All language subtitles for 6 Secrets.Of Skin

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 HE'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 HAIRS
AT 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
EXTRASENSORY ABILITIES.

WE'RE EVEN DISCOVERING
THE COMPLEX ECOSYSTEM

LIVING ON OUR SKIN.

OH, JIM, THAT'S AWFUL.
IT REALLY IS.

IN THIS EPISODE, I'LL FIND OUT
HOW SKIN ALLOWS ANIMALS

TO HAVE MORE THAN
JUST FIVE SENSES...

OH!
SO POWERFUL.

...LIKE BEING ABLE

TO DETECT ELECTRICITY
OR EVEN SEE HEAT.

THAT WAS INCREDIBLY QUICK,
THOUGH.

YEAH.THAT WAS SUCH A STRIKE.

AND I'LL DISCOVER
JUST HOW COMPLEX

OUR SENSE OF TOUCH
REALLY IS...

THAT MUST BE SO SENSITIVE.

...AS I EXPLORE
HOW SKIN HAS EVOLVED

TO GIVE ANIMALS SUPER SENSES.

I'M GOING TO REVEAL
THE SECRETS OF SKIN.

IN ALL THE VARIED HABITATS
IN WHICH ANIMALS LIVE,

THEIR SKIN HAS COME
TO PLAY A KEY ROLE

IN HELPING THEM
GATHER INFORMATION

ABOUT THEIR
DIFFERENT ENVIRONMENTS.

WE OFTEN THINK
ABOUT FIVE MAIN SENSES --

SIGHT, HEARING, TASTE,
SMELL, AND TOUCH,

BUT ACROSS THE NATURAL WORLD,
SKIN HELPS ANIMALS

SENSE IN WAYS
WE FIND HARD TO IMAGINE.

ANIMALS DETECT TOUCH IN VARYING
DEGREES OF SENSITIVITY.

BUT SENSITIVE DOESN'T
ALWAYS MEAN FRAGILE.

CROCODILES, ALLIGATORS,
CAIMAN, AND GHARIALS

ARE COLLECTIVELY KNOWN
AS CROCODILIANS.

THERE ARE 23 SPECIES

LIVING IN TROPICAL AREAS
ACROSS THE WORLD.

AS ONE OF OUR PLANET'S
MOST FORMIDABLE HUNTERS,

THEY SIT AT THE TOP
OF THE FOOD CHAIN.

THEIR SKIN HAS
AN INCREDIBLE SENSITIVITY

WHICH HAS GIVEN THEM
THE EDGE OVER OTHER ANIMALS.

I'VE COME TO THE U.K.'s
ONLY CROCODILIAN ZOO,

JUST OUTSIDE OXFORD,
TO SEE SOME OF THEM UP CLOSE.

WHAT SPECIES
DO WE HAVE IN HERE?

SO, THESE, THIS IS OUR
BIG GROUP OF NILE CROCODILES.

WE'VE GOT 35 INDIVIDUALS
IN THIS ENCLOSURE,

AND THEY'RE ALL QUITE YOUNG.

I MEAN, THEY GET MUCH BIGGER
THAN THIS, DON'T THEY?

THEY DO.

THEY'RE ONE OF
THE LARGEST SPECIES

OF CROCODILIAN
THAT WE HAVE ON THE PLANET.

AND ADULT MALES CAN REACH
LENGTHS OF UP TO FIVE METERS,

SO QUITE A LOT BIGGER
THAN THIS.

THAT'S ME WITH YOU
ON MY SHOULDERS

AND THEN A BIT MORE, ISN'T IT?YEAH.

SO, WHAT DO NILE CROCODILES
EAT IN THE WILD?

WELL, THROUGH THEIR LIFE,
THEY EAT DIFFERENT THINGS,

SO, THEY START OFF,
WHEN THEY'RE HATCHLINGS,

EATING SMALL INVERTEBRATES,
SMALL REPTILES, AMPHIBIANS,

FISH, THINGS LIKE THAT.

AND AS THE CROC GROWS,

THEIR PREY SIZE INCREASES,
AS WELL.

I'M SUDDENLY FEELING LESS
CONFIDENT STOOD NEAR THE EDGE,

'CAUSE THEY CAN JUMP,
AS WELL, CAN'T THEY?

THEY CAN JUMP.

THE PERFECT APEX PREDATOR
ON OUR PLANET.

IT'S TIME FOR THESE CROCODILES'
MAIN MEAL --

CHICKEN ON A STICK.

