Original subtitles

NARRATOR: Imagine an alien that can float through space

with a giant brain shaped like a doughnut,

eight arms growing out of its head,

and three hearts pumping blue blood.

This alien lives right here on earth.

It's called the cuttlefish...

...a flesh-eating predator who's a master of illusion,

changing its shape and color at will.

It can hypnotize its prey...

or even become invisible.

MARK NORMAN: They've developed this skin

that can do the amazing changes in color and changes in shape,

and you couldn't get a weirder-looking animal.

ROGER HANLON: Every place they go, they are morphing into something

that looks a lot like that environment.

NARRATOR: How does an animal that's related to a slug

manage such clever tricks?

NORMAN: You get a sense there's a hell of a lot

going on in those brains, but we're struggling

to kind of understand how they work.

NARRATOR: NOVA dives into a stunning and bizarre world,

as researchers probe the surprising brainpower...

Three, two, one...

NARRATOR: ...and explore the conjuring magic

of one of the strangest creatures alive today.

JESSE PURDY: We are testing an animal that's very alien.

It's as close, perhaps, as we're going to get

to studying an animal on another planet.

NARRATOR: "Kings of Camouflage," right now on NOVA.

Major funding for NOVA is provided by the following:

Supporting NOVA and promoting public understanding of science.

And by the Corporation for Public Broadcasting

and by contributions to your PBS station from:

NARRATOR: Dive into the oceans off Europe or Australia

and you might encounter a strange and elusive animal.

This is nature's greatest master of disguise...

the cuttlefish.

Its visual wizardry and clever behavior

have fascinated and mystified scientists for years.

NORMAN: When you come across your first cuttlefish,

they are the most amazing creatures.

They're either a pair of eyes staring out of a bush of seaweed

or they're these sort of small, alien spaceship,

and you couldn't get a weirder looking animal underwater.

NARRATOR: Captivated by these bizarre creatures

is marine biologist Mark Norman,

based at the Museum Victoria in southern Australia.

NORMAN: The thing that fascinates me about cuttlefish is

that they are so different from what's familiar to us.

And when you dive with them and see all the things

they're capable of, you just can't help being drawn to them.

NARRATOR: Cuttlefish have been performing their own brand of magic

for millions of years in oceans around the world,

though not in the Americas.

Technically, cuttlefish aren't fish at all,

but mollusks-- soft-bodied animals without a spine--

a group that includes snails and clams.

But these animals have no outer shell.

They're a kind of cephalopod,

along with their more famous cousins, octopus and squid.

Cuttlefish might be lesser known,

but they're no less talented.

In the blink of an eye,

their skin can change color, pattern, even shape.

NORMAN: They've developed this skin that can do

the amazing changes in color and changes in shape.

And what fascinates me the most

is how different cuttlefish species

have taken that basic tool that probably evolved for camouflage

and they've taken it a step further and said,

"All right, how can we use this in other ways?"

NARRATOR: So what else are these peculiar animals capable of?

There are over 100 different species of cuttlefish.

One of the strangest lives in the waters of Indonesia,

and Mark Norman has come here to try and track it down.

NORMAN: Very nice place.

What is the diving like?

NARRATOR: With the help of local guide Ronald Sarante,

Mark will search the reefs

for the elusive Broadclub cuttlefish,

a shape-shifter with some particularly weird habits.

Okay, are you ready, Mark?

Yep, after you.

NORMAN: The first problem when you come to these sorts of tropical areas

is just even finding an animal.

You swim over huge areas of reef,

and you're probably swimming over lots of animals,

but you have no idea they're there

because they're excellent at camouflage.

NARRATOR: Cuttlefish often have favorite stomping grounds,

and it's Ronald's local expertise

which brings Mark face-to-face

with his first Broadclub cuttlefish.

NORMAN: When you first approach cuttlefish,

within sort of ten or 15 minutes,

you can get fairly close to them.

