How do sperm whales and Cuvier’s beaked whales dive to depths of over 2km without imploding?


How do sperm whales and Cuvier’s beaked whales dive to depths of over 2km without imploding?

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The imploding only happens. When you try to put low pressure with a hard shell. Pressure builds up, kaboom.

Whales are squishy and mostly liquid, which doesn’t compress. The only real air cavities of low pressure are their lungs, and those get squeezed down without much problem, same as with human free divers, you can see their chest/sternum/belly move up into the rib cage quite a bit.

I think below a certain limit even the standard lungs would have a problem, so I think some of the real deep diver have some other biological mechanisms to help.

And I remember reading that way down that things like enzymes and basic biological process start running into trouble

Because there’s no large pressure vessel filled with air inside them.

They’re mostly made of water

Sperm whales have a few biological tricks up their little sleeves to prevent the kind of pressure difference which would lead to implosion.

They store up to one ton of a very interesting fatty liquid called spermaceti in their heads, which solidifies and expands when diving into deeper colder waters which then creates a counter-pressure. Sperm whales can also deliberately thaw the frozen spermaceti by redirecting their blood flow when they want to resurface.

Their ribs are also attached to their spines by way of flexible cartilage, which allows them to compress their ribcage when diving deep.

It’s a fascinating subject.

A submarine is filled mostly with air.

A whale is filled mostly with water.

Aside from the air in the lungs, whales are mostly filled with incompressible stuff, and as the pressure outside rises, there’s very little problem letting the pressure inside the whale also rise. The lungs are basically collapsed in an orderly fashion, so they aren’t a problem either.

Having internal pressure equal to external pressure means that the whale’s insides are pushing just as hard to get out of the whale’s skin as the water is pressing to get inside, so the forces are balanced and the skin feels no great force.

By contrast, a submarine has a rigid surface which attempts to keep the interior at roughly the same pressure as the atmosphere above the water. This means that the water outside is pushing in much much harder than the air inside.

Why don’t we build submarines that increase the air pressure inside to match the water pressure outside?

The unhelpful answer is that we do sometimes. Temporary underwater structures called *caissons* erected to build bridges are regularly pressurized to 3+ atmospheres, reducing the strength needed for the walls.

The US has an undewater research facility called Aquarius that’s kept at about 2.6 atmospheres internally.

Workers on oil rigs and some other very deep applications go to 30+ atmospheres!

The main problem with this is that it’s very dangerous to change pressure quickly for humans. Deep water workers must spend hours or days acclimating as they travel in each direction. This isn’t ideal for most military operations (where you may need to change depth very rapidly), and is impractical for small, mobile units; you generally have to build a small habitat for divers to live in for several days while they work at depth.

There’s also some health effects of humans living at very high pressures, but it’s mostly that we need much more time to transition.

Whales have a number of adaptations that let them adjust to the changing pressures very quickly, most notably that they don’t hold their breathe when they dive, instead emptying their lungs and relying purely on oxygen already in their blood. This is less to do with full lungs being a sack of air to compress, and more to do with nitrogen in their lung-air getting forced into their blood (this ultimately causes the Bends, which can be very painful or even lethal and is one of the main reasons humans need to change pressure slowly).

Who knew being squishy and liquid could be an advantage for deep sea diving? Take notes, hard-shelled creatures. 🐳🌊