[ Chuckling ] OH!

SO POWERFUL.

CROCODILIANS DIDN'T GET TO BE
THE APEX PREDATORS THEY ARE

SIMPLY BY USING BRUTE FORCE.

THE REAL SECRET TO THEIR SUCCESS
IS HIDDEN IN THEIR SKIN.

IN THE MURKY WATER
WHERE THEY HUNT,

CROCODILES CAN'T ALWAYS RELY
ON THEIR EYES.

SO, EMBEDDED IN NEARLY EVERY
SINGLE SCALE ACROSS THEIR BODIES

ARE HIGHLY SENSITIVE
PRESSURE RECEPTORS.

AND THESE ARE ABLE TO DETECT

THE SMALLEST OF RIPPLES
IN THE WATER...

...MAKING IT POSSIBLE

TO JUDGE THE DISTANCE
AND POSITION OF ANY ANIMAL

WITHOUT USING THEIR EYES.

THE SAFEST WAY TO SEE
THESE SENSORY ORGANS UP CLOSE

IS ON A BABY ALLIGATOR.

SHAUN, THIS ONE'S MUCH SMALLER
THAN EARLIER.

I FEEL MUCH HAPPIER BEING
THIS CLOSE TO THIS LITTLE GUY.

BUT IT'S A DIFFERENT
SPECIES, AS WELL, ISN'T IT?

YEAH, THIS ONE'S
AN AMERICAN ALLIGATOR.

BUT IT'S A GOOD OPPORTUNITY TO
REALLY HAVE A LOOK AT THE SKIN

AND SEE HOW IT WORKS
AND ALSO HOW IT HELPS HIM HUNT.

YOU CAN SEE INSTANTLY,
ON THE BACK, REALLY STRONG,

THICK SKIN,
THAT REALLY ARMORED AREA,

BUT NOT THE SAME
AROUND THE MOUTH.

YOU CAN SEE IT'S
A DIFFERENT TYPE OF SKIN,

AND LOTS OF LITTLE SPOTS
OR HOLES, REALLY.

THAT'S RIGHT.

ALL THOSE LITTLE BLACK DOTS
AROUND THE JAW

ARE SENSORY ORGANS.

WHILE ALLIGATORS HAVE
THESE PRESSURE RECEPTORS

JUST ON THEIR SNOUT,

CROCODILES HAVE THEM
ALL OVER THEIR BODIES.

EACH ONE IS A MILLIMETER-LONG
DOME ON THEIR SKIN,

COVERED BY A FLEXIBLE SCALE.

INSIDE ARE HUNDREDS
OF NERVE FIBERS.

ANY MOVEMENT ON THE SURFACE
OF THE SCALE IS PICKED UP

BY THE NERVE FIBERS UNDERNEATH.

IT'S BEEN ESTIMATED
THAT EACH DOME IS

10 TIMES MORE SENSITIVE
THAN A HUMAN FINGERTIP.

THEY'RE EFFECTIVELY SEEING,
BUT WITHOUT THEIR EYES.

THEY'RE SEEING WHERE
THESE VIBRATIONS ARE,

THEY'RE FEELING
THESE VIBRATIONS,

AND THAT'S IN ORDER
TO HUNT PREY, RIGHT?

THAT'S EXACTLY RIGHT, YEAH.

WE WANT TO SEE HOW
THESE SKIN RECEPTORS WORK

BY SETTING UP A SIMPLE TEST
INVOLVING OUR BABY ALLIGATOR.

THE TUBES ARE IN PLACE
TO MAKE SURE

THE ALLIGATOR CAN'T SEE
WHERE THE FOOD IS.

AND TO MAKE SURE IT CAN'T HEAR
WHERE THE FOOD IS,

I'VE EVEN ADDED
SOME WHITE NOISE.

[ WHITE NOISE WHOOSHES ]

I DROP SOME CHICKEN
INTO ONE OF THE PIPES.

FILMED IN SLOW MOTION,
AS THE CHICKEN HITS THE WATER,

IT CREATES SMALL RIPPLES.

THESE EXPAND OUT INTO THE POOL.

AND AS THEY TOUCH THE ALLIGATOR,
IT TURNS.

THE MOMENT I DROPPED THE CHICKEN
INTO THAT TUBE,

IT TURNED AND IT LOOKED,

AND IT DID COME THIS WAY
A SECOND OR SO

AFTER THAT CHICKEN
HIT THE WATER.

