Deep in Kentucky’s rivers lives one of North America’s most mysterious creatures—the Eastern hellbender.
Growing up to two feet long, this flat, wrinkly salamander has earned colorful nicknames like “snot otter” and “lasagna lizard” for its slippery skin and folded body.
But behind its odd appearance lies a story about clean water, healthy habitats, and the future of freshwater ecosystems.
A new study from the University of Kentucky (UK) has revealed exactly where these rare salamanders thrive and what they need to survive.
The research, published in Freshwater Biology, shows that hellbenders prefer cool, clear streams with rocky bottoms—and they disappear when too much sediment fills the spaces beneath those rocks.
The project was led by Sarah Tomke during her Ph.D. in the Department of Forestry and Natural Resources at UK’s Martin-Gatton College of Agriculture, Food and Environment.
Working with department interim chair Steven Price, Tomke used cutting-edge environmental DNA (eDNA) to search for hellbenders across 90 sites in 73 rivers.
Instead of turning over heavy rocks or snorkeling for hours, the team collected water samples, filtered them, and looked for traces of hellbender DNA. This method lets scientists detect animals without ever seeing them.
They found hellbender DNA at 22 sites statewide, including 12 where the species had been recorded in the past.
“Seeing a hellbender is incredible, and holding one is next level,” Tomke said. “But my favorite part was the data—it clearly showed how stream conditions affect where hellbenders live.”
Hellbenders once swam throughout much of Kentucky but are now increasingly rare. They spend nearly all their time hidden under flat rocks in cool, oxygen-rich streams, especially in the Appalachian region and the Ohio River basin.
According to Price, spotting one in Kentucky is special. “They’re incredibly secretive,” he said. “They live under large rocks that take time and care to lift. When you find one, you know the habitat is healthy.”
The study found that local habitat mattered far more than general water chemistry or surrounding land cover. Hellbenders were much more likely to live in streams with plenty of gravel, cobble, and bedrock, and less likely to appear where fine sediment clogged the spaces under rocks. That sediment fills in the crevices where the salamanders lay eggs and where young hellbenders hide from predators.
“Fine sediment is a big problem,” Tomke said. “It destroys nest sites and the small shelters juveniles need to survive. Without those spaces, the animals can’t reproduce or live long.”
The research also revealed when hellbenders are easiest to detect using eDNA. Early fall—especially September—proved ideal, as the salamanders shed more DNA during their breeding season.
While Tomke’s team didn’t discover brand-new populations, their roadmap worked: after her study, Kentucky Department of Fish and Wildlife biologists found hellbenders at two of her eDNA-positive sites, confirming the method’s accuracy.
Price described the project as the most extensive eDNA survey for hellbenders in Kentucky’s history. “Sarah’s work gives us clear goals,” he said. “Keep sediment out of streams, protect rocky streambeds, and restore forested banks. That’s how we give this species a fighting chance.”
Hellbenders are more than just fascinating relics of ancient evolution—they’re indicators of clean water. When hellbenders disappear, it often means the entire river ecosystem is in trouble.
“Everyone can help,” Price said. “Stabilizing eroding streambanks, managing farm runoff, and planting trees along rivers all make a difference. When we protect hellbenders, we protect the health of our waterways—and our communities, too.”
