Do fish breathe water?
I think it is reasonable to say that fish breathe water similarly to the way we breathe air. They extract oxygen from water by moving it across their gills, while we extract oxygen from air by inhaling fresh air into our lungs. Some would say that fish are not really ‘breathing’ water since the fish is not fully ‘inhaling’ the water (only passing the water through the mouth and out the gills). But gills are kinda like having your lungs in your cheeks. Some fish like sharks need to keep moving to keep new water with new oxygen moving across their gills. Most fish however can move their mouths, gills and gill covers in such a way that moves water constantly across the gills (so that the fish does not have to move through the water all the time). In the sense that this is the fishes process for extracting oxygen from its natural medium (water), I guess you could call this process ‘breathing’. In fact, the American Heritage Dictionary online defines ‘gill’ as: ‘The respiratory organ of mos
