Axolotl.... Ambystoma mexicanum

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Axolotl.... Ambystoma mexicanum

Post  Admin on Mon Apr 23, 2012 10:53 pm

Upon first glance at looking at an axolotl, You might ask yourself exactly what kind of creature it is. With its catfish-like shaped head, the odd, frills emanating from its neck, and its fins, limbs and feet, wow weird huh?, should it be classified land- or water-dweller? So should evolutionists take heart that here is something like a living ‘transitional form’, perhaps on its way to evolving from a fish to an amphibian? Not at all. The axolotl is, a neotenic salamander, closely related to the Tiger Salamander( Ambystoma tigrinum and Ambystoma mavortium spp). Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled, As an adult, the axolotl can reach a length of up to 30 cm (12 inches) and weigh over 300 g (10 ounces), making it a fairly sizeable amphibian. It tends to have a light cream to tan colouration in captivity, with a more mottled black-and-green colouration in the wild. But it can also appear tan, grey, brown, albino or even transparent.

By far the most unusual aspect of this salamander is that it retains its larval form into adulthood. So, unlike most amphibians, which metamorphose from water- to land-dwelling as they grow, the axolotl retains its gills and fins instead of exchanging them for developed lungs and limbs. This abbreviated developmental condition is known as ‘neoteny’, and the axolotl both thrives and breeds in its larval state. Stranger still, it can be forced to complete its larval stage and transform into a normal adult salamander by applying the metabolic hormone thyroxine.It can also transform itself if it leaves its watery environment for an extended period of time, especially if its surroundings are too dry,Unfortunately, axolotls which make the incredible transition to land as an adult often experience a shortened lifespan, presumably due to the stress of transformation.

Another amazing ability of the axolotl is its fantastic regeneration and healing capabilities,Though people and most animals are able to sufficiently heal a cut, replace portions of dead or damaged skin, or even regenerate a small part of an internal organ, axolotls are virtually unique among vertebrates in that they can completely regenerate entire limbs and organs. Instead of merely forming scar tissue over a wound, as most vertebrates do when healing, the axolotl can regenerate entire body parts, including whole limbs, gills, eyes, kidneys, even large portions of its liver and its heart muscle.

The axolotl is only native to Lake Xochimilco and Lake Chalco in central Mexico. Unfortunately for the axolotl, Lake Chalco no longer exists, as it was drained by humans to avoid periodic flooding, and Lake Xochimilco remains a diminished glimpse of its former self, existing mainly as canals. 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. 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. They are currently listed by CITES as an endangered species, and by IUCN as critically endangered in the wild, with a decreasing population.
Their habitat is like that of most neotenic species—a high altitude body of water surrounded by a risky terrestrial environment. These conditions are thought to favor neoteny. However, a terrestrial population of Mexican tiger salamanders occupies and breeds in the Axolotl's habitat.

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