Bigger animals, like Elephants, or Dinosaurs for example, are in need for more oxygen than the amount of oxygen that small animals need? (humans, dogs, cats, etc)
Thanks in advance.
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$\begingroup$ If all animals need the same concentration of oxygen throughout their tissues, larger animals need more O2 because they more tissue, but metabolism is probably more important than size alone. One thing to consider isn't so much the amount of oxygen but the diffusion of oxygen. Large animals have trouble getting oxygen to all of their tissues, so they have lungs, hemoglobin, and efficient circulatory systems to move the oxygen in and CO2 out. Small animals have less tissue to diffuse through, so they can rely more on simple diffusion of atmospheric oxygen through their bodies. $\endgroup$– user137Nov 26, 2014 at 19:29
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2 Answers
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I'm not an expert but I think it's pretty obvious.. Bigger animals do require more energy and thus more oxygen for cellular respiration. They also have bigger lungs, although the rythm of the breathing is slower.
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Animals with the same metabolic rates need the same amount of oxygen per unit body mass, larger animals have slower metabolisms than smaller ones (that's also why they need less food per unit body mass). 1 ton of rats use more oxygen than 1 ton of elephant. bigger animals need better ways to distribute the oxygen, that is better ways to absorb and transport it. One of the reason Sauropods got so big was they have a much better breathing mechanism than mammals.
