Axanthism is a mutation that interferes with an animal's ability to produce yellow pigment. The mutation affects the amount of xanthophores and carotenoid vesicles, sometimes causing them to be completely absent. [1] Erythrophores and iridophores, which are responsible for red coloration and light reflecting pigments respectively, may also be affected. [2] Axanthism is most obvious in green animals, specifically amphibians, making them appear blue. Green coloration in animals is caused by iridiphores reflecting blue wavelengths of light back through the carotenoids in the xanthophores. [3] In the absence of xanthophores and carotenoids, the blue light is unaltered and reflected back normally. [4] Animals that are normally yellow will appear white if affected with axanthism.
While axanthism commonly makes green animals blue, it can also make the animal gray or even black, making it appear as if the animal has melanism; though they can be distinguished by how axanthic animals are slightly lighter and how melanistic animals produce more melanophores. [5] When iridophores are affected by axanthism, the animal typically becomes duller or darker in coloration due to a lesser amount of light reflected. [2] Typically it is only the skin that is affected, and the eyes still have iridophores.
The opposite of axanthism is xanthochromism, which is an excess of yellow coloration.
There are three basic types of axanthism in amphibians: complete to partial blue coloration, complete or partial gray or dark coloration, and normal coloration with black eyes. [2] These are not distinct categories, and there can be amphibians that have a combination of these. The first one is most common in the family Ranidae, which is also the family that happens to be most commonly affected by axanthism. It is not yet known exactly why axanthism occurs in amphibians and whether it is genetic or environmental. Axanthism seems to be most common in North America, and is more common in Northern regions; there have been over one hundred reports of blue green frogs ( Lithobates clamitans ), but only one is from the southeastern United States. [6] Axanthism is also most common in frogs, with salamanders and newts having almost no cases.
Axanthic individuals are usually at higher risk at predation by sight predators compared to normal amphibians. Axanthism can affect the camouflage and aposematic patterns of amphibians, making these individual stand out more or render their defenses useless. However, individuals that are darker than normal may have an advantage in thermoregulation, which is especially important in ectothermic vertebrates. [7]
Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contrast, have a class of cells called melanocytes for coloration.
Blue-ringed octopuses, comprising the genus Hapalochlaena, are four extremely venomous species of octopus that are found in tide pools and coral reefs in the Pacific and Indian oceans, from Japan to Australia. They can be identified by their yellowish skin and characteristic blue and black rings that can change color dramatically when the animal is threatened. They eat small crustaceans, including crabs, hermit crabs, shrimp, and other small sea animals.
Cranwell's horned frog, also called commonly the Chacoan horned frog, is a terrestrial frog in the family Ceratophryidae. The species is endemic to the dry Gran Chaco region of Argentina, Bolivia, Paraguay and Brazil. It, like other members of its genus, Ceratophrys, is commonly called the Pac-man frog, because of its resemblance to the video game character of the same name. Most adult specimens range from 8–13 cm (3.1–5.1 in) long and can weigh up to 0.5 kg (1.1 lb).
The leopard gecko or common leopard gecko is a ground-dwelling lizard native to the rocky dry grassland and desert regions of Afghanistan, Iran, Pakistan, India, and Nepal. The leopard gecko has become a popular pet, and due to extensive captive breeding it is sometimes referred to as the first domesticated species of lizard.
The alpine salamander is a black salamander that can be found in the French Alps, and through the mountainous range in Europe. It is a member of the genus Salamandra. Their species name, atra, may be derived from the Latin ater, meaning dull black. The salamanders' coloration has evolved over time, as some species are completely monochrome black and others have yellow spotting and marks. Their life expectancy is at least 10 years. There are four subspecies of the alpine salamander, with varied distribution and physical coloration. Unlike other salamanders, whose larvae are developed in water, the alpine salamander and its subspecies are a fully terrestrial species in life and gestation. They give birth to live young.
Agalychnis callidryas, commonly known as the red-eyed tree frog, is a species of frog in the subfamily Phyllomedusinae. It is native to forests from Central America to north-western South America. This species is known for its bright coloration, namely its vibrant green body with blue and yellow stripes on the side. It has a white underside, brightly red and orange colored feet, and is named after its distinctive bright red eyes.
