All language subtitles for 5 Secrets.Of.Skin

♪♪

Garrod: SKIN.

WE ALL HAVE IT.

AND SO DOES EVERY VERTEBRATE
ON THE PLANET.

IT KEEPS THE OUTSIDE OUT...

AND THE INSIDE IN.

ANIMALS MAY LOOK VERY DIFFERENT
ON THE SURFACE,

BUT WE ALL SHARE
THE SAME BASIC SKIN BLUEPRINT.

I'M BEN GARROD, PROFESSOR
OF EVOLUTIONARY BIOLOGY,

AND I'M FASCINATED

BY THIS OFTEN-OVERLOOKED
WONDER OF NATURE.

IT'S NOT JUST A CASE
THAT IT'S HAIRLESS.

THE SKIN'S
TOTALLY DIFFERENT.

NOW GROUNDBREAKING
NEW SCIENCE...

THIS IS REALLY
QUITE REMARKABLE.

IT SHOULD BE A GAME-CHANGER
FOR SO MANY PEOPLE.

[ RATTLING ]THAT SOUND -- OH, IT MAKES

THE HAIR ON THE BACK
OF YOUR NECK GO UP, DOESN'T IT?

...IS REVEALING
SKIN'S MYSTERIES.

IT REALLY TRANSFORMS
OUR UNDERSTANDING OF DINOSAURS.

I'M GOING TO EXPLORE
THE NATURAL HISTORY

OF THE BODY'S LARGEST ORGAN

TO SEE HOW SKIN
HAS ALLOWED ANIMALS

TO CONQUER EVERY HABITAT,

DISAPPEAR INTO
THEIR SURROUNDINGS,

AND DEVELOP
EXTRA-SENSORY ABILITIES.

WE'RE EVEN DISCOVERING
THE COMPLEX ECOSYSTEM

LIVING ON OUR SKIN.

JIM, THAT'S AWFUL.

IT REALLY IS.

IN THIS EPISODE,
I'LL LEARN WHY RHINOS

HAVE THE MOST HEAVILY-ARMORED
SKIN OF ANY LIVING MAMMAL...

[ RHINO GROWLS ]

...WHY THE SMALLEST
PORCUPINE QUILLS

ARE OFTEN THE MOST DANGEROUS...

♪♪

...AND DISCOVER WHY CUTTLEFISH
CAMOUFLAGE IS TRANSFORMING

THE WAY SCIENTISTS
THINK ABOUT SKIN...

♪♪

...TO DELVE INTO
THE INGENIOUS WAYS

SKIN DEFENDS ANIMALS
FROM PHYSICAL ATTACKS.

♪♪

I'M GOING TO REVEAL
THE SECRETS OF SKIN.

--Captions by VITAC--
www.vitac.com

CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS

THIS IS A MEMBER OF ONE
OF THE MOST TOXIC GROUPS

OF ANIMALS ON THE PLANET.

♪♪

SHE'S A YELLOW-BANDED
POISON DART FROG.

THESE TINY FROGS SECRETE
A VERY POTENT POISON

THROUGH THEIR SKIN.

DIRECT CONTACT WITH SOME SPECIES

CAN CAUSE NAUSEA, PARALYSIS...

AND EVEN DEATH.

♪♪

THERE ARE ALMOST 200 KNOWN
SPECIES OF POISON DART FROG

IN THE FORESTS OF CENTRAL
AND SOUTH AMERICA.

EACH ONE COMBINES TOXIC SKIN
WITH VIVID COLORS,

AND THE MORE TOXIC A SPECIES,

THE BRIGHTER COLORS
IT HAS EVOLVED.

A SINGLE GOLDEN POISON DART FROG

HAS ENOUGH POISON IN ITS SKIN
TO KILL 10 PEOPLE,

MAKING IT
THE MOST TOXIC ANIMAL ALIVE.

THESE BRIGHT COLORS ARE
A STARK WARNING FOR PREDATORS

TO BACK OFF.

BUT IF A HUNGRY BIRD DOES DECIDE
TO IGNORE THIS WARNING

AND TAKES A NIBBLE,

THEN IT WON'T BE
MAKING THAT MISTAKE AGAIN.

EACH FROG SPECIES DEPLOYS
A DIFFERENT RANGE OF TOXINS,

BUT THEY ALL BELONG TO A GROUP
OF CHEMICALS CALLED ALKALOIDS.

THE FROGS DON'T MAKE
THESE TOXINS FROM SCRATCH.

THEY'RE DERIVED FROM DEFENSIVE
CHEMICALS IN THE ANTS, BEETLES,

AND MILLIPEDES THEY EAT.

THE TOXINS ARE STORED IN GLANDS
IN THE DERMIS

AND RELEASED ONTO
THE SURFACE VIA PORES.

POISON DART FROGS
ARE ACTIVE DURING THE DAY

WHEN PREDATORS CAN SPOT THEIR
WARNING COLORS AND AVOID THEM.

MOST OTHER FROG SPECIES
TEND TO COME OUT AT NIGHT.

