What Is an Axolotl?

As legend has it, the axolotl is the Aztec god of fire and lightning, Xolotl, which disguised himself as a salamander to avoid being sacrificed. But these Mexican amphibians are impressive enough on their own, with the ability to regenerate lost limbs and stay young throughout their lives.

Their youthful traits include feathery gills sprouting from their heads like a mane, webbed feet, a dorsal fin that runs down the length of their body, and a tail. Axolotls suck in their prey, which includes crustaceans, mollusks, insect eggs and small fish.

Yet in most countries, the species cannot be traded across international borders, in part due to the concern that they’ll be poached from the wild. The amphibians once inhabited the high-altitude lakes around Mexico City, but habitat degradation has limited them to only in a few inland canals in the area. Axolotls, which are solitary creatures, reach sexual maturity at a year old, and their spawning season in the wild is in February .

Males seek out females, possibly using pheromones, and perform a courtship “hula” dance, shaking his tail and lower body. The male then deposits spermatophores, or sperm packets, on the lake floor, which the female picks up with her cloaca, a body cavity, which then fertilizes her eggs. Females can lay up to a thousand eggs (though the average is about 300) on plant material or rocks, which protects them from predators.

Because their native lakes never dry up, as is the case for many other water bodies, axolotls didnt have to trade in their aquatic traitssuch as a tadpole-like tailfor terrestrial ones, such as legs. Development for tourism and residential housing, in addition to agricultural and industrial pollution, has drastically reduced the species population. Some travel companies offer tours of these gardens, whose proceeds support axolotl conservation efforts in the area.

The word axolotl is thought to roughly translate to water monster in the ancient Aztec language Nahuatl.

Are axolotls good pets?

Axolotls are large, adorable salamanders that are native to Mexico. Though not as common as snakes or large lizards, they have a growing fan base in the exotic pet community. … Hardy and easy to care for, axolotls are great pets for people who may not have a lot of experience with exotic animals.

What do axolotls turn into?

An axolotl is a type of salamander, which is an amphibian. … The axolotl is unusual in that it doesn’t undergo a metamorphosis and develop lungs. Instead, axolotls hatch from eggs into a juvenile form that grows to become its adult form. Axolotls keep their gills and permanently reside in the water.

Can you hold an axolotl?

While axolotls are relatively hardy to slight fluctuations in their environment, they also have delicate, soft bodies with permeable skin. In fact, most of their body is made of cartilage rather than bone. That means they should not be handled unless absolutely necessary.

Is Axolotl a fish?

Axolotl is a species of salamander with a very unique genetic makeup. … Commonly mistaken for fish, axolotls are unique among the amphibian family in that they spend their entire lives in water. Indeed, axolotls are sometimes known as Mexican walking fish, on account of their appearance and adopted habitat.

axolotl, (Ambystoma mexicanum), salamander of the family Ambystomatidae (order Caudata), notable for its permanent retention of larval features, such as external gills. The species is found only in Lake Xochimilco, within Mexico City, where it is classified as a critically endangered species. The name axolotl is also applied to any full-grown larva of Ambystoma tigrinum (tiger salamander) that has not yet lost its external gills.

The axolotl (/ksltl/; from Classical Nahuatl: xltl [aolot] (listen)), Ambystoma mexicanum,[2] is a paedomorphic salamander related to the tiger salamander.[2][3][4] The species was originally found in several lakes, such as Lake Xochimilco underlying Mexico City.[1] Axolotls are unusual among amphibians in that they reach adulthood without undergoing metamorphosis. Instead of taking to the land, adults remain aquatic and gilled.

Axolotls should not be confused with the larval stage of closely related tiger salamander species ( A. tigrinum ), which are widespread in much of North America and occasionally become paedomorphic. ), fully aquatic salamanders from a different family that are not closely related to the axolotl but bear a superficial resemblance.

Axolotls possess features typical of salamander larvae, including external gills and a caudal fin extending from behind the head to the vent. [10][11] External gills are usually lost when salamander species mature into adulthood, although the axolotl maintains this feature. Males are identified by their swollen cloacae lined with papillae, while females are noticeable for their wider bodies full of eggs.

Three pairs of external gill stalks (rami) originate behind their heads and are used to move oxygenated water. The external gill rami are lined with filaments (fimbriae) to increase surface area for gas exchange. The primary method of feeding is by suction , during which their rakers interlock to close the gill slits.