They're checking out you as much as you're checking them out.

And that's the most exciting time to sit and watch

their behaviors, because after a while they get used to you,

and they will allow you to accompany them

while they go off to catch food.

And these guys have developed the most amazing way to do it.

NARRATOR: Cuttlefish are often hungry and on the lookout

for a tasty treat.

Sneaking up in coral camouflage is one hunting trick.

But if this fails, the Broadclub cuttlefish gives up all attempts

at being inconspicuous...

and instead pulls out all the stops,

with a dazzling show that seems

to stun its prey and leaves it helpless.

How can an animal turn itself into something as flashy

as a Las Vegas marquee?

Halfway around the world, at the Marine Biological Laboratory

in Woods Hole, Massachusetts,

Roger Hanlon is trying to deconstruct

the cuttlefish's visual pyrotechnics.

Checkers, anyone?

HANLON: They got white and dark...

NARRATOR: Roger's cuttlefish work hard to blend in,

even to the most unnatural environments,

thanks to their versatile skin.

There's no skin on earth like a cuttlefish.

These animals can change instantaneously.

The diversity is fantastic.

Chameleons are boring by comparison.

NARRATOR: So how does cuttlefish skin work its magic?

HANLON: Their skin is extraordinary,

because it has two ways to produce color and pattern.

NARRATOR: The secret lies in specialized layers of skin cells.

HANLON: The top layer

are the pigmented cells that give you most of the patterning,

and they are layered.

They have a yellow, a red and a brown.

One little pigment cell is

this little ball of color,

all tightly bound up so you don't see it,

and it has muscles attached to it,

and the muscles can pull that pigment sac out

into a little disc of color.

And then when the muscles let go, it just-- boink--

goes right back in and you don't see anything.

And so it's a very simple mechanism.

NARRATOR: Next, there's a deeper layer of iridescent reflecting cells

that produce blue and green, along with red and pink.

Add a white base, and the cuttlefish palette is complete.

HANLON: There is no limit to the colors they can show in their skin.

It's really marvelous.

NARRATOR: Along with color and pattern,

the skin can change its texture, too,

pushing up bumps along its surface.

HANLON: Well, this enables you to fool any visual predator there is.

It's much better than the Harry Potter invisible cloak.

There is no comparison.

This is real camouflage.

They're doing it the real way.

NARRATOR: To match their surroundings,

cuttlefish rely on their eyesight.

As strange as it may appear to us,

their W-shaped pupils provide excellent vision.

HANLON: So here you have this magnificent eye.

This eye can see things very, very well.

NARRATOR: Visual cues go straight to the brain,

and the brain, in turn, sends instructions

right to the skin cells.

HANLON: It's the fastest possible way, direct control by a nerve.

And so we call this "electric skin,"

because as soon as the information gets to the brain,

the information is taken out of the brain,

goes to the skin, and says, "Do this."

And it's just boom, boom, boom, boom, you know?

It's really quick.

NARRATOR: The cuttlefish's electric skin usually works for self-defense--

to make it disappear into the background--

but clearly, the Broadclub found a new use

for its changeability.

HANLON: My guess is that

their skin evolved for camouflage,

because as soon as they got rid of the big shell,

they had to hide from predators.

I think after that, the skin then evolved these patterns

for communication, for mating and courtship,

and in some cases, even for tricking shrimps and fishes

that they're going to eat.

NARRATOR: Back in Indonesia, Mark Norman wants to know

exactly what triggers the Broadclub

to turn itself into the ultimate exhibitionist.

NORMAN: I'm very interested in this strange feeding behavior,

and so to try and understand what's going on,

we need to get them to do this behavior on cue,

whenever we want it to happen.

By handing them live prey or decoys,

they start doing the behavior.

You can start analyzing what is it that sets them off,

when it works best.

NARRATOR: Mark's first offering of small crabs,

their favorite food, is welcome.