THESE FROGS GOT THEIR NAME
BECAUSE THEIR TOXINS WERE ONCE

USED BY FOREST HUNTERS
TO TIP THEIR DARTS.

TODAY, WE'RE FINDING
OTHER USES FOR THEM.

NOW SCIENTISTS ARE STUDYING
THE DEADLY CHEMICALS

THESE FROGS DEPLOY

IN ORDER TO DESIGN NEW
PAINKILLING DRUGS AND MEDICINES.

ONE TOXIN, EPIBATIDINE,
ATTACKS NERVES,

CAUSING NUMBNESS AND PARALYSIS.

RESEARCHERS HOPE

THAT BY UNPICKING EPIBATIDINE'S
STRUCTURE AND CHEMISTRY,

THEY MAY BE ABLE TO SEPARATE ITS
BENEFICIAL PAINKILLING EFFECTS

FROM ITS DEADLY TOXICITY.

RIGHT, YOU.

BACK IN YOUR TANK.

♪♪

NOW, YOU MIGHT THINK THIS IS
A VERY SILLY THING TO DO.

BUT CAPTIVE BRED DART FROGS...

AREN'T TOXIC AT ALL.

♪♪

FROGS BRED IN CAPTIVITY
ARE FED HARMLESS INSECTS

LIKE FRUIT FLIES,
WHICH MEANS THEY NEVER GO ON

TO DEVELOP
THE DANGEROUS TOXICITY

OF THEIR WILD RELATIVES.

♪♪

WHAT WE STILL DON'T
FULLY UNDERSTAND

IS HOW WILD FROGS CAN EAT
AND STORE THESE TOXIC COMPOUNDS

WITHOUT COMING TO HARM.

A POISON DART FROG'S SKIN
IS A WEAPON AND A WARNING.

THIS IS JUST THE START
OF THE EXTRAORDINARY WAYS

ANIMALS USE THEIR SKIN
TO DEFEND THEMSELVES.

ONE ANIMAL IS INFAMOUS
FOR THE WARNING SOUND IT MAKES

WITH A SPECIALIZED PART
OF ITS EPIDERMIS.

[ RATTLE]

THIS IS A RATTLESNAKE'S RATTLE.

♪♪

IT'S MADE
FROM THE FINAL FEW SCALES

THAT COVER THE TIP
OF THE SNAKE'S TAIL.

THEY FORM A SERIES OF HOLLOW

INTERLOCKING SEGMENTS
OF KERATIN.

THE SAME PROTEIN
AS MY HAIR AND NAILS.

THE SEGMENTS AREN'T FUSED
TO ONE ANOTHER.

THEY'RE FREE TO MOVE.

SO IF I GIVE THIS LITTLE
STRUCTURE A GOOD SHAKE...

[ RATTLE ]THE INTERLINKED CAPSULES

RATTLE AGAINST ONE ANOTHER.

RATTLESNAKES SHAKE THEIR RATTLES
TO PRODUCE A LOUD BUZZ.

THIS ALERTS LIVESTOCK
AND PREDATORS

THAT THERE'S A VENOMOUS
SNAKE NEARBY

THAT WANTS TO AVOID TROUBLE.

[ RATTLING ]

NOW, I CAN MANAGE...[ RATTLING ]

COUPLE OF RATTLES A SECOND.

THAT'S NOT REALLY ENOUGH
TO GRAB ANYONE'S ATTENTION.

TO SEE HOW A RATTLESNAKE
USES THE KERATIN

ON THE TIP OF ITS TAIL

AS A BRILLIANT
DEFENSE MECHANISM,

I NEED TO FIND A WAY
TO SHAKE IT MUCH FASTER.

♪♪

I'M VISITING AN ENGINEERING LAB

TO GET HELP
FROM THE REASSURINGLY TITLED

LECTURER IN NON-DESTRUCTIVE
TESTING, DR ROB HUGHES.

HEY, ROB.
WHAT HAVE WE GOT HERE?

HOW ARE WE
GOING TO TEST THIS?

SO, HERE WE HAVE
A VIBRATION STAGE.

NOW, THIS WORKS IN THE SAME WAY
THAT A STEREO SPEAKER DOES,

SO WE CAN, THEREFORE,
ESSENTIALLY

EXCITE SOMETHING UP AND DOWN
AT WHATEVER FREQUENCY WE WANT.

WE DO THAT USING THIS FUNCTION
GENERATOR HERE,

THROUGH AN AMPLIFIER,
TO THEN GET SENT TO THE SPEAKER.

USING ROB'S SETUP,
WE'LL BE ABLE TO SHAKE

THE RATTLE MUCH FASTER
THAN I COULD DO IT MYSELF.

THIS WILL ALLOW US
TO FIND THE RIGHT SPEED

TO GET THE BEST SOUND OUT
OF THESE KERATIN CAPSULES.

I THOUGHT WE'D START OUT
BY MOVING IT

AT FIVE TIMES PER SECOND.

