The waves, the water, the seaweed,

the sheep?

Are they eating seaweed? (sheep bleating)

We've gotta figure this out.

(mid-tempo music)

So, here's a little context to start off the story.

We're on an island, high, high, high up in Scotland,

called North Ronaldsay.

It's so remote you can only get here by ferry or airplane.

And on this small, picturesque island,

home to only 50 people,

lives a very, very rare breed of sheep: the seaweed sheep.

Meet Kevin, the authority on all-things seaweed sheep.

- [Narrator] So let's learn more about this rare species.

Welcome to Seaweed Sheep 101.

(sheep bleats)

- [Narrator] They are smaller than the average sheep,

and their wool can be black, white, gray or brown.

The males have big, curly horns.

And so do some females, and ...

(light music)

- [Narrator] As a result, the sheep were confined

to the seashore and were forced to survive on seaweed.

This changed their digestive system over time,

making them one of only two animals in the world

who are able to survive on seaweed alone.

And this wall, known as the sheep dyke,

makes sure they stay on the shore. Right, Kevin?

- [Narrator] Oh, OK, well, Heather, over to you.

- Behind me is the native sheep dyke.

This was constructed in 1832.

The North Ronaldsay sheep dyke is essential

in the genetic structure of the sheep.

North Ronaldsay sheep have a very high intolerance

to copper, so they die from over-nutrition

by grazing on the grass for too long.

So we keep them on the shore, and they eat seaweed,

which has got very low levels of iodine and copper.

(sheep bleating)

(soft music)

(soft music)

(electronic music)