Episode 10 Blow Your Mind

BOTH: We are Dr Chris and Dr Xand van Tulleken.

-And we're tracking down the most awesome...

-..incredible...

BOTH: ..and epic things in the universe!

BOTH: Come with us and discover unbelievable things

that will Blow Your Mind!

Blow Your Mind will be bringing you all the top experts

in unbelievable stuff, from icebergs to elephants, spaceships to sharks.

And, this week, it's all about amazing animals.

So hold on to your brains, here's what's coming up.

We're coming face-to-face with one of the most deadly

animals in the ocean...sharks.

Chris Packham discovers the sharks super sixth sense.

Sends a shark to sleep.

And meets some terrifying reef sharks at the bottom of the ocean.

Earlier today we saw dolphins doing something absolutely

incredible with their sixth sense.

That really was incredible.

Yes, but, not to be outdone by those dastardly dolphins,

-step forwards - the shark.

-The shark?! Step forwards?!

-But it doesn't have feet!

-Well, it's a figure of speech.

Yeah, but imagine if sharks did have feet.

Imagine them walking through your school, eating teachers

and pushing into the lunch queue.

Well, I guess that would be terrifying but they don't

have feet. Sharks do, however, have something that humans don't have.

Is it a super sixth sense?

That's right, sharks have an incredible super sixth sense.

Well, that's not easy to say.

Chris Packham has travelled to the island of Bimini in the Bahamas.

It's a hotspot for some awesome sharks.

With me is scientist Eric Stroud.

He's spent years studying sharks.

Sharks are extremely successful predators.

They can smell tiny quantities of blood over huge distances

and follow minuscule vibrations of their prey in the water.

But the shark sense that I want to investigate is very different.

It's one that we humans have no experience of at all.

Try to push them into here, yeah?

Well, if we can get him against the fence, we have a better shot.

Eric is going to demonstrate that sense with a strange experiment.

But first, we need our baby lemon shark to stay nice and still.

-OK.

-Got it.

-Got him.

-Look at that.

OK, so what we're going to do now is we're going to roll it over

-and place it into tonic immobility.

-Tonic immobility.

Go on, explain that one.

No-one is really sure why it happens, but

when the sharks are inverted like this, they kind of go to sleep.

Wow, he's just relaxed.

-It's like yoga for sharks.

-Indeed.

And there's nothing to suggest that it's stressed.

-I'm barely holding it.

-Yeah.

-I'm going to hand him to you, OK?

-OK.

And you just put your thumbs behind the pecs and just hold it.

OK, ready?

These things, obviously, I mean, it's stating the obvious,

-but they can bite. What would be the damage?

-A laceration, at this age.

-You might need stitches, actually, from this little shark.

-Oh.

-So, if anything goes wrong, just let it go.

-Let's do our experiment.

Eric's experimental kit is really simple.

Steel spoon.

-And a magnet. Thanks, EJ.

-I've been left holding the shark.

I'm not sure whether that's an enviable position to be in or not.

We have a strong magnet here that we're going to

use for the experiment and it's a pretty powerful magnet

and it'll attract the spoon out of my hand.

Eric wants to show me how our shark reacts to the magnet.

So, what we're going to do is put a blinder by the sharks eye

so he can't see what I'm doing.

'So the shark won't be able to see the magnet coming.'

-OK, I'm going to put a blinder here.

-Yeah.

'But will he sense it?'

-I'm approaching.

-Oh!

-That was a reaction.

-Excellent response.

-Wow, he jumped out of your hands!

-He did.

Whoa. I think he did sense it. That little shark does not like magnets.

Let's see that again, in slow motion.

And there he is sleeping, a little sharkey snooze. Whoa!

He is out of there!

Now, our little shark was completely unharmed but,

he's so sensitive to the magnet, he jumped to get away from it.

But why?

Well, it's down to the fact that sharks have a sixth sense.

Sharks have organs called the ampullae of Lorenzini,

bit of a mouthful.

And these are dark openings along the front of their noses.

These are jelly filled tubes that are specially designed to

sense the electrical current in the water

and they sit just beneath the skin of the shark.

They're extremely sensitive

and able to pick up tiny electrical volts in the ocean.

Now, we humans have nothing like this in our bodies.

To us, this is completely alien.

But why would a shark need an unusual superpower like this?

It helps them to find food.

They can locate the heartbeat of, say,

a crab or stingray underneath the sand.

When that animal is beating or it's moving,

the muscles generate a very weak electromagnetic field

and that's what their noses are gearing in on.

We're, in a sense, simulating that.

The movement of the magnet across the sharks nose induces that

electromagnetic current.

But we're just doing it many times greater than a stingray or a crab.

-So it's like a sensory overload.

-Exactly.

-Hence the struggle.

Exactly.

OK, so at low levels, magnetism helps sharks to find their food

but, at high levels, it scares them off.

Well, it's a bit like our sense of sight.

So, obviously, you need light to see,

but too much light can be blinding.

Now, before we find out how magnetism affects

a group of reef sharks, Chris, what do you call a group of sharks?

Is it like fish, you call them a school?

Well, yes, but there's another collective noun for sharks.

A shiver of sharks.

Well, I'm not surprised, sharks certainly make me shiver.