THAT'S 5 HERTZ.

SO, IF WE SEND THE IMPULSE
SIGNAL IN AND START VIBRATING --

YOU CAN SEE THAT NOT MUCH
IS REALLY HAPPENING.

BUT WHAT WE CAN DO IS CYCLE
THROUGH THE FREQUENCIES,

INCREASING THE PITCH.

OKAY.
UM, SO...

[ TAPPING SPEEDS UP ]

SO THIS IS 10 HERTZ,
SO 10 TIMES A SECOND.

AND THEN WE'RE GOING TO RAMP UP
WITH MORE NOW.

SO WE'LL GO TO 20.[ RATTLING SLOWLY ]

OH, IT ALREADY...

STARTING TO SOUND LIKE IT....SOUNDS LIKE A RATTLESNAKE,

BUT IT DOESN'T SOUND LIKE
AN ANGRY RATTLESNAKE JUST YET.

THAT'S A SLIGHTLY
DISGRUNTLED SNAKE.

DEPENDS HOW ANGRY
YOU WANT IT TO BE.

THIS IS 30 HERTZ.

40 HERTZ.OH, IT'S GETTING THERE.

AND 50 HERTZ.

[ HUMMING, RATTLING ]

OKAY, IT LOOKS LIKE A RATTLE
FROM A RATTLESNAKE NOW,

THAT WEIRD, DISJOINTED,
CHAOTIC RATTLE.

BUT THAT SOUND -- OH, IT MAKES

THE HAIR ON THE BACK
OF YOUR NECK GO UP, DOESN'T IT?

YEAH.

WITH THE CLAMP VIBRATING
AT 50 TIMES A SECOND,

REPLICATING THE ACTION OF
SPECIALIZED TAIL-SHAKER MUSCLES,

THE FRAGILE CAPSULES OF SKIN
REACH THEIR FULL POTENTIAL.

THE WARNING IS LOUD AND CLEAR.

IT'S DONE ITS JOB. THERE IS
ABSOLUTELY NO DOUBT RIGHT NOW

THAT IF I HEARD THAT
IN THE WILD,

I'D BE STEPPING AWAY.

THAT'S A RATTLESNAKE
TO ME.

♪♪

WHILE A RATTLER'S NOISY WARNING

HELPS KEEP
HUNTER AND HUNTED APART,

SOME ANIMALS' SKIN DEFENSES
ARE SHAPED BY CLOSE CONTACT.

[ RHINO GROWLS ]

RHINOS ARE SOME OF THE BIGGEST
ANIMALS ON THE PLANET,

REACHING AT LEAST
A TON IN WEIGHT.

THEY ALSO HAVE THE MOST
HEAVILY-ARMORED SKIN

OF ANY LIVING MAMMAL.

♪♪

THICK ARMOR, UP TO
4 CENTIMETERS IN PLACES,

COMBINED WITH A HUGE BODY SIZE

AND A TOP SPEED
OF 50 KILOMETERS PER HOUR,

MAKES THEM ALL BUT INVULNERABLE
TO PREDATORS.

♪♪

OF THE THREE SPECIES
LIVING IN ASIA

AND TWO LIVING IN AFRICA,
THE AFRICAN WHITE RHINO

IS THE LARGEST
AND BEST-DEFENDED OF ALL.

I'VE COME TO SEE
THIS ARMORED SKIN CLOSE-UP

WITH THE HELP OF RHINO KEEPER
MARK GODWIN.

♪♪

Garrod:
MARK, HE'S BLOWN ME AWAY.

THIS GUY IS HUGE!

LOOK AT HIM.
WHAT'S THIS ONE'S NAME?

THIS IS MONTY.
HE'S ABOUT 3 1/2 TON.

AND I'M GONNA SAY HE'S
OVER 6 FOOT TO THE SHOULDER.

IF YOU WANT TO HAVE A STROKE,
FEEL FREE.

OKAY, I CAN INSTANTLY FEEL
THERE'S NO GIVE HERE.

THIS SKIN IS -- I MEAN,
IT'S COVERED IN MUD,

BUT THIS IS INCREDIBLY
TOUGH SKIN.

IT REALLY IS.

DO WE KNOW HOW THICK THIS SKIN
CAN BECOME ON MONTY?

IT'S SUPPOSED TO BE ABOUT
TO 1 1/2 INCH THICK.

SO YOU'RE TALKING, WHAT'S THAT,
4 CENTIMETERS OF SKIN THERE.

THAT IS
AN IMPRESSIVE ANIMAL.

WITH AN EPIDERMIS OF ONLY
ABOUT 1 MILLIMETER THICK,

MONTY'S SKIN GETS ITS STRENGTH
AND THICKNESS

FROM DENSELY-PACKED LAYERS

OF COLLAGEN FIBERS
IN THE DERMIS.

NOW, IN THE WILD,
I CAN'T IMAGINE

EVEN THE MOST DETERMINED
BUNCH OF LIONS

AND HYENAS ARE GOING TO TRY
AND TAKE MONTY DOWN.

