1 00:00:04,560 --> 00:00:09,480 I'm here, surrounded by one of nature's greatest wonders. 2 00:00:09,480 --> 00:00:14,040 A living structure so enormous, it can be seen from space. 3 00:00:18,080 --> 00:00:19,760 The Great Barrier Reef. 4 00:00:25,160 --> 00:00:29,480 Home to one of the most extraordinary communities of animals on the planet. 5 00:00:34,840 --> 00:00:37,640 'I've been fascinated by it for almost 60 years.' 6 00:00:45,600 --> 00:00:49,120 Here, unknown species are still being found. 7 00:00:52,040 --> 00:00:54,880 And scientists are making astonishing discoveries 8 00:00:54,880 --> 00:00:57,320 about the creatures that we thought we knew. 9 00:01:00,440 --> 00:01:03,640 'In this series, our research vessel, the Alucia, 10 00:01:03,640 --> 00:01:06,680 'will allow us to explore the reef as never before.' 11 00:01:10,400 --> 00:01:14,880 Using the latest technology, I'll visit its mysterious depths. 12 00:01:16,920 --> 00:01:21,280 Nobody has ever dived as deep as this before on the Great Barrier Reef. 13 00:01:23,240 --> 00:01:25,800 I'll learn of its surprising origins. 14 00:01:28,920 --> 00:01:32,080 And discover how this wonderfully diverse community 15 00:01:32,080 --> 00:01:35,920 has been created by some of the very smallest creatures on the reef. 16 00:01:38,680 --> 00:01:43,200 But visited by some of the most impressive animals on the planet. 17 00:01:53,200 --> 00:01:55,480 It's an ecosystem like no other. 18 00:01:57,720 --> 00:01:59,400 Vital to our oceans. 19 00:02:04,600 --> 00:02:08,280 And surprisingly, we are still uncovering its many secrets. 20 00:02:34,040 --> 00:02:37,520 The Great Barrier Reef lies on Australia's north-east coast. 21 00:02:41,120 --> 00:02:43,800 It's 1,400 miles long... 22 00:02:47,240 --> 00:02:50,760 ..and at its widest, 150 miles across. 23 00:02:53,840 --> 00:02:57,600 It consists of almost 3,000 individual coral reefs... 24 00:03:00,160 --> 00:03:02,120 ..and 900 islands. 25 00:03:05,720 --> 00:03:07,400 And for me, it's truly 26 00:03:07,400 --> 00:03:10,080 one of the most extraordinary places on the planet. 27 00:03:12,840 --> 00:03:14,200 People say to me, 28 00:03:14,200 --> 00:03:17,160 "What was the most magical thing you ever saw in your life? 29 00:03:17,160 --> 00:03:22,120 "What was the most magical moment in your career as a naturalist?" 30 00:03:22,120 --> 00:03:27,080 And I always say, the first time I put on a mask 31 00:03:27,080 --> 00:03:29,080 and went below the surface 32 00:03:29,080 --> 00:03:33,800 and moved in three dimensions just with a flick of my fin 33 00:03:33,800 --> 00:03:38,520 and suddenly saw all these amazingly multicoloured things 34 00:03:38,520 --> 00:03:41,240 living in communities right there. 35 00:03:42,240 --> 00:03:44,480 Just astounding things. 36 00:03:44,480 --> 00:03:46,360 Unforgettable beauty. 37 00:03:54,720 --> 00:03:57,840 I first came to the Barrier Reef nearly 60 years ago. 38 00:03:57,840 --> 00:04:01,080 And I remember very clearly how amazed I was 39 00:04:01,080 --> 00:04:04,040 to see such a complexity of life. 40 00:04:04,040 --> 00:04:08,200 But today, we have ways of looking at the reef, 41 00:04:08,200 --> 00:04:11,320 technical ways, which we never had before 42 00:04:11,320 --> 00:04:14,960 and give us a completely new vision of this wonderful place, 43 00:04:14,960 --> 00:04:18,800 which is surely one of the greatest treasures of the natural world. 44 00:04:25,320 --> 00:04:27,400 'Now I've returned. 45 00:04:27,400 --> 00:04:30,160 'And taking me on this journey is the Alucia, 46 00:04:30,160 --> 00:04:34,520 'a 56-metre state-of-the-art research and exploration vessel. 47 00:04:39,360 --> 00:04:43,120 'For this expedition, we've been granted unprecedented access 48 00:04:43,120 --> 00:04:46,880 'to some of the most remote corners of the Great Barrier Reef.' 49 00:04:54,400 --> 00:04:57,160 Onboard is a team of experts. 50 00:04:57,160 --> 00:05:00,360 And at our disposal, all the latest technology. 51 00:05:03,560 --> 00:05:06,440 Our mission is to reveal a hidden world 52 00:05:06,440 --> 00:05:08,280 and to complete a series of dives 53 00:05:08,280 --> 00:05:12,000 that have never before been attempted on the Great Barrier Reef. 54 00:05:15,800 --> 00:05:20,440 But to do that, we have had to bring in a very special piece of equipment. 55 00:05:22,800 --> 00:05:25,800 This is a Triton submarine. 56 00:05:29,120 --> 00:05:32,480 The very latest in submersible technology. 57 00:05:34,360 --> 00:05:37,560 And the first of its kind to be brought to these waters. 58 00:05:40,240 --> 00:05:44,360 The submersible's captain, Buck Taylor, will lead the dive team. 59 00:05:44,360 --> 00:05:49,840 With 2,000 dives under his belt, his expertise is unparalleled. 60 00:05:55,160 --> 00:05:57,400 While our film crew rigs the submersible 61 00:05:57,400 --> 00:05:59,120 with no fewer than eight cameras, 62 00:05:59,120 --> 00:06:01,920 Buck gathers the rest of the team together 63 00:06:01,920 --> 00:06:04,440 to brief us on the dives ahead. 64 00:06:04,440 --> 00:06:07,280 - COMPUTER: - "Welcome to the MV Alucia submersible team..." 65 00:06:07,280 --> 00:06:10,960 'The submersible offers spectacular filming opportunities, 66 00:06:10,960 --> 00:06:13,400 'but it's not without its dangers.' 67 00:06:13,400 --> 00:06:15,520 Coming from the rescue background, 68 00:06:15,520 --> 00:06:18,440 I've been in a submersible up to my waist in water, 69 00:06:18,440 --> 00:06:21,840 I've had a fire in a submersible. 70 00:06:21,840 --> 00:06:24,520 - COMPUTER: - "No smoking, smoking materials..." 71 00:06:25,520 --> 00:06:29,160 'As well as these hazards, Buck is also obliged to raise 72 00:06:29,160 --> 00:06:32,840 'one of the more intimate limitations of submersible life.' 73 00:06:32,840 --> 00:06:35,480 We do have facilities of a toilet onboard. 74 00:06:35,480 --> 00:06:38,920 Obviously, because it's quite confined, it's not very discrete, 75 00:06:38,920 --> 00:06:42,560 so we do have some towels out that we can hold up around you. 76 00:06:42,560 --> 00:06:46,160 It's quite interesting trying to explain about going to the toilet 77 00:06:46,160 --> 00:06:49,720 in a three-man submersible in a sort of sphere 78 00:06:49,720 --> 00:06:52,800 that's less than two metres diameter. It's quite intimate. 79 00:06:52,800 --> 00:06:55,680 He was six foot three... LAUGHTER 80 00:06:55,680 --> 00:06:57,880 We've got cameras pointing from every direction. 81 00:06:57,880 --> 00:06:59,680 - Good. - Thank you. 82 00:06:59,680 --> 00:07:02,400 Thanks very much. I'm looking forward to it a lot. 83 00:07:08,720 --> 00:07:10,400 The Alucia's first mission 84 00:07:10,400 --> 00:07:13,520 is to take us to the Barrier's stunning ribbon reefs 85 00:07:13,520 --> 00:07:15,600 in the north of its extensive range. 86 00:07:19,760 --> 00:07:22,320 It's an area of outstanding natural beauty 87 00:07:22,320 --> 00:07:25,360 and the perfect place to begin our explorations. 