Staying Alive World's Sneakiest Animals

Meet the Californian ground squirrel.

It's an endearing little rodent, but it does face a big problem.

A constant and terrifying threat.

Rattlesnakes.

Deadly serpents that hunt by smell.

Once locked on to a squirrel's scent, there's no escape.

Or is there?

You see, these squirrels have a distinctly devious con

to fool the sinister snakes,

and central to that con, is this,

one of the rattlesnake's old, shed skins.

Just watch this!

Look at that!

The squirrel's come over, picked up the skin,

and started chewing it.

They rub the mush all over their bodies.

You see, they're masking their own scent.

Now, they smell like the snakes instead.

It's fooling the principal way the ruthless rattlers

hunt them down.

The snakes just can't detect the squirrels.

It's ingenious, isn't it?

Absolutely ingenious!

They use the snakes' own scent to hide themselves.

Now, that's nature at its most devious.

And it turns out that these sneaky squirrels

aren't the only ones tricking other animals to survive.

Every day, animals face the single greatest challenge

of their lives - survive, or die.

They've got to outwit potential predators.

Find or catch food.

And then raise the next generation.

Frankly, the stakes couldn't be higher.

So, in the face of all of this,

how on earth can animals increase their chances?

I mean, would they lie, cheat,

even steal from one another just to survive?

Come on, of course they would.

Join me as I meet the world's sneakiest animals...

..who will do whatever it takes to survive.

Now, if there's anywhere on the planet where

staying alive is a constant struggle, then it's here, the African savanna.

To avoid the attention of predators,

most animals' coat colours blend in to the background.

But one in particular has perfected an incredibly sneaky disguise.

The zebra.

No, seriously, I mean it.

The zebra.

Let's just stop for a minute and think about these animals -

in particular their markings.

I mean, they are striking, stunning animals.

But, at the same time,

they might strike you as a little ridiculous when you think about it.

After all, they're living out here on the plains of Africa,

which are famed for being alive with predators.

And yet, look!

They stick out like a sore thumb.

So, perhaps this begs the question,

the age-old question,

why does the zebra have its stripes?

Well, over the years, there have been plenty of theories.

From helping to keep them cool in the heat,

or attracting a mate...

..or even a way of identifying each other.

But to be honest, none of these have stood the test of time.

Now, ground-breaking new science is suggesting that these

bold patterns are keeping the zebras safe from their enemies.

But how?

Well, perhaps there's a clue in the colours themselves.

Black and white are the two most contrasting colours.

When combined, they play tricks on the mind.

Take a look at this, and don't adjust your sets.

This is known as the cafe wall illusion.

Look at the horizontal lines,

they look sloping, diagonal,

uneven, right?

But, just look at this.

You'll see that there are no skewy or diagonal lines at all.

In fact, everything is perfectly even and horizontal.

Before, the lines looked sloping.

After, they're perfectly straight.

Black and white patterns can confuse our vision.

And they are the two most common colours used in optical illusions.

So, could it be that a phenomenon like this

could contribute to the whole enigma of the zebra's stripes?

Well, one man has been investigating exactly this.

Dr Martin How is an expert in the way that predators see their prey.

I've been studying animal vision for a number of years now

and became quite interested in what the zebra's stripes might be doing

to the visual systems of their main predators.

They've got these very strong stripes,

but nobody's really explained convincingly why they're striped.

Martin's got an exciting theory.

That the bold, contrasting patterns,

when viewed by predators, could be creating an optical illusion.

It's an idea called motion dazzle.

Let me show you how it works with an example we're all very familiar with.

Now just watch this.

If I begin to turn this bicycle wheel,

you can see that it's moving in a clockwise direction,

and it looks like it's moving in a clockwise direction.

But if I turn it more quickly, like this,

then suddenly something magical happens.

The wheel appears to be moving in the opposite direction,

it appears to be going completely backwards.

It's called the wagon wheel illusion.

The faster something rotates,

the more we struggle to process the movement.

