Published in the journal Subterranean Biology, the research marks a major milestone for the study of subterranean aquatic life in East Asia. Prior to this discovery, there were no records of freshwater cave snails within Chinese territory, and the region's subterranean freshwater mollusks were generally poorly studied.
Mythological Namesake and Unique Adaptations
Perfectly suited to its pitch-black environment, Erhaia dijiang is a true troglobiont, having evolved without eyes entirely while its ocular structures show total degeneration. Its shell is small, conical, and highly translucent, while its body is delicate and unpigmented, with slender tentacles.
Fittingly, researchers named the species dijiang after "Di Jiang," a mountain patron god from ancient Chinese mythology described as a faceless beast in the classic text Classic of Mountains and Seas (山海经). The name suits the animal's habits: in laboratory observations, the snails proved highly photophobic, actively seeking out dark crevices beneath rocks to escape light.
Beyond its mythological namesake, the species is also notable for where it was found. Discovered at an elevation of 2,062 meters, Erhaia dijiang sets a new record for the highest-altitude distribution among all known cave-dwelling snails in Erhaiidae, evidence that freshwater cavesnails can survive in karst caves at altitudes exceeding 2,000 meters.
According to the researchers, the species inhabits underwater gravel and crushed stone at depths of less than one meter, where cave water temperatures remain consistently near 20°C. While rapid water flow during the rainy season occasionally flushes a small number of snails out through the cave's outlet, they are never found in nearby surface streams and stay strictly within two meters of the cave entrance. In the lab, the snails fed on diatoms growing on rock surfaces as well as artificially supplied fish food.
Urgent Call for Conservation
However, despite marking a significant advance for the study of subterranean aquatic life in East Asia, the research team warns that the survival status of this newly discovered species is "far from optimistic."
During their initial field survey in August 2025, the population density of Erhaia dijiang was found to be extremely low. The team was only able to locate three live adult individuals and a single empty shell in the shallow underground waters, and no juvenile snails were observed. The researchers are urgently calling for extensive surveys of Chinese caves to improve our understanding of these complex ecosystems, along with the rapid formulation of conservation measures to protect these vulnerable, endemic mollusks.
Original study:
He Y-M, Xiang H-Q, Yang J-M, Zheng H, Yang S-Z, Zhou Y-F, Zheng J (2026) A new eyeless species in Erhaiidae (Gastropoda, Truncatelloidea) from a cave in Yuxi City, Yunnan, China. Subterranean Biology 56: 127-136. https://doi.org/10.3897/subtbiol.56.188075
