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00:00Nuestro planeta es el más grande puzzle de vivienda en el universo.
00:05Un colección de mundos dentro de mundos.
00:08Cada uno un ecosistema de un ecosistema de la vida.
00:17Pero cómo funcionan?
00:20El intercambio web de relaciones y la influencia de las fuerzas naturales
00:26hace cada microworld complejo y único.
00:32Así que para descubrir sus secretos,
00:35tenemos que explorarlos uno por uno,
00:39untargar sus piezas interlocking,
00:42y finalmente revelar la pieza vital,
00:46la clave a la vida itself,
00:49hidden deep within
00:51cada uno de los microworldos.
00:56Over 99% of space available for life on Earth
01:05is in the sea.
01:07From top to bottom,
01:09the ocean contains a volume of water
01:11totaling 1.3 billion cubic kilometers.
01:16It is the single largest ecosystem
01:18on our planet.
01:20Far, far larger than any terrestrial ecosystem.
01:24It is also the least explored.
01:28We know more about the surface of Mars
01:30than we do about the majority
01:31of the marine environment.
01:34This microworld
01:35is Earth's inner space.
01:43Almost 90% of the ocean
01:45lies below a kilometer
01:47and over 75%
01:49is deeper than 3 kilometers.
01:53The very deepest part of the ocean
01:55lies at 11 kilometers
01:57and would easily engulf Mount Everest.
02:01More people have walked on the moon
02:04than have visited the deepest part
02:06of the ocean.
02:08Below the upper sunlit waters
02:10is a foreboding world
02:11of darkness
02:12and crushing pressures.
02:15Despite this,
02:16it's home to countless living things.
02:21Some of the most bizarre
02:23and unlikely creatures
02:24exist in the depths.
02:27Even though they make up
02:29the majority of creatures
02:30upon our planet,
02:31we know very little about them.
02:33The vast majority of these
02:36float or swim
02:37in the water column,
02:39a world without walls
02:40or sunlight.
02:44But even at the very bottom
02:46of the ocean,
02:46there is life,
02:48somehow making a living
02:49on a flat abyssal plain
02:51that spans the seabed
02:53between continents.
02:56Recent discoveries
02:58in the deep sea
02:58have astounded
03:00the scientific community
03:01and given us an insight
03:03into another world.
03:06So just how do creatures
03:08exist in the depths?
03:10What is the key
03:11that connects all these animals
03:13and allows them to survive
03:15in a cold,
03:16dark,
03:17hostile world?
03:23Our journey starts
03:24at the surface
03:25of the open ocean
03:26in the North Atlantic.
03:31As the sun sets,
03:32a large mass of animals
03:34appear as if from nowhere
03:35to feed at the sea's surface.
03:40Millions upon millions of them.
03:42A bizarre array of jellyfish
04:00trail stinging tentacles
04:01or ingest food
04:03directly into their bodies.
04:04Among the throng
04:12are animals
04:12that defy classification.
04:16A small fish
04:18takes cover
04:18inside the body
04:20of this pelagic jelly
04:21for a very good reason.
04:27Large shoals of squid
04:28arrive to hunt
04:29at the surface.
04:30By coming at night
04:36they can avoid
04:37the eyes
04:37of daytime predators.
04:40But not all animals
04:41need eyes to hunt.
04:47Spotted dolphins
04:48use sonar
04:49in the darkness
04:50targeting their prey
04:53with pinpoint accuracy.
04:55So where do all
05:01these night-time
05:02animals come from?
05:04They ascend
05:05from a world
05:06with little or no sunlight
05:07hundreds of metres down.
05:12Every night
05:13across the world's oceans
05:15100 million tonnes
05:17of these animals
05:17rise from the depths.
05:20It's by far
05:21the largest migration
05:22of animal life
05:23on the planet.
05:25They come to exploit
05:29the abundance of food
05:30in the surface waters.
05:32An abundance
05:33that exists
05:34because of something
05:35that happens
05:36at a microscopic level.
