Axolotls in Peril

There's a good chance you’ve come across this internetfamous animal while browsing social media. It’s a frilly salamander called an axolotl (AK-suh-lah-tuhl) that some say resembles a reallife Pokémon. On TikTok, videos of people showing off their pet axolotls have racked up billions of views. Axolotl characters even make appearances in video games like Minecraft and Fortnite. What’s behind this unusual animal’s popularity? “Axolotls are really cute,” says Jessica Whited, a molecular biologist at Harvard University in Massachusetts. “They seem to always have a smile on their face.”

Axolotls have such cute features because they are neotenic. As they age and get bigger, they retain characteristics of their juvenile form (see Life of an Axolotl). “Axolotls are like Peter Pan!” says Diana Laura Vázquez Mendoza, a graduate student studying ecology at the Universidad Nacional Autónoma de México (UNAM). They never seem to grow up. “Despite being an adult, the axolotl never stops looking like a tadpole.”

You’ve probably seen this internet-famous animal on social media. It’s a frilly salamander called an axolotl (AK-suh-lah-tuhl). Some say it looks like a real-life Pokémon. On TikTok, people are showing off their pet axolotls. Their videos have racked up billions of views. Axolotl characters even appear in video games like Minecraft and Fortnite. Why is this unusual animal so popular? “Axolotls are really cute,” says Jessica Whited, a molecular biologist at Harvard University in Massachusetts. “They seem to always have a smile on their face.”

Axolotls look so cute because they are neotenic. As they age and get bigger, they keep their youthful features (see Life of an Axolotl). “Axolotls are like Peter Pan!” says Diana Laura Vázquez Mendoza. She’s a graduate student studying ecology at the Universidad Nacional Autónoma de México (UNAM). The animals never seem to grow up. “Despite being an adult, the axolotl never stops looking like a tadpole.”

But the axolotl is more than just adorable. It also has an incredible skill: This animal can regenerate, or regrow, its limbs, tail, spinal cord, and even parts of its heart! To learn more about this ability, scientists are raising and studying hundreds of thousands of axolotls in laboratories around the world (see Laboratory Animal). Yet despite their popularity and importance to science, axolotls are almost completely extinct in the wild. Due to issues like habitat loss and pollution, this smiley salamander is currently one of the rarest wild animals on the planet.

But the axolotl isn’t just adorable. It can also do something amazing. This animal can regenerate parts of its body. It can regrow its limbs, tail, spinal cord, and even parts of its heart! Scientists want to learn more about this ability. So they’re raising and studying hundreds of thousands of axolotls in laboratories around the world (see Laboratory Animal). But even though axolotls are popular and are important to science, they’re almost completely extinct in the wild. Problems like habitat loss and pollution threaten this smiley salamander. It’s now one of the rarest wild animals on the planet. 

Axolotls are native to a small region in central Mexico (see Valley of Mexico: Then and Now). Hundreds of years ago, the salamanders could be found throughout the network of lakes and wetlands that spanned the area. It was the perfect place for these amphibians—animals like frogs, toads, and salamanders that need a moist environment to live.

The ancient Aztecs— Indigenous people who once lived in the region—built their civilization around the lakes in the valley. The Aztecs grew food on floating gardens called chinampas, which are made from woven rafts anchored in shallow water. Their civilization thrived alongside axolotls. The axolotl became an important symbol in Indigenous Mexican mythology. The creature was thought to be the living representation of the god Xolotl. In the Indigenous language of Nahuatl, axolotl means “water monster.” The Aztecs also used axolotls for food and medicine. “Axolotls are an icon for Mexican people,” says Mendoza. “We can see our country’s history through the history of axolotls.”

Axolotls come from a small region in central Mexico (see Valley of Mexico: Then and Now). Hundreds of years ago, a network of lakes and wetlands spanned the area. The salamanders lived throughout them. It was the perfect place for amphibians like frogs, toads, and salamanders. These animals need a wet environment to live.

The ancient Aztecs once lived in the region. These Indigenous people built their civilization around the lakes in the valley. The Aztecs grew food on floating gardens called chinampas. To make these gardens, they wove rafts and anchored them in shallow water. Their civilization thrived alongside axolotls. The axolotl became an important symbol in Indigenous Mexican mythology. People thought it was the living image of the god Xolotl. In the Indigenous language of Nahuatl, axolotl means “water monster.” The Aztecs also used axolotls for food and medicine. “Axolotls are an icon for Mexican people,” says Mendoza. “We can see our country’s history through the history of axolotls.”

In the early 1500s, Spain invaded what is now Mexico and colonized Indigenous land including the Valley of Mexico. The area’s entire ecosystem—the community of organisms interacting with each other and their physical surroundings—changed. Many lakes were drained to build cities and control flooding. Others dried up because of climate change. That greatly reduced the axolotls’ habitat.

Today, wild axolotls are found only in the narrow canals and waterways of Xochimilco (soh-cheeMEEL-koh), a district of Mexico City. These waterways are what remains of the ancient lakes that once spanned the Valley of Mexico.

In Xochimilco, farmers still use the chinampa system to produce vegetables and flowers for Mexico City, says Mendoza. Unfortunately, the region suffers from pollution, urbanization, and the introduction of invasive species, like carp and tilapia. These fish eat young axolotls and compete with larger, mature axolotls for food.

