The Axolotl ( Ambystoma mexicanum ) is a Urodèle (a group of batrachians) originating in the Mexico. The term Axolotl (or axolote in Spanish Mexican) is of origin Nahuatl; it is composed of " atl" meaning water and of " xolotl" for dog . It also originates in the name of the god of Aztec death named Xolotl, which according to the legend took the shape of this Amphibian in order to escape the exile and was killed during its attempt.

It belongs to the animals having the capacity to pass all their life in a larval state without never metamorphosing itself as an adult, and thus to reproduce in a larval state (Néoténie). It is of this fact very studied in animal biology. For a long time one confused it with Ambystoma tigrinum (or salamander tiger), occasionally neotenic, whereas the axolotl is generally in nature.

Another of the characteristics which made the celebrity of the axolotl is its capacity to regenerate damaged or destroyed bodies. The axolotl is not only able to reconstitute for example a missing eye, but it can also recreate certain parts of its brain if they were destroyed. Its tolerance with the Clerc's Offices is also exceptional.

Description

The axolotl is an animal which seems to have a maximum of activity to the rising and laying down sun. At the end of its growth, towards the age of 18 or 24 months, the axolotl measurement between 15 and 45 cm, although the intermediate size is rather at the neighborhoods of 23 cm. The specimens reaching 30 cm are observed only seldom. Out of aquarium most of the time one finds individuals measuring in 15 cm. One notes the presence of costal furrows in the larva and the adult.

In a larval state, they have eyes without eyelids as well as gills with the very particular form of ferns , usually divided into two groups of 3 bunches branchiales, on both sides of the head. Those are not internalisées (as they are it at fish or tétards). The axolotl also has lungs and can make use of its skin to breathe.

There exist various pigmentations, of which a dark normal form (presence of Mélanine) which goes from the black to various alternatives of gray while passing by the brown ones and colors " Bronze" , and a dépigmentée form (not of black mélanine but eyes, characteristic called Leucistisme), and even a form Albino (absence of Mélanine). The albino and dépigmentées forms exist only in captivity. The latter (individuals reached of leucistism) comes from the same individual reported to Paris in 1863 in a loading bound for the Botanical garden.

The truly albino form is usually used in the animalist laboratories and stores. It was created by an American laboratory in the Années 1950 thanks to the crossing with a salamander tiger albino. None the axolotls currently sold in the trade is captured in the natural environment, this practice being prohibited. The majority descend from specimens used for research, even those available in the animaleries.

Axololts are very close to the salamanders Tigres, their forms adult comprise many similarities, supporting a little more the theory according to which Axolotl would result from a ramification of this species.

The metamorphosis of the larva axolotl as an adult results in the atrophy of its gills, the development of its lungs (rachitics at the larval state), and by a series of transformations of its body enabling him to leave its exclusively watery medium. This metamorphosis is very rare under natural conditions. It is sometimes caused by a radical fall of the level of water accompanied by an important warming. In captivity and with a axolotl in full form, it would be enough to move it of a purely watery medium towards a vivarium in which one would reduce the level of water gradually. Threatened of draining, it would then stop using its gills and would privilege its lungs. Thus over several weeks, it would be metamorphosed gradually as an adult. A precaution to be taken is to maintain an atmosphere wet in vivarium, by vaporizing water there for example (via a brumisator).

In an artificial way, a chemical stimulation of the Thyroïde can be used to start this transformation, this by the means of injections d'" iodine" or of hormones of the " type; thyroxine".

The loss of the capacity to produce themselves the hormones necessary to this transformation results from the character neotenic of this animal. Moreover this change the life expectancy of the axolotl reduces considerably, if as well is as it survives it. A axolotl at the stage neotenic can live from 10 to 15 years (although an individual observed in Paris would have lived until the 25 years age). An individual at the adult stage, will hardly exceed the 5 years to him.

Habitat

Living at the origin in the lakes Xochimilco and Chalco of the center of the Mexico, they also live in " axalapascos" (of the volcanic craters filled with water, generally called Maar). Water of these lakes has a temperature bordering to the maximum the 20°C. In winter this one falls with 6-7°C, or perhaps even less.

Vulnerable species

The QUOTE quotes the axolotl like vulnerable Espèce: The wild population was reduced with the growth of the Mexico. The axolotls are also sold as a food on the Mexican markets - it was a basic commodity of the Aztec mode.

Remarkable facts

Néoténie at the axolotl

The " term; Néoténie " indicate the fact for an animal of preserving normally youthful characters at the adulthood. In the case of A. mexicanum, it acts of the maintenance of the Branchie S at the adulthood, gills which disappear normally at the others Urodèle S. This maintenance rises from a weaker activity from its thyroid gland. This adaptation would be a consequence of the Mexican climate, the cold disadvantaging the terrestrial form which is then exposed there. An animal exposed artificially to the thyroid hormone will change, lose its gills and will acquire functional lungs, as well as a terrestrial lifestyle.