88 00:07:29,960 --> 00:07:32,200 The story of the Great Barrier Reef 89 00:07:32,200 --> 00:07:36,040 starts with its most important inhabitant, the coral itself. 90 00:07:40,120 --> 00:07:42,600 Hidden inside these branching structures 91 00:07:42,600 --> 00:07:46,600 are the thousands of tiny creatures that build these reefs. 92 00:07:51,800 --> 00:07:54,080 And they have an enormous claim to fame. 93 00:07:55,200 --> 00:07:58,920 Together, they've built the largest living structure on earth. 94 00:08:04,720 --> 00:08:08,760 But these fascinating coral creatures are only active at night. 95 00:08:08,760 --> 00:08:10,400 So to capture their behaviour, 96 00:08:10,400 --> 00:08:13,280 we'll need to do something I've never done before. 97 00:08:16,560 --> 00:08:21,000 Tonight, a team of specialist divers, scientists 98 00:08:21,000 --> 00:08:23,400 and programme-makers, like myself, 99 00:08:23,400 --> 00:08:27,560 have gathered together to have a closer look and a longer look 100 00:08:27,560 --> 00:08:31,560 at the reef at night than perhaps has ever been possible. 101 00:08:34,880 --> 00:08:36,920 When I came here 60 years ago, 102 00:08:36,920 --> 00:08:40,160 the idea of a night dive was almost inconceivable. 103 00:08:41,640 --> 00:08:46,360 It seemed to me, a beginner, to be far too dangerous. 104 00:08:46,360 --> 00:08:49,240 But now, technology is going to help me. 105 00:08:54,640 --> 00:08:57,400 'Once I'm in, it's over to Buck and the support team, 106 00:08:57,400 --> 00:08:59,720 'who remain onboard the Alucia, 107 00:08:59,720 --> 00:09:02,280 'to make sure everything goes smoothly.' 108 00:09:02,280 --> 00:09:04,320 INDISTINCT RADIO 109 00:09:06,520 --> 00:09:10,920 'They've spent months preparing for this moment.' 110 00:09:10,920 --> 00:09:12,520 SIREN WAILS 111 00:09:12,520 --> 00:09:16,240 'Our submersible, known to the crew as the Nadir, 112 00:09:16,240 --> 00:09:19,640 'has, of course, made dives like this all over the world. 113 00:09:19,640 --> 00:09:24,000 'She's descended to the deepest part of the oceans, 114 00:09:24,000 --> 00:09:27,160 'but she's never visited the Barrier Reef. 115 00:09:27,160 --> 00:09:28,960 'It's a first for all of us. 116 00:09:34,920 --> 00:09:38,440 'But before we can go anywhere, we'll need to position the Nadir 117 00:09:38,440 --> 00:09:41,120 'at a safe distance from the Alucia. 118 00:09:45,280 --> 00:09:47,560 'It's a substantial operation, 119 00:09:47,560 --> 00:09:49,720 'but finally, we're ready to get underway.' 120 00:09:51,840 --> 00:09:55,720 S.O. Nadir, just approaching the buoy. Am I clear to vent? 121 00:09:57,920 --> 00:10:00,640 - RADIO: - "Roger, Nadir. You are clear to vent, clear to vent. 122 00:10:00,640 --> 00:10:02,440 "Have a good dive, guys." 123 00:10:10,560 --> 00:10:13,920 'Sinking beneath the waves is a very surreal experience. 124 00:10:16,640 --> 00:10:19,240 'Your first instinct is to hold your breath. 125 00:10:28,920 --> 00:10:32,280 'At night, the reef is a ghostly world. 126 00:10:38,240 --> 00:10:41,120 'Tiny shrimp-like creatures dance in the lights.' 127 00:10:50,480 --> 00:10:52,160 Look at that! Wow! 128 00:10:53,920 --> 00:10:57,960 'With little light, there is a lot less colour, 129 00:10:57,960 --> 00:11:00,720 'but this is still a very magical place.' 130 00:11:05,360 --> 00:11:07,560 Ah! There's something! My first fish! 131 00:11:08,680 --> 00:11:13,960 'Our submersible will eventually take us to depths of 300 metres. 132 00:11:13,960 --> 00:11:16,480 'Now, we're only 30 metres down, 133 00:11:16,480 --> 00:11:18,840 'but that's exciting enough for a start.' 134 00:11:25,120 --> 00:11:28,440 In these dark waters, Buck needs to be careful 135 00:11:28,440 --> 00:11:31,000 as we move around the front of the reef. 136 00:11:37,280 --> 00:11:41,680 Coral reefs are sometimes described as marine cities. 137 00:11:41,680 --> 00:11:43,960 And the comparison is indeed a good one. 138 00:11:46,040 --> 00:11:49,400 We're here to take a closer look at the reef's architecture. 139 00:11:49,400 --> 00:11:51,000 Its coral buildings. 140 00:11:56,600 --> 00:12:00,720 There are more than 450 different species of hard coral. 141 00:12:02,400 --> 00:12:06,320 The plant-like structures we can see are actually made of limestone. 142 00:12:06,320 --> 00:12:09,960 And living inside are thousands of highly industrious little animals 143 00:12:09,960 --> 00:12:11,840 called coral polyps. 144 00:12:17,120 --> 00:12:19,720 At night, the water around the reef 145 00:12:19,720 --> 00:12:23,200 becomes filled with clouds of tiny microorganisms 146 00:12:23,200 --> 00:12:25,440 called the zooplankton. 147 00:12:28,160 --> 00:12:30,240 And that's what the corals eat. 148 00:12:35,680 --> 00:12:39,200 The coral polyps themselves emerge from their stony skeleton 149 00:12:39,200 --> 00:12:43,640 and start groping in the water with their tentacles. 150 00:12:46,400 --> 00:12:50,400 To see just what they're doing, we need specialised cameras. 151 00:12:53,800 --> 00:12:57,440 The coral polyps never leave the safety of their limestone homes, 152 00:12:57,440 --> 00:12:59,120 even at night. 153 00:13:03,360 --> 00:13:06,520 If something edible comes within reach, 154 00:13:06,520 --> 00:13:10,480 the polyps fire the microscopic harpoons that line their tentacles. 155 00:13:15,600 --> 00:13:19,520 The prey is stunned or killed and then pulled into the polyp's mouth. 156 00:13:21,600 --> 00:13:24,880 When you can't leave your home, it pays to be accurate. 157 00:13:26,320 --> 00:13:30,480 The coral's stinging armoury isn't used only for collecting food. 158 00:13:30,480 --> 00:13:32,880 They also use it to fight. 159 00:13:32,880 --> 00:13:36,560 Because, as has been discovered only comparatively recently, 160 00:13:36,560 --> 00:13:39,360 corals, like many animals that live on land, 161 00:13:39,360 --> 00:13:41,600 are extremely territorial. 162 00:13:41,600 --> 00:13:44,400 But in order to see the battles, 163 00:13:44,400 --> 00:13:46,680 you have to speed up time. 164 00:13:52,720 --> 00:13:56,960 The polyps of each colony collaborate to defend their patch. 165 00:13:59,760 --> 00:14:02,560 As in any big city, space is precious. 166 00:14:04,360 --> 00:14:06,840 If a rival grows too close, there will be trouble. 167 00:14:10,560 --> 00:14:12,960 These fights can last for hours. 168 00:14:17,680 --> 00:14:19,080 The competition is fierce 169 00:14:19,080 --> 00:14:21,640 as the coral colonies jostle with one another 170 00:14:21,640 --> 00:14:23,600 for the best feeding sites. 171 00:14:30,520 --> 00:14:34,000 When they're not locked in battle, the corals have work to do. 172 00:14:36,000 --> 00:14:39,880 'They must extract calcium carbonate from the surrounding seawater 173 00:14:39,880 --> 00:14:42,160 'and with it, build their homes.' 174 00:14:48,280 --> 00:14:51,800 Each coral species has its own particular way of building. 175 00:14:51,800 --> 00:14:55,040 And together, they eventually create the huge reefs 176 00:14:55,040 --> 00:15:00,360 that provide homes for all kinds of other, much larger creatures. 