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Antarctica.
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00:00:39,290 --> 00:00:44,962
The coldest, the harshest,
and the most remote continent on Earth.
3
00:00:52,136 --> 00:00:56,807
No human being has ever descended
into the depths that surround it...
4
00:01:00,353 --> 00:01:01,646
...until now.
5
00:01:09,362 --> 00:01:14,325
The deep ocean is as
challenging to explore as space.
6
00:01:17,370 --> 00:01:20,081
We know more about the surface of Mars
7
00:01:20,164 --> 00:01:23,209
than we do about
the deepest parts of our seas.
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00:01:47,858 --> 00:01:51,696
Now we can dive
these uncharted depths,
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00:01:51,779 --> 00:01:54,282
to discover what secrets lie beneath.
10
00:02:30,776 --> 00:02:35,114
Sinking down beside
the submerged wall of an iceberg,
11
00:02:35,239 --> 00:02:37,908
we enter an unforgiving world.
12
00:02:48,627 --> 00:02:52,006
These waters
are the coldest on Earth.
13
00:02:56,761 --> 00:02:58,888
As we descend into the deep,
14
00:02:58,971 --> 00:03:01,849
the pressure increases relentlessly.
15
00:03:20,034 --> 00:03:23,204
And the light from above
all but disappears.
16
00:03:30,878 --> 00:03:32,463
Yet, incredibly...
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00:03:36,801 --> 00:03:38,636
there is life here.
18
00:04:01,033 --> 00:04:02,493
We might have expected
19
00:04:02,576 --> 00:04:05,746
that deep beneath
the surface of the Polar seas,
20
00:04:06,831 --> 00:04:09,834
the waters would be truly barren.
21
00:04:17,508 --> 00:04:22,555
But, in fact, we find life here
in unimaginable abundance.
22
00:04:37,194 --> 00:04:41,740
Nor is such great abundance
confined to Antarctic waters.
23
00:04:45,077 --> 00:04:47,288
Currents carry this richness
24
00:04:47,371 --> 00:04:51,542
into the depths of almost
every ocean around the world.
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00:04:55,713 --> 00:04:58,215
Astonishingly, in the deep sea,
26
00:04:58,299 --> 00:05:02,219
there is more life
than anywhere else on Earth.
27
00:05:30,748 --> 00:05:32,833
The sunlight fades,
28
00:05:33,292 --> 00:05:34,960
and the seas darken.
29
00:05:38,923 --> 00:05:42,259
Here, in the Pacific, 200 metres down,
30
00:05:42,343 --> 00:05:45,179
we enter an alien world.
31
00:05:47,640 --> 00:05:50,059
The Twilight Zone,
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00:05:50,142 --> 00:05:52,978
a sea of eternal gloom.
33
00:06:01,028 --> 00:06:03,322
There are strange creatures here.
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00:06:04,949 --> 00:06:06,283
A pyrosome.
35
00:06:07,618 --> 00:06:12,665
A tube of Jelly two metres long
that dwarfs a visitor from above,
36
00:06:13,791 --> 00:06:16,001
an oceanic whitetip shark.
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00:06:24,969 --> 00:06:29,223
Only a tiny amount of light
filters down this far.
38
00:06:34,061 --> 00:06:39,233
Survival here means making the most
of every last glimmer.
39
00:06:48,701 --> 00:06:49,994
A swordfish.
40
00:06:59,336 --> 00:07:04,842
Its eyes are as big as tennis balls
to help it see in the perpetual dusk.
41
00:07:10,389 --> 00:07:14,393
A squid, but this is one
that lives only here.
42
00:07:15,769 --> 00:07:19,064
Its right eye
looks permanently downwards.
43
00:07:21,442 --> 00:07:24,778
But its left eye is much bigger
and trained upwards
44
00:07:24,903 --> 00:07:29,033
to detect the silhouettes of prey
swimming nearer the surface.
45
00:07:31,243 --> 00:07:34,622
No wonder it's nicknamed
the "cock-eyed squid".
46
00:07:41,211 --> 00:07:43,255
And even stranger,
47
00:07:45,549 --> 00:07:47,885
this is barreleye,
48
00:07:50,804 --> 00:07:53,641
a fish with a transparent head,
49
00:07:54,391 --> 00:07:56,310
filled with jelly,
50
00:07:56,393 --> 00:07:59,563
so that it can look up
through its skull.