05:39Photosynthesis.
05:43Tiny algae
05:44and plants
05:44known as phytoplankton
05:46use light from the sun
05:47to turn soluble carbon
05:49into organic matter.
05:52This is known
05:53as primary production.
05:57The by-product
05:58of photosynthesis
05:59is oxygen.
06:01The waters up here
06:02are rich
06:03in this important element
06:04which is essential
06:06for life.
06:0850 billion tonnes
06:10of phytoplankton
06:11is produced
06:12in the upper oceans
06:13every year.
06:15During spring
06:16in the North Atlantic
06:17when conditions
06:18are right
06:18their blooms
06:19can be seen
06:20from space.
06:24It forms the basis
06:25of the marine food chain
06:27and is fundamental
06:28to all life
06:29in the ocean.
06:35Phytoplankton
06:35is fed on
06:36by tiny animals
06:37known as zooplankton.
06:38The most common
06:40are copepods.
06:43These crustaceans
06:44are little more
06:45than a millimetre long
06:46but they're the most
06:47numerous animal
06:48in the ocean.
06:51In the North Atlantic
06:52a cubic metre
06:53of seawater
06:54may contain
06:55in excess
06:56of 100,000
06:57of them.
06:59Using their legs
07:00they create currents
07:01which push
07:02the microscopic
07:03phytoplankton
07:04into their mouths.
07:05It's the sheer numbers
07:09of phytoplankton
07:10and copepods
07:11that draw
07:12deep sea animals
07:13up at night.
07:17When dawn returns
07:19the migration
07:19is reversed
07:20and the massive army
07:22of deep sea creatures
07:23sink back down
07:24into the darkness.
07:29If we're to follow them
07:31we must use
07:31a deep sea submersible
07:33capable of withstanding
07:34immense pressures.
07:37Without one
07:39we could not survive
07:40in their world.
07:45As we descend
07:46the sun's rays
07:47are absorbed
07:48and scattered.
07:51At 200 metres
07:53we leave
07:54the photic zone
07:54and enter
07:55the first layer
07:56of the deep sea
07:57the twilight zone.
08:01At this depth
08:02there's less than
08:04there's less than
08:04one percent
08:04of the sunlight
08:05at the surface.
08:07The pressure
08:08has increased
08:08twentyfold
08:09and the temperature
08:11has dropped
08:11to four degrees.
08:12but we find a world
08:15of extraordinary beauty.
08:28With nowhere to hide
08:30in the twilight zone
08:30the best disguise
08:32is transparency.
08:36Like this squid
08:37with a delicate
08:38glass-like body
08:40almost nine centimetres long
08:50this amphipod
08:51is a giant
08:52of its kind.
08:55It's completely transparent
08:57apart from its
08:58two enormous eyes
08:59and central nervous system.
09:01Another peculiar crustacean
09:06lives like a hermit
09:07within the stolen body
09:09of a jellyfish.
09:11This shell
09:12also houses
09:13her offspring.
09:15Her habit of pushing
09:16this protective shell
09:17around
09:17has led to the nickname
09:19of pram bug.
09:26The longest jellyfish
09:28of all
09:28are the giant
09:29siphonophores.
09:31Their tentacles
09:33lined with rows
09:34of stinging cells
09:35can reach
09:36forty metres long.
09:40Of the countless
09:41billions of animals
09:42living below
09:43the photic zone
09:44only a fraction
09:45migrate into
09:46shallower water
09:47to feed at night.
09:52So what do
09:53these animals
09:54feed on?
09:57Looking out
09:58of the window
09:58of our submersible
09:59we can see
10:00a constant rain
10:01of particles
10:02slowly drifting down
10:04around us.
10:07Known as marine snow
10:09this is a vital
10:10food source
10:11for everything
10:12living below
10:13200 metres.
10:15It rains down
10:16from the sunlit waters
10:17above.
10:20But what exactly
10:21is it?