THAT COULD ONLY HAVE HAPPENED

IF IT FELT THE VIBRATIONS
THROUGH ITS SKIN.

THIS HAS BEEN SHOWN
IN EXPERIMENTS

UNDER LABORATORY CONDITIONS.

ITS SKIN IS SO SENSITIVE,
THIS CROCODILE IS ABLE TO REACT

TO THE RIPPLE
WITHIN A FRACTION OF A SECOND.

CROCODILIANS HAVE
THE MOST POWERFUL JAWS

OF ANY LIVING ANIMAL.

BUT BY USING THE RECEPTORS
IN THEIR SKIN,

THESE JAWS ALSO
HAVE THE CAPACITY

TO BE SURPRISINGLY GENTLE.

AND THIS SENSITIVITY IS
SOMETHING ALL CROCODILIANS HAVE

FROM THE MOMENT THEY HATCH.

THIS FEMALE CAIMAN'S OFFSPRING

ARE JUST EMERGING
FROM THEIR EGGS.

[ CAIMANS SQUEAKING ]

HER YOUNG ARE FRAGILE

AND NEED HELP
GETTING TO THE WATER.

TO PERFORM THIS KIND OF TASK,

SHE NEEDS A REAL LIGHTNESS
OF TOUCH --

SOMETHING ONLY HER SKIN
CAN PROVIDE.

LIKE CROCODILIANS, MANY ANIMALS
USE THEIR SNOUTS

TO PERFORM ESSENTIAL TASKS.

THIS MAKES THE SKIN
ON THE END OF ANY SNOUT

A PARTICULARLY IMPORTANT
SENSORY TOOL.

HERE IN NORTH AMERICA
LIVES THE STAR-NOSED MOLE.

AT THE END OF ITS SNOUT IS

ARGUABLY THE MOST SENSITIVE
PATCH OF SKIN ON THE PLANET.

ITS NOSTRILS ARE SURROUNDED
BY 22 FLESHY APPENDAGES

KNOWN AS RAYS.

THE SKIN ON THESE IS COVERED IN
25,000 SENSORY TOUCH RECEPTORS,

FIVE TIMES MORE THAN
IN THE HUMAN HAND.

THE MOLE PATS IT TO THE GROUND
10 TO 15 TIMES A SECOND,

SEARCHING FOR A MEAL
IN DARK TUNNELS.

IT'S SO SENSITIVE, THE MOLE
CAN TELL WHAT'S EDIBLE

IN 227 MILLISECONDS,

FASTER THAN ANY OTHER MAMMAL.

BUT THESE SNOUTS ARE SENSITIVE
IN MORE THAN ONE WAY.

THEY CAN ALSO SMELL UNDERWATER.

THE MOLE DOES THIS BY PARTIALLY
EXHALING AN AIR BUBBLE

ON THE TOP OF ITS SNOUT.

THIS ABSORBS SURROUNDING ODORS,

WHICH IT BREATHES BACK IN
TO SEE IF THERE'S FOOD NEARBY.

IF NOT, IT MOVES ON.

EVERY VERTEBRATE
HAS A NETWORK OF NERVES

CONNECTED TO THEIR
DERMIS AND EPIDERMIS,

THERE TO RELAY
REAL-TIME INFORMATION

FROM ALL OVER
THE SURFACE OF THE BODY.

[ CAT PURRING ]

THIS CAN BE A SOURCE OF PLEASURE

AND ACT AS A WARNING SYSTEM
AGAINST ATTACKS.

FROM BITING INSECTS,
FOR EXAMPLE.

[ HORSE NEIGHS ]

BUT REACTING TO WHAT YOUR SKIN
IS TELLING YOU CAN BE TRICKY,

ESPECIALLY WHEN ALL FOUR
OF YOUR LIMBS ARE ON THE GROUND.

SKIN IS PRETTY TOUGH,

AND IS GOOD AT PROTECTING US
FROM THE OUTSIDE WORLD.

BUT WHEN IT COMES
TO BITING INSECTS --

HELLO --

FOR ANIMALS SUCH AS HORSES,
THERE ARE AREAS ON THEIR BODY

THEY JUST CAN'T REACH
TO DISLODGE PESKY FLIES.

BUT HORSE SKIN HAS ADAPTED
TO SOLVE THAT PROBLEM.

JUST BELOW THE SKIN
AND THE SUBCUTANEOUS FAT LAYER

IS A THIN SHEET OF MUSCLE CALLED
THE CUTANEOUS TRUNCI MUSCLE.

