Why did the decrease in oxygen % in the atmosphere decrease the size of insects?
In: 1
Mammals (like people and whales) breathe through our lungs. Bigger mammals have bigger lungs and more powerful circulatory systems to put oxygen into our blood and move it around our bodies.
Insects (and many other invertebrates) absorb oxygen through their skins. There is a limit to how far oxygen can penetrate into their bodies. If there is more oxygen in the air it can support bigger insect bodies.
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