Why Whales Don’t Have Gills… or why we don’t colonise the Sea

“New Scientist” article on the evolution of whales and why they didn’t learn to breathe water…

Why Whales Don’t Have Gills

…basically it’s too much hard work for not enough oxygen. Whales, as mammals, need a good oxygen supply and there just isn’t enough in sea water to get at without the whale getting exhausted. Moving all that water in and out of one’s lungs/gills is very hard work – a mammal would need to breathe kilograms of sea water at a time rather than the mere grams of air it does breathe.

Often people wonder: why don’t we colonize the sea instead of space since it is so much closer?

But how close is it really? Beyond a few metres the pressure rises to levels that challenge our freedom to move – you can’t ascend too rapidly without risking the “bends”. Plus there’s very little oxygen, little light and very little else. In space pressure is never a problem and light is everywhere. In the sea any kind of heat processing suffers from the heat-sapping presence of water, but in space one can vapourise metals and silicates via concentrated sunlight.

So I have a few reservations about the whole “colonise the sea instead of space” idea. As NASA has long realised the two require similar and yet dissimilar technologies – it uses underwater laboratories as training environments for its astronauts, but isn’t planning on colonising the great oceanic deserts anytime soon.

Addendum:
Kurt9’s comment makes another good point…

The ocean is a remarkably hostile environment from a structural engineering standpoint. Seawater is corrosive and you have 50 meter rogue waves to deal with. You also have to deal with typhoons if you are not within 5 degrees latitude of the equator. Space is actually a more benign environment for structures, but is very expensive to access as of yet.

One Reply to “Why Whales Don’t Have Gills… or why we don’t colonise the Sea”

  1. The ocean is a remarkably hostile environment from a structural engineering standpoint. Seawater is corrosive and you have 50 meter rogue waves to deal with. You also have to deal with typhoons if you are not within 5 degrees latitude of the equator. Space is actually a more benign environment for structures, but is very expensive to access as of yet.

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