IT'S ANCHORED TO THE DERMIS
WITH CONNECTIVE TISSUE,

AND SO ANY MOVEMENT IN THE
MUSCLE PULLS THE SKIN WITH IT.

IMAGINE THIS FEATHER IS A FLY,

INTENT ON GETTING A MEAL
OUT OF THE HORSE.

FLY LANDS...

AND WE SEE THAT.

NOW, THIS IS A FLINCH
IN THE MUSCLE BENEATH THE SKIN.

AND IT'S THAT,
THAT WHEN THE HORSE DOES IT,

DISLODGES THE FLY

OR ANY OTHER FLYING,
BITING INSECT

THAT WOULD
OTHERWISE CAUSE A NUISANCE.

THIS IS AN INVOLUNTARY REACTION.

SENSATION ON THE SKIN
TRAVELS THROUGH NERVES,

VIA THE SPINAL CORD,
TO THE MUSCLE,

WITHOUT ENGAGING
THE HORSE'S BRAIN AT ALL.

USING TOUCH IS CERTAINLY ONE
OF THE MOST EFFECTIVE WAYS

OF GETTING A SENSE
OF AN OBJECT OR ENVIRONMENT.

BUT ONE GROUP OF ANIMALS
HAS ADAPTED THEIR SKIN

TO HELP GATHER INFORMATION
FROM A DISTANCE.

VIRTUALLY ALL OF THE 1,300
OR SO SPECIES OF BAT

AROUND THE WORLD
ARE NOCTURNAL.

IN ORDER TO NAVIGATE AT NIGHT,

MANY OF THEM EMIT
HIGH-FREQUENCY SOUND WAVES

FROM EITHER THEIR NOSE OR MOUTH,
BOUNCING THEM OFF NEARBY OBJECTS

TO GET A SENSE
OF WHAT'S AROUND THEM --

A SYSTEM CALLED ECHOLOCATION.

BUT IN THE DENSE FORESTS OR
CAVES WHERE THEY OFTEN LIVE,

THIS CAN CAUSE A PROBLEM.

WHEN FLYING AROUND A FOREST,

YOU NEED TO BE ABLE
TO FOCUS ON WHAT'S AHEAD,

ESPECIALLY IF YOU WANT
TO AVOID CRASHING INTO A TREE.

IF YOU WERE TO MAKE
A WIDE ECHOLOCATION BEAM,

LIKE THE WIDE BEAM
OF THIS TORCH,

THEN YOU'D BE GENERATING
TOO MUCH INFORMATION,

WHICH WOULD BE BOUNCING BACK
FROM SURROUNDING OBJECTS.

AND FOR A BAT, THIS RISKS BEING
OVERWHELMING AND CONFUSING.

MANY BATS HAVE ADAPTED TO
OVERCOME THIS SENSORY PROBLEM,

BUT ONE GROUP HAS FOUND A WAY
TO ENHANCE THEIR ECHOLOCATION

BY USING THE SKIN
ON THEIR FACES,

LIKE THIS PALE
SPEAR-NOSED BAT.

IT EMITS ITS ECHOLOCATION BEAM
FROM ITS NOSE.

AND IF YOU LOOK,
THIS BIZARRE STRUCTURE

ON THE FRONT OF THE FACE,
JUST HERE,

IS CALLED THE NOSE-LEAF.

THE NOSE-LEAF IS MADE OF
SKIN AND CARTILAGE.

AND BY ADJUSTING ITS SHAPE,

THE BATS CAN MANIPULATE THE SIZE
OF THEIR ECHOLOCATION BEAM.

THIS GIVES THEM THE ABILITY
TO FOCUS THEIR ECHOLOCATION,

TRANSFORMING A WIDE
AND DIFFUSE BEAM

INTO A NARROW
AND MORE FOCUSED ONE.

ALL BATS FROM THE NOSE-LEAF
AND HORSESHOE BAT FAMILIES

HAVE THIS ABILITY.

BY DIRECTING A MORE
FOCUSED BEAM,

THEY ARE ABLE TO CONCENTRATE

ON THE OBJECTS
THAT REALLY MATTER --

IMPORTANT WHEN IT COMES
TO AVOIDING TREES

AND CRUCIAL
FOR HOMING IN ON FOOD.

HOWEVER, THE INFORMATION

ANIMALS ARE ABLE TO GATHER
USING THEIR SKIN

ISN'T ALWAYS RELATED
TO THEIR NEXT MEAL.

