Researchers Revealed the Mysteries of a Rare Fish That Can Swim Upside Down

New research has given insight into the Coelacanth, an enigmatic and ancient fish that is still one of the world's rarest.

Researchers have extracted Denmark's sole specimen of this prehistoric fish from its jar of alcohol, gaining new information about how it functions.

The new information could help save this highly endangered deep water dweller.

Revelations of ancient fish

(Photo : David Clode/Unsplash)

When a South African fisherman discovered a coelacanth in his net in 1938, it was like discovering a living dinosaur - a discovery that shocked the scientific community.

The coelacanth (SEE-l-kanth) had been thought to be extinct for 66 million years.

Only roughly 300 specimens of this living fossil have been discovered since then. A single fish, "specimen number 23," has been submerged in alcohol at Copenhagen's Zoological Museum for 60 years, as per ScienceDaily.

Its anatomy is well known, as many previous coelacanth specimens have been dissected. However, little is known about the fish's physiology, or how it works.

Researchers from the Universities of Copenhagen and Aarhus have uncovered fresh information about this extremely unusual and elusive deep-sea dweller.

This fish is famous, highly rare, and shrouded in mystery. Because it lives in underwater caverns at depths of 150-200 meters, it is difficult to view alive.

And, because many of the few specimens gathered over the years had been sliced up, new procedures were needed to learn more about how it lives.

"We now know a little bit more," says Peter Rask Moller, associate professor and curator at the Natural History Museum of Denmark at the University of Copenhagen, and co-author of the study published in the journal BMC Biology.

Moller, along with Aarhus University's Henrik Lauridsen and a group of collaborators, is the first individual to do research on the Danish specimen, which has been preserved complete and has only been used for display until now.

We discovered that the coelacanth has a unique skeleton with a lot of bone mass in the head and tail but very few vertebrae.

It's one-of-a-kind. The heaviest sections of the fish are at either end, making it easier for the fish to stand on its head.

According to Associate Professor Henrik Lauridsen of Aarhus University's Department of Clinical Medicine, the balance point is a beneficial mechanism for its way of life.

The researchers also found the precise distribution of fatty tissue in the fish's body, including the quantity in its fatty bladder, because coelacanths lack a traditional gas swim bladder like modern fish.

Coelacanths

There are only two species of coelacanths known to science: one located near the Comoros Islands off the east coast of Africa, and another in the waters off Sulawesi, Indonesia, as per National Geographic.

Many scientists believe that the coelacanth's distinctive traits mark an early step in the evolution of fish to terrestrial four-legged animals such as amphibians.

Coelacanths are elusive deep-sea organisms that can be found at depths of up to 2,300 feet below the surface. They can grow to be enormous, standing 6.5 feet tall and weighing 198 pounds.

Scientists believe they could live for 60 years or more.

The most notable characteristic of this "living fossil" is its paired lobe fins, which extend from its body-like legs and move in an alternating manner, similar to a trotting horse.

A hinged joint in the skull allows the fish to enlarge its mouth for large prey; an oil-filled tube called a notochord that serves as a backbone; thick scales found only in extinct fish, and an electrosensory rostral organ in its snout that is likely used to detect prey.