Anecdote of the Botanical garden

The first axolotls imported in Europe at the 19th century, were installed with the Botanical garden of Paris. Being unaware of to them Néoténie, the professor Auguste Duméril, the creator of the Vivarium, was one day surprised to see in the basin an unknown species resembling a salamander in the place of the animal which was there. This history made great noise and caused research which outlined the phenomenon of Néoténie.

Experiment of Vilem Laufberger

Vilem Laufberger carried out in Germany a similar experiment on the axolotls. After injections of hormones making them reach the adult stage, he discovered them in a new form letting think of a new species of salamander. This is due to the fact that the axolotl is an Amphibian which evolved/moved to reach sexual maturity at the larval stage (see Néoténie).

The experiment was renewed by English Julian Hexley who did not know anything the work of Laufberger on this subject.

Other characteristics

The axolotls are used for research and much are high in captivity. Their capacity of regeneration, similar to that which one can meet in the salamanders, is particularly studied. They are able to regenerate whole bodies in a few months. In certain cases the brain could be concerned, although regeneration then observed related to only zones with secondary role.

They have also a very great capacity of transplantation, tolerating and fully assimilating bodies such as the eyes or of the zones of brain (which recover their whole capacities thereafter). In certain cases, they can restore a damaged member or create additional.

It should be stressed that this still concerns primarily only individuals at the larval stage. Once the metamorphosis carried out, this capacity is strongly reduced.

The size and the robustness of their embryos are also sources of research. Moreover, they are very easy to raise compared with other salamanders of the same family (which are consequently far from high in captivity).

Nutrition

The axolotls are carnivorous, nourishing small preys such as worms, insects and also of small fish.

• In captivity:

They can be nourished thanks to food available in animaleries, as with pellets containing fish (trout, salmon…) but also of the ground worms, the worms of vase (larvae of Chironomes plumosus , " " ) and of false tineas ( Achroia grisella and Galleria mellonella , " " ), frozen or alive. The ox heart can be recommended but is not ideal, owing to the fact that the animal proteins that it contains are not easily assimilable. The young larvae can also be nourished with Daphnie S or Artémie S (" " in English) until they sufficiently grew in order to be able to make of the more important meals.

The axolotls locate their food by the sense of smell and try to grab any potential meal. With this intention, they introduce food into their stomach by creating a depression (they use the force of the vacuum thus created). This is why it is preferable not to make cohabit a axolotl with other animals (except if all are adult) since all that appears smaller will finish inevitably in their bellies (even individuals of their own species).

The fish can damage whole or part of their gills while trying to eat them (during their sleep) what can lead to the appearance of infections.

Breedings

Starting from the scientific breedings developed ludic breedings. The axolotl became a relatively widespread animal in the animaleries devoted to the batrachians and is frequently raised by the amateurs, often in its forms of breeding dépigmentées or albino. The albino variety is regarded besides as domestic.

The axolotl lives at temperatures enters 14 and 20°C, ideally with 17-18°C. The lower temperatures slow down its metabolism (one can thus treat various diseases, around 10°C). A good cooling system is recommended to avoid too high temperatures, which would involve stress and a too large appetite in the animal. The tap water must be treated so as to remove the Chlore from it because it is toxic for him. The filters for aquarium can be used (such as a " power filter" or an immersed filter associated with an air pump). However the current thus product must be at least reduced in order not to stress the animal.

The renewal of water must ideally be made each week by section of 20%, the remains being aspired by the bottom. The small gravels are to be proscribed because the animal could swallow them by error, be wounded or even asphyxiate itself. The floating plants on the other hand are advised for the youthful ones because they get a shelter to them. For the adults, small infractuosities or caves are ideal. Lighting is not necessary, the axolotl being a night animal.

The axolotls will pass the majority of their time in the content of the basin whose installation must be envisaged consequently. An animal remaining close to surface east often in prey with a faintness (stress or disease), and must thus be the subject of much attention.

To note that the stress at the axolotls is very present in captivity. It is a species which needs enormously for hiding-places (stones, plants, etc), of a low luminous intensity as well as current almost no one for good to open out in captivity.

Cultural references

• Julio Cortázar published a news entitled “Axolotls” in 1959, published in French in the collection “the secret Weapons”
• the word axolotl frequently arises in the anglophone crosswords.
• the “tanks axolotls” of the saga of science fiction Dune, of Frank Herbert, are cellular developing tanks to proceed to the Clonage and genetic Engineering.
• In the series Pokémon , the creatures and is both inspired by the axolotls, and the French translation of Wooper is " besides; Axoloto".
• In the play Animal Crossing: Wild World , Doctor Shrunk is a axolotl.
• Primo Levi wrote in her collection “Natural histories” new “Butterflies angelica” which is strongly inspired by the axolotls.
• the group entitled a song Afternoon With the Axolotls on their album Downward is Heavenward (1997).

Places where one can see it

• Ouwehands Dierenpark Rhenen, Rhenen with the Netherlands.

See too

• a card of breeding on the axolotl
• an essential card on the axolotl and its breeding in captivity
• Care off axolotl ace farts
• Axolotl.org

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