177 00:15:13,640 --> 00:15:19,080 At night, the reef seems like an extraterrestrial world. 178 00:15:19,080 --> 00:15:22,480 But down here, we are the aliens. 179 00:15:26,240 --> 00:15:27,800 And here comes a turtle! 180 00:15:30,120 --> 00:15:32,280 Attracted by our lights. 181 00:15:32,280 --> 00:15:34,040 Come on! 182 00:15:39,360 --> 00:15:40,920 Coming straight to us. 183 00:15:51,320 --> 00:15:53,560 Isn't that great! 184 00:15:53,560 --> 00:15:55,800 'Coming face-to-face with a green turtle 185 00:15:55,800 --> 00:15:57,840 'in this setting is a rare privilege, 186 00:15:57,840 --> 00:16:01,360 'but its presence here, along with all the other reef residents, 187 00:16:01,360 --> 00:16:05,280 'is only made possible thanks to the great coral builders.' 188 00:16:05,280 --> 00:16:07,840 He doesn't look very upset, does he? 189 00:16:11,240 --> 00:16:13,320 It happens all the time on this reef. 190 00:16:23,680 --> 00:16:27,000 It's the perfect end to my first dive. 191 00:16:30,720 --> 00:16:35,120 The time has come for us to make our way back up to the Alucia. 192 00:16:45,560 --> 00:16:47,200 Welcome back, gentlemen. 193 00:16:52,520 --> 00:16:56,240 Diving on a reef at night is a thrilling experience. 194 00:16:59,400 --> 00:17:03,320 What I want to see next is how exactly these tiny coral creatures 195 00:17:03,320 --> 00:17:06,160 have created such a vast and extensive habitat. 196 00:17:10,280 --> 00:17:12,520 To answer that, we'll need to look at the reef 197 00:17:12,520 --> 00:17:14,440 from another angle entirely. 198 00:17:51,360 --> 00:17:53,640 At this height, you can begin to appreciate 199 00:17:53,640 --> 00:17:56,640 the immense size of the Barrier Reef. 200 00:17:56,640 --> 00:18:01,600 It's 2,300 kilometres long, 1,400 miles. 201 00:18:01,600 --> 00:18:05,160 It's the largest living structure on the planet. 202 00:18:08,840 --> 00:18:12,200 Reefs much like these develop in the shallow tropical waters 203 00:18:12,200 --> 00:18:15,240 that surround many an island and continental coast. 204 00:18:18,080 --> 00:18:20,240 But few can match the Great Barrier 205 00:18:20,240 --> 00:18:22,320 in either size or complexity. 206 00:18:24,880 --> 00:18:28,800 So, what is so special about the north-eastern coast of Australia? 207 00:18:31,240 --> 00:18:35,240 A clue to the answer lies in the shape of the sea floor. 208 00:18:37,560 --> 00:18:39,400 If we strip away the ocean, 209 00:18:39,400 --> 00:18:43,320 we can reveal the reason why such extraordinary growth is possible. 210 00:18:45,200 --> 00:18:49,160 The reef has grown on a very shallow continental shelf. 211 00:18:49,160 --> 00:18:53,400 Beyond which, there is a sudden and very steep 2,000-metre drop-off. 212 00:18:56,320 --> 00:19:00,960 It stands in waters with an average depth of just 35 metres. 213 00:19:00,960 --> 00:19:05,640 That's just about as far as sunlight can penetrate with any strength. 214 00:19:08,520 --> 00:19:12,400 Light is crucially important to reef-building corals 215 00:19:12,400 --> 00:19:15,160 because they have developed a special partnership 216 00:19:15,160 --> 00:19:17,880 with microscopic algae - 217 00:19:17,880 --> 00:19:21,080 plants that actually grow within tissues. 218 00:19:24,800 --> 00:19:27,000 The algae get a safe home 219 00:19:27,000 --> 00:19:30,040 and, like all plants, when they photosynthesise, 220 00:19:30,040 --> 00:19:31,760 they produce energy. 221 00:19:35,920 --> 00:19:40,480 The coral polyps use this energy to construct their limestone home. 222 00:19:45,960 --> 00:19:48,520 Together, they've built an underwater city 223 00:19:48,520 --> 00:19:52,120 on a scale that is almost impossible to comprehend. 224 00:19:56,160 --> 00:19:59,720 But amazingly, just 10,000 years ago, 225 00:19:59,720 --> 00:20:02,320 there was no coral here at all. 226 00:20:06,760 --> 00:20:11,200 The Great Barrier Reef as we know it today simply didn't exist. 227 00:20:15,400 --> 00:20:18,320 How and when these coral communities began 228 00:20:18,320 --> 00:20:22,280 is something scientists have only recently started to investigate. 229 00:20:24,400 --> 00:20:26,720 Marine geologist, Dr Robin Beaman, 230 00:20:26,720 --> 00:20:31,160 has been leading an ambitious project to scan the entire reef. 231 00:20:31,160 --> 00:20:35,080 And his data has allowed us to map the sea floor. 232 00:20:36,720 --> 00:20:40,160 David, this is a three-dimensional model of the Great Barrier Reef. 233 00:20:40,160 --> 00:20:42,920 In deeper waters, we tend to use sonar, 234 00:20:42,920 --> 00:20:46,560 in shallow waters, we tend to use underwater laser beams 235 00:20:46,560 --> 00:20:48,280 to image the sea floor. 236 00:20:51,680 --> 00:20:55,280 'By combining computer modelling and radiocarbon dating, 237 00:20:55,280 --> 00:20:57,200 'his team have been able to reconstruct 238 00:20:57,200 --> 00:21:01,000 'the key stages in the development of the Great Barrier. 239 00:21:02,160 --> 00:21:04,880 'Their research has helped identify an event 240 00:21:04,880 --> 00:21:07,440 'between 10,000 and 20,000 years ago 241 00:21:07,440 --> 00:21:11,000 'which may explain how the Great Barrier Reef was formed. 242 00:21:14,480 --> 00:21:19,080 'But surprisingly, scientists are not the only ones to tell this story.' 243 00:21:20,760 --> 00:21:24,160 Australia's Aboriginal peoples arrived on this continent 244 00:21:24,160 --> 00:21:26,560 around 50,000 years ago. 245 00:21:30,920 --> 00:21:34,000 They have been telling the story of how the reef was formed 246 00:21:34,000 --> 00:21:37,160 long before the world's scientists even knew it existed. 247 00:21:39,080 --> 00:21:43,120 To hear that story, the Alucia is taking us to Northern Queensland 248 00:21:43,120 --> 00:21:46,240 to meet a community with a very special connection 249 00:21:46,240 --> 00:21:48,200 to this underwater world. 250 00:21:57,960 --> 00:22:01,400 They are the Gimuy Walubara Yidinji people. 251 00:22:01,400 --> 00:22:04,960 And they live just outside the city of Cairns. 252 00:22:11,720 --> 00:22:15,680 This community has dwelt alongside the reef for thousands of years. 253 00:22:17,640 --> 00:22:19,400 THEY SPEAK YIDINY 254 00:22:21,280 --> 00:22:25,800 And many of their traditions hark back to those ancient times. 255 00:22:25,800 --> 00:22:28,240 THEY SING IN YIDINY 256 00:22:30,320 --> 00:22:34,520 And one of them tells how the reef came into existence. 257 00:22:34,520 --> 00:22:38,680 It's a legend that has been passed down from generation to generation 258 00:22:38,680 --> 00:22:40,680 in the form of a dance. 259 00:22:44,080 --> 00:22:47,440 Tell me the story that's connected to this dance, sir. 260 00:22:47,440 --> 00:22:52,760 It's part of our law story that's told to me by my dad, my father, 261 00:22:52,760 --> 00:22:56,320 and was told to him by his father and his grandfather, as well. 262 00:22:59,000 --> 00:23:01,240 The part of the dance that really interests me 263 00:23:01,240 --> 00:23:04,440 is the story of Gunyah and the sacred fish. 264 00:23:07,200 --> 00:23:10,400 The story starts with Gunyah going out to sea. 265 00:23:10,400 --> 00:23:14,360 And he saw a glitter in the water, which he thought was a fish. 266 00:23:14,360 --> 00:23:17,720 And when he speared it, 267 00:23:17,720 --> 00:23:22,720 he actually speared our sacred fish, the stingray. 