Breathing to avoid oxygen?

Insects use discontinuous patterns of gas exchange as a means of avoiding the toxic effects of oxygen, researchers propose in Nature this week.

The report puts forward a novel interpretation for a mechanism that has puzzled scientists for decades. The peculiar type of breathing exhibited by some insects is a cyclical pattern of opening and closing the spiracles—apertures that connect the respiratory tracheal system with the exterior.

"Two main hypotheses have been proposed to explain discontinuous breathing," senior author Timothy Bradley of the University of California at Irvine told The Scientist. One suggests that closing the spiracles reduces respiratory water loss, Bradley explained. The other suggests that the discontinuous breathing pattern may have evolved initially in underground insects as a means of better excreting carbon dioxide.

To investigate the phenomenon, Bradley and co-author Stefan Hetz measured oxygen levels within the trachea of the moth Attacus atlas at a range...