Wednesday, 11 March 2015

Creature 162: Ambystoma mexicanum

The amphibian that never grows up

Ambystoma mexicanum is a salamander commonly called the axolotl or the Mexican walking fish. They are always smiling.

The reason they are always smiling is they never grow up. Well almost never anyway. As with most amphibians the Juveniles live in the water, but the axolotl becomes reproductively mature before its body undergoes metamorphosis in order to leave the water. This state is known as neotony. Most axolotls will never begin the process of metamorphosis and will remain in the aquatic phase their whole life. It is possible to induce metamorphosis in a Mexican walking fish by adding iodine to their water. This stimulates the production of thyroid hormones which triggers the metamorphosis.  In nature this usually happens when axolotls are forced to resort to cannibalism as a food source. It may be an evolutionary response which gives the axolotl an alternative habitat when the water they live in dries up.

The axolotl also has the amazing ability to regrow its limbs if they happen to get severed. This only works if they have not undergone a metamorphosis. 

Axolotls are endemic to various lakes in Mexico. They are kept as pets all over the world but their numbers in the wild are declining.

I feel like I am stating the obvious here but the axolotl is not a fish. It is a salamander.

Kingdom: Animalia
Phylum :Chordata
Class: Amphibia
Order: Caudata
Family: Ambystomatidae
Genus: Ambystoma
Species: Ambystoma mexicanum

Image Links:

No comments:

Post a Comment