51
00:08:17,247 --> 00:08:20,626
We now know that
the Twilight Zone is a refuge
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00:08:20,751 --> 00:08:25,756
for an incredible 90%
of all fish in the ocean.
53
00:08:31,762 --> 00:08:36,016
Only at night,
do vast shoals of lanternfish
54
00:08:36,100 --> 00:08:40,270
migrate to the surface
to feed on tiny plankton.
55
00:08:51,281 --> 00:08:54,952
By day, they retreat back down here.
56
00:09:10,884 --> 00:09:13,011
Humboldt squid.
57
00:09:25,691 --> 00:09:28,861
Two metres long
and 50 kilos in weight.
58
00:09:34,241 --> 00:09:37,661
Like most squid,
they're voracious hunters.
59
00:09:45,919 --> 00:09:47,337
There are hundreds of them.
60
00:09:58,849 --> 00:10:01,268
They found a shoal of lanternfish
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00:10:01,351 --> 00:10:05,355
hiding 800 metres down,
off the coast of South America.
62
00:10:18,368 --> 00:10:21,205
Their tentacles are armed
with powerful suckers
63
00:10:21,288 --> 00:10:23,415
with which they grab their prey.
64
00:10:40,265 --> 00:10:43,477
And when there are
no more lanternfish to be found,
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00:10:45,604 --> 00:10:47,898
they turn on each other.
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00:10:59,284 --> 00:11:03,080
This squid has caught
a smaller one in its tentacles.
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00:11:07,918 --> 00:11:10,087
To hide its capture from the rest,
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00:11:10,170 --> 00:11:12,923
it releases a smokescreen of black ink.
69
00:11:26,270 --> 00:11:29,314
But then, an even
bigger one challenges it
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00:11:36,196 --> 00:11:38,615
and steals its catch.
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00:11:47,791 --> 00:11:49,167
The Twilight Zone
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00:11:49,293 --> 00:11:52,379
is the Humboldt squid's
favourite hunting ground.
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00:11:54,298 --> 00:11:55,799
They seldom go deeper
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00:11:57,342 --> 00:12:00,804
into the world
of perpetual blackness below.
75
00:12:06,226 --> 00:12:08,228
The Midnight Zone.
76
00:12:19,323 --> 00:12:22,117
Two-thirds of
a mile from the surface,
77
00:12:22,200 --> 00:12:24,494
beyond the reach of the sun.
78
00:12:30,000 --> 00:12:32,502
A giant black void
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00:12:32,586 --> 00:12:36,548
larger than all the rest
of the world's habitat's combined.
80
00:12:42,012 --> 00:12:43,680
There's life here,
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00:12:45,182 --> 00:12:47,017
but not as we know it.
82
00:12:58,528 --> 00:13:00,280
Alien-like creatures
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00:13:00,364 --> 00:13:03,241
produce dazzling displays of light.
84
00:13:16,129 --> 00:13:19,299
Nearly all animals
need to attract mates
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00:13:19,383 --> 00:13:20,926
and repel predators.
86
00:13:23,887 --> 00:13:27,432
This language of light
is so widespread here,
87
00:13:27,557 --> 00:13:32,104
that these signals are probably
the commonest form of communication
88
00:13:33,230 --> 00:13:34,898
on the entire planet.
89
00:13:36,441 --> 00:13:39,111
And yet,
we still know little about them.
90
00:14:04,428 --> 00:14:06,304
Hunters illuminate themselves,
91
00:14:06,430 --> 00:14:07,806
and by doing so
92
00:14:07,931 --> 00:14:10,308
attract inquisitive prey.
93
00:14:23,113 --> 00:14:25,365
This is fangtooth.
94
00:14:27,325 --> 00:14:31,204
It has the largest teeth
for its size of any fish.
95
00:14:33,790 --> 00:14:37,377
There are pressure sensors
all over its head and body
96
00:14:37,461 --> 00:14:41,006
which can detect anything
moving in the surrounding water.
97
00:14:47,971 --> 00:14:51,641
It's the Midnight Zone's
most voracious fish.
98
00:14:53,685 --> 00:14:57,022
But prey use light as a distraction.
