YouTube: https://youtube.com/watch?v=sfBOpUuJv1c
Previous: New Channel Alert!
Next: Cicada Symbiosis | SciShow Talk Show

Categories

Statistics

View count:904
Likes:120
Dislikes:2
Comments:22
Duration:04:06
Uploaded:2019-04-02
Last sync:2019-04-02 17:10
"The bends" is one of the biggest risks that humans have to deal with when diving, but why don't marine animals, which are diving all the time, get them?

Hosted by: Olivia Gordon

SciShow has a spinoff podcast! It's called SciShow Tangents. Check it out at https://www.scishowtangents.org
----------
Support SciShow by becoming a patron on Patreon: https://www.patreon.com/scishow
----------
Huge thanks go to the following Patreon supporters for helping us keep SciShow free for everyone forever:

Adam Brainard, Greg, Alex Hackman. Sam Lutfi, D.A. Noe, الخليفي سلطان, Piya Shedden, KatieMarie Magnone, Scott Satovsky Jr, Charles Southerland, Patrick D. Ashmore, charles george, Kevin Bealer, Chris Peters
----------
Looking for SciShow elsewhere on the internet?
Facebook: http://www.facebook.com/scishow
Twitter: http://www.twitter.com/scishow
Tumblr: http://scishow.tumblr.com
Instagram: http://instagram.com/thescishow
----------
Sources:
http://jeb.biologists.org/content/218/13/2030
https://www.diversalertnetwork.org/medical/articles/Decompression_Illness_What_Is_It_and_What_Is_The_Treatment
http://jeb.biologists.org/content/220/10/1761
https://royalsocietypublishing.org/doi/full/10.1098/rspb.2018.0482
https://royalsocietypublishing.org/doi/full/10.1098/rspb.2011.2088
http://jeb.biologists.org/content/202/20/2819
https://www.jstor.org/stable/30158447?seq=1#page_scan_tab_contents
https://www.researchgate.net/publication/320506326_Deadly_acute_Decompression_Sickness_in_Risso%27s_dolphins
http://science.sciencemag.org/content/340/6138/1234192
http://jeb.biologists.org/content/218/14/2180

Images:
https://www.istockphoto.com/photo/dark-blue-ocean-surface-seen-from-underwater-gm908062194-250177304
https://www.istockphoto.com/photo/sea-lion-underwater-looking-at-you-gm477443999-35686516
https://www.istockphoto.com/photo/mother-song-gm958303054-261673941
https://www.videoblocks.com/video/sea-turtle-swimming-in-ocean-zea-6yj
https://www.istockphoto.com/photo/walruses-swim-under-water-in-the-zoo-gm994519144-269307579
https://www.istockphoto.com/photo/two-turtles-swim-in-an-aquarium-of-the-zoo-gm947892302-258805212
[ ♪ INTRO ].

Although hollywood would have divers worrying about mega-sharks, trained professionals know that getting the bends is one of the biggest risks they face. That funny name given to the pains, numbness, or other physical complications that divers sometime experience when they surface belies just how dangerous the illness can be.

But, there are animals that dive all the time. Like seals and and whales for example. Some of them go way deeper than humans could ever even dream of — like, over thousand meters below the surface.

So why don’t marine animals get the bends? Well, it turns out they do, sometimes, but they also have adaptations that help keep them safe. The bends, or decompression sickness, happen because of the higher pressure divers experience.

When fluids — like blood — are under greater pressure, they can absorb more gas. So that pressure means more of the air in a diver’s lungs — especially nitrogen gas — is absorbed into their blood, and therefore their tissues in general. When that diver surfaces and the pressure drops, their blood can no longer hold all that gas, so it starts to bubble out again — and lots of those bubbles all at once.

They can damage tissues, which might mean a little tiredness, joint pain, and tingling, or, in the worst cases, spinal cord injury or even death. While this is mostly a concern for SCUBA divers because they’re breathing in more nitrogen with every breath, there have been a few cases in breath-holding free divers too, especially after repeated dives. In general, the deeper a diver goes and the longer they stay down, the more gas is absorbed.

And once that happens, returning to the surface slowly so the bubbling is minimized is basically all you can do to avoid major problems. But it’s hard to come up slowly when, you know, you need to breathe. Since many marine animals dive a lot and for long periods of time, it really begs the question why they don’t seem to have this problem — and if their tricks can help us dive deeper or for longer.

In most animals that dive for a living, the biggest advantage they have is that they can collapse part of their lungs and have their blood flow over the deflated part. This creates what’s called a ventilation-perfusion mismatch. Basically, there’s less blood where the gas is, so less gas gets absorbed.

This ability is possible because their lungs are super stretchy and they have a stiff windpipe where all the air that gets squeezed out can sit. Studies show that seals can divert up to 70 percent of their air, for example, and sea lions up to 57 percent. Whales and dolphins seem to do a similar thing, and they may go a step further.

Research suggests they have partially deflated lungs all the time — then, when they dive, they can tweak the distribution of air and divert their blood to create the mismatch. This is similar to what sea turtles seem to do — they move their blood around, rather than the air. But what’s really cool is that scientists think the degree of deflation or the routing of blood flow can be somewhat controlled in some species — it doesn’t just happen passively as the animal dives.

That could explain the few cases where we do see marine animals with the bends: when they’re caught in nets or have been stressed out. For one reason or another, they either couldn’t or didn’t control their ascent. But while separating the air in your lungs from the blood is a neat trick, it also means less oxygen gets into the blood — the mechanism affects all gases in the lungs.

Marine mammals seem to deal with this by storing and transporting more oxygen in their bodies in the first place — reserves that they can tap into while they’re down deep. Other species, like turtles, likely tolerate lower oxygen levels in general. While we’ve got a lot of this figured out in certain species, there are some mysteries that remain — like what penguins and other diving birds do.

But since the ways animals avoid the bends all seem to be built into their bodies, it’s not likely that they’re going to help people avoid decompression sickness. No stretchy lungs for us. Thanks for asking!

And a special thank you to all our channel members. Your support helps us make educational science videos like this one, so we really appreciate it! Being a channel member has its perks.

You’ll get a badge next to your name, for example. And you’ll also gain access to our QQ inbox, where you can pose questions like this one that we might make into an episode. To learn more about becoming a channel member, you can click that button below that says “Join” — the one right next to the Subscribe button. [ ♪OUTRO ].