Yes, a lot of people don’t realize this but we, just like fish, need oxygen to dissolve in fluid before we can use it. But oceans and lakes don’t have very much dissolved oxygen compared to air, so what our lungs have done is create what is basically a pond the size of a tennis court and folded it up to fit in our chest so that there’s this massive surface available for oxygen to dissolve through, and then hemoglobin binds to that oxygen as fast as it’s getting dissolved, which makes space for more oxygen to get dissolved as new air is inhaled.

Whale kidneys look a lot like lungs for this same reason. Whales need to filter a bunch of salt out of the water they ingest as they eat while still holding onto that water, so they need a lot more surface area in their kidneys to produce super concentrated urine that’s kind of an orangey brown color.