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Fallacy_Spotted t1_iye0phm wrote

Reply to comment by dan_dares in How is O2 introduced to blood in the alveoli? by LemmeKermitSuicide

Diffusion requires no added energy so it is very efficient. It is not optimized for space though.

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dan_dares t1_iye30sq wrote

Efficient takes into account many factors, having to grow a massive organ for gaseous diffusion isn't very efficient.

Insects that rely on diffusion through spiracles, have an upper limit on size as diffusion is so slow

Diffusion is energetically cheap however, so systems evolved around it

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_AlreadyTaken_ t1_iye3ql4 wrote

Which is why you got huge insects in periods of greater oxygen levels like during the Carboniferous.

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dan_dares t1_iye4so7 wrote

Yep the inherent limitation of spiracles..

But the alternative is 8 foot tall insects, so i'll take that.

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