♪♪ -The oceans are full of wonder... an alien world waiting to be explored... ♪♪ ...a place of extraordinary life-forms... with intriguing social lives... and incredible intelligence.

[ Dolphin squeaking ] To reveal their secrets, a hidden team goes undercover.

♪♪ Spy Creatures.

♪♪ The most innovative undersea robots in the world.

♪♪ They not only look like the animals they film, they interact with them as no human can.

♪♪ Equipped with hidden cameras... ♪♪ ...they reveal their astonishing lives.

♪♪ As our spies join their undersea world... they shed light on some of the mysteries of the deep.

♪♪ ♪♪ As our spies search the ocean for intelligent life, they find ways of thinking that must be seen to be believed.

♪♪ A family of sperm whales, the most intelligent creatures in the ocean... ♪♪ ...and owners of the largest brains on the planet.

♪♪ These intellectual giants show a social intelligence that appears similar to our own.

♪♪ To gain insights into their minds, a spy is sent among them... ♪♪ ...an autonomous submersible programmed to follow the whales.

♪♪ At almost 10 feet long, it's the same size as a newborn calf.

Large enough to hide an array of cameras... ♪♪ ...but small enough to arouse the maternal interest of a female.

♪♪ Her curiosity hints at what she may be thinking... ♪♪ ...a desire to reach out and make friends.

♪♪ Seen through the camera eye of our spy... ♪♪ ...it's a meeting with a sentient mind.

♪♪ ♪♪ A first contact with an inquisitive and questioning being.

♪♪ Our spy's hydrophones now capture something extraordinary... [ Whale clicking ] She attempts to communicate.

♪♪ Another sign of her social intelligence.

♪♪ She uses the same clicks when greeting other whales.

♪♪ Her open jaw means she's introducing herself to our spy.

[ Clicking continues ] ♪♪ ♪♪ Waiting in the wings is a real calf.

♪♪ In a touching sign of approval, she invites the youngster to meet our spy creature.

♪♪ An encounter far closer than ever imagined.

♪♪ The camera even reveals his hitchhiking companions.

♪♪ Harmless remora fish... enjoying a free ride.

♪♪ ♪♪ Our spy is gaining an insight into how relationships form among whales.

♪♪ Being allowed so close is a sign of acceptance.

♪♪ The mother is so trusting, she leaves her calf and heads to the ocean depths.

♪♪ She'll dive nearly 2 miles below... ♪♪ ...leaving a friend to look after her calf.

♪♪ Spy Whale seems to be welcome, too.

Together, they'll stay with the calf until the mother returns.

♪♪ Our spy is now perfectly placed to discover more about the social intelligence of the whales.

♪♪ Meanwhile, in the coral reefs of Indonesia, there are more intelligent life-forms to be found.

The smartest of all is the coconut octopus.

♪♪ As well as a main brain in its body, each of its eight arms has a brain of its own.

♪♪ All nine brains can think for themselves or even think as one when required.

♪♪ To help figure it out, another spy is needed... ...one programmed to walk in a similar way.

Its aim is to communicate with the octopus... ...to find out how clever it really is.

What must he be thinking?

Then a clue...

He's working out whether he's met a friend or a foe.

It seems our spy is a friend.

♪♪ Just as well.

He certainly has plenty of enemies.

♪♪ His soft body means everyone's out to get him.

♪♪ And not just him.

♪♪ Such dangers are small-fry compared with the oceans' top predators.

Blacktip sharks hunt octopus.

♪♪ Fortunately, our spy doesn't smell like one... ♪♪ ...not so the real thing.

He may hide, but they could still find him.

♪♪ Time for some quick thinking.

♪♪ A hollow bamboo shows promise.

♪♪ But its open entrance is far from ideal.

Our spy may have the answer.

It's just what the octopus needs.

But will he dare take it from him?

♪♪ ♪♪ Like a seasoned thief, he tries to avoid raising suspicion.

♪♪ Being aware of what others could be thinking is a sign of deep intelligence.

♪♪ ♪♪ ♪♪ A perfect fit!

And just in time!

♪♪ ♪♪ With nothing worth eating, the sharks move on.

♪♪ The coconut octopus need hide no more.

♪♪ As a sign of acceptance, he shows his true feelings.

♪♪ As their relationship grows, there'll be plenty more to discover.

♪♪ [ Macaques screeching ] Of all seagoers, few are more clever than these Thailand macaques.

Spy Macaque is discovering how they survive on this remote island.

It, too, has a camera in its eye.

[ Macaques screeching ] It can not only film above the surface... but underwater, too.

