Lungless Frog Adaptation Reduces Buoyancy

Barbourula Kalimantanensis - The frog, which has no lungs and breathes through its skin, was found in a remote part of Indonesia's Kalimantan province on Borneo island, a discovery that researchers said Thursday, April 10, 2008, could provide insight into what drives evolution in certain species. Image Credit: David Bickford - AP

Lungless Frog Adaptation Reduces Buoyancy

The Bornean Flat-headed Frog, which looks a little unusual, in that it’s shape is rounded and features skin flaps and folds, was first sighted about thirty years ago and officially noted about one year ago, breathes through its skin in an osmosis like process.

Combination image shows a Map of Borneo (A) showing the Indonesian portion, Kalimantan, in the South-Central part of the island, and (B) Barbourula kalimantanensis in anterior view, and (C) laternal view showing extreme flattening. Barbourula kalimantanensis, a rare and primitive frog living in a remote Borneo stream has no lungs and apparently absorbs oxygen through its skin, researchers reported on April 9, 2008. Image Credit: REUTERS/David Bickford/National University of Singapore/Handout (UNITED STATES)

The lungless nature of this frog is a unique trait and is shared by only a few amphibious species that include some salamanders and a wormlike creature known as a caecilian.

The frog discovery could help scientists understand the environmental factors that contribute to "extreme evolutionary change" since its closest relative in the Philippines and other frogs have lungs.

"These are about the most ancient and bizarre frogs you can get on the planet [Oblate Spheroid]," David Bickford - Evolutionary Biologist at the National University of Singapore, said of the brown amphibian with bulging eyes and a tendency to flatten itself as it glides across the water.

Combination image shows a comparison of (A) the mouth and pharynx of a American Bullfrong (rana catesbeiana), showing glottis, tongue, and esophageal opening, and (B) Barbourula kalimantanensis showing tongue, no glottis, and enlarged esophageal opening leading directly to the stomach. Barbourula kalimantanensis, a rare and primitive frog living in a remote Borneo stream has no lungs and apparently absorbs oxygen through its skin, researchers reported on April 9, 2008. Image Credit: REUTERS/David Bickford/National University of Singapore/Handout (UNITED STATES)

This excerpted from Yahoo! News –

Frog without lungs found in Indonesia
By MICHAEL CASEY, AP Environmental Writer - Thu Apr 10, 5:20 PM ET

BANGKOK, Thailand - 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.
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"They are like a squished version of Jabba the Hutt," he [David Bickford] said, referring to the character from Star Wars. "They are flat and have eyes that float above the water."

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 "evolutionarily 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, rapidly 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.
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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."
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