Our brain tries to simplify what we're seeing,

but it gets the direction wrong.

To investigate whether something like this could be happening

with the zebra's monochrome stripes,

Martin developed a computer model to analyse footage.

What we've got here is the original footage

of the zebras moving from left to right,

and below, we've got the output of the model.

The brightness of the colour shows you where the movement is happening

and the colour itself tells you the direction,

so the green areas are moving to the right,

and the red areas are moving to the left.

OK, but there is a mass of red in there,

does that mean that those parts of those zebra, to the predator,

look like they're moving completely in the opposite direction,

-back to the left?

-That's exactly right,

and it demonstrates that it's the stripes that are causing the effect.

Let's just be clear on this.

Here, we've isolated the two key colours.

As the zebras are walking to the right,

the model should only be showing green, no other colours.

Remarkably, the red we are seeing

is suggesting that a predator would perceive the zebras to be moving

in completely the opposite direction.

Just like the bike wheel.

Predators must precisely judge the speed and direction

of their prey in order to make a kill.

This research shows that, as zebras start moving,

the stripes create a miraculous and disorientating illusion.

Making it harder for the predators to home in on them.

In a hunt, every second counts.

So this dazzling form of defence

could be confusing predators just enough

for the zebras to escape and live to see another day.

It's an outstandingly sneaky trick.

Zebras have transformed themselves

into a walking, trotting, galloping optical illusion,

which both deceives and deters their predators.

If I'm honest with you,

up until now I've never really given them a second look.

I've always thought of them as small stripy ponies,

living out here to be eaten by something more interesting,

but no longer.

I now see them as unique and beautiful animals,

creatures that have pulled off an incredible deception

to produce one of the most effective anti-predator strategies

that we have on our planet.

Motion dazzle is a brilliant way to confuse hunting predators.

But animals have other ingenious ways to outwit their enemies.

One creature's sneaky strategy is to avoid being detected

in the first place.

You're looking at a northern leaf-tailed gecko,

and these animals are incredibly difficult to spot.

Try focusing just here.

Now that really is a master of disguise.

I had a book when I was a kid, it had a photograph of one of these,

and I could barely believe it existed.

You can only find them here in Northern Queensland,

in the tropical forest,

and it is one of the largest geckos in the world.

They feed at night,

but it's when they sleep during the day that they have a big problem.

This forest is alive with hungry eyes.

All looking to prey on an exposed lizard.

You see, our gecko is too big to hide away

or tuck in under bark.

So, stuck out on a limb in broad daylight,

it deploys its party trick.

The gecko has developed an ability that we can only dream of.

Just watch this.

It vanishes into thin air.

The gecko's vanishing act starts with its skin.

It's covered in a series of strongly contrasting patterns.

In close up, they really stand out,

but from a distance, they break up the gecko's body shape,

and its outline...

..allowing it to blend seamlessly into any forest background.

It's known as disruptive camouflage.

Even their eyes have it.

But there are other clues the gecko's predators could pick up on.

Any three-dimensional object, no matter how well camouflaged,

has the potential to produce a shadow,

and this shadow is a dead giveaway to any predator.

To combat this, geckos have very loose skin,

which they flatten against the trees when they're trying to hide.

To complete their vanishing act, the geckos have subtle fringes

that run around the edges of their bodies,

particularly on their tails,

and these serve to break up their outline

and any sharply defined edges.

By using these principles,

animals have perfected the ultimate camouflage.

The effectiveness, the sheer beauty of these devious disguises,

is quite mind-blowing.

Just look at these sneaky creatures.

Can you make it out?

It's a dead leaf butterfly from Malaysia.

What about these animals?

These are pygmy seahorses, from New Guinea.

And finally, how about the incredible disguise of this hooded grasshopper?

And, for our leaf-tailed gecko, and yes, it is still here,

perfecting this disguise means one important thing,

it can rest - it can sleep here in the open,

and avoid the attention of predators all day long.

Now, it's all very well some animals being able to blend

perfectly into their background, that's clearly a great advantage.