THE SENSITIVITY
OF AN ANIMAL'S SKIN

CAN DIRECTLY INFLUENCE HOW
THEY INTERACT WITH THE WORLD.

IN FACT, A SMALL PATCH OF SKIN
FOUND ON SOME ANIMALS

HAS ARGUABLY HAD MORE OF
AN IMPACT ON OUR PLANET

THAN ANY OTHER.

SOME OF THE MOST SENSITIVE SKIN
IS FOUND ON OUR FINGERTIPS,

GIVING THEM A HEIGHTENED
SENSE OF TOUCH.

THE SKIN ON EACH FINGERTIP
CAN DETECT RIDGES

4,500 TIMES SMALLER
THAN A HUMAN HAIR.

THIS SENSITIVITY
GIVES OUR 10 DIGITS

THE POWER TO GRIP, FEEL, BUILD,
CRAFT, AND EVEN READ --

ABILITIES THAT ARE REMARKABLE,

BUT WHICH WE OFTEN
TAKE FOR GRANTED.

IN ORDER TO FULLY EXPLORE

JUST HOW OUR SENSE OF TOUCH
REALLY WORKS,

WE DON'T NEED A BIOLOGIST,
WE NEED AN ENGINEER.

PROFESSOR NATHAN LEPORA
MAKES ROBOTS

THAT MIMIC
THE HUMAN SENSE OF TOUCH --

RESEARCH THAT SHEDS LIGHT
ON THE COMPLEXITY OF OUR SKIN.

HI, NATHAN.
HI, BEN.

HOW ARE YOU?NICE TO MEET YOU.

YEAH, YOU TOO.
WHAT HAVE WE ACTUALLY GOT HERE?

I CAN SEE CABLES AND I CAN SEE
THE BIG BLACK DOME HERE.

WHAT IS THIS?THIS DOMELIKE STRUCTURE IS,

IF YOU LIKE,
A VERSION OF OUR FINGERTIP.

AND WHAT HAPPENS IF YOU TOUCH
THE FINGERTIP NOW?

GO AHEAD.

AH.

SO, WHAT I'M SEEING,
I'M DISPLACING

THOSE LITTLE LUMPS AND BUMPS.YEAH.

THEIR MOVEMENT GIVES INFORMATION
ABOUT THE CONTACT ON THE SKIN.

ENGINEERS HAVE BEEN TRYING

TO REPLICATE
OUR SENSE OF TOUCH FOR DECADES.

AND THESE BUMPS ON THE INSIDE OF
NATHAN'S ARTIFICIAL FINGERTIPS

MIMIC HOW ACTUAL
FINGERTIPS WORK.

WHEN YOU TOUCH SOMETHING,

MOVEMENT ON THE SURFACE
OF YOUR SKIN

IS PICKED UP BY SENSORS
IN YOUR DERMIS AND EPIDERMIS.

CALLED MECHANORECEPTORS,

THESE SEND A SIGNAL
VIA NERVES TO YOUR BRAIN.

THERE ARE ABOUT
200 MECHANORECEPTORS

PER SQUARE CENTIMETER
IN THE TIPS OF YOUR FINGERS.

AND INSIDE
THE ROBOTIC FINGERTIP,

A SMALL CAMERA DOES THIS JOB

BY DETECTING THE MOVEMENT
OF THE BUMPS.

IT TRANSMITS THAT FEELING,
THAT SENSITIVITY, THAT IMPACT,

THROUGH TO A CENTRAL
PROCESSING AREA.

NOT THE BRAIN, BUT THE LAPTOP.EXACTLY.

IN THIS CASE,
IT USES VISION AND IMAGE,

WHEREAS IN OUR FINGERTIPS,
WE HAVE NERVES

WHICH SEND THAT INFORMATION
TO THE BRAIN.

I'M TOUCHING THAT SO GENTLY,

AND YOU CAN SEE ON YOUR SCREEN
WHERE IT'S MOVING.

THAT'S INCREDIBLE.
IT REALLY IS.

MOST ROBOTS ARE PRE-PROGRAMMED
TO DO THE TASKS THEY PERFORM,

BUT NATHAN'S TECHNOLOGY MEANS
THAT THE ROBOTS OF THE FUTURE

WILL BE ABLE
TO REACT INTELLIGENTLY

TO THE WORLD AROUND THEM.

THIS ROBOT IS GOING TO USE
ITS OWN SENSE OF TOUCH

TO FEEL OVER THAT
QUITE DELICATE PORCELAIN HEAD

THAT I BORROWED
FROM MY WIFE.

