They say love is blind, but that doesn’t mean it’s easy to get eyeless cave salamanders to mate.
Still, that’s what biologists at the San Antonio Zoo’s Center for Conservation and Research have been able to achieve, through repeated trial-and-error efforts over several years. Recently, researchers there have been able to get three endangered salamander species to reproduce, two for the first time ever in captivity.
Though the researchers work with smaller and less popular animals than the typical zoo fare of lions, elephants, and giraffes, species like salamanders hold incredible value for humanity, explained zoo Vice President Danté Fenolio, a conservation biologist specializing in cave-dwelling critters who has worked around the world.
Cave species have unusual adaptations to help them survive in total darkness with long gaps between meals. Because of this, their genetics hold tantalizing clues to help biomedical researchers learn more about conditions like diabetes and eye conditions, Fenolio said.
They also can serve as warnings of contaminated drinking water aquifers, the kind of information that would be vital to a city like San Antonio. The city relies heavily on water stored in the Edwards Aquifer, a limestone rock layer below our feet.
“If you are a groundwater organism — blind cave fish, blind salamander, blind cave crayfish, doesn’t matter — if there’s a contamination event, where are you going to go?” Fenolio told the Rivard Report on a visit to the center last month. “If there’s something wrong with the water, they’re the first to know, and they’re the first things that could show you signs of it.”
On Feb. 26, Fenolio and center manager Bekky Muscher-Hodges offered a tour of some of the shipping containers and trailers converted to laboratories tucked away behind the zoo’s public-facing exhibits. Inside, they showed where they keep blind cave crayfish, eyeless catfish, Texas horned lizards, and, of course, salamanders.
The center serves as a sort of conservation mechanic’s shop, where skilled technicians tinker with how best to preserve and care for some of the species most at risk for extinction. Its staff are unabashed champions of the animals that don’t get the love and attention showered on large land-dwellers.
“The vast majority of species that need our help don’t fall into the cute, warm and fuzzy bucket,” Fenolio said.
That week, zoo staff were proudly showing off baby Texas blind salamanders. These eyeless, slow-moving creatures have a semi-translucent skin covering their roughly 3-inch torso, along with spindly limbs and red gills that look like antlers branching from their heads. They may look strange to us surface-dwellers, but these adaptations are perfect for life underground.
But when they’re still the size of grains of rice, Texas blind salamanders look surprisingly like other baby salamanders. For one thing, they have eyes, which look like black dots on their tiny faces.
As they get older, these eyes slowly disappear in response to genetic triggers, Fenolio said. In cave fish, biomedical researchers have been able to use such eye loss as a model for degenerative eye diseases that affect people, he said.
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There are other mysteries as well. Even though Texas blind salamanders have successfully reproduced in about a half-dozen facilities, scientists still don’t know how exactly they do it. At the zoo, researchers came to work one day and found viable eggs.
“It was amazing,” Muscher-Hodges said. “Baby anything is really cool, but a baby endangered species is just amazing.”
Zoo staff arrived at the clutch of salamander babies through “trial and error,” she said. All they know is when they put a particular group of male and female Texas blind salamanders together, they got eggs. Other groups of salamanders had been together for more than a year with nothing to show for it. Researchers don’t yet know what causes sparks to fly when one salamander meets another in the dark crevices of the Edwards Aquifer.
“I guess when you run into each other in the aquifer, there’s two things you can do,” Muscher-Hodges said. “One of them is eat and one of them is try to make more blind salamanders.”
Fenolio thinks they’ll eventually find “what levers to pull” to get Texas blind salamanders to breed. After all, he and his colleagues cracked the romance code on Georgia blind salamanders and reticulated flatwoods salamanders, even though it took more than 10 years for each.
Fenolio described the process of creating a perfect love nest for Georgia blind salamanders. Based on what little they understood about their finicky needs, he and Muscher-Hodges knew they needed to replicate an underground spring.
“I can’t tell you why, but that’s what they like,” Fenolio said. “And I only know that because I work with cave divers, and they tell me that’s where they see them.”
They eventually landed on a system with a pump pushing water up through a pile of limestone rubble. Soon after they got it right, they had their first batch of viable eggs.
Researchers like them will likely have more problems to deal with in the future. Most conservation biologists consider the world to be entering the sixth major die-off of species in Earth’s history, with 1 million species on track to die off in the coming decades. Biologists often refer to the causes as the five horsemen of the apocalypse – habitat loss, invasive species, overharvesting via hunting and fishing, pollution, and climate change.
Fenolio has seen the carnage firsthand over a 30-year career working with endangered animals. The extinction crisis is creating a new category of species like Mexican axolotls, a hugely popular aquarium salamander originally native to the high-altitude lakes around Mexico City.
Thanks to urbanization and pollution, axolotls can no longer live in their native habitat, Fenolio said. In effect, they’ve become ecologically homeless. Without major changes, other species are likely to join them on that list.
Fenolio thinks that’s something everyone should care about.
“Things are coming; really big things,” he warned. “And nobody’s paying attention.”