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    Re: Sperm whale buoyancy.
    From: Henry Halboth
    Date: 2007 Mar 25, 20:28 -0500

    Lu,
    
    Rest assured Lu, it doesn't affect free divers and I assume not sperm, or
    any other,. whale or atmospheric pressur breathing creature.
    
    Henry
    
    ----- Original Message -----
    From: "Lu Abel" 
    To: 
    Sent: Friday, March 23, 2007 8:19 PM
    Subject: [NavList 2475] Re: Sperm whale buoyancy.
    
    
    >
    >  From what I remember about the "bends," it comes when an excess of
    > nitrogen (due to breathing pressurized air) bubbles out of the blood at
    > normal atmospheric pressure.   It seems to me that this should not
    > affect free-divers (or sperm whales) since their air intake has been at
    > atmospheric pressure and not artificially higher pressures.
    >
    > Lu Abel
    >
    > glapook{at}PACBELL.NET wrote:
    > > Gary LaPook Adds:
    > >
    > > Giving more thought to this issue, I don't think the real issue is the
    > > buoyancy of the lungful of air, which goes away quickly with depth,
    > > but the absorption of the air in the lungs into the blood and tissues
    > > of the whale when under great presure. SCUBA divers are taught about
    > > the absorption of nitrogen into the blood and tissues when breathing
    > > air under pressure for some time while under water. If a diver
    > > surfaces too quickly then this gas turns into bubbles in the tissues
    > > and blood and caused the "bends." Under the great pressure at a
    > > thousand meters I would expect all of the gasses in the lungs would
    > > have been absorbed by the whale's blood and tissues leading to a
    > > massive case of the bends on surfacing. But if the whale exhales prior
    > > to diving there would be no air to be absorbed so no problem with the
    > > bends. Human record setting free divers have gone down about 400 feet
    > > on a lungfull of air but they are down such a short period of time
    > > that they do not have a problem when surfacing. Anybody else have any
    > > thoughts on this?
    > >
    > > On Mar 21, 1:00 pm, glap...{at}PACBELL.NET wrote:
    > >
    > >>Gary LaPook wrote:
    > >>
    > >>
    > >>Regarding the question of whether the whale exhales before sounding.
    > >>Even if his lungs were full at the start of the dive so that the whale
    > >>would have to fight this buoyancy this problem would quickly go away
    > >>in the first couple hundred feet where at 6 atm pressure the air would
    > >>be reduced to only 1/6th its surface volume and buoyancy.
    > >>
    > >>On Mar 20, 3:48 am, "George Huxtable" 
    > >>wrote:
    > >>
    > >>
    > >>>Let me start with in apology. This has little (indeed, nothing) to do
    > >>>with navigation, but about the hydrostatics of sperm whales. If such
    > >>>question are of no interest to a reader, he should press "delete" now.
    > >>
    > >>>I raise this matter in the hope that others who know more about the
    > >>>matter than I do can point to where I can find answers. What
    > >>>information I have comes from "Whales of the World", by Lyall Watson,
    > >>>a volume I've respected, but which hasn't satisfied my questions.
    > >>
    > >>>My wife and I were recently introduced to two "resident" sperm whales,
    > >>>who spend their time patrolling an ocean trench which happens to come
    > >>>close inshore off Kaikoura, New Zealand.
    > >>
    > >>>Sperm whales are the ones with an enormous squareish head, with a
    > >>>small jaw below it; the head is an immense can of pure spermaceti oil,
    > >>>containing many tons of the stuff. Their way of life is a strange one,
    > >>>even by whale standards. They earn their living by swimming down
    > >>>vertically to the bottom, at depths of a kilometre, sometimes much
    > >>>more, to graze on squid living near the bottom. These dives commonly
    > >>>last for 40 minutes or more. Then they return vertically to the
    > >>>surface to breathe air, for 10 minutes or so. A sequence that's
    > >>>regular as clockwork.
    > >>
    > >>>It has set me wondering about the physics of the problems that face
    > >>>such a creature, alternating between regimes at such widely different
    > >>>pressure, and how it has managed to solve them. Roughly speaking, the
    > >>>pressure at a kilometre deep is 100 atmospheres, and any gas at that
    > >>>pressure is compressed to only one hundredth of its volume at the
    > >>>surface. In general, the volume of liquids and solids, and that of
    > >>>seawater, changes little with pressure. They are pretty
    > >>>incompressible.
    > >>
    > >>>There's no way that a whale could exist on a big breath, as a
    > >>>pearl-diver does, over all that time. Instead, I understand that a
    > >>>sperm whale is adapted to rely on oxygenated blood that has been
    > >>>recharged while it was breathing at the surface, and its tissues are
    > >>>dark red or black because they hold large quantities of that
    > >>>oxygen-rich blood.
    > >>
    > >>>My first question is this; does such a whale take a last lungful of