99
00:15:01,902 --> 00:15:04,821
A decoy of luminous ink.
100
00:15:14,247 --> 00:15:16,708
Down here, in this blackness,
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00:15:18,835 --> 00:15:22,547
creatures live beyond
the normal rules of time.
102
00:15:29,387 --> 00:15:32,933
Siphonophores are virtually eternal.
103
00:15:33,016 --> 00:15:36,937
They repeatedly clone themselves,
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00:15:37,104 --> 00:15:40,941
some eventually growing
longer than a blue whale.
105
00:16:05,924 --> 00:16:09,094
Down here, it snows.
106
00:16:17,561 --> 00:16:20,605
Continuous clouds of organic debris
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00:16:20,730 --> 00:16:23,441
drift slowly down from above.
108
00:16:30,824 --> 00:16:33,118
This is food,
109
00:16:33,243 --> 00:16:37,414
and a whole variety
of filter feeders depend on it.
110
00:16:40,625 --> 00:16:41,960
Jellyfish.
111
00:16:50,760 --> 00:16:53,597
And delicate sea cucumbers.
112
00:17:13,283 --> 00:17:16,119
The 1% of marine snow they miss
113
00:17:16,828 --> 00:17:19,456
eventually settles on the sea floor.
114
00:17:48,318 --> 00:17:50,070
Over millions of years,
115
00:17:50,153 --> 00:17:54,866
it forms a layer of mud
up to a mile thick.
116
00:17:59,246 --> 00:18:01,164
It's an empty plain
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00:18:01,248 --> 00:18:04,251
that covers half
the surface of our planet.
118
00:18:31,194 --> 00:18:35,532
The deep seabed may,
at first, appear lifeless,
119
00:18:37,742 --> 00:18:42,372
but it's home to a unique
cast of mud dwellers.
120
00:18:45,125 --> 00:18:46,710
The sea toad.
121
00:18:49,587 --> 00:18:53,633
It is an ambush predator
with an enormous mouth
122
00:18:55,593 --> 00:18:57,721
and infinite patience.
123
00:19:08,732 --> 00:19:12,235
This fish has been
living for so long here
124
00:19:12,319 --> 00:19:15,822
that its fins have changed
into something more useful.
125
00:19:22,287 --> 00:19:23,580
Feet.
126
00:19:28,585 --> 00:19:31,921
They help it shuffle about
on the sea floor.
127
00:19:52,942 --> 00:19:55,445
The flapjack octopus.
128
00:20:00,450 --> 00:20:03,078
It hovers just above
the surface of the mud
129
00:20:03,161 --> 00:20:07,290
as it delicately sifts through it
searching for worms.
130
00:20:10,794 --> 00:20:14,964
But it can jet away
at the first sign of danger.
131
00:20:34,317 --> 00:20:37,487
A sixgill shark,
as big as a great white.
132
00:20:39,072 --> 00:20:42,700
It may not have eaten
for an entire year.
133
00:20:49,374 --> 00:20:51,501
It patrols the mudplains
134
00:20:51,584 --> 00:20:54,379
using a minimum amount of energy.
135
00:21:08,518 --> 00:21:09,727
High above,
136
00:21:09,853 --> 00:21:12,397
the carcass of a huge sperm whale
137
00:21:12,522 --> 00:21:14,691
is slowly decaying.
138
00:21:21,281 --> 00:21:24,701
This will be a bonanza
for the creatures of the deep.
139
00:21:25,743 --> 00:21:27,036
Food.
140
00:21:27,620 --> 00:21:29,289
Thirty tonnes of it.
141
00:21:42,886 --> 00:21:46,973
Finally it settles on the ocean floor
142
00:21:48,641 --> 00:21:51,728
and its presence is soon detected.
143
00:22:01,404 --> 00:22:03,323
Sixgills sharks
144
00:22:03,406 --> 00:22:06,284
have an exceptionally
acute sense of smell.
145
00:22:11,247 --> 00:22:15,418
Just 25 minutes
after the whale's carcass arrives,
146
00:22:17,629 --> 00:22:19,589
a sixgill finds it.
147
00:22:41,611 --> 00:22:45,031
Each bite releases
blood into the current.
148
00:23:28,241 --> 00:23:31,661
The news that food
is here spreads quickly.
