Axolotls are salamanders, though I’m guessing you might be noticing a slight difference between
these critters and other salamanders. No, no, that’s not a decorative headpiece to win the
affections of other axolotls. The funny-looking, wispy filaments surrounding the head of nearly
every axolotl are actually external gills. These gills are present because axolotls,
unlike most other salamanders, are neotenous. To understand the meaning of this let’s consider how
most salamanders develop: the life cycle of the salamander begins with an egg. From that
egg hatches a juvenile salamander commonly called the larval stage. During this stage, they’ll have
“in between” bodies with external gills and dorsal fins until they mature enough to reach adulthood.
Fully metamorphosed adults will have lungs and breathe air, meaning the external gills are no
longer needed. They’ll also become terrestrial, so they don’t need fins made for movement in water.
Most Axolotls, however, don’t ever technically reach adulthood. Can you spot some of the larval
characteristics in this “full grown” axolotl? This brings us back to the definition of neoteny
which occurs when the larval or juvenile stage of an animal is able to reproduce.
In a sense, they never grow up - they’re like Peter Pan salamanders.
In retaining their larval characteristics, axolotls end up spending their whole life in
water. This wouldn’t be an issue if the only place they’re found in the world
wasn’t being drained for drinking water and contaminated with city pollution.
Axolotls are from Mexico, living wildly only in the waterways surrounding Mexico City. They were
once abundant in Lakes Chalco and Xochimilco, but Lake Chalco no longer exists and Lake Xochimilco
is now just a system of canals. Where twenty years ago scientists were able to locate over
5,000 axolotls in one square kilometer (0.386 square miles) they now count only 35. This is why
axolotls are listed as critically endangered in the wild and unless something changes really fast,
it’s likely we will see them go extinct in the wild within our lifetime. There
are efforts being made to help raise awareness of axolotls. Plus, while this may not be a long-term
solution for wild living axolotls, they’re relatively easy to keep and breed in captivity
so it’s hopeful that their species has a chance of survival through captive programs.
Something cool about captive kept axolotls is that most of them can be traced back to
a group of axolotls that were shipped to Paris for research purposes in the 1860s,
so scientific research isn’t pulling individuals from the wild! Axolotls are researched because
they can regenerate lost limbs and they’re resistant to cancer, among other awesome traits.
In the wild, axolotls have limited natural predators which include herons, though introduced
large fish species such as carp now prey on them in more recent decades. Axolotls themselves
are mainly carnivorous eating fish, molluscs, crustaceans, and insects, though young axolotls
eat algae, as well. On this diet, they grow to be up to a foot (30.48cm) in length! Wild living
axolotls are usually dark in color with mottled markings, but color variants are common especially
among captive kept individuals. Males and females will mate about a year or two after hatching
and females will produce hundreds (100-300) of individual eggs to be laid on aquatic vegetation.
The babies hatch after two to three weeks and they’re completely on their own from that point
onward. Axolotls can live up to fifteen years, though half that length is more of an average.
Something observed in captive axolotls is that when a rare individual does undergo
metamorphosis - thus losing their external gills - their life-expectancy is decreased.
The Aztec language (Nahuatl) is where the name of axolotls originated. Roughly translated it means
“water dog.” A myth regarding axolotls speaks of an Aztec god who transformed into an axolotl in
order to escape his brother intent on killing him. I dunno, they look pretty godly to me…
For more facts on axolotls please check out the links in the description,
there’s a lot more to learn. Tell us your axolotl tales in the comments. Please give
a thumbs up if you enjoyed this episode and we’ll see you next time on Animal Fact Files!