External gills are used for respiration, although buccal pumping (gulping air from the surface) may also be used to provide oxygen to their lungs. Axolotls displaying variations in colorAxolotls have four pigmentation genes; when mutated they create different color variants. [14] In addition, there is wide individual variability in the size, frequency, and intensity of the gold speckling and at least one variant that develops a black and white piebald appearance on reaching maturity.

Because pet breeders frequently cross the variant colors, double homozygous mutants are common in the pet trade, especially white/pink animals with pink eyes that are double homozygous mutants for both the albino and leucistic trait. Axolotls also have some limited ability to alter their color to provide better camouflage by changing the relative size and thickness of their melanophores. The axolotl is currently on the International Union for Conservation of Nature’s annual Red List of threatened species.

Today, the axolotl is still used in research as a model organism , and large numbers are bred in captivity. They are especially easy to breed compared to other salamanders in their family, which are rarely captive-bred due to the demands of terrestrial life. One attractive feature for research is the large and easily manipulated embryo , which allows viewing of the full development of a vertebrate.

The feature of the axolotl that attracts most attention is its healing ability: the axolotl does not heal by scarring and is capable of the regeneration of entire lost appendages in a period of months, and, in certain cases, more vital structures, such as tail, limb, central nervous system, and tissues of the eye and heart. They can also readily accept transplants from other individuals, including eyes and parts of the brainrestoring these alien organs to full functionality. In some cases, axolotls have been known to repair a damaged limb, as well as regenerating an additional one, ending up with an extra appendage that makes them attractive to pet owners as a novelty.

It is believed that during limb generation, axolotls have a different system to regulate their internal macrophage level and suppress inflammation , as scarring prevents proper healing and regeneration. An axolotl undergoing metamorphosis experiences a number of physiological changes that help them adapt to life on land. These include increased muscle tone in limbs, the absorption of gills and fins into the body, the development of eyelids, and a reduction in the skin’s permeability to water, allowing the axolotl to stay more easily hydrated when on land.

Sirens and Necturus are other neotenic salamanders, although unlike axolotls, they cannot be induced to metamorphose by an injection of iodine or thyroxine hormone. Six adult axolotls (including a leucistic specimen) were shipped from Mexico City to the Jardin des Plantes in Paris in 1863. Unaware of their neoteny, Auguste Dumril was surprised when, instead of the axolotl, he found in the vivarium a new species, similar to the salamander.

[ citation needed ] Vilem Laufberger in Prague used thyroid hormone injections to induce an axolotl to grow into a terrestrial adult salamander. Neoteny has been observed in all salamander families in which it seems to be a survival mechanism, in aquatic environments only of mountain and hill, with little food and, in particular, with little iodine. In this way, salamanders can reproduce and survive in the form of a smaller larval stage, which is aquatic and requires a lower quality and quantity of food compared to the big adult, which is terrestrial.

If the salamander larvae ingest a sufficient amount of iodine, directly or indirectly through cannibalism , they quickly begin metamorphosis and transform into bigger terrestrial adults, with higher dietary requirements. The axolotl is a popular exotic pet like its relative, the tiger salamander ( Ambystoma tigrinum ). As for all poikilothermic organisms, lower temperatures result in slower metabolism and a very unhealthily reduced appetite.

[40] In captivity, axolotls eat a variety of readily available foods, including trout and salmon pellets, frozen or live bloodworms , earthworms , and waxworms . If gravel (common in aquarium use) is used, it is recommended that it consist of smooth particles of a size small enough to pass through the digestive tract. [43] One guide to axolotl care for laboratories notes that bowel obstructions are a common cause of death, and recommends that no items with a diameter below 3 cm should be available to the animal.

In 2020, it was announced that the axolotl will be featured on the new design for Mexico’s 50- peso banknote, along with images of maize and chinampas . ), “Functional morphology of gills in larval amphibians” , Respiration and metabolism of embryonic vertebrates: Satellite Symposium of the 29th International Congress of Physiological Sciences, Sydney, Australia, 1983 , Perspectives in vertebrate science, Dordrecht: Springer Netherlands, pp. ^ a b Safi, Rachid; Bertrand, Stphanie; Marchand, Oriane; Duffraisse, Marilyne; de Luze, Amaury; Vanacker, Jean-Marc; Maraninchi, Marie; Margotat, Alain; Demeneix, Barbara; Laudet, Vincent (2004-02-01).