268 00:23:22,720 --> 00:23:25,880 So the fish got angry and it started to rise up. 269 00:23:25,880 --> 00:23:30,360 And with its wings, it made the sea rough 270 00:23:30,360 --> 00:23:32,800 and it caused the sea to rise. 271 00:23:34,880 --> 00:23:39,240 Take us back to the time when the first human beings arrived here. 272 00:23:39,240 --> 00:23:40,920 What was it like then? 273 00:23:40,920 --> 00:23:42,960 The coastline would have been very different. 274 00:23:42,960 --> 00:23:45,360 So the coastline would have been right out here, 275 00:23:45,360 --> 00:23:47,240 on the edge of the Great Barrier Reef. 276 00:23:47,240 --> 00:23:49,320 The sea level was much lower 277 00:23:49,320 --> 00:23:52,160 and they would have fished and hunted the coastline. 278 00:23:52,160 --> 00:23:53,680 These were limestone hills 279 00:23:53,680 --> 00:23:55,840 that would have been eucalypts, marshlands. 280 00:23:55,840 --> 00:23:58,080 There would have been mangrove swamps. 281 00:24:01,840 --> 00:24:04,840 But roughly 14,000 years ago, 282 00:24:04,840 --> 00:24:08,480 the climate started to dramatically change. 283 00:24:08,480 --> 00:24:10,360 It was the end of the Ice Age. 284 00:24:10,360 --> 00:24:13,840 And all that water started to inundate the continental shelf 285 00:24:13,840 --> 00:24:18,040 and start to flood this vast, flat landscape. 286 00:24:18,040 --> 00:24:20,520 - And in one man's lifetime? - Absolutely. 287 00:24:20,520 --> 00:24:24,840 So, people living here are going to have to retreat? 288 00:24:24,840 --> 00:24:27,360 Absolutely. It would have been a dramatic time for them. 289 00:24:27,360 --> 00:24:29,360 They would have been following the coastline 290 00:24:29,360 --> 00:24:31,440 as it prograded further and further back 291 00:24:31,440 --> 00:24:33,320 as the water was flooding the shelf. 292 00:24:33,320 --> 00:24:37,480 The rate of change was so great that in these very flat areas here, 293 00:24:37,480 --> 00:24:41,440 the coastline would have moved back by hundreds of metres every year. 294 00:24:41,440 --> 00:24:43,240 - Every year? - Every year. 295 00:24:44,720 --> 00:24:47,720 Gosh! That's formidable. 296 00:25:02,320 --> 00:25:05,800 So our story is about the sea rising. 297 00:25:05,800 --> 00:25:09,040 And there used to be a cliff further out. 298 00:25:09,040 --> 00:25:12,000 And past the cliff is where the ocean used to be. 299 00:25:12,000 --> 00:25:13,880 Now, that's really remarkable. 300 00:25:13,880 --> 00:25:18,440 Because Western science is just beginning to make discoveries 301 00:25:18,440 --> 00:25:21,400 that seem to suggest that the sea, 302 00:25:21,400 --> 00:25:25,520 10,000, 20,000 years ago, was way, way out there, 303 00:25:25,520 --> 00:25:27,640 which is exactly what your story says. 304 00:25:27,640 --> 00:25:29,520 - Extraordinary. - Yes. 305 00:25:29,520 --> 00:25:33,280 A folk memory of an event that happened all that time ago. 306 00:25:33,280 --> 00:25:37,160 Yeah. And the only way we can keep it alive 307 00:25:37,160 --> 00:25:40,320 - is through our song and our dance. - Yes. 308 00:25:40,320 --> 00:25:43,520 Just to keep that going through our culture. 309 00:25:44,680 --> 00:25:46,120 So the tradition lives. 310 00:25:46,120 --> 00:25:48,160 - Yes. - It's wonderful. 311 00:25:52,560 --> 00:25:56,400 'It is truly astounding to think that this story has survived 312 00:25:56,400 --> 00:25:59,560 'for so many years and across so many generations. 313 00:26:03,320 --> 00:26:07,280 'And that it coincides with what scientists are now discovering 314 00:26:07,280 --> 00:26:09,640 'about the age of the Great Barrier.' 315 00:26:13,120 --> 00:26:16,880 The polyps that built the reef arrived as spawn, 316 00:26:16,880 --> 00:26:19,000 swept here by the ocean currents. 317 00:26:21,160 --> 00:26:23,680 Corals are not new to the planet. 318 00:26:23,680 --> 00:26:27,000 They've been around for at least 500 million years. 319 00:26:34,880 --> 00:26:38,800 The new reefs provided homes for thousands of animals, 320 00:26:38,800 --> 00:26:42,880 and very quickly, a whole new community began to establish itself. 321 00:26:46,280 --> 00:26:48,040 Today, the Great Barrier Reef 322 00:26:48,040 --> 00:26:51,800 has one of the most diverse communities of animals on the planet. 323 00:26:56,120 --> 00:27:00,000 And it's the story of these remarkable reef residents 324 00:27:00,000 --> 00:27:02,400 that I want to investigate next. 325 00:27:04,680 --> 00:27:09,440 To do that, the Alucia is taking me north to a very special place. 326 00:27:11,200 --> 00:27:13,360 Lizard Island. 327 00:27:21,040 --> 00:27:23,400 It's one of the 600 continental islands 328 00:27:23,400 --> 00:27:25,760 scattered across the Great Barrier Reef. 329 00:27:30,320 --> 00:27:35,000 And its shallow lagoon is known for its exceptional biodiversity. 330 00:27:39,440 --> 00:27:42,160 'With the Alucia anchored in deeper water, 331 00:27:42,160 --> 00:27:46,040 'a more modest mode of transport will be needed to reach the shore. 332 00:27:49,640 --> 00:27:52,520 'I first visited Lizard Island in 1957. 333 00:27:54,520 --> 00:27:57,000 'Then, it was completely uninhabited. 334 00:28:00,320 --> 00:28:03,880 'Little did I know how important this remote outpost would become 335 00:28:03,880 --> 00:28:06,680 'in helping us to understand the coral reefs. 336 00:28:09,920 --> 00:28:12,600 'But today, that's exactly what this remarkable place 337 00:28:12,600 --> 00:28:14,600 'is world-renowned for.' 338 00:28:18,600 --> 00:28:21,760 Here, for the past few decades, there has been a research station 339 00:28:21,760 --> 00:28:26,360 where scientists can study continuously and in detail 340 00:28:26,360 --> 00:28:30,840 the full complexity of the community of animals that makes up the reef. 341 00:28:34,880 --> 00:28:39,600 Every year, Lizard Island hosts 100 different research projects. 342 00:28:42,080 --> 00:28:44,360 Here, scientists are shedding new light 343 00:28:44,360 --> 00:28:46,400 on the lives of the reefs' residents 344 00:28:46,400 --> 00:28:49,520 and the way in which this complex community works. 345 00:28:52,680 --> 00:28:57,280 Thanks to their research, we now know that coral reefs rival rainforests 346 00:28:57,280 --> 00:29:00,240 in the vast numbers of species they support. 347 00:29:03,440 --> 00:29:06,920 The first question is, where does all that diversity come from? 348 00:29:11,720 --> 00:29:13,960 Lizard Island reefs owe their richness 349 00:29:13,960 --> 00:29:17,320 to the special plants that, in places, fringe the shores. 350 00:29:19,720 --> 00:29:21,720 They link land and sea 351 00:29:21,720 --> 00:29:24,360 and they're vital to the coral reef community. 