149
00:23:40,169 --> 00:23:43,840
Two more ravenous sixgills arrive.
150
00:23:52,765 --> 00:23:56,477
Within 12 hours,
there are seven enormous sharks
151
00:23:56,561 --> 00:23:58,104
Jostling with one another
152
00:23:58,187 --> 00:24:01,024
as they compete to tear off mouthfuls.
153
00:24:13,411 --> 00:24:16,080
No one is prepared to back off
154
00:25:00,958 --> 00:25:02,794
Twenty-four hours later,
155
00:25:02,919 --> 00:25:05,922
and a third of the carcass has gone.
156
00:25:38,204 --> 00:25:40,540
The first arrival has gorged
157
00:25:40,623 --> 00:25:42,667
until it's completely full.
158
00:25:47,714 --> 00:25:49,465
This single meal
159
00:25:49,549 --> 00:25:53,219
may be enough to sustain it
for a whole year.
160
00:25:59,642 --> 00:26:03,020
Now, the clean up team arrives.
161
00:26:06,232 --> 00:26:09,694
Spider crabs carrying coral
in their hind legs,
162
00:26:10,319 --> 00:26:13,406
presumably as makeshift body armour.
163
00:26:21,831 --> 00:26:24,000
There are rock crabs here too.
164
00:26:26,586 --> 00:26:31,007
They probably detected the carcass
almost as soon as the sharks,
165
00:26:32,425 --> 00:26:34,594
but they can't move as fast.
166
00:26:39,223 --> 00:26:42,810
A month on,
and over 30 species of scavenger
167
00:26:42,894 --> 00:26:46,272
are clearing away
the last edible fragments.
168
00:26:48,733 --> 00:26:52,904
But now, the scavengers
are attracting their own predators.
169
00:26:59,368 --> 00:27:02,705
Scabbardfish, habitually
swimming upright,
170
00:27:02,789 --> 00:27:05,249
are picking them off one by one.
171
00:27:26,896 --> 00:27:29,565
Some of the whale's teeth
have been dislodged
172
00:27:29,649 --> 00:27:32,401
as the skeleton starts to fall apart.
173
00:27:35,905 --> 00:27:40,910
Four months later,
there is nothing left but a few bones.
174
00:27:48,751 --> 00:27:50,753
But even they are food
175
00:27:55,174 --> 00:27:56,467
for something.
176
00:28:03,474 --> 00:28:05,309
Zombie worms.
177
00:28:09,438 --> 00:28:13,109
They tunnel into the bones
by injecting acid
178
00:28:13,985 --> 00:28:18,114
and so reach the tiny amounts of fat
that still remain there.
179
00:28:20,491 --> 00:28:22,118
It may take decades,
180
00:28:22,201 --> 00:28:26,372
but eventually,
the last of the bones will crumble,
181
00:28:26,455 --> 00:28:31,127
and the whole 30-tonne carcass
will have been recycled.
182
00:28:38,467 --> 00:28:41,888
A whale fall is a temporary oasis
183
00:28:41,971 --> 00:28:44,056
in the desert of the sea floor.
184
00:28:47,560 --> 00:28:50,396
But there are permanent oases here too.
185
00:29:05,202 --> 00:29:07,622
Rocks projecting above the mud
186
00:29:07,705 --> 00:29:11,167
provide anchorage for deep sea corals.
187
00:29:29,852 --> 00:29:33,689
As far down
as three and a half miles,
188
00:29:33,773 --> 00:29:36,692
there are more species of coral
in the deep
189
00:29:36,776 --> 00:29:39,362
than on shallow tropical reefs.
190
00:29:48,371 --> 00:29:52,291
Without sunlight,
they rely solely on food
191
00:29:52,375 --> 00:29:54,043
drifting in the current.
192
00:29:57,421 --> 00:29:59,048
And they grow
193
00:29:59,215 --> 00:30:02,551
Just a hair's breadth a year.
194
00:30:08,265 --> 00:30:12,228
But some of them
can live for 4,000 years.
195
00:30:19,068 --> 00:30:22,238
They, like their
shallow water relatives,
196
00:30:22,405 --> 00:30:25,908
provide homes for all kinds
of other creatures.
197
00:30:52,309 --> 00:30:54,228
Growing among the corals,
198
00:30:54,311 --> 00:30:57,148
is one of the most beautiful of sponges.