But it doesn't trigger too many light switches.

Next step:

offer a bigger lure, like a toy lobster.

Will this do the trick?

The lobster proves irresistible,

for as long as it looks alive.

Once it stops moving,

the Broadclub seems to lose its motivation.

When Mark brings the lure back to life,

the performance promptly resumes.

But not for very long.

This cuttlefish is getting bored with toys

and is ready for the real thing.

Cuttlefish like their meals alive.

So does the size of a potential meal trigger these light shows?

NORMAN: Well, it seems that for smaller prey or once they're well fed,

that they almost don't bother doing it.

But with the bigger lures and the bigger crabs,

the cuttlefish do a really good,

detailed display to sort of, um, stun or to dazzle the prey

long enough to slow them down.

And then the cuttlefish could come in and nail them

in the way it wanted to.

In the case of the crabs,

the cuttlefish wanted to grab it from behind,

so those big, dangerous claws

are out of the way of the attacker.

NARRATOR: It's all about positioning.

If you don't want to lose one of your arms,

you've got to get just the right grip on your prey.

With his next offering,

Mark gets an even better view of the show.

NORMAN: The most interesting is when you offer a Broadclub cuttlefish

a live animal in a glass jar.

It gives you a perspective where you can move the jar around

and see what it looks like from the prey's point of view.

It looks like they're sort of

effectively hypnotizing their prey.

It's fantastic.

They get very excited, come in and nail the glass,

get confused the water is solid

and they can't get through the water, and they continually try

and get in at different angles on these glass containers.

NARRATOR: Every cuttlefish starts off

with the same hungry determination,

but Mark can't fool them for long.

NORMAN: They learn really quickly.

It only takes a few strikes before they realize

they're not getting the crab, it's a total waste of time.

You can sort of see them mentally turn off

and sort of drift away.

You get a sense there's a hell of a lot going on

in those brains, but we're struggling

to kind of understand how they work.

NARRATOR: As alien as they seem,

cuttlefish do share something with us...

big brains.

While humans have one of the biggest

brain-to-body ratios among mammals,

cuttlefish and octopus top the list for all invertebrates.

Their large brains most likely evolved hand in hand

with their complicated and changeable skin.

HANLON: There are up to 20 million

of these pigment cells in the skin,

and to control 20 million of anything is going

to take a lot of processing power.

And it has to have a large brain to make all this work.

NARRATOR: But does a big brain necessarily mean cuttlefish are intelligent?

Looking for answers is Jesse Purdy,

a comparative psychologist

at Southwestern University in Texas.

PURDY: Can we know more about ourselves

by studying another animal?

And as a comparative psychologist, I think we can.

By understanding their world a little bit

can give us more insight into our world.

NARRATOR: But how do you measure an animal's brainpower?

PURDY: The work with cuttlefish is at a very early stage.

Not a lot of people have done learning experiments

with cuttlefish.

So we need to start at a very basic stage

and then move up the ladder.

(motor clicking)

NARRATOR: Here at Southwestern,

cuttlefish are being tested

for the most basic levels of learning.

For example,

if you put a windup plastic fish into a cuttlefish tank,

at first it mistakes it for food,

but once it realizes how unappetizing the toy is,

from then on, the cuttlefish will ignore it.

But can you teach the cuttlefish

that the toy has a different meaning?

PURDY: The experiment that we do

with Troy the toy fish is actually asking that question.

Okay, here we go. You ready?

I'm ready. All right, Shannon...

PURDY: The experiment as you see it looks very simple.

You see somebody simply drop a toy fish in

and then a little bit later drop a fish in.

NARRATOR: One question is,

whether or not cuttlefish can learn

to associate the toy fish with the promise of food.

Sure enough,

if Troy the toy is consistently joined by a real fish,

then the cuttlefish will pay close attention to him.

But with a separate test group,

Troy swims alone and no meal appears.

So for those cuttlefish,

Troy will hold absolutely no interest.

