Mysterious cave dwelling creature is going blind — one eye at a time, researchers say
Deep in the underwater caves of the Philippines, a thin, slithery creature moves between the rocks.
Living its life in almost complete darkness, it has no use for eyes — so it is getting rid of them.
Researchers from National Sun Yat-sen University in Taiwan announced the discovery of a new species of moray eel living in the waters of Filipino and Australian caves, according to a May 29 news release.
“The cross-national research team of NSYSU found a small-sized, brown-colored Moray eel … with very small eyes in an underwater cave environment with almost no light, and even the unilateral eyes of some individuals disappeared completely,” the researchers said in a May 30 Facebook post.
The researchers set baited traps in two different anchialine caves, a body of water that is landlocked but connects to the ocean underground, according to their study, published in Raffles Bulletin of Zoology on March 29.
In those traps they captured nine eels, with “very small eyes, a relatively long tail, and a comparatively large number of vertebrae,” unlike any known species of moray eel.
The researchers took measurements and photographed the specimens, and saw that some of them had two eyes, some of them had only one eye covered by a layer of skin, and two of the specimens had no eyes at all.
By comparing the trapped eels to other known species, researchers determined that this one had never been discovered before.
The researchers named it Uropterygius cyamommatus, the first reported moray eel in anchialine caves, according to the study.
The researchers believe that they have caught evolution in action, seeing varying stages of adaptation in the different eel specimens they collected.
The species is transitioning from a species that relies on sight to one that no longer needs to see, relying instead on their other senses. The eels have begun the adaptation process but have not completely bred out eye development.
“Eons ago, before they retreated to the inky depths of the caves, the ancestors of these eels may have needed their eyes to hunt and detect predators,” Richard Pallardy wrote about the study in Science. “But now, in the absence of light, eyes have become unnecessary—and too costly for the body to make.”
The researchers said fish with small eyes or no eyes are extremely rare, according to the release, so it’s important to study the changes this species is experiencing.
Baidu Translate was used to translate the release from National Sun Yat-sen University.
This story was originally published May 30, 2023 at 2:56 PM with the headline "Mysterious cave dwelling creature is going blind — one eye at a time, researchers say."