But what about if these species then want to move

from one habitat into another?

Then it could clearly be a disadvantage.

Unless they had the ability to change their camouflage,

and, ultimately, if they could continue to change that disguise...

..they would come up with nature's invisibility cloak.

Something that you might think is a bit far-fetched,

but I've got to tell you that it isn't,

there's a creature living out there right now that can do just that.

And what a splendid creature it is.

What do you mean you can't see it?

It's in the middle there, amongst the seaweed.

I give you the cuttlefish.

Unfortunately for them,

they are one of the most sought-after meals in the ocean.

Their bodies have no physical protection,

so they've come up with a cunning defence.

They transform themselves entirely to match their surroundings.

In his US-based lab, cuttlefish expert Dr Roger Hanlon

is investigating how they conjure up these incredible illusions.

He's presenting the cuttlefish with different backgrounds...

..and then pulling the rug out from underneath them.

It reveals just how quickly they can adapt.

As Roger is discovering,

the key to this seemingly supernatural power is their skin.

Well, this is truly amazing,

perhaps some of the most beautiful skin on Planet Earth,

and they need elegant skin

because they have to create these colours and patterns,

and contrasts to create this camouflage.

So, in the top layer of the skin

they have these beautiful pigmented organs, we call them chromatophores.

Chromatophores are tiny packages of different coloured pigment.

Each individual chromatophore is pulled and stretched by muscles

controlled by the brain, turning a dot into a circle of colour.

The combined effect of three million chromatophores,

and other specialist cells,

changes the cuttlefish's colour and pattern in an instant.

This amazing colour-changing ability

is made even more remarkable by one astonishing fact.

Cuttlefish are colour-blind.

Yes, that's right.

They can't even see the colours they're trying to match.

So, how on earth do they match their surroundings quite so perfectly?

Well, recently Roger and his colleagues have discovered

the cuttlefish's beautiful secret.

Dotted across their skin are specialist cells containing opsin.

It's a protein usually only ever found in eyes.

So, this is a marvellous strange discovery,

they seem to have light-detecting molecules distributed in the skin

and these are the same molecules that are in the retina in the eye.

In effect, their skin can sense - possibly even "see" - colour.

But then these great illusionists have another show-stopping trick.

The cuttlefish have this morphing skin.

The skin can actually go from flat to three-dimensional,

think ultimate goose bumps in a human, for example.

No other animal can do this.

The cuttlefish morph and change texture to match any surroundings.

It's an extraordinary ability.

These clever cuttlefish, and their close relatives, octopus,

have the most amazing shape-shifting vanishing act

that I've ever seen.

And, when it comes to playing hide-and-seek with predators,

these deceitful creatures are always the winners.

Camouflage is a wonderfully sneaky and successful way

to avoid predators.

So many different animals depend on it to survive.

But, you know, for even the best-camouflaged animals

there's a problem.

You see, the second they move, the illusion is blown.

It really doesn't matter how well-hidden they are, it spoils the trick.

But nature always finds a way.

So, could there be an even craftier ploy?

One that could protect a conniving creature around the clock?

No matter where they were, or what they did.

A disguise that all predators would want to avoid all of the time.

Venomous, toxic, or decidedly deadly.

Many animals use bright warning colours

to declare the threat that they pose.

Predators learn to avoid these animals.

They know the consequences if they try to eat them.

But sometimes, all is not as it seems.

Two snakes, both displaying classic warning colouration.

Both residents of here, the south-eastern United States.

But one of these snakes is deadly venomous.

It's the eastern coral snake.

The venom is packed with neurotoxins which paralyse the breathing system,

so one bite is pretty much certainly fatal.

That would be a snake to avoid.

But the other snake is a barefaced liar.

The scarlet king snake is absolutely harmless.

The big question is,

which is which?

Because in a moment, I'm going to take one of these two snakes

out of the jar, bare-handed.

So, which one will it be?

Which would you choose?

No, I don't think so.

I'm going to go for this snake.

This snake is the scarlet king snake.

