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4 The axolotls are fascinating creatures also known as the Mexican walking fish, which isn’t exactly correct since they’re well-known amphibians who love the water!
Famed as a national icon in Mexico and perhaps the most recognizable salamander in the world, the axolotls face a looming threat to their entire existence.
These mesmerizing that are engulfed in myths and legends are critically endangered with somewhere between 50 to 1000 individuals left, thanks to excessive pollution, invasive species, habitat loss, and overfishing.
In this post, we’ll be looking at what axolotls are, their most prominent features, the factors that have driven them to the brink of extinction, why are they essential for science, and how to protect them. Let’s get started!
Physical Characteristics
Scientific Name: Ambystoma mexicanum
Class: Amphibian
Genus: Ambystoma
Order: Urodela
Family: Ambystomatidae
Conservation Status: Critically endangered
Population: Approximately 50 – 1000
Life Span: 10 -15 years
Size: On average 10 inches (25 cm) but could go up to 12 inches (30 cm)
Weight: 2.11 (59.8 grams) to 8 ounces (226.8 grams)
What is an Axolotl?
Axolotls are a species of salamander. More precisely, these amphibians are closely related to the tiger salamander (both belong to the Ambystoma genus).
Due to their cute and somewhat goofy appearance, axolotls are pretty popular and also have a bit of lore surrounding them. According to legends, axolotls originate from the Aztec god (named Xolotl) of fire and lightning’s attempt to evade being sacrificed by disguising himself as a salamander.
The lore, however, only accounts for a minor part of the fascination humans have expressed for centuries. Humans, or scientists, in particular, are captivated by the amphibian’s ability to defy the laws of biology.
Axolotls do not conform to the laws of metamorphosis and can grow back entire limbs if lost and repair damage to the spinal cord, heart, and brain. Due to their fascinating regeneration factor, axolotls are a prevalent research subject for biologists.
They’re also able to keep their body “young” for as long as they can live and never outgrow their larval when undergoing metamorphosis, a phenomenon termed neoteny.
Due to this phenomenon, axolotls are a little different from common amphibians.
Normally. Amphibians need to lay their eggs in the water to reproduce (some species have devised ways to get around their need for water). After hatching, these eggs take their time to metamorphose into adult forms, capable enough to live and survive on land.
On the other hand, axolotls prefer to remain in the water instead of land and only use their lungs occasionally, because they are “neotenous,” which means they do not metamorphose into an adult form capable of living on land. Instead, they retain features from their juvenile stages, such as tails and gills.
Axolotls are currently critically endangered because of their rapidly dwindling numbers in the wild, with only somewhere between 50 to 1,000 individuals left.
Head over to our post on ‘The 5 Most Endangered Animals in 2022’ to learn more about other critically endangered animal species.
What Does an Axolotl Look Like?
Although some axolotls can grow up to 18 inches in length, the average axolotl is between 9-12 inches in size. The most prominent feature of the amphibian is its gills. Axolotls sport feathery gills that protrude from their head like a lion’s mane, along with a tail and a dorsal fin that spans their entire body.
Axolotls are also equipped with fully-functional lungs that allow them to breathe air through their skin. And if their cute and goofy appearance wasn’t enough of an appeal, axolotls are almost always seen smiling.
These smiles, however, can quickly change when it’s time to eat. An Axolotl mouth produces a powerful suction force, like a vacuum cleaner that ropes prey in whenever it’s time to eat.
What do Axolotls Eat?
Axolotls are carnivorous in nature. They usually eat worms, small fish, and tadpoles. However, that isn’t all. Axolotls are, by no means, shy animals when it comes to eating; they can gobble down virtually anything that can fit into their mouth.
In fact, an axolotl will even eat other salamanders and small animals as long as they can swallow them in one go.
They only target food that can be swallowed whole since they’re incapable of chewing. Their teeth are capable enough to clamp down and capture their food, but they aren’t sharp enough to help axolotl chew or tear its prey apart.
Lab axolotls usually eat salmon pellets, blackworms (Lumbriculus variegatus), and brine shrimp.
How does Axolotl Reproduce?
In their natural environment, axolotls can lay eggs up to six times a year. The spawning season for wild axolotls is usually in February as they love to lay their eggs towards the end of winter.
This is also why experts recommend lowering the temperature to below 15 ° C to encourage captive axolotls to reproduce.
Axolotls follow an exciting procedure to reproduce. Here’s how:
- The process begins when the female axolotl secretes pheromones (smell) into her surrounding waters.
- The male axolotls are quick on the take and seek the female out to perform a “hula” dance for courtship by shaking their lower body and tail.
- If the female acknowledges the said courtship, it’ll respond by nudging the male with her snout, which signals the male to proceed.
- The male then drops sperm packets (also known as spermatophores) on the lake floor to essentially finish its part of the process.
- The female then uses her body cavity, the cloaca, to collect the spermatophores and fertilize its eggs.
Although a female axolotl can lay as many as 1000 eggs at a time, the average count, around 300, is much lesser.
Axolotl eggs, which are usually laid on the surface of rocks and friendly plants to ward off predators, can take around two weeks to hatch. Once outside, the larvae require little to no parental help and generally swim off on their own.
When do Axolotls Become Sexually Mature?
Wild axolotls usually reach sexual maturity at around seven months of age. However, this can fluctuate between different axolotls.
Generally speaking, any axolotl larger than 7 inches (18 cm) in size and above a year in age has reached adulthood and can reproduce.
How to Differentiate between a Male and a Female Axolotl?
