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In reply to Fred Hebard's question, copied below, my answer is "No, I doubt 
it". The point being that whatever the sea pressure is,
that is being applied to the lung-area of a sperm whale to collapse it, that 
same sea-pressure, and a bit more, is being applied to
the head area, because it's a few feet lower down in the sea, because of the 
creature's head-down orientation as it makes its
vertical dive. And surely, those pressures must transmit themselves to the 
whale's interior, because it's constructed of such
flexible stuff. So I don't quite see how the remaining bubble of air remains 
at that lower level, unless it's held there by some
muscular power creating a bit of extra pressure at the level of the lungs.

But there's a lot of speculation in that, and much ignorance, on my part. I'm 
simply doing my best to apply physical principles to a
whale/water system. We need access to an expert on whale physiology. I wonder 
where you find a helpful cetologist?

We are discussing fine points here, and unlike the sperm whale, I am well out of my depth.

George.

================
|
| Wouldn't the pressure difference be provided by the sea in the form
| of the collapsed lungs?
|
|
| On Mar 25, 2007, at 1:24 PM, George Huxtable wrote:
|
| > That mechanism for avoiding the "bends" seems plausible, but there's a
| > question occurs to me that isn't answered. As explained by Watson,
| > those air receptacles, being in the head, are many feet below the lung
| > area, when the whale is diving, almost vertically, with its head down.
| > So how does the whale ensure that the remaining bubble of air,
| > shrinking as it compresses, doesn't float upwards into the lungs, but
| > instead stays down at the head-end? That must be achieved by some sort
| > of muscular control of the chest cavity to provide the necessary
| > several-pounds-per-square-inch of pressure difference.

contact George Huxtable at george@huxtable.u-net.com
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.


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