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    Re: Sperm whale buoyancy.
    From: George Huxtable
    Date: 2007 Mar 26, 00:23 +0100

    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.
    | 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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