In the early 1500s, Spain invaded what is now Mexico. People from Spain colonized Indigenous land, including the Valley of Mexico. The area’s entire ecosystem changed. That’s the community of organisms together with their physical surroundings. Many lakes were drained to build cities and control flooding. Others dried up because of climate change. That greatly reduced the axolotls’ habitat.

Today, wild axolotls are found only in Xochimilco (soh-chee-MEEL-koh), a district of Mexico City. They live in its narrow canals and waterways. That’s what remains of the ancient lakes that once spanned the Valley of Mexico.

In Xochimilco, farmers still use the chinampa system. They grow vegetables and flowers for Mexico City, says Mendoza. Sadly, the region suffers from pollution and urbanization. And invasive species, like carp and tilapia, have been introduced. These fish eat young axolotls. They also compete with larger, mature axolotls for food.

In 1998, scientists estimated that there were about 6,000 axolotls per square kilometer (15,500 per square mile) in Xochimilco. Two decades later, their population had dropped to fewer than 36 axolotls per sq. km (93 per sq. mi). Scientists now estimate that between 50 and 1,000 individuals remain in their natural habitat.

Today, far more axolotls— roughly 1 million of them—can be found in aquariums in homes and laboratories than in the wild. Nearly all axolotls in captivity are descended from a small population collected by a scientific expedition in the 1860s and taken to a zoo in Paris, France. There, the captive axolotls reproduced and eventually developed a mutation, or change, to their genetic code. It caused the animals to have little or no coloring in their skin, producing the pink and white axolotls most people are familiar with. In the wild, axolotls are brown or black. 

In 1998, scientists estimated the number of axolotls in Xochimilco. There were about 6,000 per square kilometer (15,500 per square mile). Two decades later, their population had dropped by a lot. Fewer than 36 axolotls per sq km (93 per sq mi) were left. Scientists now estimate that between 50 and 1,000 axolotls remain in their natural habitat.

Today, around 1 million axolotls live in aquariums in homes and laboratories. That’s far more than live in the wild. Nearly all captive axolotls came from a small group of animals. Scientists collected this population in the 1860s and took them to a zoo in Paris, France. There, the captive axolotls reproduced. Over time, they developed a mutation, or change, to their genetic code. It caused the animals to have little or no coloring in their skin. The result was the pink and white axolotls that most people recognize. In the wild, axolotls are brown or black.

Unfortunately, “having axolotls in fish tanks does not lead to the survival of wild axolotls,” says Mendoza. And that’s a big problem. Axolotls are a key component of Xochimilco’s food web, or interconnected food chains of what eats what within an ecosystem. Their numbers also help scientists track the health of the waterways in Mexico City: If axolotls are having trouble surviving, that means the entire ecosystem is unhealthy.

The extinction of wild axolotls would also negatively affect medical research. “Losing the ability to study any animal in its wild habitat is a huge loss,” says Whited, the molecular biologist from Harvard. Studying axolotls in their natural habitat helps scientists understand how and why the animals evolved, or changed over time, to develop the ability to regenerate lost body parts.

Sadly, “having axolotls in fish tanks does not lead to the survival of wild axolotls,” says Mendoza. And that’s a big problem. Axolotls are a key part of Xochimilco’s food web. That’s a system of food chains, or what eats what within an ecosystem. The animal’s numbers also help scientists track the health of Mexico City’s waterways. If axolotls are having trouble surviving, the entire ecosystem is unhealthy.

The extinction of wild axolotls would also be bad for medical research. “Losing the ability to study any animal in its wild habitat is a huge loss,” says Whited, the molecular biologist from Harvard. Scientists want to understand how the animals evolved, or changed over time, and gained the ability to regrow lost body parts. Studying axolotls in their natural habitat could help.

To protect wild axolotl populations in Xochimilco, scientists at UNAM have teamed up with local chinamperos, or farmers who grow crops on chinampas. They launched an ongoing project that aims to unite ancestral farming practices with axolotl conservation.

At the end of canals between the floating gardens, researchers have installed mesh gates to keep invasive species out and increase the rare salamanders’ chance of survival. These gates also contain aquatic vegetation that helps filter and clean contaminated water. Many chinamperos have even agreed to stop using pesticides that can pollute the water. 

Scientists at UNAM are working to protect wild axolotl populations in Xochimilco. They’ve teamed up with local chinamperos. These farmers grow crops on the chinampas. Together, they launched an ongoing project. It aims to combine traditional farming practices with axolotl conservation.

Canals run between the floating gardens. At the ends of the canals, researchers have installed mesh gates. This keeps invasive species out, and it increases the rare salamanders’ chance of survival. The gates also contain aquatic vegetation. These plants help filter and clean polluted water. Many chinamperos have even agreed to stop using pesticides that can pollute the water.

The chinamperos and researchers at UNAM want to create an environment where wild axolotl populations can once again grow and thrive. When conditions are suitable, the scientists also plan to reintroduce axolotls raised in captivity to the area, says Mendoza. The project benefits both the people and the ecosystem of Xochimilco, all while working to revive the wild population of a creature that is beloved the world over.

The chinamperos and researchers at UNAM want wild axolotl populations to grow and thrive again. They’re trying to create the right environment for this. When conditions are right, the scientists also plan to release captive axolotls in the area, says Mendoza. The project benefits both the people and the ecosystem of Xochimilco. At the same time, it’s working to restore the wild population of a creature that is beloved around the world.