Strange Species of Fish with Legs that Can Crawl like Shrimp on the Sea Floor

This fish can be likened to a kind of “transforming robot” in the animal kingdom. When strolling along the ocean floor, it uses its legs to crawl like a shrimp. In instances where swimming is necessary, its wing-like fins can be unfurled instantly.

The moustached fish, which appears to be composed of parts from various animals, excels at walking and foraging for food.

The moustached fish is particularly skilled at hunting prey while walking on the ocean floor using its six limb-like appendages, to the extent that some other fish follow them to wait for feeding opportunities. This was revealed in two recent studies published on September 26 in the journal Current Biology.

The moustached fish showcases a variety of vibrant colors.

The moustached fish is a unique family of fish found in various regions across the globe. At first glance, it resembles the glassfish but is more colorful and vibrant.

The most noticeable feature of the members of this fish family is the legs on both sides of their body, which enable them to crawl along the ocean floor just like shrimp. It is known that these appendages were once part of the fins but have evolved into an independent structure. Besides facilitating movement, these legs are also used by the moustached fish to stir up the sand in search of food.

The moustached fish resembles the glassfish.

David Kingsley, co-author of both studies and a professor at the Stanford University School of Medicine, first encountered the moustached fish in the summer of 2016 after attending a seminar at the Marine Biological Laboratory in Woods Hole, Massachusetts, USA. Before leaving to catch his flight, Kingsley stopped by a small aquarium and spotted the moustached fish.

“The moustached fish completely amazed me because it has the body of a fish, wings of a bird, and multiple legs like a crab. I had never seen a fish that appeared to be made up of parts from so many different animals,” Kingsley stated. He and his colleagues decided to study them in the lab.

Another intriguing feature of the moustached fish is its wing-like pectoral fins, which are spread out whenever it needs to swim. Furthermore, the moustached fish is one of the few fish species capable of producing sound. To achieve this, it vibrates its swim bladder. According to expert analysis, the moustached fish uses sound as a means of communication with its peers or to deter predators when in danger. It has been noted that the moustached fish can grow up to 1 meter in length.

Researchers brought several moustached fish back to the laboratory of co-author Nick Bellono, a professor at Harvard University, to study whether they could locate buried prey. They observed that the fish alternated between short swimming bursts and walking. They also scratched the sandy bottom of the tank for food without needing any visual cues about the prey’s location.

To continue their research, the experts brought additional moustached fish but quickly realized they were not like the original group. The new group did not dig or locate buried prey.

This led to unexpected findings for the researchers. The original fish were northern moustached fish (Prionotus carolinus), while the fish lacking the ability to sense and primarily using their legs for walking were the striped moustached fish (Prionotus evolans).

The moustached fish may provide scientists with the opportunity to study how new body parts emerge during the process of evolution, how new traits develop, and how the brain evolves and adapts to such changes, according to co-author Corey Allard, an expert at Harvard University. “These strange little fish have so much to explore that we might not be able to find from more conventional research organisms, such as mice,” he said.