Echolocation: How Dolphins and Bats See with Sound

Okay, we're rolling! And look, the bats are already out!

Right on cue. They're hunting by sound, not sight.

But I can't hear a thing. Are they silent?

Far from it. They're screaming, just above your range.

Screaming? Then how on earth don't they deafen themselves?

Tiny middle-ear muscles clamp down with every single call.

Every single call? That's absurdly precise!

Near prey, it's up to two hundred calls a second!

Wait, is that the buzzing on the detector?

Exactly. We call it the feeding buzz.

Poor moths. They don't stand a chance, do they?

Don't write them off. Many moths can hear bat calls.

And tiger moths click back! Some can actually jam the sonar!

An insect waging electronic warfare? No way!

Well... often the clicks just warn that they taste foul.

Right, from bats to dolphins! Same trick underwater?

Same principle, different plumbing. They click with nasal phonic lips.

And that bulge on the forehead? Is that the speaker?

Spot on. It's the melon, a fatty acoustic lens.

The melon. Biologists really are terrible at naming things.

Wait till you hear they listen through their jaw.

Through their jaw? You're pulling my leg!

Honestly, the lower jaw is packed with fat that channels echoes.

So could a dolphin basically see my skeleton?

Um, sort of... more a rough sketch than an X-ray.

But bats and dolphins aren't remotely related, are they?

That's the beauty of it! Evolution solved it twice!

Even a hearing gene, prestin, shifted in parallel in both.

The same genetic tweaks? In a bat and a dolphin?

Okay, confession... I tried clicking in my kitchen earlier.

And? Did you find the fridge?

Mostly I found the door frame. With my face.

Keep practising. In expert human echolocators, the visual cortex lights up.

Right, viewers, get clicking! Just mind the door frames!