199
00:31:00,776 --> 00:31:04,613
This is Venus' flower basket.
200
00:31:12,288 --> 00:31:14,540
These sponges have lodgers.
201
00:31:15,458 --> 00:31:16,709
Shrimps.
202
00:31:25,634 --> 00:31:27,845
There are plenty
of predators on the reef
203
00:31:28,304 --> 00:31:30,306
so the shrimps are fortunate.
204
00:31:34,894 --> 00:31:37,021
Both this male and female,
205
00:31:37,146 --> 00:31:40,316
were swept into this sponge
when they were tiny larvae,
206
00:31:40,524 --> 00:31:43,360
along with the minute particles of food
207
00:31:43,486 --> 00:31:45,488
on which the sponge feeds.
208
00:31:49,533 --> 00:31:53,537
They found each other
and have been here ever since.
209
00:32:08,928 --> 00:32:11,055
Now, they're full-grown
210
00:32:11,180 --> 00:32:13,766
and the female is carrying eggs.
211
00:32:27,113 --> 00:32:31,534
Once hatched, the larvae will swim
out through the sponge's walls.
212
00:32:38,040 --> 00:32:40,751
But the shrimps will never leave.
213
00:32:42,086 --> 00:32:43,295
They can't.
214
00:32:50,052 --> 00:32:54,056
They're now far too big
to go out the way they came in.
215
00:32:54,723 --> 00:32:56,892
And, no doubt,
they will live longer here
216
00:32:56,976 --> 00:33:01,730
than they would if they were
wandering about on the reef unprotected.
217
00:33:14,952 --> 00:33:18,247
But how one
of the simplest of all animals,
218
00:33:18,414 --> 00:33:23,085
a sponge, is able to build
such a complex structure
219
00:33:23,586 --> 00:33:25,588
to the great benefit of the shrimps
220
00:33:27,339 --> 00:33:28,591
is a mystery.
221
00:33:29,592 --> 00:33:31,927
And, surely, a marvel.
222
00:33:49,195 --> 00:33:50,321
But today,
223
00:33:50,446 --> 00:33:54,366
their timeless world
is being reduced to rubble.
224
00:34:02,666 --> 00:34:07,463
As over-fishing empties
the surface waters of the seas,
225
00:34:07,546 --> 00:34:11,133
trawlers have started
to ransack the deep.
226
00:34:14,470 --> 00:34:17,389
Now, countless numbers of the reefs
227
00:34:17,473 --> 00:34:20,017
that have flourished here for millennia
228
00:34:20,142 --> 00:34:22,144
lie in ruins.
229
00:34:52,716 --> 00:34:53,926
Over time,
230
00:34:54,009 --> 00:34:57,721
organic matter on the sea floor
slowly decays
231
00:34:58,597 --> 00:35:00,015
producing methane.
232
00:36:04,330 --> 00:36:06,540
In the Gulf of Mexico,
233
00:36:06,623 --> 00:36:10,627
these eruptions also release
a super salty liquid.
234
00:36:19,094 --> 00:36:20,262
Brine.
235
00:36:31,774 --> 00:36:34,610
Five times heavier than sea water,
236
00:36:35,277 --> 00:36:38,655
it accumulates in great pools
on the sea floor.
237
00:36:44,620 --> 00:36:47,456
It's difficult to make sense
of the sight.
238
00:36:54,797 --> 00:36:58,008
A lake of concentrated salt water,
239
00:36:58,133 --> 00:36:59,968
fifteen metres deep,
240
00:37:01,011 --> 00:37:02,679
at the bottom of the sea.
241
00:37:10,854 --> 00:37:14,566
Around its margin,
perhaps even more strangely,
242
00:37:14,650 --> 00:37:17,319
there is a profusion of life.
243
00:37:24,576 --> 00:37:28,872
Giant mussels that can live
or grow for a century or more,
244
00:37:28,997 --> 00:37:30,582
pack tightly together,
245
00:37:30,666 --> 00:37:34,837
dwarfing the shrimps and squat lobsters
that feed around them.
246
00:38:04,700 --> 00:38:07,953
Cutthroat eels, scavengers,
247
00:38:08,036 --> 00:38:10,372
come to the shores of the brine lake
248
00:38:10,456 --> 00:38:12,374
in search of something edible.
