June 13, 2019
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World is poorly designed, but copying nature helps: Biomimicry for filtering seawater

I’ve heard that the world is poorly designed, but copying nature helps. Fresh from the land of biomimicry, here’s to penguins.


Penguins’ have got a nifty organ that magically turns seawater drinkable. Caveats being it’s a gland not an organ, and when it doesn’t directly converts seawater to freshwater, it filters out salt from their blood.
It’s known to us as the supraorbital gland, and it’s present in almost all marine birds. You can tell if you’ve ever seen a crusty film around the nasal openings near their beaks.
They need this gland because had it been their kidneys doing all the filtering out, they could only successfully manage to pull out urine which is at 1/3 rd the concentration of sea water. And salty blood isn’t a good thing, the body starts taking water from the tissues and it rapidly spirals down to dehydration.
This gland is located between the eyes and above the nose. And it works just like the kidney does; in a process known as counter-current exchange.
For visual folks, a diagram can be found here: albatross_exchange.html 44_08CountercurrSaltExcr-L.jpg
Basically, blood and the fluid in which the salt is supposed to drain flows in opposite directions, which ensures that the blood will always remain saltier than the duct fluid and hence osmosis continues to occur.
As a simple analogy, you’ve got two trains (blood express and duct fluid express) running opposite to each other, and you’ve got salty passengers in blood express (who’re actually ninjas) and they’re gonna jump to the duct fluid express when they see an empty coach.
Since, the trains are running in opposite directions, once the salty passengers are in the duct fluid express, they’re only going to come across filled up coaches in blood express, and so there won’t be any jumping back and forth.
Owning how higher sodium intakes can lead to heart diseases, maybe one day penguins can help us unlock biotechnology of the future paving highly efficient ways of filtering seawater.