A fellow rowed across the Atlantic sometime in the last few years and, for drinkable fresh water, he caught fish, at least some of which had fresh water inside. So, apparently, some fish can desalinate water. Birds, too: albatrosses. (Https://www.amnh.org/exhibitions/water-h2o-life/life-in-water/surviving-in-salt-water (as accessed 11-28-17).) How do they remove the salt? More imprtantly, how come they have enough energy to do it but we humans need far too much energy for it to be feasible except in marginal conditions like military nuclear-powered submarines?
Dunno, I did an internet search and found this article:
A side note: I’ve worked with tiny man made nanochannels and it is a really hard problem to stop Na+ ions from going through while still allowed any kind of decent flow rate to occur! Here is an example of another research group’s attempts:
A further side note: I no longer work on this very difficult problem!
Nephrologists are sort of the alchemists of medicine. Blood goes in one tube, urine comes out the other. Interesting article, I really never thought about it much. Human kidneys can concentrate urine, but dolphins must do a great job. Wonder if they get kidney stones?
A lot of diseases like that are normally the product of our relatively advanced ages. Another example of that paradigm is that humans are one of the few mammals (a quick check shows the other two are types of whales) that experience menopause. I think I read in a Jared Diamond book the theory that the value of information stored in the human mind gives older people greater value, evolutionarily speaking.
I believe that other apes (some of them anyway) also undergo menopause. What fun!