249
00:38:21,258 --> 00:38:24,261
Some even venture into the brine.
250
00:38:59,129 --> 00:39:03,759
Spending too long in it
can send an eel into toxic shock.
251
00:39:16,104 --> 00:39:19,149
It' only hope
is to rise above it.
252
00:39:34,331 --> 00:39:35,999
It manages to escape.
253
00:39:45,509 --> 00:39:47,469
Others are not so lucky.
254
00:39:55,143 --> 00:39:57,563
The brine embalms their bodies,
255
00:39:59,481 --> 00:40:04,695
and the casualties of decades
accumulate around the margins.
256
00:40:25,382 --> 00:40:29,177
But parts of the deep
are even more hostile.
257
00:40:37,019 --> 00:40:38,186
In places,
258
00:40:38,270 --> 00:40:43,358
gigantic cracks stretch for many miles
across the ocean floor.
259
00:40:58,790 --> 00:41:02,878
Canyons that plunge
towards the centre of the earth.
260
00:41:10,552 --> 00:41:12,721
Scans from survey vessels
261
00:41:12,804 --> 00:41:16,433
make it possible to graphically
reconstruct an image
262
00:41:16,558 --> 00:41:19,144
of this vast submarine landscape.
263
00:41:27,069 --> 00:41:30,405
The deepest of all,
at almost seven miles,
264
00:41:30,489 --> 00:41:33,492
is the Mariana Trench
in the Pacific Ocean.
265
00:41:39,498 --> 00:41:43,251
Even Mount Everest
could disappear inside it.
266
00:41:58,850 --> 00:42:02,396
Down here, in these deep ravines,
267
00:42:02,479 --> 00:42:06,983
it was once thought that
nothing whatever could possibly survive.
268
00:42:13,949 --> 00:42:16,868
But there is life even here.
269
00:42:23,625 --> 00:42:25,544
A kind of sea slug.
270
00:42:33,385 --> 00:42:35,804
A so-called sea pig.
271
00:42:37,723 --> 00:42:40,183
They, and other simple creatures,
272
00:42:40,308 --> 00:42:45,731
manage to survive on the miniscule
amount of food that drifts down here.
273
00:42:49,234 --> 00:42:50,944
Like this starfish,
274
00:42:51,027 --> 00:42:55,198
they can withstand pressure
equivalent of 50 jumbo jets
275
00:42:55,323 --> 00:42:57,576
stacked on top of one another.
276
00:43:19,556 --> 00:43:21,433
A remote camera probe
277
00:43:21,516 --> 00:43:25,061
reveals the most
extraordinary discovery of all.
278
00:43:32,569 --> 00:43:35,947
The ethereal snailfish.
279
00:43:39,743 --> 00:43:41,828
At five miles down,
280
00:43:41,912 --> 00:43:46,041
this is the deepest living fish
so far discovered.
281
00:43:52,380 --> 00:43:54,049
No one imagined
282
00:43:54,132 --> 00:43:57,135
than an animal as complex as a fish
283
00:43:57,219 --> 00:44:00,388
could exist in such extreme pressures.
284
00:44:12,943 --> 00:44:14,694
From the greatest depths
285
00:44:14,778 --> 00:44:17,781
to the uppermost limit
of the Twilight Zone,
286
00:44:17,906 --> 00:44:21,284
it seems that there is
nowhere in the deep sea
287
00:44:21,409 --> 00:44:24,329
where life of some kind can't survive.
288
00:44:29,167 --> 00:44:30,335
And we now think
289
00:44:30,418 --> 00:44:34,130
that the deep sea may well be
where life on Earth began.
290
00:44:48,603 --> 00:44:49,729
Here,
291
00:44:49,813 --> 00:44:54,776
in a world hidden within the greatest
geological feature on Earth,
292
00:44:57,988 --> 00:45:01,783
running right down the middle
of the world's oceans,
293
00:45:01,867 --> 00:45:04,286
an underwater mountain range
294
00:45:04,369 --> 00:45:06,621
spanning the entire globe.
295
00:45:11,793 --> 00:45:13,712
The mid-ocean ridge.
296
00:45:28,310 --> 00:45:29,936
In the South Pacific,
297
00:45:30,020 --> 00:45:32,981
the ocean floor is being torn apart.
