Researchers from the New Jersey Institute of Technology have discovered an unusual new type of cavefish in Thailand which uses a unique method of locomotion to move around like creatures with four feet, and it’s even capable of climbing waterfalls.
According to Discovery News and the Washington Post, the cavefish species as been identified as Cryptotora thamicola, and not only does it use a technique similar to salamanders for movement, it also possesses several anatomical features previously only found in tetrapods – a group of four-limbed vertebrates that include creatures such as reptiles and amphibians.
“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,” Brooke E. Flammang, co-author of a new Scientific Reports paper about the creature and an assistant professor of biological sciences at NJIT, explained in a statement.
While the Cryptotora thamicola is not the only fish species capable of moving on land, no other living type of fish uses a tetrapod-like girdle to climb, the researchers explained. These cavefish, which are also blind, are able to stick to rock and travel up waterfalls thanks to its unusual body, and it could provide new insight into the evolution of tetrapods.
A ‘huge’ finding that may have tremendous evolutionary significance
Flammang told the Washington Post that she first saw the pink-colored fish in footage collected by her co-author, also an assistant professor in the NJIT Department of Biological Sciences and was stunned by what the paper refers to as the “salamader-esque wiggle” of the creature.
As she and her colleagues explained in their study, the cavefish travels using a diagonal-couplets style, lateral sequence gait similar to the aforementioned amphibians, and has pelvic bones which are comprised of a broad puboischiadic plate linked to the iliac process of a hypertrophied sacral rib, instead of having suspended or loosely-attached bones nearly all other species of fish.
Furthermore, Cryptotora thamicola has large anterior and posterior zygapophyses, transverse processes, and broad neural spines in the vertebral column of its sacral area – features that are all closely associated with terrestrial organisms, the study authors wrote. It pulls off its odd gait by rotating its pectoral and pelvic girdles to create a wave-like motion of its axial body. The authors call it the first ever example of tetrapod-like walking behavior and morphology observed in an extant fish.
“This research gives us insight into the plasticity of the fish body plan and the convergent morphological features that were seen in the evolution of tetrapods,” Flamming said, telling Discovery News, “From an evolutionary perspective, this is a huge finding. 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.”
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Image credit: New Jersey Institute of Technology
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