MEXICO CITY — Somewhere underneath the hull of Armando Tovar's boat, the aquatic manifestation of the great god Xolotl was slithering along the muddy canal bottom, digesting bugs, laying eggs and trying to avoid extinction.
Even though he could not see the creature, Tovar knew it would be confronting its troubled environment with that weird fixed smile, the one that makes it appear to be in on some cosmic joke.
As a 9-inch salamander, of course, the ajolote (pronounced ah-ho-LO-tay) couldn't know its own cultural significance in Mexico. It couldn't know its role in the Aztec creation myth. Or its freak-show star status among biology nerds for its ability to regenerate lost limbs, heart cells and bits of brain. Or its allure, in the world of arts and letters, as both a cryptic literary symbol and a metaphor for the Mexican soul.
It couldn't know, on this placid Tuesday morning, that Armando Tovar was in this long, flat wooden boat, with his colleagues and their water-quality monitoring devices, hoping to save it from oblivion.
Tovar, 33, a biologist at Mexico's National Autonomous University, or UNAM, is one of a group of scholars seeking to solve the ecological puzzle of the ajolote and its sole habitat, the canal system of Xochimilco, the last watery remnant of the Aztec society built on the lakes and wetlands of the Valley of Mexico.
Today, Xochimilco is a heavily visited oasis of crops and canals hemmed by the teeming, concrete presence that some here call la mancha urbana, the urban stain. Its 110 miles of waterways are a place where tourists and locals fritter away Sunday afternoons, floating on brightly colored gondolas, drinking beer and taking in the area's remaining chinampas, small agricultural islands that were invented by Aztec farmers.
The precious green space scrubs carbon dioxide from Mexico City's famously polluted air, serves as a rest stop for 84 species of migratory birds and helps recharge a perilously overtaxed aquifer.
But it also is dealing with pollution issues of its own, and that has consequences for the salamander whose strangely childish looks have made waves as far as Japan, where it was the inspiration for a Pokemon character.
In 1998, Xochimilco was home to tens of thousands of ajolotes. Today, Tovar said, the number might be as low as 100.
The forces aligned against the ajolote are formidable, some as old as Mexico itself.
Luis Zambrano, the director of UNAM's Ecological Restoration Laboratory and leader of the rescue effort, said the problems started with the 16th century conquistadors who, hailing from arid Spain, saw the lake system as a problem to be solved. So they drained it, making way for a modern metropolis in which, he said, natural water systems are still often viewed as a hindrance to progress.
The researchers, despite years of restoration efforts, have struggled to undo the harm. The ajolote habitat has been degraded by water extraction, industrial fertilizers, the pressures of tourism, and untreated wastewater discharged by rogue developments inside Xochimilco's protected area.
The canals are also teeming with nonnative carp and tilapia, introduced in a misguided '70s-era aquaculture project. These heartier foreign species feast on ajolote eggs and compete for scarce resources. "I call it, 'A society's defeat, caused by society,'" Tovar said.
Last month, the director of the National Water Commission, Jose Luis Luege, said Xochimilco was in danger of deteriorating so severely that it could lose its status as a UNESCO World Heritage Site. He recommended that the federal government immediately launch an ambitious, 20-year restoration plan, the newspaper Excelsior reported.
The city and federal governments already have spent millions over the years. But Zambrano said the funding for the ajolote project is wildly inconsistent from year to year, making it difficult to plan long term.
To Zambrano, Xochimilco's famous salamander is a slimy sentinel, a canary in Mexico City's ecological coal mine. Its disappearance from the wild, he argues, would be a warning that the megacity was no longer a sustainable proposition.
Protecting the ajolote, he wrote in a recent essay, "means protecting ourselves from ourselves."
The Aztecs believed that the creature formally known as the Ambystoma mexicanum was an iteration of Xolotl, the deformed god of lightning and Charon-like ferryman of the dead to the underworld. Xolotl, the legend goes, took the form of an ajolote to escape a death sentence imposed upon him as the current universe was being created. UCLA art history professor John Pohl notes that the Aztecs also saw in the amphibian's regenerative powers a metaphor for the bounty of the lake system that sustained them.
Until recent decades, when the creature began to disappear, ajolote-derived products were important components in local folk medicine. Its flesh also was valued as a particularly tasty tamale filling.
Over the centuries, naturalists worldwide have been fascinated not only with the ajolote's regenerative abilities, but also with its state of suspended pre-adolescence: Unlike most amphibians, which trade gills for lungs upon reaching adulthood, the ajolote keeps its external gills, which appear like a spiky collar behind its curiously smiling face.
The creature's biological anomalies, historic resonance and otherworldly appearance offered an inescapable appeal to a certain kind of Latin American thinker. The ajolote was the subject of a well-known Kafkaesque short story by the late Argentine writer Julio Cortazar and has featured prominently in poems by Mexican writers Octavio Paz ("Salamander/in the abstract city/between the vertiginous geometries") and Jose Emilio Pacheco ("The ajolote is our emblem/embodying the fear of being no one/and retreating/into the perpetual night, in which the gods/rot under the mud").
In 1987, the Mexican academic Roger Bartra, in his influential book "The Cage of Melancholy," embarked on an extended meditation on the ajolote, comparing it to the Mexican national character, a "strange amphibian" that is developmentally suspended, ajolote-like, between the primitive and the modern.
As Tovar and his colleagues toured a muddy, green chinampa, their boat docked, they said they didn't buy into Bartra's assertion that the animal bears "the terrible weight of symbolizing the Mexican national character."
But that didn't mean they weren't taking advantage of the ajolote's notoriety. To Tovar, the ajolote — cute, as far as salamanders go — serves as a kind of polar bear for the effort to save Xochimilco. It is their sympathetic critter. At a recent environmental fair, the biologists hawked copies of a children's book with a smiling cartoon ajolote on the cover, piloting one of Xochimilco's famous boats.
"In truth, the ajolote itself is not so important to me … or, rather, it's only important in the broader context of this threatened environment," Tovar said. "The ajolote is our flag."
But an intellectual pedigree and a cute face can help only so much.
Tovar's colleague Leonardo Sastre said the group contracts with local fishermen to haul an average of 100 tons of nonnative fish out of the canals each year. Yet their populations are still growing. At one point, on the prow of the little boat, he pointed as the normally still water began to shudder and quake.
"Look," he said. "Tilapia."
The rescue team is also working with an environmental group to encourage farmers on the chinampas to raise their crops without the fertilizers that harm the water. But less fertilizer means more work.
Carlos Sumano, a member of the environmental group, dreams of the day when hip Mexico City chefs who subscribe to the slow-food movement will buy regularly from the chinamperos. But , he said, fewer than a dozen of the hundreds of the farmers have changed their ways.
Standing on the bank of a canal, Tovar showed examples of plants that have been introduced to naturally clean the water of contaminants, including a free-floating, spongy specimen known in English as duckweed. The vegetation has been introduced in some small canals that are also outfitted with barriers to block nonnative fish.
These trench "refuges" for the ajolote have been somewhat successful; however, they cover only about 1,600 square yards of water, a tiny fraction of the canal system. Sastre said there wasn't enough financing to do more.
Two cages were submerged in the dark water of one trench, dusted with bright green duckweed. They contained 15 ajolotes hatched inside. Their parents were raised in a lab.
The biologists are not ready to release them into the wild. They worry that could introduce new diseases and genetic problems to the ecosystem. And for now, Tovar said, the water beyond the clean trench was too filthy for them to survive in.