It's the faker.

And just look at it,

it is absolutely beautiful.

In this neck of the woods,

it helps to remember a rhyme that could save your life.

"Red touches yellow, could kill a fellow.

"Red touches black, friend to Jack."

And here, the red-and-black bands are touching,

so this is our harmless king snake.

Round here, this snake is certainly on the menu for many larger animals.

So, it's evolved a sneaky tactic.

This is a classic case of imitation.

The harmless king snake is mimicking its deadly rival,

the coral snake,

in the hope that predators will buy this con and leave it well alone.

Well, that's the theory at least.

But I see a problem.

You see, they're not exactly the same, are they?

So, could this mimicry really confer protection on this cheating snake?

Unbelievably, until recently,

it had never actually been tested in the field, that is until now.

Professor David Pfennig is an expert

in the king snake's masterful mimicry.

Earlier in the year, he set out replicas

of both snakes,

in front of camera traps.

He's investigating...

..how predators really react to these warning colours.

I can't wait to see the results.

So, David, how did the experiment go?

It worked out fabulous, and you can see we found a real diversity

of animal life appearing on our videos.

OK, so, a great range of species,

but at least two of those animals are potential predators of the snake.

The grey foxes and the coyotes would be predators of these snakes.

The raccoons would probably be, as well.

When we look at the reactions of these predators to the snakes

we find that they're treating them as if they were real snakes.

But surely, the bright warning colouration

has to be putting off the majority of attacks?

That's right.

Generally, they're not attacking our fake snakes, they're avoiding them,

and you can see this avoidance in several of these clips.

Sometimes they do go after them,

and they do attack them, at a very low frequency though.

What do you see in terms of a difference between the number

of fake coral snakes and the number of fake king snakes being attacked?

They're equally likely to be attacked.

So even though the coral snake and the king snake

have different ring order, predators are avoiding both.

So, despite not looking EXACTLY the same,

the mimetic king snake is still gaining all of the advantage

of its phony warning colours.

The reason why that works

is that the coral snake is really, really deadly,

it can kill an adult human, it could kill any of these predators.

So, just vaguely looking like it is good enough to get you by.

Just as I gambled with my life earlier...

No.

..if a predator wanted to eat one of these two snakes

and picked the wrong one,

it could cost them their life.

So, they tend to play it safe,

avoiding any snake with obvious warning colours.

Mimicry really is an excellent strategy for survival.

It's a brilliantly cunning way to protect yourself from predators

24 hours a day.

So, it's hardly surprising that, when one species evolves

to be deadly dangerous, others sneak in and copy them.

Mimicry is a successful survival strategy

used by animals the world over.

Impersonating others has entirely changed the way that animals

look and even how they behave.

But what if animals could adapt their behaviour and make

deliberate, strategic decisions about when and how to trick others?

Well, then, they could pull off the sneakiest con tricks of all.

One of these animal hustlers lives here, in the forests of Panama...

..white-faced capuchins.

This group are a close-knit family.

Together, they defend a territory that they depend upon to survive.

But other monkey troops are trying to take their turf.

And as a consequence of that, these monkeys are always in conflict.

Fighting is a dangerous business.

Injuries are common.

In fact, more capuchins are killed by each other than by predators.

The stakes couldn't be higher.

Guarding a territory obviously takes teamwork.

An individual capuchin can't keep an invading troop out on its own

and obviously, from that troop's point of view,

it makes sense to look after the territory. They need it to survive.

But let's just stop for a moment

and think about the implications on the individual monkeys.

Yes, it's their duty to help defend the territory...

..but that takes time and energy, and then

there's the likelihood of getting seriously injured.

And for a monkey like this, that is a huge dilemma, and it's

led to the evolution of some extraordinarily treacherous tactics.

These monkeys are part of a long-term study.

Leading the research is primatologist Meg Crofoot.

She's going to show me just how sneaky these monkeys can be.

By playing a recording of a neighbouring troop,

she's simulating a territorial invasion.

