9306537 Lighton If any animals on Earth could as easily have evolved on a different planet, in terms of sheer difference from humans, those animals are insects. For example, insects have arrived at entirely different answers from ours to the problem of breathing, or obtaining oxygen and releasing carbon dioxide from their tissues. Air is delivered directly to their tissues via internal tubes or tracheae, rather than indirectly via the bloodstream, as with us. This allows insects to attain far greater metabolic intensity, but imposes a penalty in terms of water-loss rates from their respiratory systems. Most insects exist in a perpetual state of near dehydration because of their high surface area to volume ration, so minimizing respiratory water loss rates is extremely important to them. They do this by breathing at very infrequent intervals - perhaps once every five minutes in insects as small as ants, using a complicated and poorly- understood breathing strategy called discontinuous ventilation. The proposed work will explore the occurrence, mechanisms, biophysics, metabolic modulation, and water-loss significance of discontinuous ventilation, using ants as experimental insects. Because insects are by far the most numerous and successful animals on the planet, the way they breathe is not only intrinsically interesting; it has implications ranging from applied science through theoretical biology to evaluating the effects of pesticides and pollutants, and the biological significance of global temperature changes. ***