So we're seeing a difference between these two groups.

And the difference is learning.

Hydrophone, check.

Okay, guys, we're ready to go here.

NARRATOR: The next step is to see if the animal can learn to do something

in order to get fed--

like pressing a button on a vending machine,

or in their world, hitting a jar to receive a reward.

PURDY: There's an orienting response.

NARRATOR: Sound familiar?

(tape rewinding)

Remember when the Broadclub cuttlefish was shown crabs

in a jar?

After a few frustrated jabs, it quickly lost interest.

But in this test,

some cuttlefish are rewarded from an automated feeder.

Strike the jar, get a snack.

These cuttlefish quickly learn this trick

and will keep hitting the jar.

Cuttlefish easily master the most basic learning skills.

So researchers need to come up with more difficult challenges

if they want to really measure their brainpower.

PURDY: Are cuttlefish intelligent?

I'm absolutely convinced that they are.

So, where do we go from here?

Is it the level of cognitive complexity

that we think these animals are capable of?

Have we seen how smart they are at this point?

And I don't believe we have.

NARRATOR: For any creature,

when it comes to intelligence, what matters most is

how it helps you survive in the real world,

so you can pass on your genes to a new generation.

And there's one place where the wiliest cuttlefish

play their most elaborate tricks.

(birds cawing)

It's late May in southern Australia.

Life on shore is just settling down for the winter.

But beneath the waves, things are heating up.

It's the mating season

for the Australian Giant cuttlefish,

and thousands of them are swimming

into the spawning grounds.

NORMAN: Giant cuttlefish coming together

to breed is the most dazzling shows that they can do

in these color and shape changes.

And it's spectacular when you see them

just come to life in these big displays.

It's sort of like they rip off their Clark Kent outfit

and out comes Superman, or Supercuttlefish.

NARRATOR: Giant cuttlefish can grow over three feet long.

Eye to eye, the big males try to outdo each other

with the most intimidating body patterns.

The smaller females seem unimpressed.

NORMAN: It's usually a very secretive behavior

in lots of other animals, including other cuttlefishes,

and you're lucky to even come across breeding aggregations.

But to see thousands of them here is just spectacular.

And so for several months

they give up the pretense of looking like seaweed

or hiding in amongst the sand

or the mud, and they go, "Bugger it!

"We're just gonna look fantastic, and we're gonna fight

with each other and we're gonna impress females."

And they totally ignore us.

We can sit in amongst them, they can almost sit on our head,

and that's when the best displays come out.

NARRATOR: During mating,

males outnumber the females,

sometimes ten to one.

And they're all looking

for the chance to pass on their genes.

While a female lays eggs beneath a rock,

a big male tries to monopolize her,

staving off the other hopeful suitors.

Sometimes intimidation alone won't work,

and the competitors hurl themselves

into a violent and bizarre-looking wrestling match.

Like an octopus, they'll squirt out

an inky smoke screen when it's time for a hasty retreat.

But size and strength aren't the only ways to impress the ladies.

Thanks to the cuttlefish's skin-morphing talents,

the smaller males have a clever trick up their sleeve.

NORMAN: The really interesting thing in this system

is actually far less obvious.

And when you first dive with them, you don't see it.

It takes a while before you realize what's going on.

The small males, who have no chance

in a contest with a big male,

are actually doing something completely different.

They're effectively cross-dressing.

They're dressing up as a female by pulling in their webs

and putting on this mottled color pattern...

and gliding past these big, aggressive males,

pretending to be a female,

and will come in to the female underneath.

NORMAN: And what happens is, as another big male comes in

and a potential conflict between these big guys starts up,

the sneaker male will start mating with her--

successfully mate with the female--

while the big guy isn't even aware of it.

NARRATOR: The cross-dressers' success is all the more impressive

because the females often play hard-to-get,

as Roger Hanlon has seen firsthand.