10:22the density
10:25and exuberance
10:26of life
10:27at the surface
10:27of the ocean
10:28far outweighs
10:29that of the deep sea.
10:32This is where
10:33marine snow
10:34originates.
10:38A pod of
10:39common dolphins
10:39prepare to hunt.
10:43They're homing in
10:44on a shoal of mackerel
10:45swimming near the surface.
10:47Waiting
10:51are flocks
10:51of shearwaters
10:52hoping for the fish
10:53to be driven
10:54within range.
10:59The mackerel
11:00swim in a tight ball
11:01for safety.
11:03Working as a group
11:04the dolphins
11:04drive the bait ball
11:05upwards
11:06towards the
11:07waiting shearwaters.
11:10Shearwaters
11:10dive deep
11:11to grab their share.
11:14Caught
11:15between the birds
11:15and the dolphins
11:16the mackerel
11:17have nowhere to go
11:18and the frenzy
11:19builds.
11:25The commotion
11:26attracts a school
11:27of yellowfin tuna.
11:31These 2 meter
11:32long fish
11:33are capable
11:33of bursts
11:34of speed
11:34of 75 kilometers
11:36per hour.
11:37This doesn't deter
11:46the shearwaters
11:47which continue
11:48to feast
11:48on the shoal
11:49beneath.
11:58Eventually
11:59nothing remains
12:00of the huge
12:00shoal of mackerel
12:01except for scraps
12:03of flesh
12:03and scales.
12:07Leftovers
12:08faeces
12:09dead and dying
12:10plants and animals
12:11have only one way
12:12to go
12:13and that's
12:14down.
12:16This
12:17is marine snow.
12:23Millions of tiny
12:25creatures
12:25such as this sea spider
12:27filter the snow.
12:29It's feathery appendages
12:30gathering particles
12:31that are then drawn
12:32through its jaws.
12:38As a result
12:39the nutritional value
12:41of marine snow
12:41declines with depth.
12:45Feeding activity
12:46also uses up
12:48precious reserves
12:49of dissolved oxygen.
12:51Without photosynthesis
12:52to replace it
12:53oxygen decreases.
12:57So as we descend
12:59life begins to thin out.
13:01But it becomes
13:03ever more
13:04extraordinary.
13:08At 500 metres
13:10it appears
13:11completely dark
13:11to human eyes.
13:13The pressure
13:14is 50 times
13:15what it was
13:16at the surface
13:16and there's only
13:17the tiniest remnant
13:18of sunlight
13:19filtering through.
13:21Animals here
13:22have adapted
13:22to cope
13:23with extreme pressure
13:24and their eyes
13:25have evolved
13:25to become
13:26disproportionately large.
13:27The owner of this pair
13:31gazes ever upwards
13:32into the gloom
13:33seeking the silhouette
13:36of its prey
13:36against the faint
13:38downwelling light.
13:39To escape the attention
13:44of super sensitive eyes
13:46fish here
13:47have evolved
13:47light transmitting cells
13:49on the underside
13:50of their body.
13:53Using graphics
13:54we can see
13:54how these
13:55exactly match
13:56the background light.
13:59With this
13:59their silhouette
14:00breaks up
14:01making them appear
14:02almost invisible
14:03from below.
14:09By 800 metres
14:11the pressure
14:12is 80 times
14:13what it was
14:13at the surface
14:14and the temperature
14:16is below
14:173 degrees centigrade.
14:19Oxygen levels
14:20have also decreased
14:21to less than 5%
14:23of what they were
14:24at the surface.
14:26This is called
14:27the dead zone.
14:29But something
14:30still manages
14:31to live here.
14:33Vampyra toothis
14:38infernalis
14:39the vampire squid
14:41from hell.
14:43Vampire squid
14:44have lived in the depths
14:46for 200 million years.
14:49They share
14:50physical characteristics
14:51with octopus
14:52and squid
14:52and are thought
14:54to be a missing link.
