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These are the user uploaded subtitles that are being translated: 1 00:00:01,200 --> 00:00:06,000 Our Planet is the greatest living puzzle in the universe. 2 00:00:06,000 --> 00:00:10,440 A collection of worlds within worlds. 3 00:00:10,440 --> 00:00:12,400 Each one a self-contained ecosystem 4 00:00:12,400 --> 00:00:14,400 bursting with life. 5 00:00:17,840 --> 00:00:19,840 But how do they work? 6 00:00:21,640 --> 00:00:24,640 The intricate web of relationships 7 00:00:24,640 --> 00:00:28,360 and the influence of natural forces 8 00:00:28,360 --> 00:00:32,840 makes each microworld complex and unique. 9 00:00:33,880 --> 00:00:37,280 So, to discover their secrets, 10 00:00:37,280 --> 00:00:40,600 we need to explore them one by one. 11 00:00:40,600 --> 00:00:44,160 Untangle their interlocking pieces 12 00:00:44,160 --> 00:00:47,800 and ultimately reveal the vital piece, 13 00:00:47,800 --> 00:00:50,240 the key to life itself 14 00:00:50,240 --> 00:00:54,640 hidden deep within each of nature's microworlds. 15 00:01:05,920 --> 00:01:07,640 Galapagos is arguably 16 00:01:07,640 --> 00:01:10,280 the most pristine archipelago on Earth. 17 00:01:14,240 --> 00:01:18,320 It's a unique living world of truly enchanting islands. 18 00:01:24,800 --> 00:01:26,760 Nowhere else on our planet 19 00:01:26,760 --> 00:01:31,320 are the connections and dependencies within ecosystems so clear. 20 00:01:38,800 --> 00:01:42,200 Charles Darwin was the first to see this 21 00:01:42,200 --> 00:01:44,720 when he visited the islands over 170 years ago, 22 00:01:44,720 --> 00:01:47,600 but, as we will discover, 23 00:01:47,600 --> 00:01:49,800 he only saw part of the picture. 24 00:01:52,320 --> 00:01:55,360 What the makes the Galapagos so unique 25 00:01:55,360 --> 00:01:57,360 is that many of the creatures that live here 26 00:01:57,360 --> 00:01:59,880 are found nowhere else on Earth. 27 00:02:06,560 --> 00:02:09,880 Even more extraordinary is that there is life here at all 28 00:02:09,880 --> 00:02:13,080 on these barren, isolated islands. 29 00:02:16,400 --> 00:02:18,040 And what life! 30 00:02:21,040 --> 00:02:23,240 It's a bizarre collection of creatures... 31 00:02:26,360 --> 00:02:29,720 ..from swimming lizards 32 00:02:29,720 --> 00:02:32,640 to tropical penguins 33 00:02:32,640 --> 00:02:35,320 and cormorants that can't fly. 34 00:02:39,120 --> 00:02:41,960 How has a place so harsh and isolated 35 00:02:41,960 --> 00:02:43,640 become a showcase for evolution 36 00:02:43,640 --> 00:02:47,360 and home to such a motley crew of creatures? 37 00:02:47,360 --> 00:02:50,240 And what is the pivotal piece 38 00:02:50,240 --> 00:02:52,400 that links all these animals to each other 39 00:02:52,400 --> 00:02:55,280 and to the islands they inhabit? 40 00:02:57,120 --> 00:02:58,680 To discover that, 41 00:02:58,680 --> 00:03:01,480 we must look at how these islands were created in the first place. 42 00:03:02,840 --> 00:03:05,000 Galapagos lies on the Equator, 43 00:03:05,000 --> 00:03:08,720 600 miles off the coast of Ecuador. 44 00:03:08,720 --> 00:03:11,320 In this isolation lies part of the reason 45 00:03:11,320 --> 00:03:14,360 for the archipelago's unique wildlife. 46 00:03:16,720 --> 00:03:19,360 These islands are not a broken off piece of a continent. 47 00:03:19,360 --> 00:03:22,160 And they haven't been created from coral reefs 48 00:03:22,160 --> 00:03:23,920 like some other tropical archipelagos. 