James Rule

speaker

92 appearances 1 recordings 1 series first heard Jul 2026 last heard 31 Jul

James Rule’s voice in public audio — every appearance, attributed to the second.

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Recordings per month over the last 12 months — 1 in all, peaking in Jul 2026 with 1.

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The Science Show · Looking inside cells, and how seals hear so well underwater · 31 Jul 2026 podcast

is to relieve the pressure of the air in the ear canal and in the middle ear.

So you might know if you've ever dived down quite deep in the ocean or been up in a plane is as you go up and down, pressure changes and your ears need to adjust to the pressure of the new environment outside of your head.

Seals need to do this too when they dive underwater.

So this tissue fills with blood

And it essentially squeezes the air in the ear canal and the middle ear cavity to reduce the space it occupies and relieve this pressure difference.

However, once they've done that, they have filled their ear canals and middle ear cavity with a blood-filled tissue.

And blood is similar in density to water.

And so just like that, their ears work underwater.

Yes, essentially.

Right.

Depends on the seal.

So some seals can dive up to hundreds of metres deep, but the most impressive ones are animals like the southern elephant seal, which is being recorded over two kilometres deep in the ocean.

And we actually, as part of a study, scanned a southern elephant seal and they have quite a lot of this tissue in their ear.

In fact, the space that the air occupies in their ear is quite tiny.

When did this ability to hear underwater evolve?

So what my colleagues and I did is when we looked at this tissue, it actually had fundamentally changed the bony structure of the ear.

So because this tissue was in the way and it would swell up, other parts of the ear had moved around to avoid it.

And so this was great because fossils are the remains usually of bones.

And so we were like, okay, well, can we look at the fossil record and tell when this tissue originated and therefore maybe when underwater hearing originated?

So we CT scanned a whole bunch of fossils and we essentially found that seals evolved their amphibious hearing over 26 million years ago.

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