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- Title
Axolotls and neoteny: those who forgot to grow up.
- Authors
Proorocu, Marian; Petrescu-Mag, I. Valentin
- Abstract
This article is a descriptive work on a special type of reproduction, a strangeness for vertebrates: Ambystoma mexicanum. The axolotl is an amphibian that does not develop lungs and retains its external gills from the larval stage. The gills allow the animal to lead an underwater life. The axolotl reaches sexual maturity without going through metamorphosis, thus presenting the phenomenon of neoteny. Sexually mature individuals live in the larval stage all their lives and are able to reproduce in the larval stage. The axolotl has a physiological peculiarity in that it lacks thyroid-stimulating hormone. In related species, this hormone is required for the thyroid to produce thyroxine for the axolotl to initiate metamorphosis. The axolotl does, however, have the ability to undergo metamorphosis if experimentally given the missing hormone. After artificially induced metamorphosis, the individual is able to lead a terrestrial life (indicating that the suppression of metamorphosis occurred relatively recently in the course of axolotl evolution). In other words, axolotls were once amphibians, just like their relatives, the salamanders. Although tens or hundreds of thousands of generations of his ancestors did not walk on land, the artificially metamorphosed axolotl did not lose the instincts of terrestrial life (locomotion, feeding, chasing prey, avoiding predators, etc). Another method of artificially inducing metamorphosis is by injecting iodine, which is used by the salamander's body in the production of thyroid hormones. A metamorphosing axolotl goes through a series of anatomical, morphological and physiological changes that help it adapt to terrestrial life. These changes include increased muscle tone in the limbs (because on land the specific gravity becomes greater and the body needs musculature to support or pull the body), absorption of gills and appendages specific to swimming, development of eyelids and a reduction in skin permeability to water, allowing the axolotl to stay hydrated longer when on land.
- Subjects
AXOLOTLS; NEOTENY; EMBRYOLOGY; PHYLOGENY; AMBYSTOMA mexicanum; SALAMANDERS; METAMORPHOSIS
- Publication
Extreme Life, Biospeology & Astrobiology, 2022, Vol 14, Issue 1, p12
- ISSN
2066-7671
- Publication type
Article