Lungless frog could shed light on evolution

The discovery of a rare species of Indonesian frog that breathes without lungs could shed light on how evolution works, a scientist said on Friday.

A dissection of the frog, found on Borneo island last August, showed it breathed entirely through its skin, biologist David Bickford said.

While many frogs breathe partially through their skin, the Barbourula kalimantanensis is the first to have entirely evolved away from having lungs, he said.

This runs counter to one of the key events in evolution, when animals developed primitive lungs and moved from water to land.

“Here is a frog that has reversed that trend; it has totally turned against the conventional wisdom, if you will, of millions of years of evolution,” said Bickford, a biologist at the National University of Singapore.

The frog appears to have shed its lungs over millions of years to adapt to its home in the fast-flowing cold-water rivers in the island’s rainforests, Bickford said.

Cold water contains more oxygen, making it possible to breathe through skin, he added.

Only three other amphibians—two species of salamander and a worm-like creature called a caecilian—are known to have evolved to breathe without lungs.

“It’s like a cookie, it’s almost completely flat. So initially when you pick it up in the water you know this thing is strange,” said Bickford. “It’s surprisingly cute, you know, like a bulldog is cute.
It’s one of those things that is so ugly, it’s cute.”

Hundreds of new species of insect, animal and plant have been discovered on Borneo, with a find every month on average, conservation group WWF has said.

Other recent exotic discoveries include poisonous “sticky frogs”, “forest walking catfish” able to travel short distances out of water and the transparent “glass catfish”.—Sapa-AFP

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