14:56Highly specialised
14:58blood cells
14:58allow them to live
15:00in this low oxygen
15:01environment.
15:03Despite its hellish name
15:04and fierce look
15:05vampire squid
15:07are placid creatures
15:08averaging only
15:0928 centimetres
15:10in length
15:11and are completely
15:12harmless.
15:17Get too close
15:18to a vampire squid
15:19and it puts on
15:20the most amazing
15:21light display.
15:26Bioluminescent bacteria
15:27in its arms
15:27and on its body
15:28dazzle and confuse
15:29potential predators.
15:33And with that
15:34it disappears
15:36into the darkness.
15:42Beyond a thousand metres
15:44we enter the dark zone
15:46where not even
15:47the faintest remnant
15:48of sunlight can penetrate.
15:49Yet when we switch off
15:52the submersible lights
15:53we see
15:54bioluminescence.
15:56There is life
15:57even here.
16:00Furthermore
16:00oxygen levels
16:01have risen.
16:04And that's because
16:05we're now in
16:05a deep water current
16:07called the
16:07Great Ocean Conveyor.
16:11When surface water
16:13enriched in oxygen
16:14by photosynthesis
16:15meets polar ice
16:16it sinks
16:19beyond the first
16:20thousand metres
16:21and flows
16:22towards the equator
16:23carrying oxygen
16:26to the very
16:27deepest corners
16:28of the abyss.
16:31Here in the dark zone
16:33we find the real
16:34monsters
16:35of the deep.
16:43Oxygen
16:44may be plentiful here
16:45but food
16:46is scarce
16:47and bioluminescence
16:48is the only light
16:49available.
16:53Most of the flashing
16:54lights we can see
16:55come from deep water
16:56copepods.
16:57They provide food
16:58for other
16:59deep sea animals.
17:04To a hunting squid
17:06this flashing light
17:07looks like food
17:08but in the darkness
17:10nothing is what it seems.
17:16food by bioluminescent
17:18bacteria living
17:19in the antenna
17:20of an angler fish.
17:23The angler fish
17:24can easily accommodate
17:25the squid
17:26in its extendable stomach.
17:30Many deep sea fish
17:31have disproportionately
17:32large stomachs.
17:35In this sparse
17:37cold world
17:37it might be many days
17:39between meals.
17:40natural selection
17:45has produced lures
17:46of all shapes
17:47and sizes
17:48each used
17:50to tempt prey
17:51to within easy reach.
17:56This wolf trap angler
17:58has a lure
17:58hanging amidst
18:00its formidable teeth.
18:01In this dazzling
18:04battlefield
18:05prey have developed
18:06some surprising
18:07methods of escape.
18:10Deep water shrimps
18:11confuse attackers
18:12by spinning
18:13and releasing
18:14a bioluminescent glue.
18:19While the shrimp
18:20makes its escape
18:21the glue sticks
18:22leaving the attacker
18:24glowing in the face
18:25of its own enemies.
18:26The shrimp's red colour
18:31is also
18:32its camouflage.
18:34In the dark zone
18:36the eyes of most predators
18:37are tuned to the blue
18:38or green
18:39of bioluminescent light.
18:42So to them
18:43a red shrimp
18:44is almost invisible
18:46but not to one
18:48deep water resident
18:49the dragon fish.
18:54This predator
18:55has evolved
18:56red bioluminescent
18:57headlights
18:57below its eyes
18:58that are sensitive
19:00to red light.
19:03Its target
19:04doesn't see it
19:05until it's too late.
19:12Descending ever further
19:14we eventually
19:15reach the sea floor
19:16six kilometres down.
19:21The pressure here
19:22is more than
19:23600 times
19:24that of the surface
19:25and temperatures
19:26are close
19:27to zero degrees.
19:31It takes many weeks
19:33for marine snow
19:34to descend this far.
19:37Here it forms
19:38a vast blanket
19:39of soft sediment
19:40over a kilometre thick
19:41the abyssal plain.