    > >>>air down when it dives, or not? If it does, that air provides buoyancy
    > >>>as the whale starts to dive from the surface, just when it isn't
    > >>>needed, as it would have to be overcome by downward drive from the
    > >>>tail flukes. A whale isn't built like a submarine, with a steel hull
    > >>>to resist external pressure, but is flexible, allowing outside
    > >>>pressures to be transmitted throughout its structure. So, at a few
    > >>>atmospheres of pressure, buoyancy from any inhaled air has been
    > >>>largely lost, and at a kilometre deep any air aboard is compressed to
    > >>>only 1% of its original volume, so virtually none of that buoyancy
    > >>>remains when it's at the bottom. Just where buoyancy might be most
    > >>>useful, at take-off, to return to the surface, especially in an
    > >>>emergency. It's hard to imagine that such a creature puts itself in
    > >>>such danger as to be negatively buoyant at the bottom, and completely
    > >>>reliant on tail-power to drive upwards out of any fix.
    > >>
    > >>>It seems to me, then, that hydrostatically speaking, any air taken
    > >>>aboard prior to the dive is disadvantageous. I learn, from Watson's
    > >>>book, that the rib-cage is designed to collapse completely. Indeed,
    > >>>that's absolutely essential, to allow any air in the lungs to compress
    > >>>down to almost nothing. What I ask, is whether that collapse of the
    > >>>ribs takes place deliberately before the dive, or during it?
    > >>
    > >>>Evidence in the other direction comes from the first spout of a sperm
    > >>>whale on surfacing, the first outward breath that gives rise to the
    > >>>old cry of "there she blows"; according to accounts I have read it is
    > >>>always more conspicuous than later blows. Does this first blow come
    > >>>from air that's been taken down to depth and brought back again, or
    > >>>does it actually follow a first, unseen, inward gasp of air? Does
    > >>>anyone know?
    > >>
    > >>>A related question is the purpose of that immense tank of spermaceti
    > >>>oil, which takes up most of a sperm whale's enormous head. What's it
    > >>>really for? Watson points to a possible function as a focussing
    > >>>element in conjunction with the sperm whale's ultrasonic transducer,
    > >>>but also mentions the possibility of adjusting buoyancy by regulating
    > >>>its temperature, in relation the temperature variation with depth of
    > >>>the sea water. It seems to me unlikely to be possible to change the
    > >>>temperature of such a great mass of oil in a timescale that would be
    > >>>useful over a 40-minute dive. However, certain oils and waxes do
    > >>>change their volume (and therefore buoyancy) quite significantly as
    > >>>they melt and solidify; indeed, it's likely that the thermostat in the
    > >>>cooling circuit of your car engine will rely on such an effect. It's
    > >>>clear that the oil, being lighter that water, could be useful  anyway,
    > >>>in compensating for the creature's weight of bone, to get the average
    > >>>buoyancy right. Being right at the fore-end of a whale, it must tend
    > >>>to make it tail-heavy, which may be useful in keeping up the blowhole
    > >>>on the tip of its nose, out of the water, when it sleeps.
    > >>
    > >>>Another question that arises relates to the whale's digestive system.
    > >>>No doubt, a whale's digestion continues to act while it's at the
    > >>>bottom, presumably evolving large quantities of methane and carbon
    > >>>dioxide. Under such high pressure, that compressed gas may not provide
    > >>>much volume or buoyancy at the bottom, and it seems likely that carbon
    > >>>dioxide, under pressure, will dissolve into any watery fluid, just as
    > >>>it does in a bottle of "pop" (at much lower pressures). But on return,
    > >>>as the animal approaches the surface, any gases, that it hasn't
    > >>>expelled while down below, will expand, and may also come out of
    > >>>solution, as when you take the cap off a pop bottle. Any such increase
    > >>>in volume will tend to be dramatic, as the surface is neared, doubling
    > >>>in the final 30 feet! To avoid an explosion, does a whale produce a
    > >>>gigantic fart, as it nears the surface? Whalers' accounts often refer
    > >>>to the disgusting fishy smell that comes with a whale's first blow,
    > >>>but I wonder whether the source of that smell may be not from the
    > >>>blowhole, but from the other end, bubbling up as it surfaces.
    > >>
    > >>>How, I wonder, has a sperm whale evolved in such a way as to solve
    > >>>those problems presented by hydrostatics, Archimedes principle and the
    > >>>Gas Laws? These are no more than musings, from my position of woeful
    > >>>ignorance about whale physiology. No doubt they have been asked, and
    > >>>answered, by those with a better understanding. If anyone can provide
    > >>>those answers, or point me toward them, I will be grateful.
    > >>
    > >>>George.
    > >>
    > >>>contact George Huxtable at geo...---.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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