The cavefish found in India weigh 10 times heavier than previously known cave fish and may be a new species still evolving. In Um Ladaw Cave in meghalaya, northeastern India, biologist Daniel Harries holds a newly discovered cave fish, the largest cave fish in the world. Photo by ROBBIE Shone
At present, there are about 250 species of known subsurface fish on Earth, living in a dark and food-starved world, and are generally very small, only a few centimeters long. But in an underground cave in northeastern India, researchers found a larger cave fish that is nearly 45 centimeters long and weighs 10 times more than any known cave fish. Locals report that they occasionally see this newly discovered cave fish in Himmpe Cave, where waterfalls flow from underground waterholes. Photo by ROBBIE Shone
At present, there are about 250 species of known subsurface fish on Earth, living in a dark and food-starved world, and are generally very small, only a few centimeters long. The fish, recently described in the journal Cave and Karst Science, may still be evolving and will become a new, independent species. Um Radu Cave has three vertical rock walls, one of which, as shown in the picture, resembles a beautifully carved rock scroll. Here, British cave explorer Nicky Bayley climbed the rope leading to the top. During the rainy season, the cave will be flooded and will not be accessible. Photo by ROBBIE Shone
Harries' expedition was led by professional caving explorer Thomas Arbenz, who found the fish in a cave in the Indian state of Meghalaya. The area is rich in soluble rocks and limestone, which are easily etched by rain, resulting in many caves. Meghalaya is also one of the most rainy places on earth. Pictured: Um Radu Cave, where British caving explorer Nicky Bayley catches a cave fish with a large net, harries (center) watches from the sidelines. The expedition team didn't know at first how big the cave fish were or how big their nets were. Photo by ROBBIE Shone
The expedition team saw a picture of the fish from an explorer and guessed it was a new species. But when they saw the fish in the Um Ladaw cave, more than 90 meters underground, they were surprised. Pictured: Harries held and examined the fins of this cavefish, which are anatomically similar to the surface-dwelling yellowfin knot fish (Tor putitora), but the cavefish lack well-developed eyes and pigmentation. Photo by ROBBIE Shone
Why they got so big and what exactly they fed on remains a mystery, Harries said. The expedition team had not weighed them yet because it would be difficult to get the scales into the cave, but he estimated that they would weigh nearly a kilogram. Pictured: The researchers cut a small piece from the fin for DNA analysis and then put it back into the water. Photo by ROBBIE Shone
According to locals, they occasionally see the eyeless fish in the Chympe cave, which is also inhabited by bats that produce feces to feed cave creatures. Bats have not been found in Um Ladaw Cave, where newly discovered cavefish survive on a food of unknown origin — perhaps vegetation and debris washed down from the surface.
Photo by ROBBIE Shone