As well as being able to swim, it has a fully waterproof camera eye.

Perfect for filming these free divers searching for shellfish.

♪♪ They can hold their breath for a minute or more.

♪♪ ♪♪ When they come up for air, there's more seafood to find.

♪♪ Our spy has acquired Spy Oyster.

Together they capture a filming first.

These monkeys have gone fishing, grabbing whatever is trapped in the pools.

[ Macaques screeching ] It takes quick-witted reactions... ...and a firm grip.

The fish course over, there's more seafood on the menu... ...oysters embedded in the rocks.

They can't be removed by brute force alone.

It's a task only the best minds can crack... ...those that can wield a tool.

[ Macaque screeches ] A treat worth the effort.

♪♪ Finding the right rock is a knack.

♪♪ ♪♪ It must be the correct weight and size.

Like this one, designed for the job in hand.

♪♪ Even so, he must be careful.

♪♪ One slip could be nasty.

♪♪ It's the perfect tool... ...or was.

Oh, well.

Knowledge comes with experience.

It starts with a sense of curiosity.

But others are curious, too.

♪♪ Climbing with a spy cam isn't easy.

♪♪ Whoops!

No matter.

If you're smart, you know how to have fun.

♪♪ ♪♪ A chance to make friends and let off steam.

[ Macaques screeching ] ♪♪ As our spies found, macaques, cast away on a remote island, have found clever ways to adapt.

♪♪ Creative thinking can also be used to find a mate.

In the Sea of Japan, there's even a sea creature who creates works of art.

♪♪ Spy Pufferfish is on a mission to find it.

♪♪ The artist in residence won't be found among the coral.

It needs a blank canvas to work with... something only the sand provides.

♪♪ And here it is.

An exquisite sand sculpture found nowhere else on earth.

♪♪ ♪♪ The artist at work is a male Japanese pufferfish.

He's designed his masterpiece to lure in a mate.

An artistic creation to delight a female's eye.

He uses a fin to plow a furrow... ...while other fins sweep the sand into ridges.

The gullies channel the finest particles towards the center.

The result is a fully functional work of art.

It's now Spy Puffer's turn.

[ Soft whirring ] ♪♪ ♪♪ Artworks are best viewed at a distance.

♪♪ ♪♪ Oh, dear...

Nothing compares to the true artist.

♪♪ The female will decide.

Spy Puffer's creation is hardly worth a second look.

She's after a masterpiece.

But for this discerning art critic, there's still room for improvement.

Especially when some debris spoils the design.

A blemish easily dealt with by the male.

But it still needs some finishing touches... ...such as shells to decorate the ridges.

They're more than an artistic flourish.

They stabilize the ridges, slowing the water that might stir the center... ...for this is where the female will lay her eggs.

But the male has run out of shells, and the female is losing interest.

Spy Puffer becomes the artist's assistant.

♪♪ The finishing touch he needs.

♪♪ ♪♪ All this striving for artistic perfection is a test of his fitness.

♪♪ Satisfied with the aesthetic details, the female enters the nest.

♪♪ They join together, cheek-to-cheek.

♪♪ Then, quick as a flash, the eggs are laid and fertilized.

♪♪ With a little help from Spy Puffer, the next generation of artists is on its way.

While pufferfish think creatively, fish shoals all think together.

They show swarm intelligence, moving as one.

They mirror the moves of their nearest neighbors.

Their group thinking is about to be tested by smarter minds.

♪♪ Marlin... one of the ocean's fastest predators.

♪♪ They use teamwork to drive mackerel up from the depths, forcing them to the surface in even tighter balls.

♪♪ And they're not alone.

Sea lions soon join in.

♪♪ Among them is a new spy creature.

Spy Sea Lion.

Like the real thing, its flexible body lets it maneuver among the shoals.

♪♪ Its eye cams gain a sea lion's view as the marlin spear their prey.

♪♪ Like master swordsmen, they use their 3-foot-long bills as deadly weapons.

♪♪ As the hunt continues, our spy films an insider's view.

It won't be working alone.

As frigate birds gather, another spy joins... ...one that captures the marlins' skills from the air.

They corral the shoal, concentrating the ball, letting them pick off the fish on the outside.

But they don't have it all their own way.

[ Whirring ] The marlin will soon be competing with those with far greater intelligence.

Spy Sea Lion now has plenty of company.

They are here in their hundreds.

♪♪ Working together, they steal the bait ball from the marlin.

♪♪ Our spy reveals what happens once the sea lions take over.

It joins them as they unite to split the ball... ...capturing a sea lion's view from inside the shoal.

It shows how the fish move as one.