352 00:29:25,720 --> 00:29:27,320 They're mangroves. 353 00:29:29,880 --> 00:29:32,560 Taking shelter amongst the roots 354 00:29:32,560 --> 00:29:37,000 are thousands of juvenile fish of all shapes and sizes. 355 00:29:37,000 --> 00:29:40,720 Many of these little fish look harmless enough, 356 00:29:40,720 --> 00:29:43,360 but when they grow up, they will become 357 00:29:43,360 --> 00:29:46,720 some of the most ferocious predators on the reef. 358 00:29:46,720 --> 00:29:49,560 Indeed, the existence of these mangrove nurseries 359 00:29:49,560 --> 00:29:53,080 is one of the reasons why the fish populations of the reef 360 00:29:53,080 --> 00:29:56,720 are among the most varied and richest in the world. 361 00:30:00,880 --> 00:30:04,560 The mangroves are not only nurseries, they're playgrounds. 362 00:30:07,640 --> 00:30:11,720 The aim of the game here is to survive the most vulnerable stage 363 00:30:11,720 --> 00:30:14,960 of any animal's life, being a juvenile. 364 00:30:19,320 --> 00:30:21,240 Baby turtles... 365 00:30:22,600 --> 00:30:25,440 ..rays and even sharks take refuge here. 366 00:30:30,160 --> 00:30:34,320 These juvenile blacktips are just a few weeks old. 367 00:30:34,320 --> 00:30:36,600 And only one sixth of the size they will be 368 00:30:36,600 --> 00:30:40,200 when they make it out on to the reef as adults. 369 00:30:42,040 --> 00:30:43,720 For the first year of their lives, 370 00:30:43,720 --> 00:30:46,960 the mangroves play a vital role in keeping them safe. 371 00:30:49,320 --> 00:30:53,160 As infants, they're vulnerable to predation from larger sharks. 372 00:30:55,560 --> 00:30:59,480 But the tangle of mangrove roots keeps the big predators out 373 00:30:59,480 --> 00:31:02,240 and stops them making meals of the youngsters. 374 00:31:07,360 --> 00:31:08,680 When the young are ready, 375 00:31:08,680 --> 00:31:11,640 they will eventually leave this sheltered world behind 376 00:31:11,640 --> 00:31:15,200 and make their way to the reef beyond the mangrove roots. 377 00:31:21,920 --> 00:31:24,760 The next challenge will be to find their place 378 00:31:24,760 --> 00:31:27,320 in one of the most crowded ecosystems on the planet. 379 00:31:35,480 --> 00:31:39,080 Getting on the property ladder here is no easy feat. 380 00:31:41,640 --> 00:31:45,160 Which is why one of the reefs' most celebrated characters 381 00:31:45,160 --> 00:31:47,840 has developed a very special relationship. 382 00:31:51,760 --> 00:31:55,440 Clownfish deal with the problem of overcrowding 383 00:31:55,440 --> 00:31:59,960 by sharing space with another creature, gigantic anemones. 384 00:32:05,320 --> 00:32:08,680 They've formed a relationship in which both parties benefit. 385 00:32:11,480 --> 00:32:15,360 Anemones have tentacles that are packed with stinging cells. 386 00:32:15,360 --> 00:32:19,520 Most fish touching one get a very nasty sting, 387 00:32:19,520 --> 00:32:21,880 but not the clownfish, 388 00:32:21,880 --> 00:32:25,920 thanks to the protective layer of mucus that covers its body. 389 00:32:29,040 --> 00:32:31,880 The clownfish keeps the anemone in good health 390 00:32:31,880 --> 00:32:33,960 by removing unwanted parasites. 391 00:32:35,280 --> 00:32:39,120 And in return, the anemone offers security. 392 00:32:39,120 --> 00:32:42,560 Its stinging cells ward off the sort of creatures 393 00:32:42,560 --> 00:32:44,920 which would otherwise threaten the clownfish. 394 00:32:49,600 --> 00:32:54,760 When the time comes for a pair to breed, that protection will be vital. 395 00:32:59,320 --> 00:33:02,520 A female may lay up to 1,000 eggs 396 00:33:02,520 --> 00:33:05,160 on the rock beneath her anemone home. 397 00:33:09,400 --> 00:33:11,200 As she delicately attaches them, 398 00:33:11,200 --> 00:33:15,880 the male follows closely behind, fertilising the eggs as he goes. 399 00:33:20,080 --> 00:33:23,680 A week will pass before the young are ready to emerge. 400 00:33:27,520 --> 00:33:30,040 Hatching only happens at night, 401 00:33:30,040 --> 00:33:33,040 so to record it, we have to use infrared cameras 402 00:33:33,040 --> 00:33:35,920 in a specialised filming environment. 403 00:33:38,000 --> 00:33:42,080 This is the very first time that this behaviour has been filmed. 404 00:33:44,680 --> 00:33:47,400 With gentle encouragement from their father, 405 00:33:47,400 --> 00:33:49,640 the young are helped on their way. 406 00:33:57,960 --> 00:34:01,640 Once the little larvae are set free, they're on their own. 407 00:34:03,160 --> 00:34:05,760 They'll spend the first few weeks of their life 408 00:34:05,760 --> 00:34:07,760 developing in the open ocean. 409 00:34:10,720 --> 00:34:12,320 But how will the young clownfish 410 00:34:12,320 --> 00:34:14,880 find their way back to the coral reefs 411 00:34:14,880 --> 00:34:17,560 after drifting many miles out to sea? 412 00:34:25,000 --> 00:34:28,600 To understand that, we will have to tune into a sense 413 00:34:28,600 --> 00:34:32,480 we don't normally associate with this colourful underwater world. 414 00:34:35,400 --> 00:34:36,960 Sound. 415 00:34:42,240 --> 00:34:46,360 Coral reefs are surprisingly noisy places. 416 00:34:46,360 --> 00:34:50,400 Fish and invertebrates produce a whole range of clicks 417 00:34:50,400 --> 00:34:52,720 and grunts and snaps. 418 00:34:52,720 --> 00:34:57,400 The healthier the reef, the more varied and numerous its inhabitants 419 00:34:57,400 --> 00:34:59,800 and the louder this chorus is. 420 00:35:02,280 --> 00:35:05,120 We now know that fish, just like birds, 421 00:35:05,120 --> 00:35:08,600 vocalise most at dawn and dusk. 422 00:35:11,280 --> 00:35:14,680 Damselfish call to defend their territory. 423 00:35:14,680 --> 00:35:17,360 GRUNTING 424 00:35:18,840 --> 00:35:21,520 Seahorses click to attract a mate. 425 00:35:21,520 --> 00:35:23,920 CLICKING 426 00:35:26,600 --> 00:35:29,240 Others create a very different soundscape 427 00:35:29,240 --> 00:35:31,720 simply by carrying out their daily duties. 428 00:35:31,720 --> 00:35:33,800 SQUAWKING 429 00:35:36,880 --> 00:35:39,800 Parrotfish crunching through the hard coral 430 00:35:39,800 --> 00:35:41,920 are a constant on the reef. 431 00:35:44,440 --> 00:35:47,160 Fish perceive sound in two different ways. 432 00:35:47,160 --> 00:35:50,160 Many have internal ears, but underwater, 433 00:35:50,160 --> 00:35:53,000 they can also feel sound as a vibration. 434 00:35:56,760 --> 00:36:02,200 The noise is a key indication that the community is in good shape. 435 00:36:02,200 --> 00:36:04,960 In fact, the louder the noise on a reef, 436 00:36:04,960 --> 00:36:07,960 the more inviting it is to newcomers. 437 00:36:07,960 --> 00:36:11,080 Newcomers like the young clownfish. 438 00:36:16,520 --> 00:36:19,080 This little male is no bigger than a button, 439 00:36:19,080 --> 00:36:23,200 but the time has come for him to find his place in the big city. 440 00:36:29,920 --> 00:36:34,040 At this stage, his swimming abilities leave something to be desired. 