49 00:03:25,680 --> 00:03:29,280 This microworld has been born from forces deep within the Earth. 50 00:03:31,840 --> 00:03:36,680 Galapagos is one of the most volcanic places on the planet. 51 00:03:38,960 --> 00:03:42,520 And it regularly proves it with spectacular geological shows. 52 00:03:45,200 --> 00:03:49,760 The archipelago is plumbed into Earth's molten core. 53 00:03:52,800 --> 00:03:57,720 The islands have been created by a unique quirk of geology, 54 00:03:57,720 --> 00:04:02,040 known to scientists as the Galapagos hotspot. 55 00:04:02,040 --> 00:04:05,680 It's a thin part of the Earth's crust 56 00:04:05,680 --> 00:04:10,160 that periodically pushes up molten rock towards the surface. 57 00:04:10,160 --> 00:04:14,520 And the eruptions create islands. 58 00:04:15,880 --> 00:04:17,880 For 20 million years, 59 00:04:17,880 --> 00:04:21,720 the hotspot has continued to give birth to new land. 60 00:04:28,400 --> 00:04:30,040 As new islands form, 61 00:04:30,040 --> 00:04:31,240 they are carried away 62 00:04:31,240 --> 00:04:32,520 from the hotspot 63 00:04:32,520 --> 00:04:34,000 on shifting tectonic plates 64 00:04:34,000 --> 00:04:35,280 towards South America 65 00:04:35,280 --> 00:04:36,760 creating the string of islands 66 00:04:36,760 --> 00:04:38,400 we see today. 67 00:04:42,960 --> 00:04:47,680 This raw geology makes for a very tough place to live. 68 00:04:49,320 --> 00:04:53,320 And affects the bizarre creatures and relationships in Galapagos. 69 00:04:54,760 --> 00:04:59,480 But how did life get all the way out here in the first place? 70 00:05:03,280 --> 00:05:05,680 To colonise such remote islands, 71 00:05:05,680 --> 00:05:08,920 life would face many daunting challenges. 72 00:05:08,920 --> 00:05:13,120 To get here, any living thing would first have to cross 600 miles 73 00:05:13,120 --> 00:05:17,360 of open ocean from the nearest mainland. 74 00:05:17,360 --> 00:05:20,720 Plants are the first pioneers of any new landscape. 75 00:05:22,760 --> 00:05:25,760 Their seeds float here 76 00:05:25,760 --> 00:05:27,600 or are blown in, 77 00:05:27,600 --> 00:05:32,000 or they may be carried in the feathers or droppings of sea birds. 78 00:05:34,240 --> 00:05:37,440 Just getting here is a formidable challenge. 79 00:05:39,320 --> 00:05:43,320 Getting a foothold in the lava landscape is something else. 80 00:05:44,520 --> 00:05:47,040 But life finds a way. 81 00:05:49,640 --> 00:05:53,480 The whole terrestrial system is dependant on a few plants 82 00:05:53,480 --> 00:05:55,560 to kick start the colonisation. 83 00:05:56,600 --> 00:06:00,080 Mangroves are true ocean voyagers. 84 00:06:00,080 --> 00:06:01,880 Their seeds are tough enough 85 00:06:01,880 --> 00:06:05,560 to withstand the desiccating effect of months in salt water. 86 00:06:07,120 --> 00:06:10,200 Lava cactus pioneer the colonisation of the land. 87 00:06:16,240 --> 00:06:20,560 While Opuntia cactus open up the land still further. 88 00:06:22,200 --> 00:06:23,640 With so few species, 89 00:06:23,640 --> 00:06:26,720 the delicate dependencies between those species 90 00:06:26,720 --> 00:06:29,080 makes for some incredible relationships. 91 00:06:38,200 --> 00:06:41,280 Many of the native flowering plants in Galapagos are yellow. 92 00:06:45,720 --> 00:06:48,800 And that's because the only species of bee 93 00:06:48,800 --> 00:06:52,360 that's managed to make it here and pollinates the flowers 94 00:06:52,360 --> 00:06:53,720 is attracted to yellow. 