![\"Bornean](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2024\/05\/17183509\/SEI_204626746.jpg?width=1200\")
<\/div>The Bornean flat-headed frog has lungs after all<\/p>\n
Chien Lee\/naturepl.com<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
A tiny frog from Borneo was thought to be the only known frog species with no lungs \u2013 but it turns out they do have lungs after all.<\/p>\n
In 2008, a team led by David Bickford<\/a> at the National University of Singapore dissected 11 specimens of the rare Bornean flat-headed frog (Barbourula kalimantanensis<\/em>). They were surprised when they couldn\u2019t find any of the frogs\u2019 lungs<\/a>. \u201cImmediately upon opening up the Barbourula<\/em>, something was weird,\u201d says Bickford.<\/p>\n These frogs are fully aquatic and live in cold and fast-flowing streams, so after running a couple of tests, the researchers reasoned that the lunglessness was an adaptation to<\/a> their habitat. While breathing through the skin doesn\u2019t usually give amphibians enough oxygen to forgo lungs \u2013 just one caecilian and a few salamanders so far are known to be lungless \u2013 this species was thought to be the first frog getting its fix solely through the island\u2019s oxygen-rich rivers. Large lungs filled with air would also make the frogs more buoyant and susceptible to strong currents.<\/p>\n But now, David Blackburn<\/a> at the Florida Museum of Natural History and his colleagues have taken another look at two of Bickford\u2019s specimens. They ran them through a high-resolution micro-CT scanner<\/a> and saw a respiratory system with small, thin lungs hiding in plain sight.<\/p>\n <\/p>\n \u201cRight away, both of us were like, why is there a hole on the bottom of the mouth? That\u2019s not supposed to be there,\u201d says Blackburn. He had spotted the glottis, where the mouth connects with the lungs.<\/p>\n Bickford says he is \u201cvery happy\u201d science has learned more about this rare, elusive species. He adds that these lungs are \u201cvery, very tiny\u201d for the frog\u2019s size, so he still thinks that Barbourula<\/em> largely relies on oxygen taken in through its skin.<\/p>\n \u201cI\u2019m very open to the possibility of the reduced lungs having some kind of function, but I\u2019m sceptical,\u201d he says.<\/p>\n This development was not entirely unexpected, according to Rafe Brown<\/a> at the University of Kansas, who was not involved in the study. After 15 years, Blackburn was armed with better technology and more extensive frog collections to compare with. Brown says many more species now need to be studied, to better understand whether all frogs that have evolved to live in streams have shrivelled lungs, and whether others have potentially lost their ability to breathe through them.<\/p>\n Topics:<\/p>\n<\/section><\/div>\n