154 years ago, Albert Gunther, a German-born, British zoologist, described the deep-sea fish "Scalecus ingeserus" which has movable, separate bony supports in its pectoral fins for movement above the seabed.
After that long period since its discovery, Chinese researchers succeeded in recording a strange movement performed by this fish using those supports, which is walking sideways and backwards, a movement that has never been observed before in any other type. This allowed them to capture video of the fish alive and in its natural environment, rather than relying on preserved specimens to study its shape and anatomy only.
Shovel-like appendages
While this strange movement was the most important discovery, researchers were in for other surprises in studying this fish, which is distinguished by its unique appearance that combines the characteristics of shrimp and fish, earning it the title of "fish-shrimp hybrid" in the media.
“Another unique feature discovered is the function of its external appendages, which resemble a farmer’s trowel, ” said Han Tian, lead author of the study and PhD researcher at the School of Marine Sciences at Sun Yat-sen University, in a statement . “Although this structure is supposed to hinder its movement, it allows it to sense potential prey in the seabed sediments, or even dig in surface sediments to search for food efficiently.”
He adds that "at the same time, this creature retains its pectoral fins, which have evolved into flat, rounded plates, improving its balance while walking and swimming, while the rigid supports in its fins and tail, which resemble the tail supports of a shrimp, enable it to make quick and sudden jumps when it senses danger."
The mystery of light sensitivity
During the filming, the scientists made a valuable observation: the fish did not seem to be greatly affected by the approach of the diving vehicle, but it did show a response when the vehicle shone its light on it, before swimming away.
The researchers believe that this observation indicates that the fish's eyes still possess a degree of sensitivity to light.
Scientists believe that this sensitivity may reflect the fact that the fish did not live in the deep sea throughout its evolutionary history, a hypothesis they stressed needs further study.
These discoveries demonstrate the importance of observing the behavior of a living animal in its natural habitat, an advantage afforded by modern technologies such as diving vehicles.
Han says, "Studying a preserved specimen can reveal a lot about an animal's anatomy, but it doesn't necessarily explain how it uses its organs while moving or searching for food. Modern diving vehicles allow us to see these creatures move, feed, and interact with their environment."
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