95 00:06:53,720 --> 00:06:56,720 So there's little point in being anything else. 96 00:07:02,040 --> 00:07:05,440 The integrity of the food chain relies on the few insects 97 00:07:05,440 --> 00:07:07,280 pollinating the plants, 98 00:07:07,280 --> 00:07:09,720 because the next layer of creatures depend on them. 99 00:07:14,600 --> 00:07:17,280 Reptiles are a true hallmark of Galapagos, 100 00:07:17,280 --> 00:07:22,120 not necessarily because they deal better with the conditions here, 101 00:07:22,120 --> 00:07:25,360 but because they managed to get here in the first place. 102 00:07:26,600 --> 00:07:30,360 Reptiles are adept at surviving in salt water, 103 00:07:30,360 --> 00:07:34,440 so they stand a good chance of getting through a vast ocean crossing. 104 00:07:36,120 --> 00:07:40,160 Once here, they had to adapt to what's on offer 105 00:07:40,160 --> 00:07:44,600 and, in doing so, became the next integral layer of the ecosystem. 106 00:07:47,640 --> 00:07:51,440 Land iguanas rely on Opuntia cactus as their staple food. 107 00:07:55,520 --> 00:07:57,840 On the more barren islands, 108 00:07:57,840 --> 00:08:00,160 the shells of saddle back giant tortoises 109 00:08:00,160 --> 00:08:05,000 have evolved quirky shapes to allow them to stretch their necks upwards 110 00:08:05,000 --> 00:08:07,360 to higher, tasty cactus morsels. 111 00:08:10,360 --> 00:08:13,280 But the cactus also relies on the tortoise. 112 00:08:13,280 --> 00:08:17,840 They spread their seeds in their droppings as they roam the islands. 113 00:08:17,840 --> 00:08:22,840 At the top of the food chain, the surprising relationships continue. 114 00:08:22,880 --> 00:08:27,520 The top predator here isn't what you might expect. 115 00:08:27,520 --> 00:08:30,960 This is the Galapagos hawk. 116 00:08:35,560 --> 00:08:38,240 The challenge for a female hawk is to find enough food 117 00:08:38,240 --> 00:08:42,480 to raise her young in such a barren place. 118 00:08:42,480 --> 00:08:45,720 With next to no small mammals to hunt 119 00:08:45,720 --> 00:08:50,040 she turns her attention to what dominates the land here. 120 00:08:51,480 --> 00:08:54,480 Marine iguanas nest for only a few weeks each year. 121 00:08:59,000 --> 00:09:01,520 Which doesn't leave her much time. 122 00:09:08,520 --> 00:09:10,480 But she simply must succeed. 123 00:09:23,760 --> 00:09:25,960 One life ends... 124 00:09:29,560 --> 00:09:31,080 ..and another begins. 125 00:09:36,520 --> 00:09:39,040 But there's another reason so many creatures here, 126 00:09:39,040 --> 00:09:41,880 like the Galapagos hawk, are endemic, 127 00:09:41,880 --> 00:09:44,520 found nowhere else on Earth. 128 00:09:49,520 --> 00:09:53,640 In Galapagos, we see unique species everywhere we look. 129 00:09:53,640 --> 00:09:57,800 Not just on land, but also at sea. 130 00:10:08,080 --> 00:10:11,320 Galapagos sea lions might look like any other sea lion. 131 00:10:11,320 --> 00:10:13,640 But the science proves otherwise. 132 00:10:15,200 --> 00:10:19,560 Their ancestors arrived here from California 2.5 million years ago, 133 00:10:19,560 --> 00:10:21,880 but they've continued to evolve here in isolation 134 00:10:21,880 --> 00:10:24,360 and are now so different 135 00:10:24,360 --> 00:10:26,400 they're considered a new species. 