Ken O'Sullivan

One is to echolocation, which is to see the underwater world, to navigate the underwater world.

Because if you think anybody's ever been in the water, you've ever been in the sea with, you know, goggles or dive mask.

In Ireland, it's a good example.

You might see 10 meters on the best days.

Most days it's two or three meters.

If you came out of your house in the morning and the fog was so thick, you could only see a few meters.

Well, your sight isn't of much use to you.

And what's happened is that these animals over millions of years have evolved and developed really sophisticated acoustics.

So they put these clicks out through their skulls, all whales and dolphins do it.

And then they listen for the echo that comes back.

And based on that echo, they can paint a picture, an x-ray type image in their brain to show what's there.

So they use it to navigate, to find their prey, but they also use the clicks to speak to each other.

Difficult to know.

Our equipment wasn't good enough to measure distance, but the area we were in was 3,000 metres deep and they actually have been found.

It's known that they dive down to 3,000 metres to hunt in the deep ocean.

And remembering that once you go below 600 metres, you're in total darkness in the ocean.

So their acoustic senses and their hearing is the only thing they can use to navigate.

So all whales and dolphins, they pass air from their lungs up through the nasal cavities.

And they've got something called phonic lips, phonic being of speech, of sound.

And then that pushes the click out through their skulls.