441 00:36:39,360 --> 00:36:42,920 But his hearing is so sensitive, he can tell over hundreds of metres 442 00:36:42,920 --> 00:36:44,520 if a reef is suitable. 443 00:36:47,480 --> 00:36:49,440 His journey can last days. 444 00:36:51,040 --> 00:36:54,400 The final approach is usually made at night to avoid predators. 445 00:36:56,400 --> 00:37:00,040 How fish hear and respond to sound of a healthy coral reef 446 00:37:00,040 --> 00:37:03,120 is a major area of study here on Lizard Island. 447 00:37:03,120 --> 00:37:07,240 And the scientists have a simple way of collecting these fish for study. 448 00:37:08,560 --> 00:37:11,280 A light trap, like this one at Lizard Island, 449 00:37:11,280 --> 00:37:15,760 is one way of assessing the way that the reef is working. 450 00:37:17,960 --> 00:37:22,560 Like moths to a flame, the young are attracted by the light. 451 00:37:24,200 --> 00:37:26,920 'By sampling the newest members of the community, 452 00:37:26,920 --> 00:37:29,640 'scientists can figure out how far these juvenile fish 453 00:37:29,640 --> 00:37:32,440 'are willing to travel for a good home.' 454 00:37:36,760 --> 00:37:40,720 In the case of the clownfish, juveniles have been known to travel 455 00:37:40,720 --> 00:37:44,080 250 miles before they find a reef. 456 00:37:51,120 --> 00:37:55,200 Fortunately, for the majority, it's usually a much shorter journey. 457 00:37:59,760 --> 00:38:02,160 While they rarely return to the particular anemone 458 00:38:02,160 --> 00:38:03,880 beside which they hatched, 459 00:38:03,880 --> 00:38:07,640 60% find a new home on the same reef. 460 00:38:13,840 --> 00:38:17,360 For the clownfish and the anemone, cooperation is the key 461 00:38:17,360 --> 00:38:20,920 to success in this extremely crowded environment. 462 00:38:27,680 --> 00:38:31,120 Other residents, however, take a very different approach. 463 00:38:33,680 --> 00:38:38,120 Rather than share their home, they fiercely defend their territories. 464 00:38:41,840 --> 00:38:43,960 This is a mantis shrimp. 465 00:38:46,800 --> 00:38:49,760 Spotting the competition is half the battle. 466 00:38:51,680 --> 00:38:54,280 There are many different species of mantis shrimp 467 00:38:54,280 --> 00:38:56,840 but they all have one thing in common, 468 00:38:56,840 --> 00:38:58,680 superb vision. 469 00:38:58,680 --> 00:39:02,920 The 400 million-year-old visual system of the mantis shrimp 470 00:39:02,920 --> 00:39:07,800 is the most complex in the entire animal kingdom. 471 00:39:07,800 --> 00:39:12,280 Its eyes are mounted on two stalks, giving it independent vision, 472 00:39:12,280 --> 00:39:15,320 but whereas our eyes produce binocular vision, 473 00:39:15,320 --> 00:39:19,120 each one of theirs produces three different images. 474 00:39:20,160 --> 00:39:25,080 Not only that, whereas we have three photoreceptors in our eyes, 475 00:39:25,080 --> 00:39:30,160 the mantis shrimp has up to 16, giving it access to 476 00:39:30,160 --> 00:39:34,880 parts of the spectrum that we can't even see, let alone imagine. 477 00:39:37,880 --> 00:39:42,280 And they can use their amazing vision to devastating effect. 478 00:39:47,080 --> 00:39:50,520 While some are armed with spears, others carry clubs. 479 00:39:57,080 --> 00:39:59,600 Many are champion boxers. 480 00:39:59,600 --> 00:40:01,120 They can deliver a punch 481 00:40:01,120 --> 00:40:04,480 that accelerates faster than a .22 calibre bullet. 482 00:40:10,240 --> 00:40:12,840 These powerful blows are used to stun their prey 483 00:40:12,840 --> 00:40:14,560 and defend their burrows. 484 00:40:19,680 --> 00:40:24,040 Mantis shrimps are one of the more house-proud residents on the reef. 485 00:40:25,800 --> 00:40:27,920 In fact, they're compulsive cleaners. 486 00:40:35,880 --> 00:40:38,520 They keep their burrows meticulously neat. 487 00:40:41,520 --> 00:40:44,280 With all that effort, it's hardly surprising that they're 488 00:40:44,280 --> 00:40:45,680 fiercely territorial. 489 00:40:48,320 --> 00:40:50,760 In fact, mantis shrimps have earned themselves 490 00:40:50,760 --> 00:40:53,440 a reputation for being somewhat ill-tempered. 491 00:40:55,000 --> 00:40:58,280 But scientists have discovered that there's another side 492 00:40:58,280 --> 00:40:59,840 to these macho males. 493 00:41:01,360 --> 00:41:05,120 This young hopeful is trying to catch the eye of a potential mate. 494 00:41:06,400 --> 00:41:09,280 He starts by showing off his paddle-like antennae. 495 00:41:13,440 --> 00:41:16,200 His technique may not be very impressive to us 496 00:41:16,200 --> 00:41:19,680 but he is, in fact, sending the female secret signals. 497 00:41:22,800 --> 00:41:26,000 And that is possible because mantis shrimps can see 498 00:41:26,000 --> 00:41:29,280 and reflect a kind of light that absolutely no other 499 00:41:29,280 --> 00:41:31,840 creature in the world that we know of can see... 500 00:41:33,480 --> 00:41:34,520 ..including us. 501 00:41:36,880 --> 00:41:41,320 The male's display is a private invitation for this female to dance. 502 00:41:50,000 --> 00:41:51,880 So far, so good. 503 00:41:51,880 --> 00:41:54,040 She makes her way to the dance floor. 504 00:42:01,960 --> 00:42:05,160 If the male can impress the female with his performance, 505 00:42:05,160 --> 00:42:07,720 she will choose him to father her offspring. 506 00:42:17,640 --> 00:42:20,480 It seems that this male has all the right moves. 507 00:42:25,360 --> 00:42:28,480 The final phase of courtship, however, usually takes place 508 00:42:28,480 --> 00:42:32,120 out of sight, within their burrows. 509 00:42:38,200 --> 00:42:41,640 The mantis shrimp is arguably one of the reefs most colourful 510 00:42:41,640 --> 00:42:44,520 characters and typifies the key to survival here. 511 00:42:49,040 --> 00:42:54,680 Each resident species has had to carve out its own particular niche 512 00:42:54,680 --> 00:42:58,560 and that is what has created this extraordinary diversity. 513 00:43:00,520 --> 00:43:05,480 Here, life can evolve 50% faster than in other marine environments. 514 00:43:07,960 --> 00:43:11,200 The tiny creatures that have built this remarkable ecosystem 515 00:43:11,200 --> 00:43:17,000 have created a habitat so complex that it supports all kinds of life. 516 00:43:21,200 --> 00:43:23,840 But none of the reef's residents would be here 517 00:43:23,840 --> 00:43:26,560 without one truly extraordinary event. 518 00:43:28,320 --> 00:43:30,320 It occurs just once a year 519 00:43:30,320 --> 00:43:33,440 and is one of the greatest of all natural spectacles. 520 00:43:37,280 --> 00:43:41,400 It wasn't until the 1980s that scientists discovered it, 521 00:43:41,400 --> 00:43:43,120 here on the Great Barrier. 522 00:43:45,480 --> 00:43:47,000 On a few nights of the year 523 00:43:47,000 --> 00:43:48,760 when the conditions are just right, 524 00:43:48,760 --> 00:43:50,920 all along the length of the reef, 525 00:43:50,920 --> 00:43:55,040 corals of many different species suddenly erupt. 