shark alligator
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The metabolism of an animal is estimated by determining rates of carbon dioxide production (VCO2) and oxygen consumption (VO2) of individual animals, either in a closed or an open-circuit respirometry system.   VO2 max is a measurement of the maximum amount of oxygen an individual uses during physical activity. It is measured as milliliters of oxygen used in one minute per kilogram of body weight.  It relates energy production via aerobic metabolism to oxygen consumption during the action of the ETC.