19:45These plains
19:46cover a third
19:46of the Earth's surface.
19:49By the time
19:50the snow gets here
19:51it only contains
19:52a fraction
19:52of its original energy.
19:57Under such extreme conditions
19:59we would expect
20:00the abyssal plain
20:01to be lifeless.
20:03But even here
20:04we find life.
20:17Deep water sea urchins
20:19must sift large quantities
20:21of sediment
20:22to survive.
20:23The strange balloon-like
20:25sacks on their backs
20:26may be filled
20:27with a noxious substance
20:28to deter predators.
20:31Abyssal shrimps
20:32use their elongated antennae
20:34to feel for tiny particles
20:35of food floating around
20:37in the darkness.
20:41Life here may be sparse
20:43but because the abyssal plains
20:45cover such a large area
20:46of the Earth's surface
20:47they're home
20:48to some of the most
20:49numerous animals
20:50on the planet.
20:53Fish have been found
20:54living
20:55as far down
20:56as 8 kilometres.
20:58This rat tail
21:00is one of the most
21:01common species.
21:03The white spots
21:04around its eyes
21:05are paws
21:05sensitive to the
21:07slightest movement
21:08vital in the inky
21:09blackness
21:10of the abyssal plain.
21:11Just occasionally
21:16in this nutrient-poor
21:17environment
21:18a feast arrives.
21:20A dead tuna
21:21doesn't lie unnoticed
21:22for long.
21:25This deep-sea congoreal
21:26has picked up the scent
21:28from far off.
21:30Down here
21:31a good sense of smell
21:33is a lifesaver.
21:37The carcass
21:38also attracts
21:39the attention
21:40of one of the deep's
21:41most elusive creatures
21:43the six-gilled shark.
21:47These rarely seen sharks
21:48are active hunters
21:50and can grow
21:51to 5 metres in length.
21:53This type of shark
21:55has been around
21:56for at least
21:57200 million years.
21:59There are many opportunistic
22:03scavengers
22:04on the seafloor.
22:06They'll detect
22:07even the tiniest scent
22:08in the water
22:08and will move in
22:10from miles around.
22:12Deep-sea crabs
22:13and scavenging
22:14arrow-tooth eels
22:15are soon joined
22:16by giant isopods.
22:19Related to wood lice
22:20these strange-looking
22:22monsters
22:22are half a metre long.
22:24Within hours
22:28the carcass
22:29is stripped
22:30to nothing.
22:32Even the bones
22:33are eating.
22:36Where food is
22:36at a premium
22:37nothing is wasted.
22:39When life was first
22:47discovered thriving
22:48in the abyss
22:49it was a complete surprise.
22:51But the depths
22:52revealed another secret
22:54that shook the foundations
22:56of scientific thinking.
23:00A secret that lay here
23:02on the mid-ocean ridges.
23:05These undersea mountain ranges
23:07are the longest
23:08geological structure
23:09on earth.
23:11Part of a continuous
23:1265,000 kilometre chain
23:15extending across
23:16the face of the planet.
23:19This is the front line
23:20of plate tectonics.
23:23Here the seafloor
23:24is parting
23:25at about 2 centimetres
23:27a year.
23:29When submersibles
23:31first visited the ridges
23:32in the 1970s
23:33they found towering
23:35basalt chimneys
23:36known as black smokers
23:38spewing hot water
23:40and hydrogen sulfide
23:41from deep inside
23:43the earth's crust.
23:44At 400 degrees centigrade
23:46these smokers
23:47are hot enough
23:48to melt lead.
23:51It was here
23:52that they made
23:52one of the most important
23:54scientific discoveries
23:55of the 20th century.
23:58Dense populations
23:59of marine animals
24:00living in a toxic
24:02deep sea environment
24:03without any reliance
24:05on energy
24:06from the sun.
24:10In one location
24:11they found swarms
24:12of deep sea shrimps.