136 00:10:26,400 --> 00:10:28,600 Though they come ashore to breed, 137 00:10:28,600 --> 00:10:30,800 water is their natural environment 138 00:10:30,800 --> 00:10:33,520 and they depend on the richness of the seas. 139 00:10:37,800 --> 00:10:40,320 The flightless cormorant is a real Galapagos oddity 140 00:10:40,320 --> 00:10:44,160 and has evolved to suit a purely aquatic existence. 141 00:10:56,160 --> 00:10:58,640 With no real land predators to escape from, 142 00:10:58,640 --> 00:11:01,200 flight was of limited use. 143 00:11:03,320 --> 00:11:06,440 Under water their wings were actually a hindrance, 144 00:11:06,440 --> 00:11:09,520 and, over time, they dwindled to mere stubs. 145 00:11:09,520 --> 00:11:12,160 The entire species are now bound 146 00:11:12,160 --> 00:11:15,640 to a tiny stretch of the Galapagos coast. 147 00:11:15,640 --> 00:11:19,160 Even some creatures that can easily leave the islands 148 00:11:19,160 --> 00:11:21,560 are also considered endemic. 149 00:11:21,560 --> 00:11:25,080 Like the waved albatross. 150 00:11:25,080 --> 00:11:27,200 After months fishing further out at sea, 151 00:11:27,200 --> 00:11:32,160 the first touchdown isn't always graceful. 152 00:11:40,480 --> 00:11:43,240 95% of the world's population 153 00:11:43,240 --> 00:11:46,560 return to just one Galapagos island each year to breed. 154 00:11:50,440 --> 00:11:52,720 These birds mate for life. 155 00:11:52,720 --> 00:11:56,360 The first challenge is to find their partners. 156 00:11:56,360 --> 00:12:01,000 When they do, they rekindle their relationship with a delightful duet. 157 00:12:01,000 --> 00:12:06,080 THEY SQUAWK 158 00:12:21,600 --> 00:12:24,280 Over the last few hundred years, 159 00:12:24,280 --> 00:12:27,400 the Galapagos has been seen as a living laboratory, 160 00:12:27,400 --> 00:12:29,440 helping us to understand 161 00:12:29,440 --> 00:12:30,960 how creatures specialise 162 00:12:30,960 --> 00:12:33,720 and evolve to suit their environment. 163 00:12:33,720 --> 00:12:36,760 There is one example, above all others, 164 00:12:36,760 --> 00:12:39,720 that reveals just that - Darwin's finches. 165 00:12:41,680 --> 00:12:46,480 Few terrestrial birds managed to make it to these isolated islands. 166 00:12:46,480 --> 00:12:48,160 The finches that did make it 167 00:12:48,160 --> 00:12:51,000 now fill all the various niches available. 168 00:12:54,760 --> 00:12:57,520 The finches share a common ancestor, 169 00:12:57,520 --> 00:12:59,600 but have evolved into many different forms 170 00:12:59,600 --> 00:13:02,760 to exploit their new habitats. 171 00:13:02,760 --> 00:13:05,800 Different finches each rely on different plants 172 00:13:05,800 --> 00:13:08,760 and creatures to make a living. 173 00:13:08,760 --> 00:13:11,920 They have evolved to take the place of woodpeckers. 174 00:13:11,920 --> 00:13:14,600 They've become tool users. 175 00:13:21,320 --> 00:13:25,280 Others have developed larger beaks for cracking seeds. 176 00:13:26,920 --> 00:13:29,000 They've even turned into vampires. 177 00:13:30,600 --> 00:13:35,120 These finches learnt that sea bird blood makes a nutritious meal, 178 00:13:35,120 --> 00:13:37,080 full of protein and minerals. 179 00:13:37,080 --> 00:13:41,120 These avian vampires don't kill their host, 180 00:13:41,120 --> 00:13:44,240 though the blood meal must surely weaken the larger bird. 181 00:13:46,120 --> 00:13:50,760 Galapagos finches are such a clear example of how creatures can evolve 182 00:13:50,760 --> 00:13:54,640 that Darwin eventually saw in these little birds 183 00:13:54,640 --> 00:13:57,280 the foundations for his big theories 184 00:13:57,280 --> 00:14:00,680 on evolution by natural selection. 