[extropy-chat] HISTORY: Solved & Unsolved Riddles

[Stephen J. Van Sickle]

On Fri, 2003-11-07 at 07:35, Robert J. Bradbury wrote:

> > 4. How can sperm whales hold their breath for half an hour at a time,
> > descend into the abyss, and have fights to the death with giant squid
> > and then surface without getting the bends or nitrogen narcosis? We
> > can't do that even with all our fancy diving gear unless we mix helium
> > with our air supply and spend hours depressurizing... or can we?
> 
> Now that is a very interesting question -- my best bet would be that
> they have evolved to be tolerant nitrogen bubbles in the bloodstream.
> To the best of my knowledge there isn't a clear reason that nitrogen
> bubbles should be harmful (i.e. they aren't toxic in any way).

No, the answer is very well established.  Nitrogen narcosis and the
bends are the result of breathing compressed air.  Whales and other sea
mammals don't breath compressed air; they don't breath at all under
water.  Even humans can perform feats if holding their breath that would
result in a scuba diver getting the bends, in the competitive event
known as free diving:

http://www.divingfree.com/

More in depth (sorry) explanation here:

http://www.madsci.org/posts/archives/may97/864759869.Zo.r.html

It is also firmly established that whales and other sea mammals simply
have a more efficient oxygen metabolism, easily explaining 1/2 hour
underwater.  Even humans have vestiges of this, in what is known as the
"diving reflex":

 http://www.bartleby.com/61/50/D0305000.html
http://animals.about.com/library/dyk/bldyk-diving.htm
http://www.deeperblue.net/article.php/225

steve vs