One man who's probably shivering in his boots right now is

Chris Packham, who's about to come face-to-face with

a shiver of very fierce looking reef sharks.

Ooh!

Chris and the researchers are heading to Triangle Rock,

a well known gathering place for large, Caribbean reef sharks.

And they've been joined by marine biologist Pat Rice.

They're going to try an experiment putting a sharks magnetic sense up

against their most powerful instinct - their urge to eat.

Yeah, here they are, look. Caribbean reef sharks.

Slap it on the water.

-Oh!

-Beautiful sharks, aren't they?

They're stunning, absolutely stunning, aren't they?

So, they're here. Let's get going.

Wow.

Stunning they may be,

but to do this experiment, I'm going to have to jump in with that lot.

I know they're only 2m but they look a little bit bigger than

I imagined a 2m shark.

Maybe it's the water, maybe it's acting as a lens

and exaggerating their length.

Pat now needs to set up the experiment, 8m down on the sea bed.

So, what is the experiment?

OK, so on the sea floor they're going to make two circles.

One circle is going to be made out of powerful magnets,

the other circle, which is going to look the same,

is just made out of black bricks.

And then, in the centre of each circle,

they're going to put shark food.

So they want to test whether or not the sharks are put

-off by the magnetic field around the circle of magnets?

-Exactly.

Now, sharks are well known for their killer instinct

and one of their most powerful senses is their sense of smell.

Sharks have been known to detect a drop of blood in water

at over 500m away.

That's the length of five football fields.

Wow, so we know that the sharks can definitely smell the food

that's in the centre of both circles?

Exactly, we know they can smell it but will they go for the food

when it's surrounded by an invisible magnetic force field?

Just watch this.

On the sea floor, Pat and safety diver Vincent, are setting up

the circle of magnets into which we will put our bait.

We need to be sure that the sharks aren't simply

deterred by a circle of black objects, so Pat has made

a second circle of ordinary bricks covered in black tape.

We'll put bait in the two circles and see what happens.

The magnets are powerful.

But will they repel the sharks?

Wow, I do not fancy being Chris Packham at the moment.

Yeah, me neither.

But, did you know that they're developing magnets as shark

-repellents on everything from fish hooks to surfboards?

-Really?

That is genius.

Well, when I go swimming tomorrow, I'm going to make sure I bring this.

Chris, I don't think there are sharks in our local swimming pool.

Well, better safe than sorry.

Hm, well, let's go and see how Chris Packham is getting on with

those super scary reef sharks.

BOTH: Watch out, Chris!

Now, I'm told that the sharks in this spot have never yet

attacked a human.

But, to do this experiment, we need to deliberately tempt them

in very close.

We've arrived on the bottom.

On this side is the ring of bricks, the placebo, if you like,

and here on this side is the ring of magnets.

So now all we've got to do is introduce the bait.

OK, we've got sharks here, already they're coming in.

Pat's got some bait here, some tasty tuna,

we're going to try and fix this in the centre of each of the circles.

We're in the water with hungry sharks

and in our bare hands we've got some fish.

'All of those sharks up by the boat will now be able to smell

'the bait down here with us.'

Here comes a shark, now.

It's bypassed the magnets.

And it's gone straight into the brick circle

and it's taken the bait.

'Now there's no bait in the bricks,

'will they show an interest in the bait in the magnet circle?'

Look at that, it turns as if it could sense that bait

and turned away.

It can tell there's food there,

it must be able to see all of the other fish currently feasting on it.

But it wouldn't go inside that ring of magnets.

'Time to put fresh bait in the bricks, and I've barely had a

'chance to retreat when a shark makes straight for

'the brick circle again.'

Look at that, it's a monstrous great animal.

'But, so far, they haven't touched the bait in the magnets.

'It's two nil.'

It tweaked them and definitely flinched away.

'And yet, they're clearly hungry.'

Not me. No, not me.

'We are down to our last piece of bait for the brick circle.

'And it doesn't last long.'

And it snaffled the food from the brick circle.

'But there's no doubt, the magnets are repelling the sharks.'

It seems almost confused by those magnets.

But the bait remains in the circle.

'Although undetectable by us,

'in the sharks mind, our magnetic force field is overwhelming.

'So strong, it even overrides the sharks primal urge to feed.'

That was mind-blowing.

Who would have thought these cold blooded killers could be

put off by a magnetic field?

Well, their sixth sense is just

so sensitive that the magnets are too much for it.

It would be like sitting hungry in front of your favourite sandwich,

but every time you try and have a bite, you get an electric shock.

Eventually, you'd give up.

ELECTRIC SHOCK

Yeah, eventually I would give up. And I'm really hungry.

Well, don't worry about that, Chris,

because here are some of the most jaw-dropping, mind-blowing

moments from the amazing animals we've seen this week.

We've seen super dogs with superpowers.

And cat burglars that steal their neighbour's food.

Dolphins that can recognise themselves.

And sharks with a sixth sense.

We've seen elephants that get emotional.

Cheeky chimps that lie to each other.

And cockatoos that can pick a lock.

We've discovered how animals use their unbelievable senses,

ingenious brains and social circles to dazzle us.

And make us realise that we're not so different, after all,

from these truly amazing animals.

Wow, those are some awesome animals.

And it's not just animals, next time we're going to be discovering

even more awesome things. So join us to Blow Your Mind.