Does shallow water blackout exist in water dwelling mammals?

[TXexplorer]

Hello, everyone. This is my first post. I was spurred to sign up in hopes of getting some info on the following questions:

1) Does SWB exist among mammals that primarily live in water?
2) If yes, why is it less rare? (This is an assumption based off the simple fact that they are truly water adapted)
3) If no, and given that we still share somewhat similar adaptations to our water dwelling counterparts, why are we prone to SWB and they are not? Is it simply that we are more likely to push our limits and less in-tune with our physiology?
4) Are there practices that mammals such as seals, dolphins, whales, and so on, perform that have been translated to human freediving performance increases?

I appreciate any and all responses, be they scientifically based or pure speculation. A web search came up with next to zero on this subject.

Thanks in advance. Looking forward to your responses.

 

[growingupninja]

Look up Sebastian Murat's posts if you want to bone up on similarities and differences on humans and seals.

But in short, to answer your first question, aquatic mammals do not experience SWB, at least not the same as people. They suffocate and die from lack of O2, unlike people who BO, stop breathing, and then (terminal breath) inhale water and drown. I don't have links to the studies but we know this because human drowning victims always have microbes in their blood stream that comes from water in the lungs--heart was pumping at the time of terminal breath. Aquatic mammals who have been discovered dead from lack of O2 do not have these microbes--their hearts just stopped pumping at some point from lack of O2, although I imagine as they near critically O2 levels their motor control and consciousness would become impaired.

 

[everestlead]

I have never read any longitudinal studies regarding SWB in mammalians...the thought has crossed my mind...usually after reading Mayol's theories regarding Homo delphinus. What little I have gleaned has been from anecdotal observations from other marine researchers...these observations parallel Lance's post...cetaceans and pinnipeds apparently have an imbedded turn-around mechanism hardwired to their parasympathetic nervous system (the brain stem) and, through lower PPO triggers as well as CO2 build-up...they ascend. In 30 years of being a marine researcher/diver and reading of scientific publications, I believe that Marine mammals don't drown unless they are confined, trapped or ill/injured. Of course, that probably doesn't answer your questions...but it would make a fascinating study!

 

[charlie.]

i know the dive reflex in seals takes their heart rate down to 1-2 beats per min so maybe they would experience it but they have such a long dive time they wouldnt need to push it to the point of BO

 

[Speardiver1]

Is shallow water blackout so different than just blackout? In the end both are caused by lack of oxygen to the brain, although what leads up to the blackout in each circumstance may differ. Is the OP's question specifically about SWB or blackout in marine mammals in general. It is an interesting topic.