How come fish can breathe under water, but are unable to inhale oxygen if theyre out of the water? If theyre able to filter it trough water, shouldnt they be able to use it directly?

Question

How come fish can breathe under water, but are unable to inhale oxygen if theyre out of the water? If theyre able to filter it trough water, shouldnt they be able to use it directly?

In: Biology

Answer 1

They breath through gills and those, when out of water, collapse. Think of human hair – in the water it is flowing around, but ones you take the head out of the water – it falls down.