“The Axolotl (Ambystoma mexicanum), a Neotenic Amphibian, Expresses Functional Thyroid Hormone Receptors” . “Vision and the skin camouflage reactions of Ambystoma larvae: the effects of eye transplants and brain lesions”. “A review of the theories of vertebrate neurulation and their relationship to the mechanics of neural tube birth defects” .

“Modulating the immune response and the pericardial environment with LPS or prednisolone in the axolotl does not change the regenerative capacity of cryoinjured hearts” .

Forget anything you thought you knew about unusual creatures, because were here to introduce one of the weirdest in the natural world: the axolotl. This truly unique creature, a member of the salamander family, is commonly referred to as the walking fish and youll soon figure out why.

Size 15-45 centimetres Weight 50-250 grams Lifespan 10-15 years Colour and characteristics several known pigmentation types, including brown, black, albino, grey and pale pink; external gill stalks and a caudal dorsal fin as a result of neoteny Wild population 700-1,200 approx. Several axolotl pens have been placed in strategic positions around Mexico Citys canals, offering shelter to the animals, while biologists have started working on a project to reintroduce lab-bred individuals back into Xochimilco as a means of bolstering numbers and encouraging natural breeding.

Should an animal lose a foot, for example, theyre able to regenerate the limb in a relatively short space of time something which scientists believe could hold great biological value for human medicine and the treatment of certain degenerative diseases. And while there are still huge numbers of axolotls in captivity, scientists are concerned that inbreeding is impacting their long-term health and genetic characteristics effectively weakening their value from a biological standpoint.

Axolotl

TheAxolotls should not be confused with the larval stage of closely related tiger salamander species (As of 2020extinction

Description[edit]

A sexually mature adult axolotl, at age 18–26 months, ranges in length from 15 to 45 cm (6 to 18 in), although a size close to 23 cm (9 in) is most common and greater than 30 cm (12 in) is rare. Axolotls possess features typical of salamander larvae, including external gills and a caudal fin extending from behind the head to the vent.Their heads are wide, and their eyes are lidless. Their limbs are underdeveloped and possess long, thin digits. Males are identified by their swollen cloacae lined with papillae, while females are noticeable for their wider bodies full of eggs. Three pairs of external gill stalks (rami) originate behind their heads and are used to move oxygenated water. The external gill rami are lined with filaments (fimbriae) to increase surface area for gas exchange.Axolotls have barely visible vestigial teeth, which develop during metamorphosis. The primary method of feeding is by suction, during which their rakers interlock to close the gill slits. External gills are used for respiration, although buccal pumping (gulping air from the surface) may also be used to provide oxygen to their lungs.Axolotls have four pigmentation genes; when mutated they create different color variants. The normal wild-type animal is brown/tan with gold speckles and an olive undertone. The five more common mutant colors are leucistic (pale pink with black eyes), golden albino (golden with gold eyes), xanthic (grey with black eyes), albino (pale pink/white with red eyes) in which is more common in axolotls than some other creatures and melanoid (all black/dark blue with no gold speckling or olive tone).

Habitat and ecology[edit]

The axolotl is only native to the freshwater of Lake Xochimilco and Lake Chalco in the Valley of Mexico. Lake Chalco no longer exists, having been drained as a flood control measure, and Lake Xochimilco remains a remnant of its former self, existing mainly as canals. The water temperature in Xochimilco rarely rises above 20 °C (68 °F), though it may fall between 6 and 7 °C in the winter, and perhaps lower.Surveys in 1998, 2003, and 2008 found 6,000, 1,000, and 100 axolotls per square kilometer in its Lake Xochimilco habitat, respectively.The wild population has been put under heavy pressure by the growth of Mexico City. The axolotl is currently on the International Union for Conservation of Nature’s annual Red List of threatened species. Non-native fish, such as African tilapia and Asian carp, have also recently been introduced to the waters. These new fish have been eating the axolotls’ young, as well as their primary source of food.Axolotls are members of the tiger salamander, orThe axolotl is carnivorous, consuming small prey such as molluscs,

Use as a model organism[edit]

Today, the axolotl is still used in research as a model organism, and large numbers are bred in captivity. They are especially easy to breed compared to other salamanders in their family, which are rarely captive-bred due to the demands of terrestrial life. One attractive feature for research is the large and easily manipulated embryo, which allows viewing of the full development of a vertebrate. Axolotls are used in heart defect studies due to the presence of a mutant gene that causes heart failure in embryos. Since the embryos survive almost to hatching with no heart function, the defect is very observable. The axolotl is also considered an ideal animal model for the study of neural tube closure due to the similarities between human and axolotl neural plate and tube formation; the axolotl‘s neural tube, unlike the frog’s, is not hidden under a layer of superficial epithelium.