185 00:14:02,480 --> 00:14:04,960 These would shock the world 186 00:14:04,960 --> 00:14:07,640 and revolutionise biology. 187 00:14:07,640 --> 00:14:11,000 But there is a further key to working out how all this life 188 00:14:11,000 --> 00:14:14,960 is interconnected and intrinsically linked to the islands. 189 00:14:17,080 --> 00:14:20,960 Something even Darwin didn't realise. 190 00:14:20,960 --> 00:14:22,880 To discover what that is, 191 00:14:22,880 --> 00:14:25,640 we must look to where island life concentrates - 192 00:14:25,640 --> 00:14:27,640 the coast. 193 00:14:29,120 --> 00:14:32,760 The community of coastal creatures is heavily interlinked 194 00:14:32,760 --> 00:14:35,880 and the dependency between them is clear to see. 195 00:14:40,280 --> 00:14:44,800 Sally Lightfoot crabs clean dead skin off the basking marine iguanas. 196 00:14:48,040 --> 00:14:53,040 Lava lizards also use the iguanas as lookout posts. 197 00:14:55,720 --> 00:14:58,840 These endemic animals are true opportunists. 198 00:15:00,600 --> 00:15:03,200 Any advantage here is worth taking. 199 00:15:04,680 --> 00:15:06,840 Sea lions become hunting grounds. 200 00:15:11,680 --> 00:15:14,520 It's a relationship that works for everyone. 201 00:15:14,520 --> 00:15:17,040 Well, except the fly. 202 00:15:22,520 --> 00:15:27,520 On the coast, we see creatures that depend on the land to breed. 203 00:15:34,360 --> 00:15:36,280 And on the seas to feed. 204 00:16:00,760 --> 00:16:03,080 Their lives are linked to the sea. 205 00:16:08,520 --> 00:16:11,760 There is something special about the seas here 206 00:16:11,760 --> 00:16:15,160 that all coastal creatures rely on. 207 00:16:15,160 --> 00:16:19,400 And a clue to what that is can be found beneath the beds of lava. 208 00:16:22,040 --> 00:16:26,880 There is one seabird here that you'd never expect to find on the equator. 209 00:16:28,840 --> 00:16:32,640 The world's only tropical penguins. 210 00:16:34,240 --> 00:16:38,080 These lava tubes once flowed with molten magma. 211 00:16:38,080 --> 00:16:39,800 Now the penguins rely on them 212 00:16:39,800 --> 00:16:44,520 to hide their vulnerable chicks from the baking sun. 213 00:16:44,520 --> 00:16:48,040 But the real secret to how Galapagos penguins can survive here 214 00:16:48,040 --> 00:16:51,120 is down to something in the seas. 215 00:16:57,360 --> 00:16:59,760 Although the archipelago lies in the path 216 00:16:59,760 --> 00:17:01,280 of a number of warm water systems, 217 00:17:01,280 --> 00:17:03,280 Galapagos is also washed 218 00:17:03,280 --> 00:17:06,320 by a tongue of cold, Antarctic water 219 00:17:06,320 --> 00:17:08,720 called the Humboldt Current. 220 00:17:12,280 --> 00:17:14,040 The penguin's ancestors 221 00:17:14,040 --> 00:17:18,840 were brought to Galapagos by that cool Humboldt Current, 222 00:17:18,840 --> 00:17:21,840 and it continues to sustain the surviving population to this day. 223 00:17:28,440 --> 00:17:31,920 This cooler water holds more life-giving oxygen 224 00:17:31,920 --> 00:17:36,000 than warmer tropical waters that are typically found at this latitude. 225 00:17:38,400 --> 00:17:42,640 The cool water combines with the equatorial sun 226 00:17:42,640 --> 00:17:45,280 to feed the marine ecosystem. 227 00:17:45,280 --> 00:17:49,600 It makes for one of the most productive tropical marine environments in the world. 228 00:17:51,840 --> 00:17:56,880 All sea creatures depend on these life-giving currents. 