Scientist Dr. Randal Voss gets the occasional reminder that he’s working with a kind of superstar. When he does outreach events with his laboratory, he encounters people who are keen to meet his research subjects: aquatic salamanders called axolotls.
The amphibians’ fans tell Voss that they know the animals from the internet, or from caricatures or stuffed animals, exclaiming, “‘They’re so adorable, we love them,’” said Voss, a professor of neuroscience at the University of Kentucky College of Medicine. “People are drawn to them.”
Take one look at an axolotl, and it’s easy to see why it’s so popular. With their wide eyes, upturned mouths and pastel pink coloring, axolotls look cheerful and vaguely Muppet-like.
They’ve skyrocketed in pop culture fame, in part thanks to the addition of axolotls to the video game Minecraft in 2021. These unusual salamanders are now found everywhere from Girl Scout patches to hot water bottles. But there’s more to axolotls than meets the eye: Their story is one of scientific discovery, exploitation of the natural world, and the work to rebuild humans’ connection with nature.
A scientific mystery
Axolotl is a word from Nahuatl, the Indigenous Mexican language spoken by the Aztecs and an estimated 1.5 million people today. The animals are named for the Aztec god Xolotl, who was said to transform into a salamander. The original Nahuatl pronunciation is “AH-show-LOAT”; in English, “ACK-suh-LAHT-uhl” is commonly used.
Axolotls are members of a class of animals called amphibians, which also includes frogs. Amphibians lay their jelly-like eggs in water, and the eggs hatch into water-dwelling larval states. (In frogs, these larvae are called tadpoles.)
Most amphibians, once they reach adulthood, are able to move to land. Since they breathe, in part, by absorbing oxygen through their moist skin, they tend to stay near water.
Axolotls, however, never complete the metamorphosis to a land-dwelling adult form and spend their whole lives in the water.
“They maintain their juvenile look throughout the course of their life,” Voss said. “They’re teenagers, at least in appearance, until they die.”
A signature feature of the axolotls’ forever-young look is their frilled external gills, which help them breathe in their watery home — the only spot they’re found in the wild: Lake Xochimilco in Mexico City.
It’s a bit of a scientific mystery why axolotls don’t transform into adult, land-dwelling versions of themselves. One hypothesis, according to Dr. Luis Zambrano, a professor of zoology at the National Autonomous University of Mexico, is that the environment in Lake Xochimilco had enough resources for the salamanders that “it was by far better for them not to expend energy transforming and stay in the lake.”
The 10-square-mile Lake Xochimilco is a unique body of water, a natural drainage basin with slightly salty water. More than 1,000 years ago, Xochimilca people in the region invented an agricultural system of human-made floating islands called chinampas. The chinampa system, with its drainage canals surrounding the islands, is still used by farmers called chinamperos today. The islands provided habitats and hiding places for the axolotls, which thrived among the chinampas for 1,000 years.
However, the chinampas of Lake Xochimilco are no longer thriving, and neither are the salamanders. “The problems started at the beginning of the last century,” Zambrano said.
Axolotl problems
As Mexico City grew and became more industrialized, the need for water brought pumps and pipes to the lake, and eventually, “it was like a bad, smelly pond with rotten water,” Zambrano said. “All of our aquatic animals suffer with bad water quality, but amphibians suffer more because they have to breathe with the skin.”
To add to the axolotls’ problems, invasive fish species such as carp and tilapia were introduced to the lake, where they feed on axolotl eggs. And a 1985 earthquake in Mexico City displaced thousands of people, who found new homes in the area around the lake, further contributing to the destruction of the axolotls’ habitat.
These combined threats have devastated axolotl populations. According to the International Union for Conservation of Nature, there are fewer than 100 adult axolotls left in the wild. The species is considered critically endangered.