526 00:43:55,040 --> 00:43:58,080 It's the great spawning event 527 00:43:58,080 --> 00:44:00,840 and it's one of the wonders of the natural world. 528 00:44:02,840 --> 00:44:04,360 It's the one time in the year 529 00:44:04,360 --> 00:44:07,920 when the corals themselves don't just grow by branching, 530 00:44:07,920 --> 00:44:13,120 but reproduce sexually, and it's vital for the survival of the reef. 531 00:44:13,120 --> 00:44:15,440 In recent years, we've learned a great deal 532 00:44:15,440 --> 00:44:19,080 about the many factors that influenced the moment of spawning. 533 00:44:22,120 --> 00:44:25,480 But even though we know it occurs within days of the full moon in 534 00:44:25,480 --> 00:44:29,800 October or November, the trigger that starts it all is still a mystery. 535 00:44:34,840 --> 00:44:38,200 The light of the moon is, perhaps, the most influential, 536 00:44:38,200 --> 00:44:40,000 but there are many other factors, 537 00:44:40,000 --> 00:44:44,880 including the temperature of the water and the state of the tides. 538 00:44:44,880 --> 00:44:47,320 And as the moment approaches, 539 00:44:47,320 --> 00:44:49,680 all along the length of the reef, 540 00:44:49,680 --> 00:44:51,800 there's a mounting sense of excitement. 541 00:44:55,920 --> 00:44:58,880 Fish and other predators gather. 542 00:44:58,880 --> 00:45:01,480 This will be an opportunity for a feast. 543 00:45:09,800 --> 00:45:11,400 The timing has to be exact. 544 00:45:13,000 --> 00:45:16,960 Each species of coral has its own particular triggers, 545 00:45:16,960 --> 00:45:20,800 but they must synchronise their behaviour to ensure their success. 546 00:45:22,480 --> 00:45:25,160 Just half an hour before the big event, 547 00:45:25,160 --> 00:45:27,880 there is the first sign of the spawning to come. 548 00:45:31,480 --> 00:45:35,040 Small bundles of sperm and eggs bulge from the polyps. 549 00:45:41,120 --> 00:45:44,320 When the moment is right, there is a mass release. 550 00:46:11,960 --> 00:46:15,880 For hundreds of miles all along the coast, the corals erupt. 551 00:46:38,920 --> 00:46:43,120 Only with daybreak can you see the true scale of the event. 552 00:46:48,040 --> 00:46:52,720 Great ribbons of coral spawn drift over the surface of the sea. 553 00:47:00,240 --> 00:47:02,160 After the coral has spawned, 554 00:47:02,160 --> 00:47:05,880 the billions of developing larvae are swept far and wide 555 00:47:05,880 --> 00:47:07,600 by the tides and the currents. 556 00:47:08,800 --> 00:47:13,320 The vast majority will be eaten by fish and other creatures, 557 00:47:13,320 --> 00:47:17,600 but the few survivors must then find a place to settle, 558 00:47:17,600 --> 00:47:21,440 either on a newly-vacated site on an existing reef 559 00:47:21,440 --> 00:47:23,600 or perhaps to found a new one. 560 00:47:31,480 --> 00:47:33,720 The newest coral recruits will continue 561 00:47:33,720 --> 00:47:36,960 the work their ancestors began almost 10,000 years ago. 562 00:47:48,720 --> 00:47:53,440 They are the essential organisms on which the whole reef depends. 563 00:48:00,000 --> 00:48:02,400 The Great Barrier is what it is 564 00:48:02,400 --> 00:48:05,520 because the tiny coral polyps never stop building. 565 00:48:08,280 --> 00:48:12,720 And what they have created is one of the wonders of the natural world. 566 00:48:21,680 --> 00:48:24,760 Next time, we'll cross the Great Barrier Reef 567 00:48:24,760 --> 00:48:26,880 to meet its extraordinary visitors. 568 00:48:34,520 --> 00:48:35,880 I will meet turtles 569 00:48:35,880 --> 00:48:39,160 that may have travelled thousands of miles to get here 570 00:48:39,160 --> 00:48:40,720 and the remarkable people 571 00:48:40,720 --> 00:48:43,080 who are trying to save them from disaster. 572 00:48:48,960 --> 00:48:53,120 I will come face-to-face with the great predators of the reef. 573 00:48:53,120 --> 00:48:55,360 Wow. There's a huge shark. 574 00:48:55,360 --> 00:48:57,400 They are so beautiful in the water. 575 00:49:02,040 --> 00:49:05,920 And we'll meet a whale that seeks out human contact, 576 00:49:05,920 --> 00:49:08,720 a behaviour that happens nowhere else on Earth. 577 00:49:10,440 --> 00:49:12,560 Some come from the open ocean, 578 00:49:12,560 --> 00:49:15,920 others from the land immediately inshore 579 00:49:15,920 --> 00:49:18,880 and still others from the sky, 580 00:49:18,880 --> 00:49:22,760 to complicate still further the intricate community 581 00:49:22,760 --> 00:49:26,000 that is known as the Great Barrier Reef. 582 00:49:45,000 --> 00:49:46,120 For this series, 583 00:49:46,120 --> 00:49:50,080 the production team set themselves an ambitious challenge. 584 00:49:50,080 --> 00:49:54,120 They wanted me to experience the Great Barrier Reef as never before. 585 00:49:58,320 --> 00:50:02,040 To achieve that, we teamed up with a very special research vessel... 586 00:50:04,200 --> 00:50:06,240 ..the Alucia. 587 00:50:06,240 --> 00:50:08,360 There aren't many boats like this in the world and 588 00:50:08,360 --> 00:50:10,760 it's a kind of magic carpet for us. 589 00:50:10,760 --> 00:50:13,200 It allows us to float around the reef 590 00:50:13,200 --> 00:50:15,800 and for David to tell different parts of the story. 591 00:50:18,120 --> 00:50:21,160 On board, all the latest technology, 592 00:50:21,160 --> 00:50:23,520 helicopters, a laboratory 593 00:50:23,520 --> 00:50:25,320 and advanced mapping systems. 594 00:50:30,320 --> 00:50:31,960 At the helm of Alucia, 595 00:50:31,960 --> 00:50:33,520 Captain Frank Alika. 596 00:50:35,040 --> 00:50:37,720 The task of getting the ship into position 597 00:50:37,720 --> 00:50:41,160 for the first big submarine launch rests on his shoulders. 598 00:50:43,120 --> 00:50:45,680 Some parts are charted less well than others, 599 00:50:45,680 --> 00:50:48,000 but this particular bit, there's quite a lot of bombies 600 00:50:48,000 --> 00:50:50,440 and things out there that are likely to jump up and bite you 601 00:50:50,440 --> 00:50:53,240 on the bottom, and that's really not what you want. 602 00:50:56,440 --> 00:50:58,920 Fortunately, he's a lot more hands on 603 00:50:58,920 --> 00:51:01,920 than the skipper was on my first visit in 1957. 604 00:51:06,640 --> 00:51:08,040 But it was very primitive. 605 00:51:08,040 --> 00:51:10,600 The camera was wound up by clockwork 606 00:51:10,600 --> 00:51:13,320 and it was just me and the chap with a 16mm camera 607 00:51:13,320 --> 00:51:14,600 and I did the recording. 608 00:51:16,000 --> 00:51:20,080 It may have been a modest shoot but it was, in its way, ground-breaking. 609 00:51:22,200 --> 00:51:24,040 We worked on locations on the reef 610 00:51:24,040 --> 00:51:26,400 where film crews had never been before. 611 00:51:29,200 --> 00:51:33,640 60 years later, I'm told we are poised to make history once again. 612 00:51:36,520 --> 00:51:38,400 This time, to reach new areas of reef, 613 00:51:38,400 --> 00:51:42,720 I'll have to rely on the Triton submersible. 