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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@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...@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...@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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