Insects the most numerous and diverse group of animals don't have lungs. Instead, they have a system of internal tubes called tracheae that are known to exchange oxygen through slow, passive mechanisms, including diffusion. But this study demonstrates that beetles, crickets, ants, butterflies, cockroaches, dragonflies and other insects also use rapid cycles of tracheal compression and expansion in their head and thorax to breath.
Tracheal compression was not found for all types of insects studied, but for those where it was found compression patterns varied within individuals and between species. The three species most closely studied (the wood beetle, house cricket and carpenter ant) exchange up to 50% of the air in their main tracheal tubes approximately every second. This is similar to the air exchange of a person doing moderate exercise.
Promising new technique
Up until now, it has not been possible to see movement inside living insects. This problem has been solved by using a synchrotron, which generates one of the strongest x-ray beams in the world, to obtain x-ray videos of living, breathing insects. "This is the first time anyone has applied this technology to study living insects," says co-author Wah-Keat Lee, a physicist at the Argonne National Laboratory.
A synchrotron is a large, circular, particle accelerator. The one at Argonne, called the Advanced Photon Source, has a circumference of about one kilometer and accelerates electrons almost to the speed of light. Doing this generates radiation, includin
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Contact: Greg Borzo
gborzo@fieldmuseum.org
312-665-7106
Field Museum
23-Jan-2003