and not a horn at all.

And today, we're talking about narwhals,

unicorns of the sea.

Nice shirt.

- Thanks.

(light piano music)

- My grandfather, Jacques Cousteau,

studied and explored the Earth's ocean.

I do too.

And our submarine is in arctic waters,

searching for the narwhal.

(errr, errr, er, er)

Oh, he's a beauty.

Now, narwhals can grow up to 17 feet in length,

and their front tooth can grow up to 10 feet in length.

It's the only straight tusk in the world.

But typically, these are only found on males

and are actually full of up to 10 million nerve endings,

helping the narwhal detect pressure, salt levels

and even temperature in the water.

Here's an interesting fact,

a narwhal tusk is flexible.

It can bend about one foot in any direction,

without breaking.

It was originally thought that

these tusks were for dueling.

But a new theory suggests, they're for attracting a mate.

Narwhals don't migrate like other whale species.

They spend their entire lives in icy, arctic waters

hunting squid, fish and crab.

If you want to see one live,

you'll have to come up north

because narwhals don't thrive in captivity.

Rather, they die.

Some animals, we humans just can't tame.