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01:10Winter in Antarctica.
01:13The temperature has dropped to minus 70 degrees centigrade
01:17and winds of 120 miles an hour blow across the desolate ice scape.
01:22Antarctica is in continuous darkness.
01:25Only its fringes see the bleak winter light.
01:28The sea freezes over for hundreds of miles,
01:31effectively doubling the size of the continent.
01:35In winter, the Antarctic is a very lonely place.
01:40As the temperature plummets and the sea ice forms,
01:43most of the wildlife that came down here
01:45to take advantage of the brief summer season
01:48is forced to retreat north again.
01:51Practically nothing stays,
01:53for to survive in the deep south at its most bitterly hostile
01:57requires a very special animal with very special adaptations,
02:02and just such a creature is the Weddell seal.
02:07No other mammal lives throughout the year as far south as this.
02:13These seals are just 800 miles from the pole
02:17and they stay here winter and summer.
02:20Like all Antarctic seals,
02:22they have a thick layer of blubber to insulate them from the cold,
02:25but the real key to their success in surviving here
02:28is their ability to keep open holes in the ice
02:32so that they have access to the sea the year round.
02:37The holes made by the seals are the only things
02:40that break the white monotony over hundreds of square miles of sea ice.
02:45The seals, with no escape to the open ocean,
02:48are forced to stay near the holes.
02:51Each is a gateway to and from the underwater world
02:55in which the seals hunt and find shelter.
03:00Underwater, the temperature never drops below minus 1.8 degrees.
03:05The seals retreat down here during the worst winter storms
03:09and so keep comparatively warm.
03:19When you dive beneath the ice,
03:22you enter, within seconds, a totally different world.
03:27Here, within a foot or so of the gale-swept,
03:30savagely cold wilderness above,
03:32illuminated only by the dim blue light filtering through the ceiling of ice,
03:37there is stability, peace, and an eerie, unforgettable beauty.
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04:25Animals need special adaptations
04:27to live in water that is below zero centigrade.
04:31Most fish would explode if they touched this glacier wall.
04:35Crystals would immediately form in their cells.
04:38These survive because their tissues are loaded with antifreeze.
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04:49Life beneath the ice, compared with the white desert above,
04:53is extraordinarily rich.
04:55There are all kinds of invertebrates, including giant jellyfish.
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05:27It's a very sheltered place,
05:29for the permanent sea ice overhead
05:31provides year-round protection from waves and storms.
05:36But food is scarce,
05:38and many of these creatures have become scavengers.
05:41These starfish make a meal of seal feces.
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05:49Whale seals can dive to 750 meters, possibly more, in search of food.
05:55At these depths, in permanent darkness,
05:58they encounter a world dominated by stalked sponges.
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06:06Growing extremely slowly in the cold,
06:09the Antarctic invertebrates become giants.
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06:21Returning from depths where a human being would be crushed,
06:24seals surface suffering none of the effects of deep diving
06:28that can cripple human swimmers.
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06:39October in the far south.
06:42Female Weddell seals haul out on the sea ice to give birth.
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06:55Imagine the shock of leaving a womb at plus 37 degrees centigrade
07:00and being dropped on the ice into a world at minus 20.
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07:34The pup has to suckle and build a layer of blubber as fast as possible.
07:39It usually manages to double its weight in 10 days,
07:42for Weddell milk is 60% fat,
07:45one of the richest produced by any mammal.
07:49Remarkably, after one week, the pup is ready for a swim.
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08:08The mother is anxious to get her pup accustomed to the water
08:11before the weather deteriorates.
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08:27At this time, more than any other, breathing holes are jealously guarded.
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09:02Weddells have an especially wide gape and long canine and incisor teeth
09:07which enable them to scrape away the ice that is constantly forming
09:11and threatening to close their breathing holes.
09:15Their teeth aren't impervious to this wear and tear
09:18and are gradually worn down so that eventually the seal can't eat.
09:23As a consequence, Weddells die at about 20 years,
09:27half the age of other Antarctic seals.
09:31A male defends an underwater territory
09:34and mates with all the females that use his breathing holes.
09:37It's an effective way of acquiring a harem
09:40because females must have a refuge below the ice
09:43from the extremes of the winter weather.
09:50It might seem that there could not be a more harsh existence than this,
09:54but the environment here is comparatively constant
09:57and these seals are adapted to it,
10:00protected by a coat of dense hair
10:02and insulated by blubber immediately beneath the skin.
10:07Indeed, Weddells do far better than most other seals.
10:12If they are sufficiently fattened in the six weeks before their wean,
10:1695% of pups will survive.
10:26These seals, the most southerly in the world,
10:29live in the shadow of the largest active volcano in Antarctica,
10:33Mount Erebus.
10:35Mount Erebus
10:40Erebus is a mountain of extremes.
10:43In the crater, molten lava bubbles away at 600 degrees centigrade,
10:48and yet, on the summit, temperatures rarely rise above minus 45 degrees.
10:54Even here, there is life.
10:56The heat of the volcano produces steam
10:59that rises to the rim and melts the snow and ice,
11:02leaving bare patches of rock, home to heat-loving bacteria and algae.