229 00:17:57,120 --> 00:18:01,600 It's the reason the fish life so is rich, 230 00:18:01,600 --> 00:18:03,880 both in abundance and diversity. 231 00:18:11,560 --> 00:18:16,000 The volcanic character of the islands also plays its part. 232 00:18:22,840 --> 00:18:25,320 The flanks of the volcanoes draw cold water up 233 00:18:25,320 --> 00:18:27,400 from the deep ocean to the surface. 234 00:18:30,640 --> 00:18:33,680 It makes the seas around the youngest, most barren islands 235 00:18:33,680 --> 00:18:37,680 the most productive in the archipelago. 236 00:18:37,680 --> 00:18:40,160 And it is here that we find the largest communities 237 00:18:40,160 --> 00:18:43,040 of a truly bizarre creature 238 00:18:43,040 --> 00:18:47,080 that has evolved a lifestyle linked to the productivity of the seas. 239 00:18:50,040 --> 00:18:52,880 Galapagos Marine iguanas are the only sea-going lizard 240 00:18:52,880 --> 00:18:54,800 found in the whole world. 241 00:18:57,360 --> 00:19:00,480 The barren lava shore offers little to feed on, 242 00:19:00,480 --> 00:19:05,320 so it's not surprising that their terrestrial ancestors 243 00:19:05,320 --> 00:19:08,160 took to the rich waters to find food. 244 00:19:12,360 --> 00:19:16,120 What is astonishing is that they've evolved to eat only marine algae. 245 00:19:20,760 --> 00:19:24,640 But in doing this, the iguanas face a dilemma. 246 00:19:24,640 --> 00:19:28,160 They need the algae but it lies in cold water, 247 00:19:28,160 --> 00:19:32,160 a real problem for a cold-blooded creature. 248 00:19:34,400 --> 00:19:38,240 If they get too chilled, they become sluggish and eventually can't swim. 249 00:19:38,240 --> 00:19:41,520 So they need to offset periods of diving 250 00:19:41,520 --> 00:19:46,080 with time spent in strong equatorial sun. 251 00:19:46,080 --> 00:19:51,080 We can see how it works by looking at the iguanas in thermal imagery. 252 00:19:54,760 --> 00:19:58,560 As they bask, the lethal chill is driven away, 253 00:19:58,560 --> 00:20:01,800 giving them more energy to take the plunge again. 254 00:20:05,360 --> 00:20:07,960 By raising their temperature to 37 degrees centigrade, 255 00:20:07,960 --> 00:20:11,560 they buy themselves time. 256 00:20:11,560 --> 00:20:14,320 They can return to the cold water to find the algae. 257 00:20:16,480 --> 00:20:21,480 Smaller, younger individuals forage in the shallows. 258 00:20:21,560 --> 00:20:25,720 The larger individuals must dive deeper and for longer 259 00:20:25,720 --> 00:20:29,960 to tap the richer pastures that will sustain their greater size. 260 00:20:38,040 --> 00:20:42,720 Larger males can hold their breath for up to 30 minutes. 261 00:20:42,720 --> 00:20:45,520 But the clock is ticking. 262 00:20:49,160 --> 00:20:54,200 It is crucial to find food, feed and get out. 263 00:21:03,680 --> 00:21:05,520 They return to the safety of shore 264 00:21:05,520 --> 00:21:08,160 but their temperature is now dangerously low. 265 00:21:13,120 --> 00:21:14,960 But basking will re-warm them 266 00:21:14,960 --> 00:21:18,400 and aid in the digesting of that algae meal. 267 00:21:21,440 --> 00:21:23,600 Every day they walk this temperature tightrope. 268 00:21:28,360 --> 00:21:30,880 It's a remarkable lifestyle that's evolved over millennia. 269 00:21:33,080 --> 00:21:36,440 Their reliance on a single resource can be very productive, 270 00:21:36,440 --> 00:21:39,240 but also very precarious. 