614 00:51:42,720 --> 00:51:46,880 And she's very flexible in terms of how shallow we can come, as well. 615 00:51:46,880 --> 00:51:48,760 She'll work in 1,000 metres happily, 616 00:51:48,760 --> 00:51:51,360 but we can also work in the splash zone, 617 00:51:51,360 --> 00:51:54,560 so her actual trim system is very good. 618 00:51:54,560 --> 00:51:57,280 Amazing visibility, as you'll see when you get in. 619 00:51:57,280 --> 00:51:59,000 Yes, she's a little bit flash. 620 00:52:02,720 --> 00:52:05,720 With just a few short hours before the first big dive, 621 00:52:05,720 --> 00:52:08,520 the excitement and pressure is building on deck. 622 00:52:12,160 --> 00:52:14,680 This will be the last opportunity for the crew 623 00:52:14,680 --> 00:52:16,360 to check the camera gear 624 00:52:16,360 --> 00:52:18,760 and make sure everything is perfectly in place. 625 00:52:21,160 --> 00:52:22,800 It's been a busy morning already. 626 00:52:22,800 --> 00:52:24,760 We've had soundmen, cameramen 627 00:52:24,760 --> 00:52:26,960 trying to fit all their gear into the sub. 628 00:52:26,960 --> 00:52:29,560 We're sort of running out of space for bodies. 629 00:52:31,840 --> 00:52:34,840 There are lots of worries when you put your 88-year-old presenter 630 00:52:34,840 --> 00:52:36,080 in something like this. 631 00:52:36,080 --> 00:52:39,280 I mean, it's got a very small area at the top to get into. 632 00:52:39,280 --> 00:52:41,280 There are all sorts of things that can go wrong. 633 00:52:41,280 --> 00:52:42,640 We're always very cautious. 634 00:52:46,120 --> 00:52:47,920 And even the most limber of sub operators 635 00:52:47,920 --> 00:52:49,480 will struggle getting in the sub. 636 00:52:49,480 --> 00:52:51,440 David's incredibly active and fit, 637 00:52:51,440 --> 00:52:53,320 but he's 88 and so we were slightly worried 638 00:52:53,320 --> 00:52:55,440 about how he might get into the sub. 639 00:52:57,400 --> 00:52:59,880 Yeah, that's it, that's the one. 640 00:52:59,880 --> 00:53:01,520 OK, so we're just going to... 641 00:53:01,520 --> 00:53:04,680 See that landing, he'll guide you right in. 642 00:53:04,680 --> 00:53:07,040 And then you can put your foot there, David. 643 00:53:07,040 --> 00:53:09,360 Keep coming. Nearly there. That's it. OK. 644 00:53:11,080 --> 00:53:12,840 You can rest against me if you want. 645 00:53:12,840 --> 00:53:14,400 Nearly sat on the pilot! 646 00:53:14,400 --> 00:53:17,840 - That's all right, I'm used to it. - That's what he's there for. 647 00:53:19,040 --> 00:53:21,400 David, as usual, defied all our thoughts 648 00:53:21,400 --> 00:53:23,640 and just went straight in without any trouble 649 00:53:23,640 --> 00:53:25,560 as though he was a 25-year-old. 650 00:53:25,560 --> 00:53:28,680 - Rest it on your lap. Is that OK? - Yep. 651 00:53:33,720 --> 00:53:37,920 So, that's hatch secure and we are ready. 652 00:53:40,160 --> 00:53:42,680 The sub weighs almost eight tonnes 653 00:53:42,680 --> 00:53:45,560 and getting it into the water is a major operation. 654 00:53:48,440 --> 00:53:50,960 There's something quite extraordinary about the Triton 655 00:53:50,960 --> 00:53:52,880 being launched, standing here on deck. 656 00:53:52,880 --> 00:53:56,280 Suddenly, the whole back deck area of the ship comes alive. 657 00:53:56,280 --> 00:53:57,800 You've got people running around. 658 00:53:57,800 --> 00:54:00,760 Everything's incredibly detailed and carefully planned, 659 00:54:00,760 --> 00:54:03,400 but you're sort of caught in a whirlwind as ropes fly 660 00:54:03,400 --> 00:54:05,680 and the submarine starts to move forwards. 661 00:54:05,680 --> 00:54:07,640 You know, this is a very exciting moment. 662 00:54:07,640 --> 00:54:11,480 You know, this is a big day, even in the world of David Attenborough. 663 00:54:17,640 --> 00:54:19,640 As we disappear beneath the waves, 664 00:54:19,640 --> 00:54:21,360 out on a support vessel, 665 00:54:21,360 --> 00:54:25,040 underwater cameraman Steve Hudson prepares to film the sub 666 00:54:25,040 --> 00:54:26,440 as it explores the reef. 667 00:54:29,800 --> 00:54:32,280 So, Nick and I are going to jump in the water, 668 00:54:32,280 --> 00:54:35,120 descend to a maximum depth of about 30 metres 669 00:54:35,120 --> 00:54:37,640 and shoot exterior shots of the submarine 670 00:54:37,640 --> 00:54:39,240 as it cruises over the reef. 671 00:54:41,160 --> 00:54:42,920 It can be pretty tiring. 672 00:54:42,920 --> 00:54:45,400 You have to swim in front of it, swim behind it, 673 00:54:45,400 --> 00:54:47,040 swim beneath it, swim above it, 674 00:54:47,040 --> 00:54:49,040 trying to get a multiple of shots. 675 00:54:51,080 --> 00:54:54,960 But today, because of the strong currents, visibility is poor. 676 00:54:59,320 --> 00:55:03,960 At first, Steve struggles to locate the sub through the cloudy water. 677 00:55:21,000 --> 00:55:23,080 Finally, he makes visual contact. 678 00:55:30,040 --> 00:55:32,880 Before we descend deeper and beyond his reach, 679 00:55:32,880 --> 00:55:35,440 Steve must get his exterior shots of the sub. 680 00:55:37,520 --> 00:55:39,240 Lead cameraman Paul Williams 681 00:55:39,240 --> 00:55:41,800 captures the action from inside the vessel. 682 00:55:43,520 --> 00:55:45,000 To get the best footage, 683 00:55:45,000 --> 00:55:47,720 the divers need to coordinate with the sub team. 684 00:55:49,440 --> 00:55:52,440 It's a task easier said than done. 685 00:55:52,440 --> 00:55:53,920 We're literally in a bubble. 686 00:55:53,920 --> 00:55:56,200 We can't talk to the divers outside. 687 00:55:56,200 --> 00:55:58,480 We had this rather crude hand signal. 688 00:55:58,480 --> 00:55:59,920 You know, it's like, 689 00:55:59,920 --> 00:56:02,320 "Get out of shot," or, you know, 690 00:56:02,320 --> 00:56:04,440 "Well, just move over that way a bit." 691 00:56:20,760 --> 00:56:22,920 Can you see his hand signals, yeah? 692 00:56:34,520 --> 00:56:36,360 He's saying, "Thank you." 693 00:56:36,360 --> 00:56:37,680 Thank you and... 694 00:56:37,680 --> 00:56:39,920 We're just going to do the descent now. 695 00:56:48,080 --> 00:56:49,760 'As the vessel dives deeper, 696 00:56:49,760 --> 00:56:53,160 'we're treated to some spectacular sights... 697 00:56:53,160 --> 00:56:54,240 Oh, how beautiful. 698 00:56:56,440 --> 00:56:59,160 '..which show why the reef is one of the most dazzling 699 00:56:59,160 --> 00:57:00,800 'habitats on the planet.' 700 00:57:06,760 --> 00:57:08,640 Oh, look at this lot. 701 00:57:08,640 --> 00:57:10,920 It's jolly nice that someone of my age 702 00:57:10,920 --> 00:57:13,720 can be taken down in fantastic comfort. 703 00:57:13,720 --> 00:57:15,320 Grey reef shark there. 704 00:57:15,320 --> 00:57:18,720 No problem about breathing. No problem about talking. 705 00:57:18,720 --> 00:57:21,720 No problem about your movements. 706 00:57:21,720 --> 00:57:22,760 There's another. 707 00:57:24,880 --> 00:57:26,160 You're just sitting there 708 00:57:26,160 --> 00:57:29,720 and looking at one of the most extraordinary places on Earth. 709 00:57:29,720 --> 00:57:31,440 A privilege given to very few.