In the remnants of one small lake, surrounded by the overpopulated outgrowths of Mexico city, lives one of the most unusual species on the edge of extinction. It is the axolotl salamander that uniquely spends its whole life in larval form and can regenerate entire body parts!
Ordinarily, amphibians undergo metamorphosis from egg to larva and larva to adult form. The Axolotl is unique in that it retains its larval features thoughout its life, a condition called neoteny. This means that although they have an adult size, they have retained external gills, a wide head with lidless eyes, and have underdeveloped limbs. Axololts differ from most other salamanders in that they live permanently in the water. Although they develop rudimentary lungs, they breath through their beautifully-shaped external lungs.
Axolotls can live up to 15 years on a diet of worms, insects and small fish. Having located food by smell, these fascinating creatures capture their prey by sucking it in with vacuum force. Like all amphibians, it is poikilothermic (its body temperature is dependent upon its surroundings). They are typically black or mottled brown, but albino and white and pastel varieties are somewhat common, particularly among axolotls kept as pets. They make good pets and are always smiling cheerfully. Axolotls were a staple of the Aztec diet, which gives us an idea of how plentiful they were.
Axolotls are extensively used in scientific research. Not only because of their rare neoteny, ease of breeding and large embryos, but especially because of their unique ability to regenerate most body parts! In a period of months, they can grow entire new limbs and even portions of the brain and spine can be regenerated. An axolotl that for example loses its foot will usually grow one back over a period of a few weeks!
Axolotls last remaining native habitat exists only as polluted canals because of the dramatic urbanization of Mexico city . The only surviving wild population is very small, as recent surveys suggest that fewer than 1200 axolotls remain. Although as of 2008 axolotl in the wild are listed as a critically endangered by the IUCN, the last wild population is still decreasing and urgent action is necessary to restore this uniques animal number and habitat.