271 00:21:42,720 --> 00:21:45,600 The dependency of creatures on the cool water currents 272 00:21:45,600 --> 00:21:48,240 comes sharply into focus 273 00:21:48,240 --> 00:21:52,200 when that life-giving current is switched off. 274 00:21:54,680 --> 00:21:58,120 And when it is, the results can appear catastrophic. 275 00:21:59,920 --> 00:22:02,040 Every three to six years, 276 00:22:02,040 --> 00:22:05,920 the seas around Galapagos undergo a dramatic change. 277 00:22:08,640 --> 00:22:10,640 Pacific trade winds slacken 278 00:22:10,640 --> 00:22:14,000 and warm water shoots East across the ocean. 279 00:22:17,760 --> 00:22:20,920 The blanket of warm water engulfs Galapagos. 280 00:22:23,400 --> 00:22:27,600 It chokes off the cool life-giving currents that feed the archipelago. 281 00:22:29,800 --> 00:22:33,040 And the marine food chain collapses. 282 00:22:36,400 --> 00:22:39,160 This is El Nino, 283 00:22:39,160 --> 00:22:42,160 one of the most destructive weather systems on Earth. 284 00:22:47,400 --> 00:22:48,920 Its position on the equator 285 00:22:48,920 --> 00:22:51,520 means that Galapagos is right in the line of fire 286 00:22:51,520 --> 00:22:56,480 and gets more and stronger El Nino events than anywhere else. 287 00:22:59,880 --> 00:23:03,200 For creatures linked to the land, isolated on these islands, 288 00:23:03,200 --> 00:23:05,720 there is nowhere to go when El Nino hits. 289 00:23:13,920 --> 00:23:15,840 The El Nino of 1982 290 00:23:15,840 --> 00:23:18,400 was the most extreme in 400 years. 291 00:23:21,720 --> 00:23:24,840 Populations of animals were decimated. 292 00:23:29,640 --> 00:23:32,480 El Nino creates a seesaw of productivity 293 00:23:32,480 --> 00:23:35,280 for a number of years every time it hits. 294 00:23:38,160 --> 00:23:41,240 But it's not all bad. 295 00:23:41,240 --> 00:23:44,240 The warm water creates wetter weather, 296 00:23:44,240 --> 00:23:46,320 so, while the marine creatures suffer, 297 00:23:46,320 --> 00:23:49,240 the land system goes into overdrive. 298 00:23:50,600 --> 00:23:53,800 There is an explosion of life 299 00:23:53,800 --> 00:23:56,840 and an increase in colonisation between the islands. 300 00:24:00,320 --> 00:24:03,520 The seesaw then swings back. 301 00:24:03,520 --> 00:24:05,840 When cooler seas return, 302 00:24:05,840 --> 00:24:07,960 the marine system rebounds 303 00:24:07,960 --> 00:24:10,200 but the land system now suffers 304 00:24:10,200 --> 00:24:14,520 until normal conditions return. 305 00:24:14,520 --> 00:24:17,800 El Nino appears to be one of nature's great destructive events. 306 00:24:20,240 --> 00:24:23,800 But El Nino also reveals with great clarity 307 00:24:23,800 --> 00:24:27,200 the natural processes at work in Galapagos. 308 00:24:29,360 --> 00:24:34,120 The stress El Nino creates acts as a gruelling test 309 00:24:34,120 --> 00:24:38,160 in the race of survival of the fittest. 310 00:24:38,160 --> 00:24:42,560 The individuals that do survive thrive. 311 00:24:46,200 --> 00:24:49,240 They and their offspring flourish after the crisis. 312 00:24:53,160 --> 00:24:57,480 With less competition, this becomes a land of opportunity. 313 00:24:57,480 --> 00:25:02,200 El Nino shows how crucial the upwelling cool water is 314 00:25:02,200 --> 00:25:05,240 to feeding Galapagos. 315 00:25:06,760 --> 00:25:10,480 And it also shows how profoundly the islands' isolation 316 00:25:10,480 --> 00:25:13,000 affects the resident creatures here. 317 00:25:15,840 --> 00:25:19,520 But there is a twist in this tale of isolation, 318 00:25:19,520 --> 00:25:23,240 a final key that unlocks a greater understanding of the Galapagos. 