NOW, THAT'S AN ESSENTIAL SKILL
TO HAVE WITH OUR TOUCH,

'CAUSE WE USE THAT TO FEEL
THE SHAPE OF OBJECTS

WHEN WE PICK OBJECTS UP
OR TO RECOGNIZE OBJECTS.

THE SENSITIVITY OF THE
MECHANORECEPTORS IN OUR SKIN

MEANS OUR FINGERS
CAN EASILY TRACE AN OBJECT

WHILE APPLYING
CONTINUOUS PRESSURE.

BUT THIS IS ACTUALLY
A HIGHLY COMPLICATED TASK.

AND THIS HASN'T BEEN
PRE-PROGRAMMED AT ALL, HAS IT?

Lepora: NO,
IT'S COMPLETELY AUTONOMOUS.

IT'S FIGURING IT OUT FOR ITSELF
AS IT MOVES OVER THE HEAD.

NATHAN KNOWS THAT,
IN ORDER TO BE USEFUL,

THESE ARTIFICIAL FINGERTIPS NEED
TO BE INCREDIBLY SENSITIVE.

SO HE'S ADAPTED
HIS FINGERTIP DESIGN

TO MAKE A ROBOT HAND
WITH A SENSE OF TOUCH.

I'LL SHOW YOU ANOTHER EXPERIMENT
NOW WHERE WE'LL GET THE HAND

TO PICK UP
A VERY DELICATE OBJECT --

THIS ORIGAMI CRANE...[ Chuckling ] RIGHT.

...WITHOUT CRUSHING IT.

HERE IT GOES.

AS THE ROBOT'S FINGERS COME
INTO CONTACT WITH THE CRANE,

IT SENSES HOW MUCH PRESSURE
TO APPLY

WITHOUT BENDING THE PAPER --

SOMETHING WE CAN
DO INSTINCTIVELY

USING THE MECHANORECEPTORS
IN OUR SKIN.

OH, LOOK.
YEP.

SEE, IT HASN'T EVEN SQUEEZED
THE HEAD IN THAT MUCH.

IT'S BARELY TOUCHING IT.
I MEAN, THAT --

THAT MUST BE SO SENSITIVE.

THAT'S SO IMPRESSIVE.

IT'S BASICALLY THE LIGHTEST
POSSIBLE GRASP IT CAN DO

AND STILL HAVE ENOUGH SECURITY
TO HOLD THE CRANE.

THERE MUST BE
SO MANY APPLICATIONS

FOR THIS IN THE FUTURE.

WELL, THERE'S A FEW
PRESSING NEEDS

FOR THIS TYPE OF TECHNOLOGY --
PROSTHETIC HANDS.

SO, WITH THIS KIND
OF TECHNOLOGY,

YOU COULD, IN PRINCIPLE,
EMBED TACTILE SENSORS

WITHIN THE PROSTHETIC HAND
AND RESTORE A SENSE OF TOUCH

IF YOU WERE ABLE TO CONNECT IT
UP TO THE HUMAN NERVOUS SYSTEM.

ENDLESS POSSIBILITIES.YEAH, EXACTLY.

THERE REALLY ARE.

FINDING FOOD IS HIGH ON
EVERYONE'S LIST OF PRIORITIES.

BUT WHEN YOUR FOOD
DOESN'T WANT TO BE FOUND,

HAVING SHARP SENSES
CAN MAKE ALL THE DIFFERENCE.

AND ONE HUNTER'S SKIN
HAS ADAPTED

TO GIVE IT
A MASSIVE ADVANTAGE,

BECAUSE IT IS ABLE
TO SENSE ELECTRICITY.

THIS AMAZING PIECE OF BIOLOGY
IS THE SNOUT OF A SAWFISH.

WE CALL IT ITS ROSTRUM.

YOU CAN SEE THESE PROJECTIONS
ALL THE WAY ALONG.

THEY'RE MADE OF THE SAME STUFF
AS THINGS LIKE HUMAN TEETH,

BUT THEY'RE NOT QUITE TEETH
IN THE TRADITIONAL SENSE.

HOWEVER, WHAT'S AMAZING
ABOUT THE ROSTRUM OF A SAWFISH

IS THAT NOT ONLY
IS IT A DEADLY WEAPON,

BUT IT CAN ALSO DETECT
MINUTE ELECTRICAL IMPULSES.

