A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sperm whale buoyancy.
From: Henry Halboth
Date: 2007 Mar 25, 20:28 -0500
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@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. > > > > > > > > > > > > > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To unsubscribe, send email to NavListemail@example.com -~----------~----~----~----~------~----~------~--~---