It may not seem like much -- a little blind cavefish squirming its way up a rock -- but researchers say this is one of the most unique fish on the planet.
"What these fish do in complete darkness is they stick to the rock and they climb waterfalls completely underwater," Daphne Soares, an assistant professor at the New Jersey Institute of Technology, said in a video news release.
The fish, found in Thailand, is called Cryptotora thamicola, and the way it can walk and climb is unlike any other known fish. In fact, it moves almost like a salamander, Soares and her fellow researchers wrote in the journal Nature Scientific Reports.
They believe this fish may be a living link to a key moment in evolution, when finned creatures of the sea became the limbed creatures of the land.
While there are other fish that can appear to walk, they use their fins and generally rely on the flow of water around them to keep upright.
But, according to the new research, this cavefish is able to support its own bodyweight against gravity using its pelvis and vertebral column.
A 2009 video shows the fish in action:
"From an evolutionary perspective, this is a huge finding," said Brooke E. Flammang, also an assistant professor and another another author of the paper. "This is one of the first fish that we have that is a living species that acts in a way that we think they must have acted when they evolved from a fluid environment to a terrestrial environment."
She said the fish could offer a glimpse at the moment in evolution when life transitioned from the sea to the land some 420 million years ago.