In a remote cave chamber in northeastern India, scientists have stumbled upon a startling find—a cave fish unlike any other known species. This discovery, detailed in the journal Cave and Karst Science, challenges our understanding of subterranean life and offers a rare glimpse into the rapid evolution of these enigmatic creatures.
Biologist Daniel Harries, part of an expedition led by professional cave explorer Thomas Arbenz in Meghalaya state, was taken aback when he encountered a fish nearly a foot and a half in length—ten times larger than previously known subterranean fish. The species, found in the Um Ladaw Cave over 300 feet below the surface, is teeming with dozens of these unusually large fish.
Harries, a marine biologist at Heriot-Watt University in Edinburgh, described the moment of discovery, saying, “My first reaction upon seeing the fish myself was, I’m going to need a bigger net.” The fish, possibly on the path to becoming a distinct species, has raised intriguing questions about its adaptation to the cave environment.
The team, collaborating with Indian scientists Neelesh Dahanukar and Rajeev Raghavan, is delving into the genetics of the fish to confirm if it is indeed a new species. On a return visit in January 2020, the researchers collected live specimens and fin samples for lab analysis.
The mystery deepens as scientists ponder how these fish, living in perpetual darkness and with limited food sources, manage to reach such substantial sizes. Their feeding habits remain elusive, although it’s speculated that they consume vegetation washed into the cave by rain during the winter dry season. The challenge lies in understanding this unique ecosystem as access becomes impossible during the monsoons when the entire area is submerged.
Harries emphasizes the need to protect these cave environments, which are under threat globally from activities like cement production, coal mining, and water pollution. The fragile ecosystems could face extinction risks before being fully documented, highlighting the urgency of conservation efforts.
Evolution, once thought to be a slow and irreversible process, takes centre stage in this discovery. “Studies of these systems seem to indicate that very different animal forms might be able to evolve relatively rapidly,” notes Harries, emphasizing the dynamic nature of evolution in subterranean habitats.
This unexpected find opens new doors for scientific exploration, providing a unique opportunity to unravel the mysteries of evolution in the depths of Earth’s caves.
Source: National Geographic
