RE: [GZG] Biology in a vacuum

G'day,

> Don't the deep diving sperm whales have air in 
> their lungs? Their lungs are probably 
> compressible, but they still have air no?

For one Sperm whales don't go to the abyssal depths, they only go down
3000m. They also do this by having lungs that are (proportionally) less
than half those of terrestrial mammals, but they exchange much more
efficiently (so while we manage a fairly small exchange of 15% on a
breath they exchange upto 90%). They also have very high oxygen binding
as their red blood cells are larger. They also have 10 times the
myoglobin. Moreover as a whale descends the lungs are compressed (almost
to the point of collapse) and what is there is pocketed into
nonabsorptive parts of the lungs and nasal passages. A small trickle
maybe allowed via shunts to vital organs. The muscles work off the
myoglobin and can even go into heavy oxygen debt (which they work off by
breathing like crazy when they surface). They also tolerate CO2 build up
in the blood. Normal breathing and blood-oxygen transfer doesn't resume
until they're moving toward or are at the surface.

Smaller deep diving mammals actually use the same tricks and go one step
further. They breath out or only take very very shallow breaths before
they dive.

SO basically whales do it by keeping air pockets to a minimum, which is
the way all deep sea creatures do it too. They don't have air filled
bladders they have oil filled. Less pressure concerns that way, less
equalisation issues for the degree of vertical movement they may do on
short time scales.

> Overall, you're still only dealing with 1 
> atmosphere of pressure which engineering wise is 
> trivial to contain.

Its relative change that's important. For instance you get some of your
most dangerous diving accidents in the top metre of the ocean, because
their the relative pressure is doubling, from there down the changes are
only incremental. So going from 1 atmosphere to no atmosphere isn't
actually trivial for biological organisms.

Cheers

Beth

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