HANLON: These females are very picky.

They reject 70% of approaches for mating.

Yet they only reject

30% of the cross-dressing males.

So this trick gets them in the door,

so to speak, past the fighting male.

And they're accepted by the female.

NARRATOR: The little guy may have crossed one hurdle,

but a female's welcoming embrace alone

won't guarantee reproductive success.

HANLON: Mating in a cuttlefish is a strange affair.

They go head-to-head, we call it.

Then they join

those eight arms together from each animal.

Then the male has one special arm underneath,

in which he reaches back and he pulls out a packet of sperm.

And then he just places that packet of sperm

right up amidst the arms of the female.

NARRATOR: It's the male's job to hand over the sperm.

But once he does, fertilization is up to the female.

She's already mated with multiple partners

and is storing their sperm in pouches under her arms.

HANLON: So now this female choosing, this takes on a new dimension.

She not only chooses mates during the day,

but she has some choice and some influence

over which sperm get used.

And guess what?

The male can do nothing about that.

NARRATOR: So whose sperm wins out in the end?

There's only one way to find out.

We actually do paternity testing,

just like humans do in a court of law.

And we use the same technique, and it's very precise.

NARRATOR: Roger was part of a team that extracted DNA samples

from all the participants-- the mother, her partners

and the babies-- to find out

who's the daddy.

HANLON: One of the biggest surprises is that

the cross-dressing males

got the very next fertilization.

And we did not expect this at all.

The only reason we can think of

is that this is a very bold, smart tactic,

and the females may be acknowledging that

in sort of evolutionary terms.

So this trick, as strange as it seems,

is very successful.

NARRATOR: Over the course of a couple of weeks,

each female will lay hundreds of eggs,

sired by many fathers,

filling up the crevices on the undersides of rocks.

The eggs will remain there for three to five months,

until the babies are ready to hatch.

But the newborns will be orphans.

The mating season marks the end

of the Giant cuttlefish's life cycle,

and the parents won't survive

to see the birth of the next generation.

NORMAN: It looks like cuttlefish only have one mating season.

It can last for up to six or eight weeks,

but it's only the one session, and then they all die.

So, some burn bright and die young,

some live slightly longer and die,

but all of them don't live very long.

So it's probably only 18 months to two years old

is how long they live.

NARRATOR: With such a short life span, it's even more surprising

how smart these creatures seem to be.

Intelligence is all about

learning to adapt to new situations.

Here at Millersville University in Pennsylvania,

Jean Boal wants to figure out just how much--

and how fast-- cuttlefish can learn.

BOAL: I think cuttlefish are remarkably intelligent animals.

So the issue is: am I smart enough

to find out how smart they are?

NARRATOR: For nearly 20 years, Jean has been running tests

with cuttlefish and their more famous cousin, the octopus.

BOAL: I began with octopuses

because there are no cuttlefish in the Americas,

so like most Americans, I'd never heard of them.

Octopuses love to destroy lab equipment.

(chuckles)

If they can possibly rip something apart, they will.

And in terms of their performance in experiments,

octopuses are unbelievably erratic.

One day, they'll be brilliant, and the next five days,

they'll act like they don't know anything at all.

Hey, everybody.

How are you today? Huh?

Once I got started working with cuttlefish,

they're very practical animals to work with.

They're very easy, and they're very engaging.

And then on top of that,

it looks like their brain size relative to body size

is perhaps even larger than octopuses.

And it would be really wonderful if we could just figure out

what they're doing with all that brain.

NARRATOR: To test her cuttlefish, Jean has created a special enclosure,

fashioned from a plastic trash barrel,

which the animals must try to escape from.

BOAL: The real difficulty for me is to find out how to ask them

so that they can tell me what they know.

They're certainly not going to tell me verbally,

so I have to design a clever enough experiment

that their behavior can tell me what they know.

And that's what's really challenging and really,

in many ways, exciting.