HIS MAIN THREAT, REALLY,
IS OTHER RHINOS.

SO MOST OF THE ARMAMENT AND THAT
IS FOR DEALING WITH OTHER BULLS

WHEN THEY COME INTO CONTACT
OVER FEMALES.

RHINOS CHARGE EACH OTHER, USING
THEIR HORNS AS BATTERING RAMS

IN BATTLES OVER TERRITORY
AND MATING.

RESEARCHERS BELIEVE
THIS AGGRESSIVE BEHAVIOR

HAS DRIVEN THE EVOLUTION
OF THE RHINO'S THICK ARMOR.

IT'S FAR TOUGHER
THAN IT NEEDS TO BE

TO SIMPLY FEND OFF PREDATORS.

♪♪

EVEN IF YOU JUST LOOK AT
THE WAY THE LEGS ARE FORMED --

THE FRONT LEGS
ARE VERY HEAVY,

SO IT'S ALL PROTECTION
AROUND THE FRONT.

THEY TEND TO LIKE TO FACE
THEIR PROBLEMS,

SO, THEREFORE, THAT'S WHERE THE
THICKER, DENSER SKIN DEVELOPS.

IT'S HELPING HIM
GET TERRITORY,

HELPING HIM BE
A BIG, DOMINANT BULL,

JUST BY THE THICKNESS
OF THE SKIN.

WHILE ADULT RHINOS ARE
PROTECTED AGAINST ALL-COMERS

BY THEIR THICK ARMOR,

IT'S A DIFFERENT STORY
FOR CALVES.

MARK, THESE ARE LOVELY.
WHO HAVE WE GOT HERE?

THIS IS RUBY, AND THE LITTLE
ONE'S STELLA.

SHE'S ABOUT 10 WEEKS OLD NOW
COMING UP.

AND I GUESS BEING THIS SMALL
AND HAVING SKIN

THAT'S, WELL, NOWHERE NEAR
AS THICK AS MUM'S,

SHE'S, IN THE WILD, VULNERABLE.DEFINITELY.

AND THAT'S WHY THE MUMS
ARE AS POSSESSIVE AS THEY ARE.

ONCE THEY GET TO FULL SIZE,
REALLY NOT MUCH CAN TOUCH THEM,

BUT WHEN THEY'RE THIS SIZE
AND SEPARATED FROM MUM,

THEY'RE VERY MUCH AT RISK.

STELLA'S SKIN IS PROBABLY
ABOUT A CENTIMETER THICK,

AND WHILE THAT'S
FIVE TIMES THICKER

THAN A 10-WEEK-OLD
HUMAN BABY'S,

IT'S NOWHERE NEAR THICK ENOUGH
TO PROTECT HER FROM PREDATORS,

SO RHINO MOTHERS
HAVE TO BE VIGILANT.

WHAT SORT OF PREDATORS
WOULD HAVE A GO

AT A BABY RHINO LIKE STELLA
IN THE WILD?

LIONS, HYENAS.

IT WOULD HAVE TO BE THE BIG ONES
OR ORGANIZED ONES.

THEY'D HAVE TO DEAL
WITH MUM, AS WELL.

YEAH.OBVIOUSLY, WHILE SHE'S WITH MUM,

SHE'S VERY WELL PROTECTED,

BUT IF ANYTHING HAPPENED,
SHE GOT SEPARATED,

SHE REALLY WOULD BE
AT THE MOST VULNERABLE.

IT'S AN INCREDIBLY RARE EVENT
AND EVEN MORE RARELY WITNESSED,

BUT PREDATORS THAT HUNT
IN GROUPS, LIKE HYENAS OR LIONS,

ARE THE ONLY ANIMALS
THAT WILL EVEN ATTEMPT

TO TACKLE
A RHINO MOTHER AND CALF.

♪♪

IT TAKES AROUND TWO YEARS
FOR A RHINO CALF

TO GROW THICK-ENOUGH SKIN

AND A BIG-ENOUGH BODY
TO BE ABLE TO DEFEND ITSELF

AND FINALLY LEAVE
ITS MOTHER'S PROTECTION.

♪♪

SOME BABIES ARE WELL DEFENDED
FROM THE DAY THEY'RE BORN.

♪♪

IN THE FORESTS
OF MADAGASCAR'S EAST COAST,

A MOTHER TENREC IS LEADING
HER CLUTCH OF BABIES

OUT OF THE NEST
TO FORAGE FOR INSECTS.

THEIR STRIPES HELP THEM HIDE
IN THE DAPPLED LIGHT

OF THE FOREST FLOOR.

THEY MAY LOOK SMALL
AND VULNERABLE,

BUT THE SKIN ON THEIR BACKS

IS A FOREST OF SHARP,
BLACK AND YELLOW SPINES.

THEIR MOTHER HAS THEM, TOO,

BUT THEY'RE HIDDEN
BY HER LONGER HAIR.

