A frog has been found in a remote part of Indonesia that has no lungs and breathes through its skin, a discovery that researchers said Thursday could provide insight into what drives evolution in certain species.
The aquatic frog Barbourula kalimantanensis was found in a remote part of Indonesia’s Kalimantan province on Borneo island during an expedition in August 2007, said David Bickford, an evolutionary biologist at the National University of Singapore.
Bickford was part of the trip and co-authored a paper on the find that appeared in this week’s edition of the peer-reviewed journal Current Biology.
Bickford says the species is the first frog known to science without lungs and joins a short list of amphibians with this unusual trait, including a few species of salamanders and a wormlike creature known as a caecilian.
“These are about the most ancient and bizarre frogs you can get on the planet,” Bickford said of the brown amphibian with bulging eyes and a tendency to flatten itself as it glides across the water.
“They are like a squished version of Jabba the Hutt,” he said,referring to the character from Star Wars. “They are flat and have eyes that float above the water. They have skin flaps coming off their arms and legs.”
Bickford’s Indonesian colleague Djoko Iskandar first came across the frog 30 years ago and has been searching for it ever since. He didn’t know the frog was lungless until they cut eight of the specimens open in the lab.
Graeme Gillespie, director of conservation and science at Zoos Victoria in Australia, called the frog “evolutionary unique.” He said the eight specimens examined in the lab showed the lunglessness was consistent with the species and not “a freak of nature.” Gillespie was not a member of the expedition or the research team.
Bickford surmised that the frog had evolved to adapt to its difficult surroundings, in which it has to navigate cold, fast-moving streams that are rich in oxygen.
“It’s an extreme adaptation that was probably brought about by these fast-moving streams,” Bickford said, adding that it probably needed to reduce its buoyancy in order to keep from being swept down the mountainous rivers.
He said the frog could help scientists understand the environmental factors that contribute to “extreme evolutionary change” since its closest relative in the Philippines and all other frogs have lungs.
Bickford and Gillespie said the frog’s discovery adds urgency to the need to protect its river habitat, which in recent years has become polluted due to widespread illegal logging and gold mining. Once pristine waters are now brown and clogged with silt,they said.
“The gold mining is completely illegal and small scale. But when there are thousands of them on the river, it really has a huge impact,” Bickford said. “Pretty soon the frogs will run out of the river.”