298
00:46:48,431 --> 00:46:51,685
Over three quarters
of the planet's volcanic activity
299
00:46:51,768 --> 00:46:54,062
occurs in the deep.
300
00:47:01,069 --> 00:47:04,948
Almost all of it along
the mid-ocean ridge.
301
00:47:09,077 --> 00:47:11,955
But from this titanic violence
302
00:47:12,080 --> 00:47:14,082
come great riches.
303
00:47:23,341 --> 00:47:27,095
Gases and scalding water
gush up through the crevices.
304
00:47:36,771 --> 00:47:39,357
Minerals condensing from these jets
305
00:47:39,441 --> 00:47:41,359
build up great chimneys.
306
00:47:42,861 --> 00:47:44,779
Hydrothermal vents.
307
00:47:48,783 --> 00:47:51,161
This one, 30 metres tall,
308
00:47:51,286 --> 00:47:53,329
has been named "Godzilla".
309
00:48:02,047 --> 00:48:04,424
Astonishingly, we now know
310
00:48:04,507 --> 00:48:08,678
that they hold as much life
as tropical rainforests.
311
00:48:16,728 --> 00:48:20,648
In places, half a million
individual animals
312
00:48:20,732 --> 00:48:23,735
are crammed into a single square metre.
313
00:48:36,664 --> 00:48:40,418
They depend entirely
for their food on bacteria.
314
00:48:43,004 --> 00:48:45,381
And they feed on chemicals
315
00:48:45,507 --> 00:48:48,259
dissolved in the searingly hot fluid.
316
00:48:55,266 --> 00:48:58,978
Crabs consume the bacterial mats
317
00:48:59,062 --> 00:49:01,064
that coat their shells.
318
00:49:15,036 --> 00:49:17,914
Others maintain
bacterial cultures,
319
00:49:18,039 --> 00:49:20,583
actually within their bodies.
320
00:49:27,215 --> 00:49:30,885
Shrimps carry such cultures
in their mouth parts.
321
00:49:31,553 --> 00:49:34,556
But that is a strategy
fraught with danger.
322
00:49:39,102 --> 00:49:43,314
To provide sustenance
for these microbes,
323
00:49:43,481 --> 00:49:46,734
the shrimps must dash
into the hot vents,
324
00:49:48,736 --> 00:49:51,990
and that risks being boiled alive.
325
00:50:06,087 --> 00:50:07,630
In the last decade,
326
00:50:07,755 --> 00:50:11,801
the number of hydrothermal vents
discovered has doubled.
327
00:50:20,018 --> 00:50:24,355
Every one has its own unique
character and community.
328
00:50:31,196 --> 00:50:35,450
But, perhaps, the most important
one of all is in the Atlantic.
329
00:50:36,951 --> 00:50:40,622
It has been named "The Lost City".
330
00:50:44,209 --> 00:50:46,961
Within its 60-metre towers,
331
00:50:47,045 --> 00:50:50,715
something truly extraordinary
is taking place.
332
00:50:54,510 --> 00:50:57,513
Under extremes
of pressure and temperature,
333
00:50:57,805 --> 00:50:59,724
hydrocarbons,
334
00:50:59,807 --> 00:51:04,312
the molecules that are the basic
component of all living things,
335
00:51:05,146 --> 00:51:08,358
are being created spontaneously.
336
00:51:20,036 --> 00:51:23,456
Indeed, many scientists now believe
337
00:51:23,539 --> 00:51:29,379
that life on Earth
may have begun around a vent like this
338
00:51:29,837 --> 00:51:32,090
four billion years ago.
339
00:51:51,859 --> 00:51:54,737
We now know
that there are deep seas
340
00:51:54,862 --> 00:51:58,032
on the moons of Jupiter and Saturn.
341
00:52:05,206 --> 00:52:09,877
If life can exist under
such extreme conditions down here,
342
00:52:10,211 --> 00:52:14,799
then surely it could exist
somewhere out there.
343
00:52:27,770 --> 00:52:31,065
Next time, we travel
to bustling coral reefs.
344
00:52:38,281 --> 00:52:42,118
Here, animals must go
to extraordinary lengths
345
00:52:43,661 --> 00:52:47,498
to get ahead of the competition
in these crowded cities.
26226
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