First Lungless Frog

Scientists have first discovered a species of lungless frog, dubbed the Bornean flat-headed frog in a remote clear, cold-water stream in the Kalimantan region on island of Borneo in Indonesia. The frog, named Barbourula kalimantanensis, gets all its oxygen through its skin.

Previously known from only two specimens, two new populations of the aquatic frog were found by the team during a recent expedition to Indonesian Borneo. (See Map Below)


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Serendipity
Nobody knew about the lunglessness before the researchers accidentally discovered it doing routine dissections, says study lead author David Bickford, a biologist at the National University of Singapore. The discovery of lunglessness in a secretive Bornean frog supports the idea that lungs are a malleable trait in amphibians, which represent the evolutionary sister group to all other tetrapods, according to the researchers. They speculate that the loss of lungs might be an adaptation to a combination of factors: a higher oxygen environment, the species’s presumed low metabolic rate, severe flattening of their bodies that increases the surface area of their skin, and selection for negative buoyancy—meaning that the frogs would rather sink to the bottom of the freezing waters it inhabits than float.

Lot More to Be Discovered in Nature
What struck the researcher the most is that there are still major firsts (e.g., first lungless frog!) to be found out in the field. He suggests that you have to do is go a little ways beyond what people have done before, to scream—voila!

Lunglessness
Of all tetrapods (animals with four limbs), lunglessness is only known to occur in amphibians. There are many lungless salamanders and a single species of caecilian, a limbless amphibian resembling an earthworm, known to science. Nevertheless, the complete loss of lungs is a particularly rare evolutionary event that has probably only occurred three times.

Under Threat
The researchers said that further studies of this remarkable frog may be hampered by the species’s rarity and endangerment. They therefore strongly encourage conservation of the frogs’ remaining habitats. This is a highly endangered frog—that we know practically nothing about—with an amazing ability to breathe entirely through its skin, whose future is being destroyed by illegal gold mining by people who are marginalized and have no other means of supporting themselves,” Bickford said. “There are no simple answers to this problem.”

Source
A report in the April 8th issue of Current Biology, a publication of Cell Press.