Some species also possess iridophores or leucophores, which do not contain true pigments, but light-reflective structures that give iridescence. An extremely uncommon type of chromatophore, the cyanophore, produces a very vivid blue pigment. Amelanism in fishes, amphibians, reptiles and birds has the same genetic etiology as in mammals: loss of tyrosinase function. However, due to the presence of other pigments, other amelanistic vertebrates are seldom white and red-eyed like amelanistic mammals.
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"Albino" California kingsnake Many reptiles labeled as albino are, in fact, not completely lacking in all colour pigments. They are actually amelanistic, not albino. Reptiles often possess at least two pigments. Among the most common are xanthin (yellow) and erythrin (red).
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As with reptiles, many amphibians labeled as albino are, in fact, not completely lacking in all colour pigments. They are actually amelanistic, not albino. Amphibians have six types of chromatophore in their skin, i.e. melanophores, xantophores, erythrophores, leucophores, cyanophores and iridophores.
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Certain alleles of this gene, TYR, at the Color locus, cause oculocutaneous albinism type 1 in humans and the familiar red-eyed albino conditions in mice and other mammals. Amelanistic ("lutino") cockatiels retain their carotenoid-based red and yellow pigments.
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Langhammer (1982) reports that matings from these albino forms with red and yellow pigments produce 25% wild coloured offspring and 75% albino fry. The albino fry were themselves divided into completely amelanistic forms, and forms which retained colouration of their parents.
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An amelanistic amphibian therefore, may still have various pigmentation. The incidence of albinism in frogs, salamanders, and newts is relatively higher than other taxa. It has been estimated that one in four hundred of these animals is albino. When albino tadpoles hatch, they are almost transparent.
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The only pigments that mammals produce are melanins. For a mammal to be unable to chemically manufacture melanin renders it completely pigmentless. This condition is more commonly called albinism. Amelanistic mammals have white hair, pink skin, and eyes that have a pink, red, or violet appearance.
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An amelanistic reptile therefore, may still have pale yellow, orange, or red pigmentation. The California Academy of Science, in the Steinhart Aquarium, as of 2015, has on display an albino American alligator named "Claude". The alligator is partially blind because of lack of pigment in its eyes.The Swamp.
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P. picta naturally occurs as a brown lizard with black markings. Some individuals may also have a white dorsal stripe. In captivity, there are several color phases available including hypo, orange, anerythristic, and amelanistic (yellow). They usually reach a size of , with some well-cared-for males reaching .
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Melanin is also present in the inner ear, and is important for the early development of the auditory system. Melanin is also found in parts of the brain and adrenal gland. The normal zebrafish embryo, above, shows the migration and maturation of melanocytes. The amelanistic embryo, below, has melanocytes but no melanin.
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An albino Burmese python. Crutchfield is well known for his work with reptiles. In 1981, he purchased the first documented amelanistic Burmese python from a Thai dealer, for US$21,000, after seeing the animal featured in a 1981 edition of National Geographic magazine. He then partnered with Bob Clark to produce the first captive-bred albino Burmese pythons from that animal.
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In many mammals, variation in the level of ASP switches melanocytes between eumelanin and phaeomelanin production, resulting in coloured patterns. Amelanistic laboratory mice, such as these, have no pigment in their skin, hair, or eyes. Their eyes are reddish. Melanocytes, and the parallel melanophores found in fishes, amphibians, and reptiles, are derived from a strip of tissue in the embryo called the neural crest.
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" This definition of albinism in mice – the inability to make tyrosinase – is extended to other mammals. While mammals derive their pigments only from melanins, fish, reptiles and birds rely on a number of pigments apart from melanins: carotenoids, porphyrins, psittacofulvins, pterins, etc. Most commonly, reptiles with a condition homologous to human OCA1A retain their reddish and orangish hues. As a result, birds and reptiles without the ability to manufacture tyrosinase are more accurately described as "amelanistic.
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