STUDENT: She's up next?

All right, come on, sweetie.

Oh, come on...

NARRATOR: 13 research subjects, with names like Bubbles, Goofy and Crook,

are tested three times a day over several months.

All right, who have we got?

We got Crook.

Okay. What time is it?

NARRATOR: Their job is to negotiate a simple maze

and to find their way out as quickly as possible.

BOAL: The cuttlefish maze has a starting tube

where they go in and just calm down

for a few seconds.

In she goes. She's in.

Three, two, one.

BOAL: Door's open.

And then, there's a larger arena,

and they have to decide whether to go right or left.

And there are features in there to help them distinguish that.

NARRATOR: In each trial, only one of the two exit doors is open.

The cuttlefish has to look for clues to pick the right one.

If there's a piece of plastic seaweed in the enclosure,

then the striped door will lead to freedom.

But if the cuttlefish

enters the maze and sees a big brick instead,

then the solid door is the way to go.

If the cuttlefish picks the wrong door,

she'll be blocked by clear plastic.

All right, this is Tad.

NARRATOR: So can a cuttlefish learn these rules?

BOAL: In you go.

The current problem that I'm working on

is "conditional discrimination learning."

Three, two, one. Can you remember the two things at once?

Open. She's in.

STUDENT: Starting.

BOAL: And we have good evidence

that the cuttlefish can do this,

which is truly extraordinary for an invertebrate animal.

There she goes.

She is out!

Great time.

NARRATOR: The cuttlefish are able to recognize and remember

at least two rules, or conditions,

for finding the open exit.

That's a level of intelligence much more common

among creatures that possess a backbone.

So what's really exciting about cuttlefish intelligence is,

we know that their relatives are clams and snails.

Those are not animals that had a need for great intelligence.

So whatever happened to cuttlefish was different.

HANLON: I think one of the reasons

they have to be so smart is, they've given up

their external body armor like a snail has.

They're soft, they're vulnerable,

they can be eaten.

Everything in the ocean eats cuttlefish.

So these animals have to get by

by their wits, so to speak.

They have to be smart.

I think it's safe to say

that cuttlefish are definitely as smart as fish.

And, in fact, they're as smart as maybe even some animals

like... birds and mammals

and other things we consider to be smarter animals.

NARRATOR: The cuttlefish's big brain,

together with its amazing camouflage,

probably evolved so they could survive

in dangerous environments filled with hungry fishes.

But one cuttlefish might have acquired another secret weapon.

Back in the tropics,

Mark Norman and Ronald Sarante are searching

for Mark's favorite cuttlefish, who has managed to thrive

in a unique and threatening landscape.

NORMAN: These muck dives on sand and mud areas

are very different.

They feel very solemn and dark and moody.

You have these black plains going everywhere.

The few animals you do pass

are either covered in poisonous spines

or pretending to be dead leaves.

You get this feeling

that it's just oppressed by predators.

NARRATOR: This is a place of the weird and the wonderful,

where standing out or blending in

all depends on whether you are predator or prey.

It's one of the few places you'll find

the rare mimic octopus.

But the strangest of them all is a creature called

the Flamboyant cuttlefish.

For a start, it's walking,

not swimming.

NORMAN: It's still really foreign for me

to watch a cuttlefish walking around on the sea floor.

They actually look like

these prehistoric lumbering monsters

sort of walking through these ancient black deserts.

NARRATOR: This enigmatic animal

has made a huge impression on Mark,

despite the fact it's only a couple of inches long.

Although the Flamboyant cuttlefish

walks most of the time, it can swim,

but just barely.

What's wrong?

Cuttlefish get their name from their cuttlebone,

a chalky internal shell filled with gas

that allows them to float.

But the tiny Flamboyant's cuttlebone has shrunk so much,

it can't float for very long.

NORMAN: They seem to have a really gentle nature.

