Axolotl
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{{Taxobox | color = pink | name = Axolotl | status = Conservation status: Vulnerable | image = Axolotl.jpg | image_width = 250px | regnum = Animalia | phylum = Chordata | classis = Lissamphibia | ordo = Caudata | familia = Ambystomatidae | genus = Ambystoma | species = A. mexicanum | binomial = Ambystoma mexicanum | binomial_authority = (Shaw, 1789) }}
The Axolotl (Ambystoma mexicanum) is an aquatic salamander native to Mexico. In the Spanish language it is called the ajolote.
The name is from the Aztec Nahuatl language, from "atl" meaning water, and "xolotl" meaning dog. It also derives its name from the Aztec God of Death Xolotl, who — according to myth — assumed the amphibian's form in an effort to escape exile, and was killed while such.
It is noted for its appearance and its demonstration of neoteny, remaining in its aquatic larval form even as a sexually mature adult, and not undergoing metamorphosis into a terrestrial form.
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Description
A fully grown axolotl, at age 18–24 months, ranges in length from 150–450 mm (6–18 inches), although a size close to 230 mm (9 inches) is most common and greater than 300 mm (12 inches) is rare. They have distinctive "fern-like" gill structures that are not covered (as are gills in fish and in frog tadpoles) — usually 3 stalks on each side of the head; axolotls also breathe through the skin and possess lungs.
In colour they range from albino or white (leucistic) to black, through greys, tans and browns. Wild axolotls are rarely white, though all leucistic (white with black eyes) axolotls are descended from a single mutant male brought to Paris in 1863 in a shipment to the Jardin des Plantes in the city. The true albino mutant common in labs and pet stores was created in an American laboratory in the 1950s through hybridization with an albino Tiger Salamander. No axolotls commercially available today are wild caught (since doing so is strictly forbidden), the majority being descended from these same research specimens, even in the pet trade.
Axolotls are very closely related to Tiger Salamanders (Ambystoma tigrinum). Some axolotls can metamorphose, although they do so rarely, and usually have to be treated with iodine or shots of thyroxine hormone to achieve the full transformation. An apparent other method is having an axolotl in good condition, removing it to a shallow tank in a vivarium and slowly reducing the water level so that it has difficulty in submerging, and eventually not being able to submerge at all; it will then stop using its gills to breath and use its lungs. It will over a period of weeks, slowly metamorphose into an adult salamander. Also, during this time, the air in the vivarium must be kept moist, and/or spraying with a fine mist of pure water. The loss of the ability to produce the hormones on their own is what results in the animal's neotenic existence. Metamorphosis also dramatically shortens the axolotl's lifespan, assuming they even survive the process. A neotenic axolotl will live an average of 10–15 years (though an individual in Paris is credited with achieving 25 years), while a metamorphosed specimen will scarcely live past the age of five. The adult form also resembles closely the adult Tiger Salamander, part proving the theory of Axolotl's being an offshoot from Tiger Salamanders, as they are generally so similar in many ways to them.
Habitat
Native to Lake Xochimilco and Lake Chalco in central Mexico, they also live in "axalapascos" (volcanic craters filled with water, maare). The wild population has been put under heavy pressure by the growth of Mexico City. Axolotls are also sold as food in Mexican markets, and were a staple in the Aztec diet. It is currently listed by CITES as an endangered species.
The water temperature in Xochimilco rarely rises above 20°C (68°F), though it may fall to 6 or 7°C (43°F) in the winter, and perhaps lower.
Special capabilities
Axolotl's neoteny
Jardin des Plantes' story
Firsts imported Axolotl in Europe during the XIXe siècle were placed in the "Jardin des Plantes" in Paris. Being not aware of their neoteny, the professor Auguste Duméril, who has created the vivarium, was surprised to see an unknown species in here (replacing the Axolotl), which was similar to a salmander. This story was then well-known and was the starting point of research about neoteny.
Vilem Laufberger's Experiment
Vilem Laufberger did a famous experiment in Germany concerning the axolotl. Using hormone injections, he persuaded an axolotl to grow into a fully adult salamander of a species that no one had ever seen. This is because the axolotl is a juvenile form of an amphibian that evolved to be sexually mature still in the 'infant' stage. The experiment was repeated by the English Julian Huxley, who was unaware the experiment had already been done.
