I’m about as much a marine biologist at George Costanza; but IIRC, whales are air breathers. (Take a deep breath, dive down and stay awhile, come back up, take another breath) Do the things that efffect divers, (eg: “The bends”, pressure, lbs/square inch, expansion of lungs, etc.) effect the whale?
Drollman–over 200 posts with a spelling mistake!
Simple…
As long as you take a breath at the surface you will not get the bends no matter how deep you dive.
The bends occur because you are breathing pressurized air off of a scuba tank. The deeper you go the more pressure you get. This is ok because the pressure of the sea wants to collapse your chest so the pressure of the air cancels out the sea pressure. Under these conditions the air your blood picks up is likewise pressurized. Again the ‘air’ in your blood is kept small by outside pressure so there are no issues.
Now, if you go up too quickly and don’t decompress, your blood won’t be able to circulate back through your lungs and dump the pressurized air it is holding. If the outside pressure drops too far the ‘air’ in your blood will expand to the point that your bnlood cells can no longer hang on to it and it gets released. The upshot is you get bubbles that collect in your joints making you all bent-up (hence the bends).
Remember, the breath of air you take at the surface is at the surface pressure. When you come back up from your dive the gas in your blood will grow no larger than it was before you submerged. Therefore whales have no problems with the bends.
Thanks, Whack!
I assume you have some diving experience. With that in mind, if a human could take a breath and dive down 3,000 ft, would the pressure force the lung to collapse? (again, my “undersea education” consists of “SubMariner” comic books–but in those “Search for the Titanic” style documantaries, they’re always talking about "the pressure) Is it just because of it’s size that the whale can survive this–or a “freak” of nature. (I hope I’m expressing my question in a suitable manner!)
Drollman!–Over 200 posts with a spelling mistake!
Well, you’d have other problems. Before you got deep enough to permanently collapse a lung, you’d be all too likely to rupture your eardrums and crush your sinus cavities. The lungs aren’t the only air pockets in the human body. Whales withstand it because they were designed to do so - we get stuck with those cute little submarines.
That’s the coolest question I’ve seen in a long time. I’m going to follow this.
Yup…I have my advanced certification (advanced adding things like night diving and underwater navigation).
Most certainly. There is actually a sport called Freediving where people compete to see how deep they can go on a breath starting at the surface. There are different categories where they use no weights, different weights and unlimited. It’s been awhile since I studied this but I think scientists pegged the maximum depth a human could manage on a freedive at around 320 feet (100 meters or so). However, the current world record (at least last I checked) is over 430 feet (so much for scientists). That said I can almost guarantee if you tried this you would kill yourself (or more likely would rush back to the surface long before getting close to that depth). The people who do this are in obscenely good shape and train very hard to achieve these depths. (NOTE: How long you can hold your breath is a component of this as well…the world record took over two minutes to reach.)
The deepest dive using scuba gear is around 1,000 feet. However, extremely deep dives (usually anything past 300 feet or so) require a special air mixture that includes helium in the tank. Again remember that as you dive using scuba gear the scuba tank sends pressurized air into your lungs. Air is over 70% nitrogen and under high pressure you are getting a LOT of nitrogen pumped into your system. This can lead to an effect called Nitrogen Narcosis which is likened to drunkeness (or so I’ve heard). Given how dangerous scuba diving can be if you don’t pay attention Nitrogen Narcosis can be a serious condition and may lead to your death (because you do something stupid like forgetting to check your air levels and running out of air while 350 feet underwater). Adding helium to the mixture avoids this but I have forgotten the mechanics of how this helps you.
Nope…not a freak. Just an animal adpated to its environment. The world record holder for air breathing animals are Sperm Whales. The deepest recorded dive of a Sperm Whale I am aware of was something over 6,000 feet and it was under water for well over an hour. However, I read that scientists suspect Sperm Whales of diving beyond 9,000 feet (by virtue of what they’ve eaten) even if they haven’t directly measured it.
You could dive as deep as your body could withstand and you could hold your breath. As Whack-a-mole so ably pointed out, the bends are strictly from breathing pressurized air.
Also, as seawitch pointed out, pretty much all the hollow areas of your body (there are a lot if you think about it) would be crushed by the pressure. Whales have adapted to this pressure by evolving (or having created for them :rolleyes: ) a flexible body structure such as cartilage in their ribs and lungs that can stand to be compressed.
How deep can humans dive? There is a sport called free diving where people dive as deep as they can while holding their breath. They then race to the surface as fast as they can.
Here are the current world records. The unlimited category (unlimited in use of a vehicle to descend and ascend) record is 168m (~550 ft) for men and 130m (~425 ft) for women.
The world record for scuba assisted diving is 308m (1010 ft) (I think).
Well, I’ve rambled long enough. Especially for a question that was already pretty much answered!
Oops…I just noticed a few other items in the OP I didn’t address.
First, though, a quick lesson that’ll hopefully make some of the other stuff make more sense.
Most people assume that when they breathe they are sucking air into their lungs. This isn’t really correct. What is actually happening is the air outside of you forcing its way into your lungs. Semantics you say? Let’s see…
The mechanics of you breathing are relatively simple. Whenyou want to take a breath your diaphragm gets pulled down (towards your stomach). This has the effect of increasing the total volume of your chest cavity. When I have a pressure of X in a volume of Y the pressure will decrease if I increase the volume. As a result the air outside of your body is now at a higher pressure than the air inside your body so some air rushes in to equalize the pressure and thus you just ‘took’ a breath (although it was really just forced on you).
Still not convinced? The same thing happens when drinking through a straw. You don’t ‘suck’ the liquid up. You lower the air pressure in the straw and the air pressure outside of that is pushing down on the surface of the liquid and forces it up the straw. Imagine you have an airtight sealed glass of water with a straw sticking out. You may get a tiny amount of liquid out of the straw when you take a drink as the bit of air at the top pushes down on the liquid but as the cup starts to empty the pressure will get lower and lower making it harder and harder for you to drink till eventually you’ll get nothing no matter how hard you suck (sooner or later the liquid itself will weigh more than the air pressure inside the cup is able to push out).
This all has some surprising consequences. Anyone here ever try to take a hose to the bottom of a pool so you could sit down there and breathe? Ok…maybe I’m the only one goofy enough to have tried but suffice it to say it doesn’t work. Anywhere around 3-5 feet of water adds too much pressure to your body to enable you to breathe underwater in this fashion. IIRC your body can only manage a pressure differential of about 3 psi and 3-5 feet of water adds more than that preventing you from breathing. Feel free to try this…it won’t hurt you because you can’t do it (just try not to breathe in any water). For this reason you either need a compressor pressurizing the hose for you or you need a scuba tank where the air is already under pressure so it can force its way into your lungs.
The flip side of this (and I’m now getting to the expansion of lungs bit in the OP) is taking a breath of air at the bottom of a pool and holding it and rising to the surface (DO NOT EVER DO THIS). In a mere 5 feet of water doing such a thing can cause an air embolism and that is a Bad Thing. An air embolism is caused when the air in your lungs starts to expand and can’t get out as would happen if you rise from a depth holding your breath after taking a breath of pressurized air down there. The air sacs in your lungs are not very strong and can start to pop releasing air into your body. Air embolisms can have varying effects depending on just how many air sacs you popped and where the air decides to collect but it is always bad and is potentially fatal. For this reason one of the primary rules in scuba diving is to breathe constantly. Sounds a little silly but they are basically saying never hold your breath while scuba diving.
Of course, air embolisms are never an issue if you take your breath on the surface for reasons I previously stated. oing under water the air will be compressed but coming back to the surface will just bring it back to the pressure you originally took your breath at so no problems for you or whales in this circumstance.
The only real danger I’ve seen with freediving is what is known as shallow water blackout. For some reason (and I don’t know why) it is possible for a diver to blackout from decreasing pressure as the diver return to the surface. Supposedly spearfishermen (and pearl hunters and the like) are very aware of this problem as if you do this often enough it seems like most people experience sooner or later. Needless to say blacking out underwater is not good and highlights another major rule of this sort of thing (scuba, spearfishing, heck…just swimming)…never do it alone.
I wouldn’t worry too much about shallow water blackout if you’re just putzing around in a pool or shallow water. This seems to occur more when a relatively deep dive is made (say more than 30 feet or so but I am just guessing…check with experts if you plan on anything more than 10-15 feet if you are concerned).
Dang…I shouldn’t have put that this way. Freediving is very dangerous (i.e. seeing how deep you can go on a single breath). What I am referring to here are people who regularly make semi-deep dives (25+ feet) from the surface (no scuba).
How rare to find a GQ thread with completely faulty answers.
Whack-a-mole is describing how divers can get an embolism. It has exactly diddly squat to do with the bends.
The bends are caused by the same principle that makes your soda fizz. Pressurized liquids hold a higher quantity of disolved gasses and when the pressure is removed the disolved gasses tend to bubble out. When diving nitrogen dissolves in the blood at a far higher rate then at the surface. When you assend too quickly it can bubble out in the blood and tissues throughout the body. This is why you have to ascend slowly after a deep dive.
Free divers can get the bends too. the air in their lungs is the same as if it were sucked in through a tank. It is compressed in to a smaller lung space by the water pressure. They do not often get the bends simply because it takes time for nitrogen to disolve and they are not remaining at pressure for that long.
how whales avoid the bends is a subject of some debate. It probably has something to do with the blood chemistry that prevents the nitrogen from bubbling out quickly. Here is a link with a brief discussion of how sonar may give whales the bends by promoting formation of microbubbles.
Damn, sent to soon, on preview I realized that my comments on whack-a-moles post were considerably overdone then hit post anyway. While his conclusion that you can’t get the bends without breathing pressurized air is faulty the rest is generally correct.
Cite please?
I’m sorry but I just don’t see it. Maybe (just maybe…I’m speculating here) if you came up really fast from a very deep free dive your cells will not be able to hang onto dissolved nitrogen as it expands very rapidly. Still, I’ve never heard of free divers suffering from the bends. The gas dissolved in your blood stream will return to the pressure of the air at the water’s surface and you certainly don’t suffer the bends there.
Any doctors in the house familiar with decompression sickness?
[sub]Another trivia tidbit: The world record dive for a land based animal is 265 meters by a King Penguin.
Also, the bends were originally called Caissons’ Disease from workers who got the bends working on building the supporting towers for the Brooklyn Bridge on the river bottom (a caisson is a watertight chamber used in underwater construction). No one before had ever been underwater water long enough and at sufficient pressure for this condition to manifest itself (at least not enough that anyone took any notice). [/sub]
From this site:
[bolding mine]
This is where whales come in, as they can dive both very deep, and for extended periods of time. There are effectively three ways an animal can adapt to overcome the bends: 1) become tolerant to the bubbles that do form, 2) develop a mechanism to suppress bubble formation in the first place, or 3) prevent the supersaturation of gas (that is, the increased volume of gas dissolved as a result of the increase in pressure) in the bloodstream. Most acquatic mammals take option 3.
Seals, as one example, limit the danger by eliminating air from the lungs as they dive (many experienced human divers do this as well), thereby limiting how much nitrogen gets absorbed into the bloodstream.
It is not known if whales exhale as they dive. However, they do have large tracheae - when extreme depths are reached, the pressure will force all of the air from the lungs into the trachea, thereby preventing (or, at least, limiting to a great extent) nitrogen absorbtion via the lungs (the trachea is reinforced with bone rings to withstand the pressure). Furthermore, blood flow to the lungs is slowed greatly during a dive; even if there is some air in the lungs prior to the lungs collapsing, little nitrogen will get absorbed.
Whoa! You’re telling me that one guy held his breath for two minutes while getting down to 430 feet, then held it for about what, 1.5 minutes, while rising to the surface? I assume you can rise much faster than dive.
So this guy held his breath for a total of 3.5 minutes? Don’t you get brain damage after 2 minutes or so? Does this mean that most freedivers are brain damaged?
Of course you suffer the bends at the surface, whatever do you think decompression chambers are for. A dissolved gas is not the same as a gas somehow suspended in a liquid under pressure as you described it in you previous post. i am not sure how this miscoinception effects your understanding but the return to one atmosphere and result that the blood is suddenly oversaturated with nitrogen is precisely the problem.
A quick google “bends free diving” provides dozens of references that free diving can result in the bends including: “The other way one can develop the bends, albeit relatively uncommon, is by free diving. Free divers who go deep and long with only the air in their lungs can dissovle enough extra nitrogen in their tissues, so that on ascent it bubbles out too quickly – causing the bends. This should not happen with free diving to shallow depths for brief periods.” From http://www.mtsinai.org/pulmonary/books/scuba/Scuba-WeeklyQuiz.htm
I was a bit short on the OP in my last post. Another factor that helps whales have been identified as the smaller ratio of lung to body size, particularly under compression which means less nitrogen is available to dissolve into the blood. As well, the extremely efficient capillary rich lungs allow for a much faster exchange of gases so nitrogen can more efectively leave the blood back into the lungs during the assent.
As a youth, and having been a very active competitive swimmer, I had worked up to holding my breath easily up to 2.5 minutes. This was only possible by being completely relaxed, hyperventilating before starting, and by remaining motionless. The best ways to do it were to lie down in bed, or hold something heavy to keep you pinned to the bottom of the pool. My record was a little over 3 minutes and was excruciatingly painful to attain. It’s not the lack of oxygen that seems to be the issue, but the involuntary convulsions that your lungs start to go through as they try to begin normal contractions again. I have met people who claim to have reached 4 minutes.
I seem to have suffered no dain bramage whatsoever.
See, when you’re holding your breath your brain is still getting oxygen. You’re thinking of the amount of time it takes to suffer brain damage with NO oxygen flow to the brain. That can happen if your carotid artery is severed, or you are put in a choke hold that cuts off the blood flow.
But when you’re holding your breath, the blood is still flowing, and oxygenation is ocurring in the brain. What causes the breathing reflex is a buildup of CO2, not a lack of oxygen. In faxt, the oxygen content of air you exhale is still reasonably high.
Don’t! Or at least don’t do it alone. If you manage to move some air it will be the same column of already breathed air over and over again, only pushed up and down through the length of the hose. Compared to the hose, your lung volume isn’t big enough to reach a sufficient amount of fresh air.
It has to do with partial pressures.
Greatly simplifying things; air is more-or-less 75% Nitrogen and 25% Oxygen and has a pressure of around 15 psi on the surface. The partial pressure of Oxygen is therefore 25% of 15 or 3.75 psi.
If I now dive down to around 30 feet, the air in my lungs is compressed and is now at 30 psi. The partial pressure of Oxygen is now 7.5 psi.
The amount of a gas that is dissolved in a liquid is related to the partial pressure. So, at 30 feet more Oxygen dissolves into the bloodstream.
Now, you need a certain amout of Oxygen in your blood to remain conscious. I’ll confess that I don’t know the actual number but for the sake of this discussion let’s say that it is the amount of Oxygen equivalent to a partial pressure of 1.5 psi.
While you are under water and holding your breath, you are using up the Oxygen supply in your blood since it isn’t being replaced. Lets suppose I have been at 30 feet for a while and have used up enough Oxygen from my blood that the amount of Oxygen there is equivalent to a partial pressure of 2 psi. Then, I start my ascent.
I am OK at 30 feet but when I get near the surface the pressure drops. The dissolved Oxygen leaves and I am left with a partial pressure equivalent of 1 psi. Nighty-night.
That’s a simplified explanation but it pretty much the mechanism involved.
Forgot to add one thing. The partial pressure problem works both ways. Above a certain concentration Oxygen actually becomes poisonious; it’s called Oxygen toxcicity. If you are breathing normal air this doesn’t become a problem until around 200 feet or so. But, a lot of recreational divers used an air mix known as “Nitrox” which contains less Nitrogen and more Oxygen. With some Nitrox mixes, the O-tox depth can rise to less than 100 feet, which is well within recreational diving depths. Nitrox divers thus have to be a bit more careful with their depth than divers breathing normal air.