♪♪

♪♪

THE BABIES WERE BORN
WITHOUT SPINES

BUT STARTED TO GROW THEM IN
THE FIRST 24 HOURS AFTER BIRTH.

TOUGH AND SHARP, EACH SPINE IS
A MODIFIED HAIR MADE OF KERATIN

AND GROWING OUT OF THE SKIN.

AND THEY'RE AN EXCELLENT
FORM OF DEFENSE.

IF A PREDATOR TRIES
TO BITE A TENREC,

THEY GET A MOUTHFUL OF SPINES
AS A PAINFUL DETERRENT.

♪♪

SPINES AND QUILLS
ARE SUCH AN EFFECTIVE WEAPON

THAT THEY'VE EVOLVED
SEVERAL TIMES

IN THE SKIN OF DIFFERENT
FAMILIES OF VERTEBRATES

IN DIFFERENT PARTS OF THE WORLD.

HEDGEHOGS ARE FOUND ACROSS
EUROPE, AFRICA, AND ASIA.

IN AUSTRALIA, YOU GET ECHIDNAS.

♪♪

BUT FOR ME,
THE CHAMPIONS ARE PORCUPINES.

THERE ARE TWO FAMILIES
OF PORCUPINE --

NEW-WORLD PORCUPINES, FOUND
IN NORTH AND SOUTH AMERICA,

AND OLD-WORLD PORCUPINES,

FOUND IN EUROPE,
ASIA, AND AFRICA.

IN BOTH FAMILIES, THE BACKS
AND SIDES OF THE PORCUPINE

ARE COVERED
WITH THOUSANDS OF QUILLS.

IF A PREDATOR GETS TOO CLOSE,
THEY ERECT

AND SPREAD THE QUILLS,

TURNING SO THEIR DANGEROUS REAR
ENDS FACE THE WOULD-BE ATTACKER.

EVEN AN EXPERT HUNTER
LIKE A LEOPARD,

CAPABLE OF TAKING DOWN
A 900-KILOGRAM ELAND,

IS NO MATCH FOR 30 KILOGRAMS
OF WELL-DEFENDED PORCUPINE.

♪♪

NOT ONLY DO PORCUPINES
HAVE THESE LONG, STRONG QUILLS

GROWING OUT OF THEIR SKIN,

BUT THEY'VE EVOLVED
TO BE DETACHABLE.

AND JUST LIKE HAIR,
THEY FALL OUT FROM THE SKIN

WITHOUT HARMING
THE OWNER AT ALL.

IF A PORCUPINE IMPALES
AN ATTACKER,

THE LOST QUILLS WILL GROW BACK
IN A MATTER OF MONTHS,

WHILE THE PREDATOR LEARNS
A VALUABLE LESSON.

♪♪

AFRICAN PORCUPINE QUILLS
ARE BIG AND IMPRESSIVE,

AND THEY CAUSE LOTS OF DAMAGE
TO ANY WOULD-BE ATTACKER.

I CAN DEMONSTRATE THIS
WITH A PIECE OF CHICKEN,

'CAUSE WHEN I STAB THE POINTY
END INTO THE CHICKEN,

IT GOES IN NICE AND EASILY,

BUT ALSO IT COMES OUT
NICE AND EASILY, TOO.

WHEN A PREDATOR LIKE A LION
IS IMPALED

BY AN AFRICAN PORCUPINE,

GROOMING BY A PRIDE MEMBER CAN
OFTEN HELP REMOVE THE QUILLS,

ALLOWING THE WOUNDS TO HEAL.

HERE, I'VE GOT THREE QUILLS
FROM A NORTH AMERICAN PORCUPINE.

COMPARED TO THE AFRICAN QUILLS,
THESE LOOK A BIT UNDERWHELMING.

THEY'RE FINER AND MUCH SHORTER.

BUT APPEARANCES
CAN BE DECEPTIVE.

AND WHEN I STAB THIS QUILL
INTO THE CHICKEN...

IT GOES IN NICE AND EASILY.

BUT WHEN I TRY
AND PULL IT OUT...

IT'S EMBEDDED. IT'S STUCK FAST.

AND, ACTUALLY,
TO REMOVE THE QUILL...

I'VE REALLY GOT TO PULL IT.

[ CLICK ]

AND YOU COULD HEAR THE FLESH
TEARING AS I RIPPED THIS OUT.

IT'S NOT NICE.

THIS IS HAPPENING BECAUSE
NORTH AMERICAN PORCUPINE QUILLS

HAVE BACKWARD-FACING
MICROSCOPIC BARBS,

AS YOU CAN SEE HERE
IN THIS ELECTRON MICROGRAPH.

THE BARBS DO TWO THINGS.

THEY SNAG ON MUSCLE AND SKIN,

MAKING THE QUILLS
HARD TO PULL OUT.

BUT RESEARCH IN 2012 REVEALED

THE BARBS ALSO HALVE
THE PENETRATION FORCE

NEEDED TO GET THE QUILLS
INTO THE FLESH.