24:16In another
24:17they found bizarre
24:18polychaete worms
24:19tolerating water temperatures
24:21of 80 degrees centigrade.
24:22No other animal
24:25on earth
24:26is known to exist
24:27at such temperatures.
24:30Clams,
24:31crabs
24:32and even fish
24:33live in large numbers
24:34around the vents.
24:38How do all these animals
24:40survive
24:41in such densities
24:42in total darkness
24:43under conditions
24:44of scalding heat
24:46and intense pressure?
24:47The answer lies
24:53in mats of bacteria
24:55that coat the chimneys.
24:58These bacteria
24:59are primary producers.
25:02They substitute
25:03for phytoplankton
25:04in a world
25:05without sunlight.
25:07Drawing chemical energy
25:08from the vent
25:09they convert
25:10soluble carbon
25:11into organic matter
25:12a process
25:13known as
25:14chemosynthesis.
25:17It is this bacteria
25:20not marine snow
25:21that is the basis
25:22of the hydrothermal vent
25:24food chain.
25:27But in order
25:28to exploit this resource
25:29they've had to adapt
25:31to living with
25:31high levels
25:32of hydrogen sulfide
25:33a poison
25:34as potent as cyanide.
25:39These giant tube worms
25:41approach 2 metres long
25:43and they incorporate
25:44vent bacteria
25:45within their bodies.
25:47The bacteria
25:50provide the worms
25:51directly with food
25:52and energy.
25:56Despite the toxic
25:58environment
25:58there's thousands
25:59of times
26:00more life
26:01at hydrothermal vents
26:02than at the abyssal plain.
26:04the sheer scale
26:11and diversity
26:11of creatures here
26:12has opened up
26:13a whole new
26:14branch of research.
26:16New species
26:17are being discovered
26:18on every single dive.
26:22So here
26:23far away
26:24from the sun's rays
26:25is a self-sufficient
26:26community
26:26thriving
26:27in the most
26:28hostile of environments.
26:29this may be a glimpse
26:33of how life exists
26:35on other planets.
26:36Our journey
26:43into the deep sea
26:44micro world
26:44has revealed
26:45some of the most
26:46unusual life forms
26:47on earth.
26:50What we've found
26:51at every level
26:51is a diverse community
26:53of animals
26:54adopting unique ways
26:55of surviving.
26:59Many of these creatures
27:00live well beyond
27:01the sun's rays
27:02but there's one thing
27:08that ties them
27:08all together
27:09wherever they dwell
27:10the need for oxygen.
27:15Even the bacteria
27:17that form the basis
27:18of hydrothermal
27:18communities
27:19need oxygen
27:20to make organic matter
27:22and oxygen
27:24can only be produced
27:26in one way
27:27as a byproduct
27:29of photosynthesis.
27:31a process
27:33driven
27:33by the sun.
27:42Even though
27:43the majority
27:43of ocean creatures
27:44remain oblivious
27:45to its presence
27:46ultimately
27:48it is the sun
27:49that allows life
27:50to exist
27:50in the depths
27:51of the abyss.
27:54The sun
27:55connects all life
27:56from the surface
27:58to the deepest
28:01reaches
28:01of the sea.
28:04We still know
28:05more about our
28:06neighbouring planets
28:07than we do
28:07the deep sea.
28:10This inner space
28:11remains the last
28:12frontier on earth.
28:14A frontier
28:15that continues
28:16to evoke awe
28:17and wonder.
28:20Who knows
28:20what discoveries
28:21are yet to be made
28:22in the largest
28:24but least explored
28:26of all
28:27our
28:27microworlds.
28:34Absolutely stunning.
28:37Later today
28:37here on BBC2
28:38at 6.30
28:39we travel to Florida
28:40America's
28:41animal paradise
28:42to witness
28:43more astonishing
28:44wildlife
28:44caught on camera.
28:46Next this morning
28:46to the skies
28:47for our film
28:48planes.
28:49Planes.
28:49Planes.
28:49Planes.
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29:14Planes.
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