A species of cavefish in Thailand has been documented walking and climbing waterfalls in a manner similar to four-footed creatures such as salamanders, in a find researchers call “huge” in evolutionary terms.

In a new study published in the journal Nature Scientific Reports, New Jersey Institute of Technology (NJIT) scientists describe the behavior in the blind, walking cavefish Cryptotora thamicola.

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Study co-author Brooke E. Flammang, an assistant professor of biological sciences at NJIT, said in a press release that the fish has anatomical features previously known only in tetrapods — four-limbed vertebrates that include amphibians and reptiles.

“What these fish do, in complete darkness, is stick to the rock and climb waterfalls, completely underwater,” Flammang said.

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While some other fish species have means of moving on land, the NJIT researchers write that no other living fish has the gait employed by the cavefish, which uses a tetrapod-like, “robust pelvic girdle” to climb.

“The pelvis and vertebral column of this fish allow it to support its body weight against gravity and provide large sites for muscle attachment for walking,” Flammang said.

The NJIT team says the find could tell scientists more about how the anatomy for land-walking evolved, as tetrapods made the long transition from finned to limbed beginning in the Devonian period about 420 million years ago.

“From an evolutionary perspective, this is a huge finding,” Flammang said. “This is one of the first fish that we have as 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.”