Other abilities
The axolotl is used in research and large numbers are bred in captivity. The feature of the salamander 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. Some have indeed been found restoring the less vital parts of their brains. They can also readily accept transplants from other individuals, including eyes and parts of the brain — restoring 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. In metamorphosed individuals, however, the ability to regenerate is greatly diminished. Another attractive feature, for research, is the large and robust embryos. Axolotls are especially easy to breed compared to other salamanders in their family, which are almost never captive bred.
Feeding
The axolotl is carnivorous, consuming small prey such as worms, insects, and small fish in the wild.
- In captivity :
They can be fed a variety of readily available foods, including trout and salmon pellets, frozen or live bloodworms, earthworms, and waxworms on occasion. Beef heart is sometimes recommended, but is not a good choice for the animal as mammal proteins are not readily digestible. Small juveniles can be fed with Daphnia or brine shrimp until old enough for the larger foodstuffs. Axolotls locate food by smell, and will "snap" at any potential meal, sucking the food into their stomachs with vacuum force. This is why other animals may not be housed with axolotls (excluding adults with adults) as anything smaller will invariably end up in their mouths — even siblings. Fish can also nibble an axolotl's gill stalks and appendages while it is asleep, leading to infection.
Elevage conditions
Image:Ambystoma mexicanum.jpg Axolotls live at temperatures of 14–20°C (54–68°F), preferably 17–18°C (62–64°F). Lower temperatures slow down their metabolism, although temperatures around 10 C (50 F) are a panacea when it comes to treating disease. Higher temperatures can lead to stress and increased appetite; use of a cooling aggregate is strongly recommended. Tapwater should be treated with a dechlorinator before the animal is introduced into it, as chlorine is harmful. A single typical axolotl should be kept in a normal 10 U.S. gallon tank with around 150 mm (6 inches) of water. A full tank without a lid can lead to the animal "jumping ship" as it were. A power filter or underwater filter run by an airpump can be used, though water flow should be kept to a minimum to avoid stressing the animal. A 20% water change should be done every week, with debris being siphoned from the bottom. Small gravel should be avoided, as the axolotl can mistakenly ingest the rocks, leading to stress and gas. Floating plants should be provided for juveniles as a hiding place, and small caves should likewise be provided for adults. No light is necessary as axolotls are nocturnal. Axolotls will spend a majority of the time on the bottom of the tank (floating is a sign of stress and illness), so design accordingly.
Cultural references
- Julio Cortazar, the Argentinian writer, made famous the Axolotl, in literature, in the short story named after the salamander
- The word axolotl is used frequently in crossword puzzles.
- Axolotl tanks are frequently mentioned in Frank Herbert's Dune series of books.
- It was often used in the early years of Mad magazine as a running gag and in-joke, for instance in a parody of Wordsworth's "I Wandered Lonely as a Cloud":
- "I wandered lonely as a clod,
- Just picking up old rags and bottles,
- When onward on my way I plod,
- I saw a host of axolotls."
- The axolotl is mentioned in the musical Children of Eden by Stephen Schwartz. In the aptly titled song called "The Naming", Adam and Eve run through a long list of animals that start with the letter "a", at one point going mentioning the axolotl.
- The fictional creatures Wooper and Quagsire from the Pokémon franchise are both based on axolotls.
- The fictional Dr. Shrunk from Animal Crossing: Wild World is an axolotl. If talked to, he will grant you emotions to use ingame.
- Axolotls are also mentioned in Primo Levi's short story, Angelica Farfalla.
- The band Hum titled a song Afternoon With the Axolotls on their 1997 album Downward is Heavenward.
- A song on the website rathergood.com called "I Like Your Pants" features the line "I'm very fond of axolotls", and in the video there's a very darling picture of a specimen.
External links
da:Axolotl de:Axolotl es:Ajolote fr:Axolotl it:Axolotl he:אקסולוטל מקסיקני nah:Axolotl nl:Axolotl ja:アホロートル pl:Aksolotl pt:Ambystoma mexicanum ru:Аксолотль uk:Аксолотль