroplast membranes.

Many animal body-parts, such as skin, eyes, feathers, fur, hair, scales and cuticles, contain pigments in specialized cells called chromatophores.

So, "a person or animal with very pale skin, white hair or fur, and pink eyes caused by a medical condition that they were born with"[13] and "a person or animal with white skin and hair and pink eyes"[14] do not include feathers, scales or cuticles of birds, fish and invertebrates, nor do they include plants.

These conditions result from fundamentally different causes to the seven types of oculocutaneous albinism that have been identified in humans (and confirmed in some other animals) and the use of the term "partial albino" is therefore misleading.

[6] One definition states that "albinism, (from the Latin albus, meaning "white"), hereditary condition characterized by the absence of pigment in the eyes, skin, hair, scales, or feathers",[19] however, this does not encompass invertebrates, nor does it include plants.

A clear definition appears to be – "Congenital absence of any pigmentation or colouration in a person, animal, or plant, resulting in white hair and pink eyes in mammals.

The absence of melanin results in abnormal development of eyes and leads to problems with focusing, and depth perception.

Melanosomes block harmful electromagnetic radiation from the sun while allowing beneficial frequencies to enter the body.

[37] Pigmentation disorders such as albinism are occasionally associated with hearing impairments in mice, rats, guinea pigs and cats.

[38] Intentionally bred albinistic strains of some animal species are commonly used as model organisms in biomedical research and also as pets.

Examples include the BALB/c mouse and Wistar and Sprague Dawley rat strains, laboratory rabbits and ferrets.

[39] Some researchers have argued that albino animals are not always the best choice for scientific studies due to the consequences of albinism (e.g. hearing and visual impairments).

[42] Albinism was observed in jungle cats (Felis chaus) and jackals (Canis aureus) along the coastline of the southern Western Ghats (Kerala and Kanyakumari coast, India).

The costs of albinism for marine mammals may include reduced heat absorption in colder waters, poor camouflage from predators, increased sensitivity to sunlight, and impaired visual communication.

[45] Famous albino mammals include Migaloo, a humpback whale living off the coast of Australia; Pinky, a bottlenose dolphin living in and around in Calcasieu Lake, Louisiana; Carolina Snowball, a popular albino bottlenose dolphin displayed at the Miami Seaquarium in the early 1960s; Snowflake, a Barcelona Zoo gorilla, and Mahpiya Ska, (Sioux for White Cloud), a buffalo in Jamestown, North Dakota,[46][47] and inspiration for Herman Melville's novel Moby-Dick, a sperm whale known as Mocha Dick.

Well-known examples are flamingos, which owe their distinct pink colour to the presence of red carotenoids in their natural food.

In birds, albinism has been defined as "a total lack of both melanins in feathers, eyes and skin as a result of an inherited absence of tyrosinase",[18] however, this ignores the effects of other pigments and structural colours.

[18] As with other animals, it has been stated that for fish to be properly described as "albino", they must have a white body and pink or red eyes.

The gross eye morphology, feeding and swimming behaviours between wild-type and albino zebrafish were indistinguishable, except under dim or bright light or low contrast.

Similarly, Mexican blind cave fish (Astyanax mexicanus) do not differ in hearing sensitivity from the normally pigmented and eyed surface-dwelling populations.

[51] The incidence of albinism can be artificially increased in fish by exposing the eggs to heavy metals (e.g. arsenic, cadmium, copper, mercury, selenium, zinc).

[53] Albinism has been reported in hagfish, lampreys, sharks, rays and numerous teleost fishes, e.g. catfishes, grunts or cyprinids.

[63] In Australia, a crocodile believed to be "part-albino" and nicknamed by people in the area as "Michael Jackson", attacked and killed a man.

[69] The albino phenotype of the pond frog (Pelophylax nigromaculatus) has been attributed to one of three mutations that created a dysfunctional tyrosinase.

[70] Albino axolotl (an amphibian) are also used widely in the laboratory as their transparent skin allows observation of the underlying tissues during limb regeneration.

It has been shown that adding astaxanthin to the feed can improve the skin and muscle colour of marine organisms and thereby increase their commercial and ornamental value.

Albinism has frequently occurred in progeny of Black Tartarian, Bing and Hedelfingen varieties of sweet cherry.

[86][unreliable source] Albino animals are often kept as pets, for example, African clawed frog, guinea pigs and peacocks.