SOUND OF MONKEY CHATTER

That's the big male, and there's a female,

looking towards the speaker with a baby on her back.

On the ground right here, look at that.

That's the alpha male in this group.

-Well, that's certainly got a response from him.

-Yup.

-Here we go, one of the juveniles.

-Yes, yes.

Wow!

-Look, look, look! Two more there.

-Two more there.

-Yeah.

So, we've seen five monkeys come this way - the big male,

the three juveniles and that one female with the baby on her back.

But two of the females looked at the speaker

and didn't come forward at all.

-They didn't seem to want to get involved in...

-No, they didn't.

-..looking after their territory.

-No.

I just saw two monkeys cheating their own family...

..in a social species that's supposed to work together!

This new discovery has surprised everyone.

But what's really interesting is that some days, these same two females do

respond to the recordings, they do rush in to help.

Another day, a different monkey cheats the troop.

To a lesser and greater extent, they're all up to it.

So, there's definitely a sneaky strategy in play here.

MONKEYS SCREECH

So, if the same monkeys don't cheat all of the time, that means

they must be making decisions every time there's a potential

conflict as to whether to cheat or not.

Yes, I think that's definitely true.

It seems to be an interesting tension between the

likelihood that the group is going to be able to win without you

and your own sort of personal desire to avoid risk entirely.

These monkeys have weighed things up and decided to cheat the group.

But it's a huge risk.

After all, it could jeopardise their own family's long-term survival.

But for the individual monkey, if it means avoiding injury,

then the con pays off.

Being able to decide which trick to pull out of the bag

and when is critical to a successful sneaky strategy.

So, what is the ultimate animal hustle?

Well, one creature really will do whatever it takes to survive.

The horned lizard, what an animal, look at it!

I'm absolutely smitten.

To me, this is gorgeous, this defines cute.

And, of course, you can see how it gets its name.

This super-spiky skin,

and this dinosaur appearance normally protects it from predators.

Normally. But occasionally,

this little animal has to pull off the riskiest con of all.

Horned lizards lay eggs and then carefully bury them.

Then they stand guard duty.

Her camouflage keeps her concealed

as she scans the horizon for any potential danger.

And what's this? A western patch-nosed snake.

That's not good.

She eyes him up, but she is not the one in danger.

You see, this is an egg-eating snake.

There's no point in staying hidden now.

It's protecting the eggs that's important.

She charges into battle.

Her frenzied attack drives the snake away.

It's a tactic that works when it comes to protecting eggs.

So, a horned lizard like this can recognise its adversary,

measure the threat to its eggs

and then decide on the appropriate defensive response.

All very clever stuff, but what about if the tables are turned?

Well, then the lizard has to change its strategy -

that's when things get REALLY interesting.

A coachwhip snake -

this snake eats lizards

and she knows it.

First, she tries a simple scam -

puffing herself up to look bigger, more intimidating.

But this doesn't fool the persistent snake.

This is now a matter of life and death.

So, she's forced into pulling the sneakiest strategy of all,

her greatest deception.

She's faked her own death.

If the snake doesn't buy the con,

this is going to backfire in a spectacularly bad way.

But snakes, you see, never eat dead animals,

unless they've made the kill themselves.

Completely confused, the snake slopes off.

A quick peek to check the coast is clear...

..and she springs back to life...

..ready for whatever life throws at her next.

Surely this has to be the ultimate predator response?

Faking your own death,

right under the nose of your most dangerous enemy?

It's audacious and it's gutsy.

And what's more, this little lizard actually decides when to fight

and when to pull off that show-stopping deception

and, by making that decision,

it can protect its eggs and keep itself alive. What about that?

In fact, I'm going to give the horned lizard a very rare ten out of ten,

not just because of the behaviour,

but also cos I'm totally in love with it. Look at it!

It's my little dinosaur!

All these extraordinarily sneaky animals have gone

to incredible lengths to fool their enemies...

..and outwit their predators.

By using deception, they've overcome one of life's greatest challenges -

staying alive.