EVERY YEAR, MANY HUNDREDS
OF NORTH AMERICAN DOGS

LEARN ABOUT THE DANGERS
OF BARBED PORCUPINE QUILLS

THE HARD WAY.

♪♪

USING YOUR SKIN
TO DEFEND YOURSELF

CAN BE EXTREMELY EFFECTIVE.

BUT CONCOCTING DEADLY SKIN
TOXINS, CARRYING HEAVY ARMOR,

AND DROPPING AND REPLACING
QUILLS TAKE TIME AND EFFORT.

♪♪

OVER MILLIONS OF YEARS,
SOME VERTEBRATES HAVE EVOLVED

A CHEAPER AND MORE SOPHISTICATED
WAY OF STAYING SAFE --

CAMOUFLAGE,

HIDING IN PLAIN SIGHT,
USING THEIR SKIN AS A DISGUISE.

♪♪

HAIR, FEATHERS, AND SKIN

CAN ALL HELP ANIMALS
BLEND INTO THEIR ENVIRONMENT.

♪♪

HOW EFFECTIVE THAT CAMOUFLAGE IS
DEPENDS ON WHO'S LOOKING.

♪♪

UNLESS YOU'RE VERY, VERY LUCKY,

YOU'VE PROBABLY ONLY EVER
SEEN A TIGER

IN A ZOO OR WILDLIFE PARK.

AND AGAINST THIS SORT
OF BACKDROP,

IT'S HARD TO IMAGINE
HOW SUCH VIVID STRIPES

COULD EVER ACT AS CAMOUFLAGE.

IN THEIR NATURAL ENVIRONMENT,

THE DISGUISE IS
A BIT MORE EFFECTIVE,

BUT THERE'S STILL NO MISTAKING
A DEADLY PREDATOR.

BUT LOOK AT THE WORLD
THROUGH A PREY ANIMAL'S EYES,

AND A TIGER'S CAMOUFLAGE
FINALLY MAKES SENSE.

CHITAL DEER,
THE TIGER'S MAIN PREY,

HAVE WHAT IS KNOWN
AS DICHROMATIC VISION.

THEY CAN'T TELL THE DIFFERENCE
BETWEEN REDS AND GREENS.

SO, TO A DEER, THE PREDATOR

BLENDS INTO ITS BACKGROUND
PERFECTLY.

♪♪

THIS MAKES IT EASIER
FOR THE TIGER

TO GET WITHIN STRIKING DISTANCE.

♪♪

♪♪

THERE'S ONLY ONE FLAW
IN THE TIGER'S STRATEGY.

♪♪

CHITAL HERDS ARE OFTEN FOUND
WITH GROUPS OF LANGURS.

♪♪

THE MONKEYS DROP FRUIT
AS THEY FEED.

BUT THAT'S NOT THE ONLY
REASON THE CHITAL STAY CLOSE.

LANGUR MONKEYS
HAVE FULL COLOR VISION.

♪♪

CHITAL HAVE LEARNED
TO RECOGNIZE LANGUR ALARM CALLS

AND RUN FOR THEIR LIVES.

[ MONKEYS CHIRPING ]

♪♪

♪♪

THE TIGER'S COVER IS BLOWN.

♪♪

IF THOSE PESKY MONKEYS
ARE GIVING THE GAME AWAY,

WHY DON'T TIGERS GO THE WHOLE
HOG AND JUST HAVE GREEN HAIR?

♪♪

THAT'S BECAUSE MAMMALS,
INCLUDING HUMANS, USE MELANIN

TO COLOR THEIR EPIDERMIS
AND HAIR, AND MELANIN

CAN ONLY MAKE BLACKS,
ORANGES, AND BROWNS.

ONLY ONE GROUP OF MAMMALS
HAS MASTERED THE ART

OF GREEN JUNGLE CAMOUFLAGE --

THE TWO- AND THREE-TOED SLOTHS.

THESE SLOW-MOVING MAMMALS
HAVE GREEN HAIR,

HELPING THEM BLEND INTO
THEIR FOREST HOME.

BUT THAT COLOR ISN'T MADE
BY THE SLOTH'S SKIN.

IT COMES FROM TINY GREEN ALGAE
THAT COLONIZE THEIR HAIR.

♪♪

EACH STRAND HAS CRACKS IN IT,

WHICH TRAP THE MOISTURE THE
MICROSCOPIC PLANTS NEED TO GROW.

♪♪

MOTHS LIVING IN THE SLOTH'S HAIR
EVEN HELP TO FERTILIZE

THE ALGAE
WITH THEIR NITRATE-RICH FECES.

♪♪

EVOLVING CAMOUFLAGED SKIN
TO HELP YOU BLEND INTO

A PARTICULAR HABITAT
IS PRETTY IMPRESSIVE,

BUT SOME ANIMALS HAVE TAKEN
A REVOLUTIONARY NEXT STEP.

I'VE COME TO PLYMOUTH
TO FIND OUT MORE

FROM MARINE BIOLOGIST
ALIX HARVEY.