SADLY, SAWFISH ARE
CRITICALLY ENDANGERED,

AND SO ARE RARELY SEEN
IN THE WILD.

THE SMALL FISH AND SHRIMP
THAT THEY LIKE TO FEAST ON

MIGHT TRY AND STAY HIDDEN.

BUT, LIKE ALL FISH, THEY
GIVE OFF TINY ELECTRIC CHARGES,

CREATING INCREDIBLY WEAK
ELECTRIC FIELDS.

AND THESE ARE A DEAD GIVEAWAY.

ON THE UNDERSIDE
OF THIS SAWFISH ROSTRUM

ARE THOUSANDS OF
TINY LITTLE PORES IN THE SKIN.

AND IF WE WERE TO PEER INSIDE
ONE OF THESE LITTLE PORES,

THEN YOU'D SEE
A TINY SENSORY ORGAN

CALLED AN AMPULLA OF LORENZINI.

NAMED AFTER THE 17th-CENTURY
ITALIAN PHYSICIAN,

THE AMPULLAE OF LORENZINI
CONSIST OF A NARROW TUNNEL

IN THE DERMIS, FILLED
WITH A CONDUCTIVE JELLY.

AT THE END IS A ROUND STRUCTURE
CALLED AN AMPULLARY BULB,

CONTAINING
ELECTROSENSITIVE CELLS.

AND THESE ARE ABLE TO PICK UP
WEAK ELECTRICAL SIGNALS --

SOMETHING AS FAINT
AS ONE BILLIONTH OF A VOLT.

THE SAWFISH IS ABLE TO SWIM
CLOSE TO THE SEABED,

WHERE IT USES ITS ROSTRUM
TO FORAGE FOR PREY.

AND WHEN IT DETECTS SOMETHING
LIKE A SHRIMP OR SMALL FISH,

IT'LL USE ITS ROSTRUM
TO DISLODGE IT BEFORE EATING IT.

BUT SAWFISH HAVE
A SECOND SENSORY ABILITY

HIDDEN IN THEIR SKIN --

ONE THEY SHARE WITH EVERY
SINGLE FISH ON THE PLANET.

IN THE SOUTHERN PACIFIC OCEAN,
A TORNADO IS FORMING.

IT ISN'T MADE OF SWIRLING AIR,
BUT MILLIONS OF FISH.

THIS IS A BAIT BALL,
A VAST SCHOOL OF FISH

THAT MOVES AS ONE
WHEN THREATENED BY PREDATORS.

THEY ARE ABLE TO REACT
IN UNISON TO ANY DANGER,

AT LIGHTNING SPEED,

SPLITTING AND RE-FORMING
BEHIND ONCOMING STRIKES.

GATHERING TOGETHER LIKE THIS
HELPS TO INTIMIDATE

AND CONFUSE
POTENTIAL ATTACKERS.

THEIR EYES HELP TO JUDGE
THE POSITION OF THEIR NEIGHBORS,

BUT MOVING WITH THIS LEVEL
OF PRECISION IS MADE FAR EASIER

BY A SPECIAL SENSORY SYSTEM
IN THEIR SKIN

CALLED THE LATERAL LINE.

MADE FROM A SERIES OF CANALS
RUNNING THE LENGTH OF THE BODY,

THE LATERAL LINE IS FILLED
WITH A JELLYLIKE SUBSTANCE

AND LINKS TO
THE SURROUNDING ENVIRONMENT

BY A NETWORK OF PORES.

THE WATER FROM OUTSIDE
MOVES THROUGH THE PORES,

STIMULATING
TINY HAIRLIKE STRUCTURES

IN THE WALLS OF THE CANALS,
CALLED NEUROMASTS.

ALL FISH USE THE LATERAL LINE
TO SENSE PRESSURE CHANGES

IN THE WATER AROUND THEM,

ALLOWING THEM TO PERCEIVE
THE SMALLEST OF MOVEMENTS

ALL THE WAY AROUND THEIR BODIES

AND ENABLING THEM TO MAINTAIN
A CONSTANT DISTANCE

FROM THE OTHER FISH
ON EITHER SIDE.

SCIENTISTS THINK
THIS HELPS FISH TO MIGRATE

IN HUGE SCHOOLS,
LIKE THESE SARDINES.

AS WITH ALL FISH, THEY RELY ON

THEIR ENHANCED PERCEPTION
THEY GET FROM THEIR SKIN.