Its swarm intelligence pitched against that of the sea lions.

This is where true intelligence shows its worth.

They work together to force the shoal apart.

They can now pick off the weak and injured.

♪♪ Sea lions can eat 30 pounds of fish a day.

♪♪ But such a colossal bait ball is too much, even for them.

♪♪ They start to play with their food rather than eat it.

♪♪ Then...something unexpected.

They gift the leftovers to the hungry marlin.

♪♪ There's even a fish for Spy Sea Lion.

♪♪ Not much use to our spy... it is to the marlin.

♪♪ The sea lions may have outsmarted swarm intelligence... but even they can be beaten by a bigger power.

♪♪ A Bryde's whale will make short work of what they've left.

♪♪ Back on the reef, there are more insights to be gained from the coconut octopus.

Spy Octopus is still nurturing its newfound relationship.

Their bond has only grown stronger.

To feed, the octopus must leave his hideaway.

As a precaution, he takes the coconut shell with him.

What was once the door to his refuge is now a mobile home.

♪♪ ♪♪ But there are more surprises in store.

The octopus is still looking to improve his security.

Some armor plating would be useful.

A shell would be perfect!

His only problem is carrying it all.

♪♪ ♪♪ This is taking defense seriously.

♪♪ All bases covered, he's perfectly placed to stage an ambush.

And what better than a crab?

The chase is on!

♪♪ But the crab has a trick of its own.

it heads to the surface.

So does the octopus.

♪♪ He makes a grab!

♪♪ The crab is firmly in his grasp, but he must eat quickly.

He's being watched.

A rival coconut octopus.

His color change shows he means business.

♪♪ To up the ante, he makes himself bigger.

♪♪ But the octopus stands his ground... before firing a salvo of shells.

He retreats to his fortified home... ♪♪ ...and grabs a discarded paint lid to act as a shield.

♪♪ He's now ready for anything... ...including taking the paint lid with him.

♪♪ ♪♪ One last challenge... ...but soon seen off.

That's how he treats his enemies.

♪♪ This is how he treats his friends.

♪♪ ♪♪ Few are as clever, but for organizational skills, he has some serious competition.

In the tropical paradise of Belize, the hermit crabs have a problem.

They've outgrown their homes... ...or their shells have become worse for wear.

They need to upsize their accommodation.

And a new home has just come on the market.

Those interested start measuring up.

This one certainly has potential.

But others, too, are showing interest... ...even squabbling over who should move in.

For some, it's too big.

For others, it's too small.

To resolve the issue, they must stop squabbling and cooperate.

To find out how, another spy goes undercover... [ Soft whirring ] ...one with a camera in its shell.

It's arrived at the perfect moment.

The crabs line up in order of size.

They don't all need grand accommodation.

They just need the next size up.

First, they must find their correct place in the queue.

They wait until everyone is assembled.

Then the house swap begins.

♪♪ The largest leaves his old home and moves into the vacant shell next door.

♪♪ Then the next size down takes over the shell he left behind.

♪♪ And so it goes on in order of size.

♪♪ ♪♪ Most are content with their new home... ♪♪ ...although one seems to have house envy.

♪♪ He's eyeing up our spy.

♪♪ He just needs to check the shell for size.

♪♪ ♪♪ It meets his requirements, so he doesn't waste time.

♪♪ But this home comes with responsibilities... ♪♪ ...ones that involve filming, too.

♪♪ ♪♪ But our new spy seems to be having second thoughts.

♪♪ His old shell was a better fit after all.

♪♪ He'll keep it for a little longer.

♪♪ Our spy is now the only crab left homeless.

[ Soft whirring ] [ Birds calling ] The Caribbean is home to yet more clever minds.

This tiny island in the Bahamas has been colonized by wild pigs.

They spend much of their day just above the tide line.

[ Pig snorting ] [ Rooster crows ] To discover how they survive on this remote island, Spy Piglet joins the team.

♪♪ Pigs are highly intelligent and sociable animals.

♪♪ So a new pig soon piques their interest.

♪♪ Nudging snouts is a friendly gesture.

♪♪ A promising start.

♪♪ Introductions over, they head to the sea.

[ Pigs snorting ] The pigs' daily ritual begins.

To find out why they enjoy swimming so much, Spy Pig is soon hot on their curly tails.

What better way to find out what's going on?

♪♪ It's clear they are expert swimmers.

♪♪ And even here they're sociable, too.

♪♪ Our spy gets another greeting.

♪♪ ♪♪ Pigs were brought to the island in the '50s, surviving on crabs and berries or whatever else they could find.

As their numbers grew, they looked to the ocean for a meal.