11:07Another extraordinary example of how life can survive
11:11in the most extreme conditions on Earth.
11:14Mount Erebus
11:30Behind Mount Erebus, the transantarctic mountains stretch in a long, broad band.
11:36They're the most extensive range on the continent,
11:39running for some 2,000 miles and separating the great east and west ice caps.
11:49Although many of the peaks are over 4,000 meters high,
11:53most of the range is blanketed by vast glaciers, which fill the valleys.
12:10Mount Erebus
12:16Hidden among the transantarctic mountains
12:19is one of the continent's greatest surprises, the dry valleys.
12:23Here is the largest area of bare rock to be found in Antarctica.
12:30It's so arid that falling snow soon evaporates and never builds up.
12:36The valley below me is the driest place on Earth.
12:39It hasn't snowed or rained here for centuries.
12:42In winter, the temperature falls to minus 52 degrees centigrade
12:46and the ground is permanently frozen to a depth of almost half a mile.
12:50In fact, conditions are so extreme
12:53that when scientists came to design a vehicle to work on the surface of Mars,
12:58they brought it to this valley in order to test it.
13:01And a clue as to the factor that creates these conditions
13:05lies in the extraordinary shape of these boulders.
13:09Although they are solid granite,
13:11they've been carved by savage winds that scream down off the ice cap.
13:18These winds are so dry that they instantly absorb any moisture in the air,
13:23and by doing so, they will desiccate and preserve organic tissues.
13:27This mummified crabeater seal, about 70 miles from the sea,
13:32has probably been lying here for 3,000 years or more.
13:38You might suppose that a place
13:41that can freeze dry the body of seals for centuries
13:45would be totally without life.
13:48But even in these extreme conditions, life does exist.
13:54Pick the right sort of rock.
13:56This is a light, porous sandstone.
13:59Give it a hit.
14:04And there, a millimetre beneath the surface,
14:07within the actual fabric of the rock,
14:09a band of green, the colour of life.
14:14It's a lichen that has managed to penetrate
14:17and colonise the microscopic spaces between the grains of the porous rock.
14:21It's the only place where it can survive
14:24in these arid, desert-like conditions.
14:30Above the dry valleys, held back by the transantarctic mountains,
14:34stretches the ice cap itself.
14:37This is the Antarctic Plateau, 3,000 metres high.
14:43There can be no more forbidding, hostile, desolate places to be
14:49than up here on the Antarctic Plateau.
14:53It's not just that human life here seems insignificant,
14:57it seems totally irrelevant.
15:01A few spots of lichens may grow on top of the glacier,
15:08a few spots of lichens may grow on boulders
15:12to within 200 miles of the South Pole,
15:16and in the summer,
15:18maybe one or two particularly adventurous snow petrels
15:22will come up here to try a nest.
15:26But come the winter, absolutely nothing living moves
15:31up here on the Antarctic Plateau.
15:38Even in summer, it's always winter here,
15:42with temperatures averaging minus 30.
15:45One and a half times the size of Australia,
15:48this is the largest area of lifeless wilderness in the world.
15:53Snow petrels, brief visitors here in summer,
15:56are forced to spend the winter hundreds of miles to the warmer north
16:00at the edge of the frozen sea.
16:08This is the frontier between life in the ocean
16:12and a desert of ice where almost no animals dare go.
16:16But one creature has to cross it, the emperor penguin.
16:32In May, when the freezing waters
16:35and the cold winter temperatures force other animals
16:38to retreat to warmer conditions in the north,
16:41emperor penguins head south.
16:56They make their way to a number of traditional nesting sites.
17:00In this one alone, there may be 25,000 birds.
17:06Emperors are unique.
17:10They are the only birds to lay their eggs directly on ice.
17:26Just hours after the female has produced her single egg,
17:30the male takes it over.
17:32The transfer has to be quick if the egg is not to freeze.
17:39The male maneuvers it into a brood pouch lined with blood vessels
17:44that keep the egg 80 degrees warmer than the outside temperature.
17:48There, under a flap of skin, it's sealed away for the winter.
17:58When the egg is safely inside the male's pouch,
18:01the females are free to go,
18:03and they start the long trek back across the sea ice
18:06to the open ocean,
18:08leaving their partners to face the coldest conditions on earth.
18:13TENSE MUSIC
18:30With temperatures of 70 below and in terrible storms,
18:34the penguins huddle tightly together for warmth.
18:37No other adult penguins are so tolerant of one another,
18:41but for emperors, this is the key to survival.
18:50The cooperation is not random.
18:53Those most exposed on the windward side
18:56move down around the huddle to the more sheltered side.
19:00This ensures that every bird gets its fair share of warmth in the middle
19:04and, in time, takes its turn in enduring the brunt of the Antarctic weather.
19:12TENSE MUSIC
19:20As midwinter approaches,
19:22the sun disappears below the horizon for the last time this season.
19:26A month of total darkness lies ahead.
19:30TENSE MUSIC
19:38Above the huddle, the southern lights, the aurora australis,
19:43blaze across the winter sky.
