Scientists Stumble on First-of-a-Kind Golden Cavefish That Still Appears To Be Evolving, Baffles Them

Deep within the dark abyss of Guizhou Province, China, in a dark, water-filled cave, researchers have made a stunning discovery—a brand-new species of golden cavefish. This freshly out-of-the-slammer species is not only stellar in its golden hue but also provides a fascinating glimpse into evolution in action. After further research, it was noted that its features still show continuous adaptation to its surroundings for its survival, stated ZSE.

Unlike many other cave-dwelling species, which have unfortunately lost their eyes over time due to the absence of light, Sinocyclocheilus xingrenensis possesses unusually large eyes, a complex trait given its dark habitat. At the same time, it lacks scales, a common adaptation among cavefish. These unique characteristics indicate that this species is still in the process of adapting to life underground. The researchers wrote, "This further suggests that most cave fishes may not have lived in cave ecosystems for more than a few million years. Thus, together with the eyes and scales, we hypothesize that the new species may be undergoing a gradual evolutionary process towards caves," stated IFL Science.

This species is distinguishable from the 80 other members of the Sinocyclocheilus genus by a set of unique features, including its golden, scaleless body adorned with irregular black markings. The study authors note, "This is related to the habitat, where the new species can be connected to surface streams through cave windows, and their life rhythms may be closely related to photoperiods." The fish also lacks the horn-like figure seen in some of its relatives, for instance, S. longicornus — a unicorn-like cavefish, also blind, discovered in 2023. As if this was not enough, upon further analysis, its pectoral and pelvic fins are placed in a manner that makes it different from other similar species, making it a stellar discovery for scientists, stated Live Science.

The presence of humungous eyes in this creature, despite its pitch-black environment, indicates that it may still rely on some light penetration through cave openings; however, this is not proven, but one can speculate. The researchers noted, "Although the population of this new species is not extremely small, its habitat is located in the center of the village, making it more susceptible to anthropogenic disturbance. Moreover, with the potential for future urbanization in the village, there is a significant risk of habitat degradation and destruction in the near future," stated IFLScience.

The discovery of this particular fish is the embodiment of the constant adaptation creatures can undergo. The researchers note, "Using the time divergence of S. xiejiahuai (a related species) as a reference, the loss of these scales occurred centrally after the Pleistocene (about 2.58 million years ago). This suggests that scale degeneration may not be very ancient, ranging from early to late Pleistocene. This is similar to the degeneration or loss of eyes of species within the genus Sinocyclocheilus during the Pleistocene. Thus, together with the eyes and scales, we hypothesize that the new species may be undergoing a gradual evolutionary process towards caves," stated Live Science.