319 00:25:25,040 --> 00:25:29,320 That key lies in how the archipelago came to be in the first place. 320 00:25:31,760 --> 00:25:34,240 For there is more to the unique geological story 321 00:25:34,240 --> 00:25:37,120 and how that affects the creatures here than many realise. 322 00:25:40,520 --> 00:25:43,080 The islands are born from the Galapagos hotspot 323 00:25:43,080 --> 00:25:46,520 and are carried towards the continent of South America, 324 00:25:46,520 --> 00:25:49,560 but they never get there. 325 00:25:49,560 --> 00:25:52,880 As the islands get carried towards the mainland, 326 00:25:52,880 --> 00:25:56,840 the tectonic plate on which they sit slides beneath the continent, 327 00:25:56,840 --> 00:25:59,080 taking the islands with it. 328 00:26:01,760 --> 00:26:03,360 Each island is born, 329 00:26:03,360 --> 00:26:06,440 lives 330 00:26:06,440 --> 00:26:10,680 and then disappears on a conveyor belt of geology. 331 00:26:12,720 --> 00:26:17,440 The Galapagos conveyor belt has created a geological treadmill, 332 00:26:17,440 --> 00:26:19,720 a continually changing home 333 00:26:19,720 --> 00:26:22,480 for the creatures that reside here. 334 00:26:26,480 --> 00:26:28,920 The archipelago may have existed 335 00:26:28,920 --> 00:26:32,600 for over 20 million years, 336 00:26:32,600 --> 00:26:35,120 but the oldest island we see today 337 00:26:35,120 --> 00:26:38,720 is only three million years old. 338 00:26:40,680 --> 00:26:44,240 Incredibly, marine iguanas as a species 339 00:26:44,240 --> 00:26:49,120 are older than the islands on which they live. 340 00:26:49,120 --> 00:26:51,720 Their ancestors arrived to islands 341 00:26:51,720 --> 00:26:55,120 that have since disappeared beneath the waves. 342 00:26:57,440 --> 00:27:00,760 Their species has moved along the geological treadmill, 343 00:27:00,760 --> 00:27:02,480 island hopping as it evolves. 344 00:27:06,840 --> 00:27:10,080 And this is the great revelation of Galapagos, 345 00:27:10,080 --> 00:27:13,880 the reason for the creatures and relationships 346 00:27:13,880 --> 00:27:15,880 that define this place. 347 00:27:17,920 --> 00:27:21,160 The volcanic conveyor belt has, for millennia, 348 00:27:21,160 --> 00:27:25,040 created a truly isolated archipelago. 349 00:27:25,040 --> 00:27:28,720 The isolation has forced the life that managed to get here 350 00:27:28,720 --> 00:27:32,600 to have to continually adapt and evolve. 351 00:27:35,000 --> 00:27:38,440 The upwelling currents are the lifeblood of the system. 352 00:27:40,360 --> 00:27:42,360 They feed and sustain life. 353 00:27:46,320 --> 00:27:49,640 It's this combination of the islands' unique geology 354 00:27:49,640 --> 00:27:53,640 and the upwelling currents that makes Galapagos so special. 355 00:27:58,440 --> 00:28:00,840 Darwin saw in the Galapagos 356 00:28:00,840 --> 00:28:02,960 a "little world within itself" 357 00:28:02,960 --> 00:28:05,280 and, 170 years on, 358 00:28:05,280 --> 00:28:07,280 this still holds true. 359 00:28:10,920 --> 00:28:13,320 The islands that inspired his groundbreaking theories 360 00:28:13,320 --> 00:28:16,440 continue to give us new insights 361 00:28:16,440 --> 00:28:21,400 into how Galapagos and all the microworlds of our planet work. 29690

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