Mary Allen
The axolotl not only looks cute and unusual; the Mexican salamander also has enviable abilities: it can replicate limbs and even parts of the spinal cord in a matter of weeks.
The Axolotl – a Mexican salamander that lives most of its life in the water. He is a strange being that cannot be classified visually immediately. Somewhere between newt, salamander, and tadpole. This is because it remains in the larval stage throughout its life but still becomes sexually mature. It’s called neoteny.
The axolotl grows up to 25 centimeters in size and up to 25 years old. The amphibian has existed for around 350 million years, but only in small numbers: there are now far more specimens living in laboratories than in the wild.
How long is the lifespan of an axolotl?
Lifespan on average – 10-15 years. Colour and characteristics – several known pigmentation types, including brown, black, albino, grey, and pale pink; external gill stalks and a caudal dorsal fin as a result of neoteny. Wild population – 700-1,200 approx.
How old do axolotls get in the aquarium?
The average life expectancy is around 15 years. Animals are even known to have reached the Methuselah age of 25. The minimum age is around eight to ten years.
Can axolotls live for 100 years?
Axolotls typically live 10-15 years in captivity, but they can live for over 20 years when they’re well-cared for. The oldest axolotl is unknown but their age could surprise them as they become more common pets as some salamander species have incredibly long lifespans (more on that below!)
Axolotl: aquatic monster with gills
The name “axolotl” comes from the Aztecs and means something like “water monster”. The animal, which is up to 25 centimeters long, makes a rather peaceful impression. On the left and right of the neck are the gill appendages, which in some species are highlighted in color and look like small trees.
The axolotl’s legs and spinal cord can regrow
And something else makes the animal special: if it loses a leg, it simply grows back within a few weeks. It can also completely regenerate parts of the spinal cord and injured retinal tissue. Nobody knows why the axolotl can regrow entire limbs complete with bone, muscle and nerves. But scientists have been on the trail for some time and have already deciphered the entire genetic information of the axolotl.
Ten times more DNA than humans
The entire genetic information of the axolotl consists of 32 billion base pairs and is therefore more than ten times the size of the human genome. The genome of the amphibian is therefore also the largest genome that has been deciphered to date. A group led by the researcher Elly Tanaka from Vienna, Heidelberg and Dresden found several genes that only occur in the axolotl (Ambystoma mexicanum) and other amphibian species. These genes are active in tissue that is regenerating.
“We now have the genetic map in hand that we can use to study how complicated structures – legs, for example – can grow back.”
Sergei Nowoshilov, co-author of the study, published in the journal ‘Nature’ in January 2018.
Entire axolotl genome deciphered
Because of its properties, the axolotl has been the subject of research for around 150 years. One of the largest axolotl colonies is cared for in the Molecular Pathology Laboratory in Vienna. More than 200 researchers conduct basic biomedical research at this institute.
Axolotl genes play key roles
Using PacBio’s technology to identify longer stretches of the genome, the axolotl genome was completely deciphered. It was noticed that an important and widespread developmental gene – “PAX3” – is completely missing in the axolotl. Its function is taken over by a related gene called “PAX7”. Both genes play key roles in muscle and nerve development. In the long term, such an application should be developed for humans.
Hardly any axolotls left in the wild
Estimating how many axolotls remain in the wild is difficult – some researchers put the number at around 2,300, but it could be far fewer. Estimates from 2009 put the copies at only between 700 and 1,200. This is mainly due to the severe pollution of the animals’ habitat in Mexico, as they like to live in sewer systems where our waste is flushed. But also in immigrant fish species that were introduced to improve the supply of protein to the population. While the settled carp like to clean the eggs, the cichlids attack the young axolotls.
Axolotl gene diversity is declining in the lab
The last specimens live in Lake Xochimilco and some other small lakes west of Mexico City. The axolotl has been considered critically endangered since 2006. Many, many more specimens now live in aquariums, laboratories, and breeding stations than in the wild. Some are even bred for restaurants in Japan. Others continue to be used for research. The gene pool shrinks over time, because the breeds are often only combined with themselves. It is not known whether the breeding axolotls still have exactly the same characteristics as their relatives in nature.
Keeping an axolotl in an aquarium
In Mexico, its homeland, the axolotl is particularly popular as a pet, almost revered. Anyone who wants to bring the little amphibians into their own four walls can do so relatively easily because they are very robust and resistant. In addition, unlike other salamanders, they only need an aquarium and no “land portion”. They all come from offspring, taking them from the wild is strictly forbidden. They like a water temperature of 15 to 21 degrees Celsius, sometimes colder. Then they can recover better from diseases. If you want to keep them together with other axolotls, then best with conspecifics of the same size. They feed mainly on live food such as small fish, snails, or small crabs.