The best or most reliable method is examining the axolotl’s cloaca. Female axolotls have a very inconspicuous cloaca, whereas males tend to have more of a visible “bulge” in the area after maturity.
Other less reliable methods include examining the body shape and tail length. Female axolotls tend to have a rounder shape (mainly due to carrying eggs) and a shorter tail.
Where do Axolotls Live?
Wild axolotls are almost exclusive to the Xochimilco lake complex in the Valley of Mexico (situated near Mexico City).
Axolotls are very well adapted to their native habitat, a region of high altitude with an average temperature of 20 °C (even during the winter), which is why they’re seldom found anywhere else.
What is the Cultural Significance of Axolotl?
In Mexico, it is widely believed that an Aztec deity (more specifically, the Aztec god of lightning and fire) tried to disguise itself as a salamander to escape being sacrificed. The God, named Xolotl, ended up disguising himself as an axolotl.
Aside from the lore, the axolotls play an essential part in Mexico’s culture. The amphibians have made various appearances in murals and cartoons. More recently, it was announced that the axolotl would appear on Mexico’s new 50-peso banknote alongside the chinampas and maize.
Why are Axolotls Going Extinct?
Axolotls are going extinct in the wild because of excessive water pollution, loss of habitat, invasive species, and overfishing.
On the IUCN conservation index, axolotls are declared critically endangered species, meaning they have a real possibility of going extinct in the coming years.
These metrics, however, only apply to the wild axolotl. Since the number of axolotls in captivity far exceeds those living in the wild. There are multiple factors that contribute to the recent loss in axolotl number.
Back in 1988, the Xochimilco lake housed more than 6,000 axolotls per square kilometer; but in the present times, there are less than 35 axolotls per square kilometer in the same lake.
Here’s why they are going extinct:
Pollution
Mexico City has been home to a lot of development in recent decades. Unfortunately, not much of this development has taken place along sustainable lines, which has contributed directly to the drop in axolotl numbers.
The spike in water pollution has made many areas of the Xochimilco lake inhabitable for axolotl and aquatic life in general.
To learn about how pollution, specifically plastic pollution, takes a toll on the environment and how you can contribute to stopping it, head over to our post on ‘Plastic Pollution | 12 Ways on How to Stop Using Plastic‘.
Invading Species
Axolotls have always sat on the top of the Xochimilco lake complex’s food chain. Thus, when a few invasive species were introduced to the habitat recently, the axolotls found themselves particularly vulnerable to their attacks.
The newer species, including animals like tilapia and perch, contribute to the decreasing axolotl population.
How do Axolotls Protect Themselves?
Axolotls can’t protect themselves from their predators. This is because, as we discussed earlier, they were at the top of the food chain in their natural habitat, the Xochimilco lake, and never required a protection mechanism. As a result, their body is soft throughout, they don’t have eyelids, and their gills protrude outwards, making them highly susceptible to predators.
Loss of Habitat
The rapid urbanization of Mexico City hasn’t only contributed indirectly by polluting the water of the Xochimilco lake complex, but it has also played a direct hand in destroying the amphibian’s habitat.
Due to rapid urbanization, large parts of the lake complex have been drained and destroyed to make way for further development. This, unfortunately, has also included Chalco Lake, which has historically been the axolotl’s primary habitat.
Head over to our post on ‘Habitat Restoration: The Ultimate Guide’ to learn about how to counter this situation.
Overfishing
Axolotl meat is something of a delicacy in Mexico City. Due to the meteoric rise in demand for Axolotl meat, many fishermen in the city have switched over to solely fishing Axolotl, which has contributed directly to the rapid decline in their population.
How to Save Axolotls?
Since the impending threat of the axolotl extinction has become increasingly real, there has been a rejuvenated effort to protect their surviving numbers.
As part of a program developed by CIBAC (Centro de Investigaciones Biológicas y Acuícolas de Cuemanco), developed in 1994, multiple pens have been placed throughout Mexico City to breed axolotls.
In 2015, The Environment and Natural Resources Ministry had the CIBACrelease 500 axolotls back to their natural habitats, of which 225 had an implanted chip to monitor their behavior.
Such programs are only a part of the overall effort needed to control the decline of the axolotl population.
The most significant step is to spread awareness regarding the drop in the numbers of Mexican amphibians and to actively discourage axolotl consumption of any sort.
Why are Scientists Concerned About Declining Axolotl Populations?
While scientists are concerned about the near-extinction status of many aquatic species worldwide, the impending danger to axolotls carries a particular concern, mainly due to their immense biological value.
Axolotls are amongst the most studied aquatic creatures, primarily due to their ability to repair entire limbs and vital organs such as the heart, brain, and spinal cord- that too, in a short period.
Scientists believe that their regenerative factor could potentially unlock a new age for human medicine and its effectiveness in treating certain types of degenerative diseases.
A recent study in April of 2021 unraveled how an axolotl’s molecules communicated between themselves to promote the amphibian’s regeneration.
While there are many axolotls in captivity, scientists have qualms over how inbreeding may affect their genetic and health characteristics in the long term.
All in all, the axolotls are of significant importance to humanity. They are an integral part of Mexican culture and were a valuable food source to the Mexican people before endangerment.
Not only that, but scientists believe that the amphibian’s biology has enough potential to usher in a new era of human healthcare.
Sadly, with the rate the axolotl population is declining, the species can die out, leaving behind a gap that would be hard to fill. Even though there is a massive population in captivity, but it is losing its natural physical and biological characteristics due to inbreeding.
Until and unless a real effort is made to conserve and increase the number of wild axolotls, the world may very well lose one of its most remarkable species due to human neglect.
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