The Pacific tree frog, also known as the Pacific chorus frog, has a range spanning the Pacific Northwest, from Northern California, Oregon, and Washington to British Columbia in Canada and extreme southern Alaska. They live from sea level to more than 10,000 feet in many types of habitats, reproducing in aquatic settings. They occur in shades of greens or browns and can change colors over periods of hours and weeks.
The spotted grass frog or spotted marsh frog is a terrestrial frog native to Australia. It is distributed throughout all of New South Wales and Victoria, eastern South Australia, the majority of Queensland, and eastern Tasmania. It is also naturalised in Western Australia, having been unintentionally introduced at Kununurra in the 1970s, apparently during the relocation of several hundred transportable homes from Adelaide.
The little grass frog is a species of chorus frog endemic to the Southeastern United States. It is currently the smallest North American anuran and occurs in a wide variety of ephemeral and semi-permanent wetlands.
Biological pigments, also known simply as pigments or biochromes, are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments. Many biological structures, such as skin, eyes, feathers, fur and hair contain pigments such as melanin in specialized cells called chromatophores. In some species, pigments accrue over very long periods during an individual's lifespan.
Autumn leaf color is a phenomenon that affects the normally green leaves of many deciduous trees and shrubs by which they take on, during a few weeks in the autumn season, various shades of yellow, orange, red, purple, and brown. The phenomenon is commonly called autumn colours or autumn foliage in British English and fall colors, fall foliage, or simply foliage in American English.
Cruziohyla craspedopus, the fringed leaf frog or fringed tree frog, is a species of frog in the subfamily Phyllomedusinae. It is found in the Amazonian lowlands in Brazil, Colombia, Ecuador, and Peru, and possibly in Bolivia.
Animal colouration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. Some animals are brightly coloured, while others are hard to see. In some species, such as the peafowl, the male has strong patterns, conspicuous colours and is iridescent, while the female is far less visible.
Neocaridina davidi is a freshwater shrimp originating from eastern China and northern Taiwan and introduced in the rest of Taiwan, Japan, and Hawaii, which is commonly kept in aquaria. The natural coloration of the shrimp is green-brown. There are a wide range of colors including red, yellow, orange, green, blue, violet, black, etc.; however, the red morph is more frequently sold. The density of coloration on adult shrimp, dependent on breeding, determines their sale price and "quality" (grading). This "quality" is purely aesthetic, as the size, behavior and other characteristics of the animal are more or less equal across varieties. Full-grown shrimp reach about 4 centimetres (1.6 in) long. They prefer clean water, with a pH of 6.5-8, and a temperature of 14–29 °C (57–84 °F) They are most comfortable at 22 °C (72 °F). N. davidi shrimp are omnivores that may live 1–2 years. These shrimps have previously been classified as Neocaridina heteropoda and Neocaridina denticulata sinensis, however are now known as Neocaridina davidi which is based on the oldest known published description of the species.
Cuttlefish, or cuttles, are marine molluscs of the order Sepiida. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of buoyancy.
Amelanism is a pigmentation abnormality characterized by the lack of pigments called melanins, commonly associated with a genetic loss of tyrosinase function. Amelanism can affect fish, amphibians, reptiles, birds, and mammals including humans. The appearance of an amelanistic animal depends on the remaining non-melanin pigments. The opposite of amelanism is melanism, a higher percentage of melanin.
Structural coloration in animals, and a few plants, is the production of colour by microscopically structured surfaces fine enough to interfere with visible light instead of pigments, although some structural coloration occurs in combination with pigments. For example, peacock tail feathers are pigmented brown, but their microscopic structure makes them also reflect blue, turquoise, and green light, and they are often iridescent.
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. Individuals with the condition are referred to as albinos.
Pain is an aversive sensation and feeling associated with actual, or potential, tissue damage. It is widely accepted by a broad spectrum of scientists and philosophers that non-human animals can perceive pain, including pain in amphibians.
Fish coloration, a subset of animal coloration, is extremely diverse. Fish across all taxa vary greatly in their coloration through special mechanisms, mainly pigment cells called chromatophores. Fish can have any colors of the visual spectrum on their skin, evolutionarily derived for many reasons. There are three factors to coloration, brightness, hue, and saturation. Fish coloration has three proposed functions: thermoregulation, intraspecific communication, and interspecific communication. Fishes' diverse coloration is possibly derivative of the fact that "fish most likely see colors very differently than humans".
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