At first, the idea that a fish could walk seems absurd, but new research has shown that a good number of fish might be able to walk on land.

The study was carried out by an international team led by scientists from the Folrida Museum of Natural History and published its findings on September 8, 2020 in the Journal of Morphology.

Asian loach fish

In a detailed study of the skeletons of the "hillstream loach" fish family in Asia, which includes one species that can walk to some extent, which is the "blind and rare cave angel fish" (cave angel fish or Cryptotora thamicola), it was revealed that there are 10 species. Others at least have the same capabilities.

By identifying the species of loach fish - which can go roaming the earth (ignoring the breathing difficulties for a moment) - the researchers hope to learn more about the possibility that the first aquatic vertebrates made their way out of the water and on land.

It is the pelvic girdle, the link between the spine and the pelvic fin, which is the key.

The team looked at the skeletons of 29 different species of the loach fish group, identified 3 different types of aquarium shapes, and found that 10 other species share the same way of bone connection as "cavefishes".

"The fish usually have no connection between their spine and their pelvic fin," says biologist Zachary Randall of the Florida Museum of Natural History, in the press release of the study, posted on the museum's website.

The prevailing idea was that blind cavefishes are completely unique in their ability to walk (Khulabush Khatanusharoen - Flickr)

Caveman fish

But before that the common idea was that cavefishes were completely unique.

But what's really cool about this paper is that it shows in great detail that stiffeners are more common than we thought in the family of houndfish loachs.

Cavefish use enlarged ribs and stable muscles to navigate through a "salamander-like wiggle" that uses their fins.

It is the only loach type that has been observed doing something like walking.

Experts believe it developed the ability as a way to navigate fast-flowing cave currents, and possibly access oxygen-rich streams that other fish cannot reach.

It can even be used to get fish in a shallow and light waterfall.

Through a combination of DNA analysis and computerized tomography (CT) scans, the researchers found evidence that these abilities were genetically transmitted and shared with other members of the loach family.

And it doesn't appear to have evolved from just one source.

The researchers found evidence that these abilities were genetically transmitted and shared with other members of the loach family (Zologish Medelingen - Wikipedia).

A better understanding of fish walking

All this gives biologists a more accurate evolutionary family tree when it comes to walking fish, and a framework for trying to identify more of them in the future, although the level of walking skill may vary from species to species.

"This study brought together a multidisciplinary team of researchers, ranging from those who do field work and study fish in their natural habitats, to geneticists and comparative anatomy," said biologist Lawrence Page of the Florida Museum of Natural History.

"The result is a better understanding of the evolution of a very rare event, which is the ability of fish to walk on land," he concluded.