With their little smiles, axolotls are one of the cutest creatures in the animal kingdom. One of the world’s most unusual amphibians, they are valuable in scientific research because they have regenerative properties. They are found mostly in the freshwater lakes and ponds of Mexico.
What do we know about these unique little critters? Let’s find out more about the enigmatic axolotl.
1. Axolotls never grow up
Literally so. They are called neotenic salamanders by the scientific community, which means they retain traits from their juvenile stage after reaching adulthood. Axolotls can reach maturity without going through metamorphosis from larva to sexually mature adult, keeping their gills and staying in the water where they were born although they grow lungs.
Sometimes, axolotls experience mutation or an external catalyst that gives them the rush of hormones that make them suddenly mature into their land dwelling adult form. They look like tiger salamanders, but they only breed with other axolotls. If you own an axolotl, you should never interfere with their biology – only scientists and trained professionals should attempt to cause maturity in axolotls as any mistake can prove to be fatal to the axolotl.
2. Axolotls have regenerative abilities – this also makes them resistant to cancer
An axolotl can regenerate its body organs and lost limbs without any scarring. They can even regrow spines and brains, and they respond well to organ transplant. This ability that axolotls have means that they are more resistant to cancer than mammals, because their limbs grow back perfectly every time. Scientists are looking to discover more about this ability in the hopes that we can do the same with humans.
3. Axolotls have gills, but they can also breathe through their lungs, their skin and the back of their throat
Axolotls have external gills that look like large, feathery branches protruding from the back of their heads. Their gills can be fanned through the water to agitate it and create more oxygen to be absorbed. About three weeks after birth, they grow lungs that allow them to breathe in the air. They don’t need to breathe through their lungs, but they have been observed to occasionally surface for a gulp of air.
Axolotls breathe primarily through their gills, but they can also breathe through their skin. Because they exhibit neoteny and never mature unless they have to, their blood vessels remain close to the surface of their soft, translucent skin. This allows for absorption and diffusion of oxygen directly to their blood vessels from the water around them.
They can also breathe through a membrane in the back of their throat called the buccopharyngeal membrane. This breathing ability is called buccal respiration by scientists. The membrane is covered by a skin flap that allows water to pass through, after which the membrane absorbs the oxygen in the water.
4. Axolotls have a mythological connection to Ancient Aztecs
The name Axolotl means “water dog”, and Ancient Aztecs revered them as part of religious lore. Xolotl was a dog-headed Aztec God of fire, lightning, deformities and death, similar to Hades in Greek mythology. In the myth, Aztec gods had to sacrifice themselves to the sun to keep it alive and moving. Xolotl transformed into an axolotl to hide because he was afraid of being sacrificed. The canine god was then trapped in the water of Xochimilco as he was unable to transform back to walk on land.
5. Wild axolotls aren’t always white
White axolotls are leucistic and come from a mutant male axolotl shipped to Paris back in 1863. His descendants were bred to be white with black eyes and they became quite popular, which is why you see many white axolotls in captivity. Wild axolotls are pink, brown or black. They can also be golden albino, white albino or blue.
6. Axolotls are small in captivity but can grow quite large
Axolotls can grow up to a foot in length, but they are normally half a foot long. They only weigh about 6 ounces because their skeleton is made of cartilage instead of bone. This is because axolotls remain part larvae, so their bones don’t calcify completely. Their gills are also made of cartilage, but they have solid teeth used for puncturing prey.
Another cool side effect of axolotls remaining in their larvae stage is that they do not have eyelids. Amphibians grow eyelids as they metamorphosize into adults and go on land. Because axolotls never turn into adults or leave the water, they never grow eyelids.
7. Axolotls have a mating dance
They are normally solitary, but from March to June during the breeding season they waltz together as part of the mating initiation phase. They rub against each other, then the male shakes his tail and drops a cone-shaped mass with a sperm cap. The female also shakes her tail and picks up the mass to fertilize herself with.
The female axolotl lays up to 1000 individual eggs that she places on plants or rocks to protect them from predators. These eggs hatch within two weeks to produce independent young. These baby axolotls are cannibalistic, eating parts of other axolotls for no clear reason. They grow out of this stage when they reach sexual maturity at 1 year old, and they can live up to 15 years.
8. Axolotls are carnivorous
They locate food through chemical cues in the water and use suction to eat their food. They normally eat small prey like worms, small fish and insects. Axolotls are bottom feeders that use the gravel they accidentally consume to regulate buoyancy and to help with digestion.
9. Axolotls are critically endangered
They may be quite common in captivity as exotic pets and laboratory research material, but in the wild they are nearly extinct due to habitat loss and invasive species predators. Axolotls don’t actually have many native predators, but carp and tilapia that have been introduced to Mexican waters quite enjoy axolotl as their prey.
Humans also threaten the existence of axolotls due to the international pet trade and traditional medicine trade.