They flap up into the water, they settle down again,

and they go back to walking

along the sea floor, back into camouflage,

back into feeding almost straightaway,

looking for something to eat out on the mud.

NARRATOR: Like its big brothers, this cuttlefish

has to grow fast, and is often on the hunt.

But to catch a tiny glass shrimp

takes very good eyesight...

and patience.

Stalking its meal in spiky disguise,

it aims its feeding tentacles like a pool player,

ready to hit the target.

(quiet crunching)

(crunching)

Eat and be eaten.

For every creature, there's a hunter lurking.

These open plains don't offer much cover,

and to be out and about in broad daylight is risky--

especially if you're neither fast nor big.

Predators are a constant threat,

and this is when the Flamboyant cuttlefish

earns its name.

Whenever it feels threatened, it puts on an alarming display.

NORMAN: When something comes too close,

they'll flare up the arms and they walk around

flashing these colors and advertising

these really bright color patterns.

And I think this is advertising the fact

that they're poisonous to eat.

If anybody gets too close,

even, like, a diver,

they show all the bright colors and it says:

"Back off. I'm poisonous."

It's either pretending it's deadly as hell

and trying to mimic something else that is dangerous,

or it's walking around confident that it, itself, is deadly.

NARRATOR: Clearly, the Flamboyant stands out

from the rest of the cuttle pack.

But is it just a big bluff

or the real thing?

Is it poisonous or not?

To find out, Mark and Ronald need to look

for a full-grown animal,

and freshly laid eggs are a good sign

that a mature female has passed through recently.

Hidden under coconut shells, they find some Flamboyant eggs.

The mother should be nearby.

In this bleak landscape,

it's a challenge for a Flamboyant mother

to find a safe spot for her eggs.

Without rocks or caves,

old shells are the next best thing.

Compared to the egg-laying frenzy of her Giant cousins,

hers is a quiet affair.

She lays up to a hundred eggs, a truly exhausting task.

And with the laying done, she'll soon die naturally.

But there's one more important mission she can help with:

assisting Mark with his toxin studies.

NORMAN: If this animal does turn out to be deadly, to be toxic,

it will be the first cuttlefish in the world

that's known to be poisonous.

We could be seeing a whole change

in the evolution of these animals.

I'm really fascinated in what it is about them that's poisonous.

Do they have a poisonous bite? Is all their flesh poisonous?

Can they squirt poisonous ink?

NARRATOR: Mark will have to take her back

to the venom labs in Australia

to unravel her potentially deadly secret.

The winter storms have finally passed,

and the deserted mating grounds

of the Australian Giant cuttlefish

slowly begin to warm.

The parents died more than three months ago,

but the next generation of Giants

is just getting started.

Sheltered in their rocky nurseries,

the eggs enclose pin-sized embryos.

Sucking up energy from the yolk,

they've grown eight arms, red-dot eyes,

and their family trait-- the cuttlebone.

In the final month,

the embryos' eyes fully develop and, still hanging upside down,

they start moving around.

By now, the egg's soft shell

has stretched to double its size,

and the bodies have outgrown the yolk ball.

Once they start floating upright,

the little Giants prepare for the outside world.

All their organs are now developed, and they can already

change the color and shape of their skin.

After about four months,

they squirt a special acid from the tip of their tail

to burn a hatching hole through the rubbery shell.

Barely the size of a fingernail,

the tiny Giants emerge like miniature adults,

with suckers, ink and all.

Nobody knows how many will survive.

In a few days, they'll start hunting tiny shrimp,

and perfect their shape-shifting repertoire.

But they've got to watch out.

They are on the menu for almost anything with a fin.

Sharks, big fish, seals-? they all love cuttlefish.

Their meaty bodies without spines or armor

make cuttlefish a protein-rich meal.

Camouflage is the cuttlefish's main defense.

While they're invisible, they're safe.

But once the cover is blown,

their only chance is to disappear behind an inky cloud.