AND WHILE THE ANIMALS
SHE STUDIES AREN'T VERTEBRATES,

YOU CAN'T TALK ABOUT
EXTRAORDINARY SKIN DEFENSES

WITHOUT INCLUDING THEM.

HI, ALIX.
HI, BEN.

LOOK AT THESE!
I LOVE THESE LITTLE ANIMALS.

THEY'RE AMAZING,
AREN'T THEY?

THEY'RE ABSOLUTELY
FANTASTIC.

SO THESE ARE THE COMMON
CUTTLEFISH, SEPIA OFFICINALIS.

THIS IS A SPECIES WE FIND
ALL AROUND THE U.K.

THEY'RE ONE OF THE BIGGEST
SPECIES OF CUTTLEFISH WE GET.

AND THEY'RE ABOUT 5 MONTHS OLD,
THESE INDIVIDUALS,

SO THEY'RE STILL BABIES.I WAS GOING TO SAY,

I'VE SEEN MUCH BIGGER
THAN THIS.

THESE ARE TINY BY COMPARISON,
AREN'T THEY?

THAT'S RIGHT. SO, THEY HATCH OUT
FROM EGGS ABOUT 1 CENTIMETER,

ABOUT THIS BIG,
AND THEN

OVER THEIR LIFE CYCLE
OF ABOUT 2 YEARS,

THEY GET REALLY, REALLY BIG,
UP TO ABOUT THIS SIZE,

SO THESE ARE ALL STILL
KIND OF BABIES IN MY EYES.

ALIX HAS CUTTLEFISH
IN THREE DIFFERENT TANKS.

SO, WE'VE GOT SAND HERE,
WE'VE GOT ROCKS,

AND THEN,
WE'VE GOT SEAWEED.

SO THESE ARE ALL
THE NATURAL ENVIRONMENTS

THEY WOULD EXPERIENCE
IN THE WILD.

AND IN EACH TANK,

THE CUTTLEFISH
ARE BEAUTIFULLY CAMOUFLAGED.

I'M JUST LOOKING
AT THIS LITTLE ONE HERE,

AND IT'S BLENDED IN PERFECTLY
WITH THE SANDY SURROUNDING.

YOU CAN REALLY SEE JUST
HOW WELL IT'S BLENDED IN.

IT'S MANAGED TO PUT SOME SAND
ON ITS BODY

AND IT'S REALLY
BROKEN UP THE OUTLINE.

THE CUTTLEFISH IN TANK TWO,
THE ROCKY TANK,

HAS VERY DIFFERENT
SKIN COLORS AND PATTERNS.

AND SO YOU FIND HERE,
IN THIS ROCKY KIND OF HABITAT,

THAT THEY WILL GET
A VERY DISRUPTIVE BODY PATTERN.

IT'S JUST
SLIGHTLY DIFFERENT.

AND, THEN, AT THE END,
WE'VE GOT A MUCH DARKER ONE.

SO HE'S REALLY ADAPTED
TO THE SEAWEED.

AND YOU CAN IMAGINE IF HE WAS
SITTING IN AMONGST THE WEEDS,

IT WOULD BE VERY, VERY DIFFICULT
TO TELL WHERE HE WAS,

PARTICULARLY AS HE'S
USING HIS TENTACLES,

ACTUALLY LIFTING HIS TENTACLES
OUT OF THE WATER,

IN ORDER TO KIND OF
DISRUPT HIS BODY

AND REALLY PRETEND
TO BE A PIECE OF SEAWEED.

ALIX'S CUTTLEFISH
ARE ALL THE SAME SPECIES,

SO HOW HAVE THEY ENDED UP
LOOKING COMPLETELY DIFFERENT?

THE ANSWER IS
ADAPTIVE CAMOUFLAGE.

A CUTTLEFISH'S SKIN
CAN RAPIDLY CHANGE COLOR

TO HELP IT BLEND SEAMLESSLY
INTO ITS SURROUNDINGS

IN THE BLINK OF AN EYE.

ONE LITTLE ANIMAL WILL CHANGE
FROM SANDY TO WEEDY TO STONY,

BUT HOW DO THEY DO THAT?

SO, CUTTLEFISH ACTUALLY

HAVE THREE DIFFERENT
COLOR-CHANGING CELLS,

BUT THE ONES THAT ALLOW THEM
TO DO THESE DIFFERENT

COLOR PATTERNS
ARE CALLED CHROMATOPHORES.

AND THESE ARE BASICALLY CELLS
THAT ARE PACKED FULL OF PIGMENT.

FOUND IN THE DERMIS,

EACH CHROMATOPHORE HAS MUSCLES
ATTACHED TO ITS OUTER WALL.

WHEN THE MUSCLES CONTRACT, THE
CHROMATOPHORE IS PULLED OPEN,

AND THE PIGMENT SPREADS OUT.

WHEN THE MUSCLES RELAX,
THE CHROMATOPHORE SHRINKS DOWN,

COMPRESSING THE PIGMENT.

