[notduncansmith]

I read that some seals can also force air into respiratory cavities in their skull, which keeps them from suffering decompression sickness.

[clort]

I am not sure how deep they would be able to go with this technique but it might be helpful in shallow water. I mean, to equalise at 20m they would need to generate 2bar (~30psi) of pressure. That is quite a lot! For reference, humans can normally push about 0.1bar (1-2psi) by blowing.. and their sinuses would need to withstand that pressure at the surface, before they dive.

Also, this has nothing to do with decompression sickness (aka 'the bends'). That is to do with dissolved gases in the blood which turn into bubbles when the pressure is lowered.

[notduncansmith]

Idk, I was just referring to Wikipedia where it says:

> Air is forced from the lungs during a dive and into the upper respiratory passages, where gases cannot easily be absorbed into the bloodstream. This helps protect the seal from the bends.

https://en.m.wikipedia.org/wiki/Earless_seal

[zaarn]

>Also, this has nothing to do with decompression sickness (aka 'the bends'). That is to do with dissolved gases in the blood which turn into bubbles when the pressure is lowered.

Dissolved gases dropping out of solution and forming bubbles is literally decompression sickness.

[clort]

Yes, I'm pretty sure that is exactly what I wrote?

[zaarn]

Dissolved bubbles in blood has everything to do with the bends.

[clort]

You have twice restated exactly what I have written, thank you.

and for clarity: 'forcing air into respiratory cavities in the skull' would not prevent the bends.

[glofish]

this is a good point, there is a lot more to diving really deep than storing a sufficient amount of oxygen. Basic physiological processes work differently at high pressures.