Why do whales get beached? Now we know.

Have you ever tried to say something while your head is underwater? Did it end up garbled, with too many bubbles coming in the way? That’s because you’re not built to say things underwater.

Humans talk by letting air out through their vocal chords. But under the water, this air rushes out too fast because of the pressure. And then it makes bubbles as it rises up. What’s more, you’ll quickly run out of breath and come up to breathe—at which point you can easily say all the things you want to.

Whales spend most of their time underwater. When they want to speak to another whale, it’s unlikely they’ll go all the way to the surface just to say what they want to say. For a long time, scientists could not figure out how the whales spoke: there were no vocal chords to be found anywhere!

It turned out that whales do in fact have vocal chords, but they’re not just valves to let the air through. Each of the vocal chords is connected to an air sac, and people think that whales can pass air in and out of these sacs without any of it getting out of their bodies. That way, whales can make the vibrations needed for noise without losing any of their air supply.

Have you ever heard whales speaking to each other? You’ll never be able to hear all of it, because a lot of it is in ultrasound, at a frequency the human ear cannot hear at all.

If you could hear them, however, you would realise that their speech is very gentle and melodious. Most people speak of whales “singing” to each other, rather than just “talking”, though those whales actually are communicating with each other, not just humming a tune.

Different tribes of whales speak their own dialects of language, which might be very different from what is spoken by whales from outside the group. So it is definitely a language — though a very musical one.

Have you ever opened your eyes under the water and tried to look into the distance? Most water in the ocean is too murky to see very far — if you depend on your eyes to see. There are advantages if you are able to make noises in the high frequencies of ultrasound.

Dolphins (which are a type of whale) don’t only use their voices to speak. They also use it to see. Dolphins have a special organ in their head called the “melon”. This melon takes the sounds made in the nasal column (behind the nose) and concentrates them into a ray of noise.

When this sound hits something and is echoed back, the dolphin can listen to the echo and make out not just where the thing is, but how big, and even what it’s made of! It’s the same thing our eyes do, except that it uses sound instead of light.

Which makes sense, because sound travels much better in water, while light doesn’t move so well.

Other whales use sound to navigate, too, but none of them are as powerful as the dolphin’s melon. Dolphins can focus their noise not just for looking, but also to stun and even kill their prey.

Have you ever wondered why so many whales end up beached even though they have such an advanced navigation system?

Many whales have been accidentally coming into too-shallow waters, and then getting stuck and being unable to get back. Whales can breathe in the air, but their bodies can’t take the stress of being out of water. Their skeletons aren’t strong enough to hold up their weight without the help of water — in fact, no skeletons can be that strong, which is why the largest creatures are found in the ocean and not on land.

If beached whales aren’t rescued and helped into the water soon, they’ll collapse under their own weight and eventually die.

But if whales can navigate so well, why do they make the fatal mistake of coming out to shallow waters? Why is it that whole pods of whales get beached in this manner? And why does it seem to be happening more and more often these days?

One theory was that if the leader of the group is unwell, then the rest of the group will blindly follow. Even when the leader makes a mistake.

Now we know that it’s not just the leader, but the whole group that is unwell. And why is it unwell? Because of the noise.

A hundred years ago, the oceans were silent. Not any more. Over the last century, increased activity in shipping, oil-drilling, and military sonar systems has turned the seas into a loud, noisy place. Whales, with their sensitive ears tuned for music, aren’t able to handle such harsh noises.

People have found that whales keep getting beached near where the U.S. Navy conduct their exercises. Whales have started getting the “benz”, a disease where nitrogen bubbles into their flesh because they speed to the surface too fast and too long, to escape the noise. Many whales have internal bleeding and burst eardrums.

Now we know why whales get beached: because they can’t see where they’re going, and don’t know where to go. Because they’re injured, bleeding, and deafened by the blinding noise.

An earlier version of this article was published in Sirius #226 21 Aug — 3 Sep 2016 “The Blinding Noise”.

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