♪♪

SO WHEN IT'S PACKED
REALLY, REALLY TIGHT,

IT'S VERY DIFFICULT
TO SEE,

AND IT'S WHAT ALLOWS THEM
TO HAVE A NICE WHITE COLOR,

AND WHEN IT'S SPLAYED OUT,
IT BECOMES A NICE DARK SPLOTCH,

AND WHEN EXTRAPOLATED OVER THE
WHOLE BODY OF THE CUTTLEFISH,

THIS IS WHAT ALLOWS THEM
TO ACHIEVE

ALL KINDS OF BODY PATTERNS.

ALL CEPHALOPODS,
INCLUDING OCTOPUS AND SQUID,

HAVE THIS AMAZING SKIN.

AND AS WELL AS CHANGING COLOR,

IN SOME SPECIES,
IT CAN CHANGE TEXTURE, TOO.

♪♪

MUSCLES IN THE DERMIS PUSH THE
SKIN INTO BUMPS CALLED PAPILLAE,

WHICH BREAK UP
THE OUTLINE OF THE BODY,

HELPING THEM TO HIDE.

WHY ARE THEY HIDING? I'M
GUESSING FROM PREDATORS, RIGHT?

THAT'S RIGHT. THEY ARE
VERY SOFT-BODIED ANIMALS.

THEY DON'T HAVE
ANY EXTERNAL HARD PIECES.

THEY CAN'T REALLY
PROTECT THEMSELVES.

SO THE BEST THING FOR THEM
IN ORDER TO AVOID BEING A MEAL

FOR SOMETHING ELSE IS JUST NOT
TO BE SEEN IN THE FIRST PLACE.

ADAPTIVE CAMOUFLAGE IS
AN AMAZING DEFENSIVE STRATEGY,

BUT THERE'S A CONUNDRUM.

A CUTTLEFISH'S EYES
ARE ON THE TOP OF ITS BODY.

SO HOW DOES IT GATHER
ENOUGH INFORMATION

ABOUT THE SURFACE
HIDDEN BENEATH ITS BODY

TO MATCH ITS COLOR
AND TEXTURE SO WELL?

SO, WE ALWAYS USED TO THINK
THIS WAS BASICALLY

THAT THEY'RE SEEING
THEIR ENVIRONMENT

AND THEN RELAYING
THAT INFORMATION

TO THEIR CHROMATOPHORES
BY THEIR BRAIN.

WE NOW THINK
THERE MAY BE SOMETHING

EVEN MORE ASTOUNDING GOING ON,
WHICH IS THAT THEY HAVE ACTUALLY

LIGHT-SENSING-CAPABILITIES
WITHIN THEIR SKIN.

RESEARCHERS HAVE DISCOVERED
TRACES OF A PROTEIN

CALLED RHODOPSIN
IN THE CUTTLEFISH DERMIS.

EXACTLY THE SAME PROTEIN

IS FOUND IN THE RETINA
OF A CUTTLEFISH'S EYES.

IT'S A LIGHT-SENSITIVE PIGMENT

THAT FORMS THE BASIS
OF CUTTLEFISH VISION.

VERTEBRATES USE SIMILAR PROTEINS
IN THEIR EYES.

THE RESEARCH
IS IN ITS EARLY STAGES,

BUT THE PRESENCE OF RHODOPSIN
IN THE SKIN

SUGGESTS CUTTLEFISH SKIN
MAY BE ABLE TO SEE.

THIS IS SOMETHING
THAT'S VERY, VERY NEW,

AND WE'RE ACTUALLY HOPING
TO CONDUCT SOME EXPERIMENTS

THIS YEAR LOOKING AT THAT,
LOOKING WHETHER,

IF THEY CAN'T SEE WHAT THE REST
OF THEIR BODY'S DOING,

ARE THEY STILL ABLE TO ADAPT

AND COLOR-CAMOUFLAGE
TO THEIR ENVIRONMENT?

IF ALIX'S RESEARCH REVEALS

THAT CUTTLEFISH CANSENSE
LIGHT AND DARK WITH THEIR SKIN,

THEN WE'LL HAVE TO COMPLETELY
REDEFINE CEPHALOPOD SKIN

AS NOT JUST AN AMAZING
MEANS OF DEFENSE

BUT AN EXTRAORDINARY
SENSORY ORGAN, TOO.

THESE CRYPTIC CUTTLEFISH
ARE FURTHER PROOF

THAT SKIN STILL HAS SECRETS

WE'RE ONLY JUST BEGINNING
TO UNDERSTAND.

♪♪

WHEN IT COMES TO DEFENDING
YOURSELF FROM OTHER ANIMALS,

SKIN PROVIDES AN INCREDIBLE
SELECTION OF WEAPONS AND ARMOR,

FROM DEADLY TOXINS
AND PIERCING QUILLS,

RIGHT THROUGH
TO CRYPTIC COLORATION.

FOR VERTEBRATES AND A FEW
VERY SPECIAL INVERTEBRATES,

SKIN WILL KEEP YOU SAFE.

♪♪

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