Regeneration[edit]

The feature of the axolotl that attracts most attention is its healing ability: the axolotl does not heal by scarring and is capable of the regeneration of entire lost appendages in a period of months, and, in certain cases, more vital structures, such as tail, limb, central nervous system, and tissues of the eye and heart.It is believed that during limb generation, axolotls have a different system to regulate their internal macrophage level and suppress inflammation, as scarring prevents proper healing and regeneration.

Genome[edit]

The 32 billion base pair long sequence of the axolotl‘s genome was published in 2018 and is the largest animal genome completed so far. It revealed species-specific genetic pathways that may be responsible for limb regeneration.

Neoteny[edit]

When most amphibians are young, they live in water, and they use gills that can breathe in the water. When they become adults, they go through a process called metamorphosis, in which they lose their gills and start living on land. However, the axolotl is unusual in that it has a lack of thyroid stimulating hormone, which is needed for the thyroid to produce thyroxine in order for the axolotl to go through metamorphosis; therefore, it keeps its gills and lives in water all its life, even after it becomes an adult and is able to reproduce. Its body has the capacity to go through metamorphosis if given the necessary hormone, but axolotls do not produce it, and must be exposed to it from an external source, after which an axolotl undergoes an artificially-induced metamorphosis and begins living on land. One method of artificial metamorphosis induction is through an injection of iodine, which is used in the production of thyroid hormones.An axolotl undergoing metamorphosis experiences a number of physiological changes that help them adapt to life on land. These include increased muscle tone in limbs, the absorption of gills and fins into the body, the development of eyelids, and a reduction in the skin’s permeability to water, allowing the axolotl to stay more easily hydrated when on land. The lungs of an axolotl, though present alongside gills after reaching non-metamorphosed adulthood, develop further during metamorphosis.An axolotl that has gone through metamorphosis resembles an adult plateau tiger salamander, though the axolotl differs in its longer toes. The process of artificially inducing metamorphosis can often result in death during or even following a successful attempt, and so casual hobbyists are generally discouraged from attempting to induce metamorphosis in pet axolotls.Neoteny is the term for reaching sexual maturity without undergoing metamorphosis.The genes responsible for neoteny in laboratory animals may have been identified; however, they are not linked in wild populations, suggesting artificial selection is the cause of complete neoteny in laboratory and pet axolotls.Six adult axolotls (including a leucistic specimen) were shipped from Mexico City to theNeoteny has been observed in all salamander families in which it seems to be a survival mechanism, in aquatic environments only of mountain and hill, with little food and, in particular, with little iodine. In this way, salamanders can reproduce and survive in the form of a smaller larval stage, which is aquatic and requires a lower quality and quantity of food compared to the big adult, which is terrestrial. If the salamander larvae ingest a sufficient amount of iodine, directly or indirectly through cannibalism, they quickly begin metamorphosis and transform into bigger terrestrial adults, with higher dietary requirements.

Captive care[edit]

The axolotl is a popular exotic pet like its relative, the tiger salamander (Salts, such as Holtfreter’s solution, are usually added to the water to prevent infection.In captivity, axolotls eat a variety of readily available foods, including trout and salmon pellets, frozen or live bloodworms, earthworms, and waxworms. Axolotls can also eat feeder fish, but care should be taken as fish may contain parasites.Substrates are another important consideration for captive axolotls, as axolotls (like other amphibians and reptiles) tend to ingest bedding material together with foodThere is some evidence that axolotls might seek out appropriately-sized gravel for use as gastroliths

In popular culture[edit]

In Frank Herbert’s fictionalArgentine writer Julio Cortázar included a short story entitled “Axolotl” in his 1956 collectionIn the Netflix seriesIn 2020, it was announced that the axolotl will be featured on the new design for Mexico’s 50-peso banknote, along with images of maize and chinampas. The banknotes are expected to go into circulation by 2022.Mojang Studios added axolotls to their sandbox game,