IN THE FORESTS
OF SOUTHEAST ASIA,

ONE ANIMAL IS USING ITS SKIN

TO PLAY A FAR MORE CLANDESTINE
GAME OF CAT AND MOUSE.

THIS IS AN ASIAN PIT VIPER.

IT'S AN AMBUSH PREDATOR.

IT WAITS MOTIONLESS ON BRANCHES
FOR SMALL ANIMALS TO APPROACH.

TO HUNT IN THIS WAY, IT RELIES
ON AN INCREDIBLE SENSORY ABILITY

HIDDEN IN ITS SKIN.

JASON SKINNER IS
AN EXPERT SNAKE HANDLER.

WHAT A BEAUTIFUL SNAKE.
HE'S GORGEOUS, JASON, ISN'T HE?

Skinner:
YEAH, GREAT COLORS.

THESE SNAKES HUNT AT NIGHT,

AND THEY DO SO USING SPECIALIZED
PITS IN THEIR SKIN,

LOCATED BETWEEN THEIR EYES
AND THEIR NOSTRILS.

THESE PITS ARE SO SENSITIVE,
THEY ARE ABLE TO PICK UP

THE TINY HEAT SIGNATURE LEFT
BY THEIR PREY IN PITCH DARK.

INSIDE EACH PIT IS A MEMBRANE

WHICH HEATS UP
WHEN HIT BY INFRARED RADIATION,

LIKE THAT EMITTED
BY A WARM RODENT.

THIS HEAT IS CONVERTED INTO
ELECTRIC SIGNALS

WHICH ARE SENT
TO THE SNAKE'S BRAIN.

PIT VIPERS, PYTHONS,
AND BOA CONSTRICTORS

ALL HAVE THIS ABILITY.

AND WE'RE GOING TO TEST
JUST HOW SENSITIVE

THESE HEAT-SENSING PITS
REALLY ARE.

OKAY, JASON.
WHAT HAVE WE GOT HERE?

SO, WE'VE GOT
TWO PING-PONG BALLS

ATTACHED TO THESE
THREE-FOOT CANES.

[ Chuckling ] RIGHT.

SO WE'RE WELL OUTSIDE
THE STRIKING RANGE.

GOOD.

THE PING-PONG BALLS
ARE IDENTICAL,

APART FROM
ONE CRUCIAL DIFFERENCE.

ONE IS FILLED WITH COLD WATER,
THE OTHER WITH WARM.

AND I'VE GOT THE WARM ONE?YES.

OOH, YEAH. YEP.

IF DANGLED IN FRONT OF HIM
AT EQUAL DISTANCES,

WILL OUR VIPER BE ABLE
TO TELL WHICH IS WHICH?

I'M QUITE NERVOUS, JASON.

I'M NOT GOING TO LIE.
[ GULPS ]

EW!
[ CHUCKLES ]

AND HE DID! [ CHUCKLES ]

OH.
[ CHUCKLES ]

THAT WAS INCREDIBLY
QUICK, THOUGH.

THAT WAS SUCH A STRIKE.YEAH.

INSTANTLY, HE WENT
FOR THE WARMER ONE.

YEAH.

THERE WAS A VERY DEFINITE
RESPONSE THERE.

THE HEAD TURNED AWAY
FROM YOURS.

YOURS WAS MOVING
AS MUCH AS MINE.

AND IT'S AS CLOSE.
YEAH.

THERE'S A VERY DEFINITE
PREFERENCE THERE.

EVEN AT NIGHT,

WHEN THE PIT VIPER
CAN'T BE SEEN BY ITS PREY,

IT CAN STILL DETECT THEM.

AND WHEN THEY COME
WITHIN STRIKING RANGE...

HE DEFINITELY
MADE HIS CHOICE.

[ LAUGHS ]

...ONE THING IS CLEAR.

IF THE PING-PONG BALL
WAS A MOUSE,

IT WOULDN'T STAND A CHANCE.

SKIN IS CLEARLY ONE OF THE MOST
DYNAMIC ORGANS ON THE PLANET

AND A CRUCIAL PART
OF EVERY ANIMAL'S SENSES.

WE OFTEN TAKE SKIN FOR GRANTED,

YET WE'VE SEEN THAT IT GOES
WAY BEYOND A SIMPLE BARRIER

BETWEEN US
AND THE OUTSIDE WORLD.

AND WHAT FASCINATES ME MOST
ABOUT SKIN IS

THAT WE STILL HAVE
SO MUCH MORE TO FIND OUT.

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

CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS