Charged
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How can fish and such tolerate the depths that we as humans struggle with? Is it blubber, thick skin, skeletal structuring...what? Also, what about decompression with them? Why dont they have to ascend slowly?
How do fish tolerate the depths?
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deltaVPR
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Well fish dont breath air therefore they dont have nitrogen dissolving and coming out of solution in there blood. Their gills allow them to get oxygen without this side effect, therefore there is no need for decompression.
We do alright with pressure, liquids and solids are relativly incompressible...its the gas that can compress and cause problems (why we have to equalize). Without gas pockets or ways of equalizing these pockets organisms are capable of copeing with the pressure quite well.
We do alright with pressure, liquids and solids are relativly incompressible...its the gas that can compress and cause problems (why we have to equalize). Without gas pockets or ways of equalizing these pockets organisms are capable of copeing with the pressure quite well.
DeNomad
Contributor
I believe fish do have air bladders of a sort to move up/down in the water column. Have you ever seen fish dragged up from deep sea fishing? Not pretty...
OP
Charged
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Additional information on this "air bladder".
Wikipedia:
Gas bladder - Wikipedia, the free encyclopedia
Video:
YouTube - 2. Gently Does It - Barotrauma explained
Wikipedia:
Gas bladder - Wikipedia, the free encyclopedia
Video:
YouTube - 2. Gently Does It - Barotrauma explained
The tissue of fish and people handle pressure quite well. Air pockets cause problems. As deltaVPR explained, we get decompression sickness because our tissues absorb nitrogen from the air we breathe. Since fish use oxygen that is dissolved in the water, that is not an issue for them.
Most fish have a swim bladder, so they have to ascend slowly, but their problem isn't decompression sickness. They have a problem with the swim bladder expanding. Sharks don't have swim bladders and generally can ascend much faster than other fish. Sand Tigers swallow air and use their stomachs like a swim bladder.
Most fish have a swim bladder, so they have to ascend slowly, but their problem isn't decompression sickness. They have a problem with the swim bladder expanding. Sharks don't have swim bladders and generally can ascend much faster than other fish. Sand Tigers swallow air and use their stomachs like a swim bladder.
Joris
Registered
The fact that fish respirate aquatically doesn't necessarily mean they don't get decompression sickness. Nitrogen in water can diffuse into their tissues, just as it does from air into ours.
Fish can apparently get the bends, see for instance:
Belaud A, Barthelemy L. 1979. Influence of body temperature on nitrogen transport and decompression sickness in fish. Aviat Space Environ Med 50(7):672-7.
I realize that the OP was talking about fish but what about diving mammels like whales? They are using the same oxygen/nitrogen mix that we are but dive to tremendous depths. I'm not clear on how fast they surface.
Art
Art
Joris
Registered
Marine mammals have many physiological adaptations that allow them to make deep, repetitive breath-hold dives (note that breath-hold diving is quite different from breathing compressed gasses).
One adaptation is they have stiffened upper airways that resist compression. It is thought that when they dive, their lungs collapse first from the pressure and the air is forced into the rigid upper airways. This would decrease gas exchange, or in other words, it would slow down nitrogen saturation.
However, there have been quite a few mass strandings of whales with symptoms of DCS that appear to be associated with navy sonar. One theory is that they are scared by the noxious boom and flee to the surface too quickly.
One adaptation is they have stiffened upper airways that resist compression. It is thought that when they dive, their lungs collapse first from the pressure and the air is forced into the rigid upper airways. This would decrease gas exchange, or in other words, it would slow down nitrogen saturation.
However, there have been quite a few mass strandings of whales with symptoms of DCS that appear to be associated with navy sonar. One theory is that they are scared by the noxious boom and flee to the surface too quickly.
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