♪♪ Tourism brought new opportunities.

Each day, boats bringing food would visit them.

[ Engines rumbling ] Until the sound of outboards became their dinner bell.

As word got around, more boats arrived until the pigs' daily excursions became a way of life.

A banquet for all.

♪♪ They may be social creatures, but manners are forgotten when mealtime arrives.

♪♪ Now it's every pig for itself.

♪♪ And not just pigs.

♪♪ Gulls know when it's feeding time, too.

[ Gulls crying ] ♪♪ The pigs' intelligence created this tourist attraction.

But it doesn't take a genius to know when all the food is gone.

♪♪ ♪♪ The search for intelligent life is taking our spy creatures to many ocean realms.

But it's the reefs that provide shelter for a quarter of all marine life.

Amongst all this abundance is Spy Crab.

[ Soft whirring ] Beyond the reef is our spy's subject of interest.

Fish that have found a way to keep safe, away from the protection of the reef.

♪♪ Our undercover crustacean will find out how they do it.

The fish in question are saddleback clownfish.

They use carpet anemones as their fortress and home.

Its tentacles are laced with a deadly toxin.

But the clownfish have acquired immunity.

No predators dare come near.

In return, the clownfish all pitch in to keep the anemone spick and span.

But to raise a family, they need somewhere safe to lay their eggs.

A bed of poison is hardly a nursery.

So a search party sets off to find something more suitable... ...with Spy Crab following on behind.

Plastics are the scourge of the ocean, but clownfish are keen on recycling.

♪♪ A flip-flop would make an ideal egg nursery, if only they could bring it back home.

♪♪ ♪♪ Even the enterprising clownfish have no use for a plastic bottle.

They dispatch it as quickly as they can.

They need something more sustainable.

♪♪ Another job for Spy Octopus.

♪♪ ♪♪ It has an environmentally friendly solution.

♪♪ Just what they were looking for!

♪♪ In an astonishing display of teamwork, they take the coconut shell to the anemone.

Among fish, such close cooperation has rarely been filmed.

But they have more work to do.

A little wash and brush-up is needed.

Then...let egg-laying begin.

♪♪ ♪♪ A nursery, at last.

♪♪ ♪♪ The male will tend the eggs, keeping them clean and well-aerated.

♪♪ A week later, their young are ready to emerge.

The reward for the clownfishes' close cooperation... one where Spy Octopus played a part.

♪♪ As our spies discovered, sea creatures have many unique ways of thinking.

But none match the intelligence of the biggest brains of all.

Spy Sperm Whale was left on babysitting duties.

It's now keeping watch on an increasingly restless calf.

Another of its cameras reveals why he's excited.

[ Whale clicking ] Below, his mother is returning.

♪♪ She's been away for many hours, and her calf is hungry.

[ Whale clicking ] He's heard his mother's unique call.

♪♪ Spy Whale follows close behind... ♪♪ ...even into the depths.

♪♪ Here, our spy captures the moment the mother positions herself vertically to feed her calf.

♪♪ Finally, he finds the spot.

♪♪ Only now does his mother release her milk.

♪♪ Instead of suckling, the calf drinks the milk as it flows into the water.

[ Whale clicking ] It's so rich, even diluted, he only needs a little to be satisfied.

♪♪ Then his mother does something surprising.

She positions herself upside down... and claps the water with her tail.

[ Rumble ] Each slap is a signal that carries for miles... [ Rumble ] ...one heard by families far and wide.

[ Rumble ] [ Whales clicking ] ♪♪ [ Rumble ] ♪♪ [ Rumble ] ♪♪ For the mother and calf, it's a special moment.

♪♪ ♪♪ A family reunion that has rarely been filmed.

♪♪ One that includes our very own spy.

♪♪ From deep in the heart of the family, it now bears witness to something extraordinary.

♪♪ Siblings, cousins, aunts, and grandmothers join together in a remarkable social event.

A meeting of intelligent minds.

♪♪ But are their thoughts ones we might recognize?

For they share the brain cells that help make us human -- specialized neurons that give us language, empathy, and culture.

They have more of these human-like cells than any animal on Earth.

It seems they are deep in conversation.

Within this incredible gathering, information is exchanged and bonds of friendship are strengthened.

♪♪ This rare event lasts only a few minutes before each group goes its separate ways.

♪♪ But for now, our spy is still deep in their midst.

♪♪ ♪♪ Next time, our spies reveal the deep feelings found among the creatures of the ocean... to discover the origins of our own emotions.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ To learn more about what you've seen on this "Nature" program, visit pbs.org.

♪♪