Saturday, December 11, 2010

Reproducing Larva - the Axolotl!

We usually see that from egg caterpillar comes out, butterfly grows out of it and fly away. But in a type of Salamander (an Amphibian) its growth into an adult is hindered and it is stopped in its larval stage itself. This larva starts also to reproduce! This animal is Axolotl (Ambystroma mexicana, Mole Salamander, 'Mexican walking fish,' 'Waterdog').

It resembles closely the larva of Tiger Salamander, a related animal that reproduces only after growing into an adult. It is found only in a Mexican lake (Xochimilco). Unlike other salamanders and frogs it lives only in water. It has three external gills behind its head on each side like tadpoles for its respiration in water. Its lungs are rudimentary.

It looks like a lizard with all its four legs. Its colour is brown or black. It is about six inches in length and lives for ten years. It is carnivorous. It sucks its prey into its stomach as a vacuum cleaner does. The female axolotl bears exceptionally large embryos. We can view all the stages of evolution to a vertebrate in it! Nowadays we (doctors) try to use Stem Cells to regenerate a lost organ. But this animal regenerates its lost body parts by itself! We transplant organs with much difficulty. But the axolotl accepts any donated organ - even brain, without any rejection! Its neoteny - the arrested evolutionary development is said to be due to the lack of production of Thyroid Stimulating Hormone (TSH). Axolotl is also kept as a pet in USA, Australia and Japan.
This wonder animal has been red-listed as a threatened species that is moving fast towards extinction. Let us preserve it alive for our posterity to view and wonder about.

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