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I was just thinking that the skull would resist the pressure more
than the lungs, so there would be a pressure differential between the
_interior_ of the skull and the lungs; but I'm no physicist nor
physiologist!

On Mar 25, 2007, at 7:23 PM, George Huxtable wrote:

>
> 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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