19:47These spectacular displays occur
19:50as subatomic particles travelling through space
19:53enter the Earth's magnetic field.
20:00TENSE MUSIC
20:17As winter recedes, the huddles begin to break up
20:21and heat that was trapped within them for so long escapes.
20:25These males, who have not eaten for 115 days,
20:30are close to death by starvation.
20:47As the sun returns to the southern hemisphere,
20:50the female emperors, sleek and fat from months of feeding at sea,
20:54begin the long march back to the rookery.
20:57The sea ice is now at its fullest extent
21:00and they may have to walk 100 miles to reach their colony.
21:14By now, the eggs have hatched
21:16and the tiny chicks are awaiting their first feed.
21:21Each female times her return
21:24to coincide with the hatching of her chick.
21:27A male, having starved for so long, can give the chick only one meal,
21:31no more than a milky secretion from his gut wall.
21:34If his partner doesn't return within ten days of the chick's hatching,
21:38he will be forced to abandon it
21:40and head for the sea to find food for himself.
21:51CHICK CALLS
21:58It's a noisy time in the colony.
22:01The courtship calling that took place before winter now brings its reward.
22:06After a separation of over three months,
22:08a bird can still recognise its partner's call.
22:14CHICK CALLS
22:20CHICK CALLS
22:30When they find one another, the pair perform their greeting ritual,
22:34so making sure that there hasn't been a case of mistaken identity.
22:38And then the female gives their chick its first proper meal,
22:42half-digested fish.
22:50CHICK CALLS
22:53She's very eager to take charge of the chick,
22:56but the male, having cared for it for so long,
22:59is reluctant to give it up.
23:01She has literally to push him back to get him to release it.
23:10CHICK CALLS
23:14The transfer is a tricky manoeuvre that must be done fast.
23:18A chick left on the ice for only two minutes will die.
23:26CHICK CALLS
23:30CHICK CALLS
23:47The males, after their four-month ordeal,
23:50near to starvation and desperate to feed,
23:53have to walk 100 miles or so back to the open sea.
24:00Mothers and chicks spend the next few weeks
24:03learning each other's call and establishing a strong bond
24:06that ensures that they will recognise one another in the months ahead
24:10when she returns from feeding trips.
24:23It's early spring and the weather is still variable.
24:30CHICK CALLS
24:36Severe storms are a real threat to the chick's survival.
24:40One that has been abandoned seeks shelter from passing adults.
24:44One of them seems interested,
24:46but the vital bond between parent and chick simply isn't there,
24:50and eventually the adult walks off.
24:54CHICK CALLS
24:57In fact, the adults do have a strong instinct to protect chicks,
25:01so much so that birds that have not managed to breed
25:04will try to take possession of a stray or abandoned chick.
25:08But this fostering never succeeds
25:10because the adult has no partner to help in rearing the waif.
25:16CHICK CALLS
25:23CHICK CALLS
25:41These desperate, unpartnered penguins
25:44will sometimes fight over a chick and crush it to death.
25:53CHICK CALLS
26:03Mortality is high.
26:05Many eggs don't hatch,
26:07and of those that do, 25% die in the first few months.
26:12Those that survive have to grow fast and fledge
26:15before the sea ice on which they live breaks up beneath them.
26:23CHICK CALLS
26:41These chicks take five months to rear.
26:44Only by incubating the eggs through the harsh Antarctic winter
26:48so that the chicks hatch at the very beginning of the short summer
26:51is it possible for the emperors to breed every year.
26:57It was to collect an emperor penguin's egg like this
27:00that men made the first-ever land journey
27:04in the bitter cold darkness of the Antarctic winter.
27:07Bill Wilson, the naturalist on Captain Scott's expedition,
27:11was fascinated about the evolutionary origin of birds,
27:15and he was convinced that the embryo in an egg like this
27:18would provide conclusive evidence of the link
27:21between the feathers of birds and the scales of reptiles.
27:25So, on June 12th, 1911, in the middle of winter,
27:29he and two companions left Captain Scott's hut here on Cape Evans
27:34and set out for the emperor penguin colony
27:38on the other side of Mount Erebus, 65 miles away.
27:42It was a trip that became known with some justice
27:46as the worst journey in the world.
27:49The weather was abominable.
27:51Their clothes and harnesses froze solid,
27:54and all three suffered terrible frostbite
27:56as they hauled their sledges over heavily crevassed terrain.
28:00On the return journey, they lost their tent in a violent storm.
28:04By a miracle, they found it again and then made it back to the hut alive.
28:09They brought back three eggs and three emperor penguin skins,
28:14one of which is still here in Scott's hut,
28:16preserved by the Antarctic cold.
28:19Although the connection between birds and reptiles is no longer in doubt,
28:23the eggs didn't provide the evidence that Wilson thought they would.
28:27But even so, the journey remains one of the great epic stories
28:31in the annals of polar exploration.
28:34In the next programme, we'll look at the history
28:37of Antarctic exploration in more detail
28:40and also see how people today survive life in the freezer.
29:10Transcription by ESO, translation by —