Scientists discover that dolphins don't get the bends

[Brian Pasic]

Researchers have known all along that the tissue of beached dolphins have pockets of gas in them like humans. But much less is known on how sea mammals dive so deep and resurface for air without any ill effect. They do not suffer the bends, or compression sickness like my human divers. If we could learn how they are able to do this we may become more effective divers ourselves!

source: Scientists discover that dolphins don't get the bends

 

[Dirty-Dog]

Maybe you'll think this is stupid, but why WOULD they get bent? They don't breath pressurized gas, like we do. They hold their breath. And unlike human free divers, they're not pushing their limits to get another 4 seconds underwater.

 

[Insta-Gator]

Sounds like another government study to discover the obvious. No compressed gas, no DCS.

 

[Tigerman]

Would be pretty darn impractical to be a marine mammal and get the bends from hunting for food, wouldnt it?
Is it "The center for figuring out real obvious things" or something that made this shocking discovery?

 

[Cave Diver]

Maybe you'll think this is stupid, but why WOULD they get bent? They don't breath pressurized gas, like we do. They hold their breath. And unlike human free divers, they're not pushing their limits to get another 4 seconds underwater.

There have been documented cases of whales getting bent, as well as free divers. Although we generally associate DCS with breathing compressed gas, that is not a necessity. I'll try and find links later regarding that.

Edit - Links:

Free divers:

Q: Can you get decompression sickness, a.k.a. the bends, from freediving?
A: Yes, but only rarely and only in extreme breath-hold diving situations. Advanced freedivers conducting repetitive deep dives for long periods underwater, with little recovery time at the surface have developed decompression sickness from an accumulation of nitrogen in the body. History has revealed commercial freedivers (those making a living harvesting pearls, sponges, lobster, fish, etc.) doing breath-hold dives for several hours in a day, to depths of 60 to 90+ feet, for periods of two minutes or more per dive, have displayed signs and symptoms of decompression sickness. However, most recreational freedivers do not come close to this phenomenon. Others have become “bent” (decompression sickness) from conducting repetitive breath-hold dives using a diving scooter. Also, never freedive after scuba diving. The high rate of ascents and descents in a freedive cause saturated nitrogen from the previous scuba dive to expand and contract in the bloodstream and tissues. This can easily lead to decompression sickness. See Freediving Safety for more information.

Source: http://www.usfreediving.org/freediving-gs-faq.htm

Whales:

http://news.sciencemag.org/sciencenow/2007/12/14-02.html

http://www.whoi.edu/oceanus/viewArticle.do?id=4720

http://www.cbc.ca/news/technology/story/2009/06/11/whales-sonar-bends-connection.html

 

[sheeper]

seems to me that the "scientists" who discovered this were not scuba divers. We've ALWAYS know this...

 

[aquaregia]

The gas is still at pressure, the volume is reduced. Not breathing from a tank only exempts you from lung overexpansion, not DCS.

 

[Dirty-Dog]

There have been documented cases of whales getting bent, as well as free divers. Although we generally associate DCS with breathing compressed gas, that is not a necessity. I'll try and find links later regarding that.

Right. I know. That falls into the part where I said "they're not pushing their limits to get another 4 seconds underwater. "

 

[hopashore]

The actual article is worth the read for anyone interested in the topic:

Bubbles in live-stranded dolphins

A high proportion of stranded dolphins show intravascular and intraparenchymal (loose connective tissue) gas bubble formation that look via ultrasound like DCS gas bubbles (i.e. not due to bacteria, decomp, etc. but rather due to tissue desaturation of gases ) Health assessments of dolphins caught in the wild did not show the same gas bubbles. Of the dolphins that were able to be released, most did not re-strand and showed normal behavioral symptoms...suggesting that the gas bubble accumulation did not have the significance that it does in humans, but not that it doesn't happen. However it doesn't look like they performed any statistical analyses on whether or not amount of gas bubble formation was correlated with death or successful release.

Authors suggest that they DO form gas bubbles on ascent...but there is often a pattern of shorter, shallow dives between deep ones that may act as "recompression" dives. That would explain why stranded dolphins, but not wild dolphins caught at in the water, displayed gas bubble formation...they were not able to undergo such recompression.

 

[Underdoc]

In an article by Robert Wong from the SPUMS Journal, vol.30 No. 1, it appears that BH divers are subject to DCS, so it may not be such a huge jump to accept that whales and dolphins, who repeatedly dive deep on held breaths, might be similarly affected. Although it does seem like a bit of a head scratcher that nature would permit this.