Blue Shark Shark Bites

My name's Steve Backshall. Self-confessed shark-obsessed.

This is Shark Bites.

This time, we meet the ultimate aquatic athlete...

..the blue shark.

Living in the open ocean, they undertake mammoth migrations.

Found in most oceans throughout the world, they're

constantly on the move, travelling to annual breeding sites

and in search of rich feeding grounds.

In the Atlantic, they journey full circle between America and Europe,

while a similar cycle in the Pacific clocks up 9,000km.

So, how does this bolt of blue achieve such massive migrations?

California's coast is the perfect place to see them on their travels.

Curious and bold, blue sharks will take a pit stop break to

investigate anything that could be food.

And it doesn't take long for one to check me out.

They have the most glorious blue shade to the skin.

Got one just nudging my camera now. Look at that!

He's right in my face!

So inquisitive, so interested.

Just sticking their noses in absolutely everything.

Any predator has to have a good-sized brain.

They have to have processing power to figure out problems,

to figure out how to catch their prey.

And you can see that that has developed a big

personality in this shark.

It really is just like... I don't know, a friendly dog.

An inquisitive nature helps them find food -

vital for keeping energy levels high during their voyage.

But these athletes also have an ingenious bit of kit to keep them

going the distance.

Surprisingly, some sharks would sink if they stopped swimming.

Unlike many fish who have an air-filled swim bladder that

gives them buoyancy, sharks, including the blue, don't.

Instead, they rely on their large liver.

In some sharks, this can be up to a quarter of their body weight,

and it's filled with oils which are lighter than water.

This gives them a little bit more buoyancy,

which means these athletes can keep going for longer.

But it's not only using this lubricated liver that

helps them keep travelling.

Ocean currents act like a conveyor belt,

so blue sharks hitch a ride on them,

saving even more energy to cross the finish line on their

marathon migration.

The blue shark. With its sleek and streamlined body,

armed with its very own buoyancy device and undertaking

mammoth migrations, it is, without doubt, the ultimate aquatic athlete.