Discovery of a blind cavefish that walks on land sheds light on the evolution of tetrapods, scientists said.
The small, one-of-a-kind fish found in Thailand may help experts understand better how life evolved on Earth, how species that live in dark places are able to forage, mate and do other activities. Ultimately, it could provide insight into how past water dwellers developed into species that walk on land.
The Walking Fish
The walking fish that has been making a buzz worldwide is the Cryptotora thamicola. Also called waterfall-climbing cave fish, this animal uses its four fins to "walk" on rocks and climb wet walls.
One of the most interesting discoveries of the researchers is that the fish has a complete set of pelvic bones attached to its spine - something that is not present in any other 30,000 species of fish all over the world.
Such characteristic is notably present in today's vertebrates living on land and in ancient tetrapods as seen in unearthed fossils. With this, the fish may serve as an extraordinary key to discovering more things about species evolution.
The waterfall-climbing cave fish was first found in 1985 in eight caves located in Northern Thailand, near the border of Myanmar. At present, the government has become overprotective of this area, limiting experts who are able to go to the caves to do research work.
A Look Back At The History Of Tetrapods
The first vertebrates that were able to walk on land were tetrapods, which had four limbs. Despite this knowledge, experts remained unsuccessful in looking for intermediate species that can demonstrate how some fish evolved to land-walkers.
Although the blind waterfall-climbing cave fish is unlikely to be a part of the family of the earliest tetrapods, its evolution surely gives a luminous spark for scientists so they could better understand how other species were able to move on land.
Scientists Stunned
In 2015, Apinun Suvarnaraksha from Thailand's Maejo University and Daphne Soares from New Jersey Institute of Technology set off to the caves where the waterfall-climbing cave fish can be found and took a video of it.
The video got the interest of Soares' colleague Brooke Flammang, who could not believe that fish can do such a thing as walking. Flammang then started working with Suvarnaraksha, who was able to return to the cave to get more information.
Suvarnaraksha caught the fish, placed it in an aquarium, filmed it and released it afterwards. He was also able to do a CT scan of a preserved specimen to add to his research materials.
Flammang was still stunned upon receiving the new data and doing the analysis, pointing to the CT scan image of the huge pelvis, which does not look like a fish pelvis at all.
"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," she says.
Ultimately, Flammang says the research gives information about how adaptable the structure of the fish body is and how these features come close to the previously discovered evolution of tetrapods.
The study was published in the journal Scientific Reports on Thursday.
