axolotl

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Related to Ambystoma mexicanum: Ambystoma tigrinum, Wooper looper

axolotl

(ăk`səlŏt'əl), a salamandersalamander,
an amphibian of the order Urodela, or Caudata. Salamanders have tails and small, weak limbs; superficially they resemble the unrelated lizards (which are reptiles), but they are easily distinguished by their lack of scales and claws, and by their moist, usually
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, Ambystoma mexicanum, found in certain lakes in the region of Mexico City, which reaches reproductive maturity without losing its larval characteristics. This phenomenon is called neotenyneoteny
, in biology, sexual maturity reached in the larval stage of some animals. Certain environmental conditions can inhibit the completion of metamorphosis; low temperature or lack of available iodine retard the action of the thyroid gland, the larval form may mature
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; in salamanders it is apparently caused by certain environmental conditions, particularly a low level of iodine in the water, which affects the functioning of the thyroid gland. The axolotl grows larger than ordinary larval salamanders and develops sexually, but it retains bushy external gills and a well-developed tail. It also has a broad head and stubby legs; its skin is a black-speckled dark brown. Permanently aquatic, never undergoing metamorphosis to a terrestrial form characteristic of amphibiansamphibian,
in zoology, cold-blooded vertebrate animal of the class Amphibia. There are three living orders of amphibians: the frogs and toads (order Anura, or Salientia), the salamanders and newts (order Urodela, or Caudata), and the caecilians, or limbless amphibians (order
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, it may grow as long as 13 in. (33 cm). It is also known as the Mexican walking fish because of its appearance.

The axolotl was not recognized as a salamander until 1865, when several specimens at the Jardin des Plantes in Paris suddenly underwent metamorphosis. After some experimentation it was discovered that when their pools were dried up most of the animals changed into the adult form. Axolotls will also mature normally if fed thyroid gland extract. The related North American tiger salamander, A. tigrinum, often exhibits neoteny in the Rocky Mts., where the iodine content of the water is low. Since the late 1990s the axolotl has become increasingly endangered in its natural habitat due to pollution and competition from introduced fish.

The axolotl is classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
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, subphylum Vertebrata, class Amphibia, order Urodela, family Ambystomidae.

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axolotl

[¦ak·sə¦läd·əl]
(vertebrate zoology)
The neotenous larva of some salamanders in the family Ambystomidae.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

axolotl

1. any of several aquatic salamanders of the North American genus Ambystoma, esp A. mexicanum (Mexican axolotl), in which the larval form (including external gills) is retained throughout life under natural conditions (see neoteny): family Ambystomidae
2. any of various other North American salamanders in which neoteny occurs or is induced
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
En este arbol fueron excluidas las especies que tuvieron menos de siete colectas en los muestreos; unicamente se consideraron siete especies de anfibios (Rheohyla miotympanum, Lithobates spectabilis, Hyla eximia, Hyla arenicolor, Leptodactylus fragilis, Smilisca baudinii y Ambystoma mexicanum) y dos de renacuajos (R.
Gardiner, "Nerve signaling regulates basal keratinocyte proliferation in the blastema apical epithelial cap in the axolotl (Ambystoma mexicanum)," Developmental Biology, vol.
A commonly used salamander species, Axolotl (Ambystoma mexicanum), has lifelong lasting neoteny and does not undergo metamorphosis naturally.
We tested the hypothesis that the laboratory model salamander Ambystoma mexicanum (= axolotl) would differentially accumulate cadmium during different concentrations.
Systematics of model organisms: the laboratory axolotl, Ambystoma mexicanum. Systematic Biology 42:508-522.
Una busqueda en ISI Web of Science (Thomson Reuters 2010) utilizando como palabras clave: malformations, morphological abnormalities, deformities, Amphibia y Mexico, genero solo un registro de Ambystoma mexicanum (Robles-Mendoza et al.
In Ambystoma mexicanum, two major axes of development are observed: a proximodistal axis initiates at the humerus/femur, radius/tibia, ulna/fibula and extends to other mesopodials, while an anteroposterior (digital) axis arises on the anterior (preaxial) border and development of both digits and distal mesopodials progresses posteriorly (postaxially) (fig.
Entre los anfibios de la familia Ambystomatidae, la especie que mas se ha utilizado como objeto de estudio es Ambystoma mexicanum, con innumerables trabajos en biologia del desarrollo y en evolucion; se conoce que los miembros de esta familia presentan una fertilizacion interna y la ovoposicion de huevos es dentro del agua y de manera estacional, anual o bianual, excepto en Ambystoma ordinarium que se reproduce durante todo el ano (Salthe 1969, Anderson & Worthington 1971).
We assayed metamorphic development, sexual maturation, and storage in the paedomorphic salamander Ambystoma mexicanum (axolotl) by manipulating larval growth rates and the initiation of metamorphosis (via treatment with the thyroid hormone, thyroxine [[T.sub.4]]) and observing consequent differential expression in days required to metamorphose (i.e., metamorphic timing), size and developmental status of gonads (i.e., maturation), and size of fat bodies (i.e., storage).