Dolphins have developed a special taste for cuttlefish.

But rather than gorging on the whole body,

they prefer to just pick off their soft arms and heads.

Leaving behind tattered bodies,

they provide a free meal for many more creatures.

But cuttlefish don't just end up on ocean dwellers' menus.

In many countries, humans are one of cuttlefish's

most voracious predators.

Cuttlefish, octopus and squid are eaten around the globe,

harvested on a large scale.

The total reported world catch

is more than three million tons per year,

worth more than $6 billion.

Our taste for all things calamari overwhelms

even their best camouflage.

But is there one cuttlefish no one should ever eat?

Back at Australia's Institute for Molecular Bioscience

in Queensland, Mark Norman is about to find out

if the colorful Flamboyant cuttlefish is truly poisonous

or just a poseur.

That's worth looking at.

NORMAN: Toxicity is really rare in these sorts

of animals.

There's thousands of species of octopus,

squid and cuttlefish and, in all the world,

there's only Blue-Ringed octopuses,

and, just recently, the little Striped Pajama squid,

are the only ones that are known to be... to be poisonous,

to be very deadly.

And so, trying to understand

the behavior of this strange little cuttlefish,

I think it's really important that we find out

whether it's pretending to be something else that's dangerous

or it, itself, is dangerous.

NARRATOR: Toxins could be anywhere,

from the skin to the inner organs.

If the Flamboyant's bite is toxic, its saliva will

contain the poison, just as in the Blue-Ringed octopus.

But it could also be mixed in with its ink.

Mark needs to analyze all body parts.

And the results?

NORMAN: Well, it turns out the Flamboyant cuttlefish is toxic.

It's... it's as toxic as Blue-Ringed octopuses,

and Blue-Ringed octopuses have killed humans from their bites.

So we've got the first deadly cuttlefish in the world,

and it's amazing on a couple of levels.

First of all, it's actually poisonous flesh--

the muscles themselves are poisonous.

So this is the first time that flesh that is deadly

has been reported in any of these groups of animals.

And secondly, the toxin itself is not known.

It's some completely different class of toxins.

And toxins like those could be the key

to whole new discoveries

for lots of human medical conditions.

NARRATOR: But beyond any potential medical use,

the toxin is exciting to Mark

because it helps explain the Flamboyant cuttlefish's

oversized confidence.

NORMAN: This is a fantastic result

because it makes sense of what we're seeing in the wild.

And this toxicity, this poisonousness,

is probably what's underpinning

the whole weird behavior of the animal.

And the fact that a group of animals

that normally swim around,

or spend a lot of time trying to be camouflaged,

have become so obvious, have given up swimming,

are walking everywhere...

it's like a major step towards a whole new line

in the evolution of these animals.

NARRATOR: Evolution means change.

So, maybe in a few million years,

the Flamboyant will march on eight legs

right onto the beaches.

Or the Broadclub will hypnotize its predators

as well as its prey.

Perhaps the Australian Giants

will invent even more daring strategies

to outwit their rivals.

Cuttlefish are amazing and perplexing creatures,

and we're still trying to understand

how all this talent evolved.

PURDY: We are testing an animal that's very alien.

I mean, it's as close, perhaps, as we're going to get

to studying an animal on another planet.

And is that exciting?

That's very exciting.

HANLON: We do not know how smart or clever a cuttlefish is,

because every time we go and do a serious bit of field work

or a lab experiment, we continue to learn new things

about their capabilities

for learning or memory or hiding.

So I think we have much more to learn.

NORMAN: I hope, in my 80s and 90s,

I'm still wandering around underwater

with a walking frame following these things around,

because it'll take a hundred lifetimes

to get a handle on these animals.

NARRATOR: Cuttlefish continue to dazzle with their outward displays.

But exactly what goes on inside their heads

will remain, for now, the real mystery.

This NOVA program is available on DVD at shopPBS.org,

or call 1-800-play-PBS.