1 00:00:27,700 --> 00:00:29,660 DAVID ATTENBOROUGH: A Perfect Planet. 2 00:00:37,180 --> 00:00:42,660 All life in the oceans depends on the continuous movement of water. 3 00:00:56,060 --> 00:00:58,340 There are not five separate oceans on Earth... 4 00:00:59,900 --> 00:01:01,460 ..but just one... 5 00:01:01,460 --> 00:01:05,820 ..whose parts are linked by powerful, unceasing currents. 6 00:01:08,060 --> 00:01:12,300 Every drop of seawater on Earth rides these currents, 7 00:01:12,300 --> 00:01:16,540 taking a thousand years to complete a single circuit. 8 00:01:20,020 --> 00:01:22,660 And where there are currents... 9 00:01:22,660 --> 00:01:24,420 ..there is life. 10 00:01:41,460 --> 00:01:43,780 Off the coast of South Africa, 11 00:01:43,780 --> 00:01:45,420 dolphins are on the hunt. 12 00:01:56,220 --> 00:01:59,380 They have found a cold-water current 13 00:01:59,380 --> 00:02:02,460 and are now travelling along it looking for food. 14 00:02:05,740 --> 00:02:08,100 Gannets follow them. 15 00:02:09,900 --> 00:02:13,660 They know that doing so is the fastest way to a meal. 16 00:02:19,540 --> 00:02:21,180 A shoal of mackerel... 17 00:02:21,180 --> 00:02:23,540 ..just what the dolphins have been looking for. 18 00:02:30,340 --> 00:02:34,220 They encircle the fish, driving them into a bait ball, 19 00:02:34,220 --> 00:02:36,620 and then trap them against the surface 20 00:02:36,620 --> 00:02:38,860 to prevent them from escaping to deeper water. 21 00:02:44,340 --> 00:02:48,260 Now, the fish are within range of the dive-bombing gannets, 22 00:02:48,260 --> 00:02:50,620 who hit the water at 50mph. 23 00:03:14,540 --> 00:03:18,460 A sudden gathering of thousands of predators brought together 24 00:03:18,460 --> 00:03:21,500 by the flow of currents. 25 00:03:36,940 --> 00:03:39,740 Last to the feast are sharks. 26 00:04:02,740 --> 00:04:05,340 In these vast, open waters, 27 00:04:05,340 --> 00:04:09,620 finding food would be all but impossible without currents... 28 00:04:10,660 --> 00:04:14,300 ..the highways of the seas that bring this life together. 29 00:04:19,180 --> 00:04:22,260 When the bait ball has been dispersed, 30 00:04:22,260 --> 00:04:26,100 all that is left are scales drifting downwards. 31 00:04:31,180 --> 00:04:35,220 They are part of a slow, never-ending blizzard 32 00:04:35,220 --> 00:04:40,260 of organic waste that eventually settles on the sea floor. 33 00:04:43,340 --> 00:04:46,620 But it doesn't stay here forever. 34 00:04:46,620 --> 00:04:50,100 The currents sweep it back up into the sunlit surface waters... 35 00:04:51,500 --> 00:04:54,940 ..where it nourishes clouds of phytoplankton... 36 00:04:57,380 --> 00:05:02,140 ..simple microscopic plants that are the pastures of the seas. 37 00:05:11,900 --> 00:05:14,740 There are thousands of different kinds, 38 00:05:14,740 --> 00:05:20,180 and together they produce half of all the oxygen in the atmosphere... 39 00:05:20,180 --> 00:05:24,380 ..more than all our forests and jungles combined. 40 00:05:26,500 --> 00:05:29,020 And, by absorbing carbon, 41 00:05:29,020 --> 00:05:33,060 they are our greatest ally in combating climate change. 42 00:05:38,420 --> 00:05:43,900 Plankton are the foundation of almost all life in the ocean, 43 00:05:43,900 --> 00:05:46,860 for, in those places where the currents bring nutrients 44 00:05:46,860 --> 00:05:50,580 to the surface, they multiply in astonishing numbers... 45 00:05:52,300 --> 00:05:54,620 ..turning the ocean green. 46 00:06:00,740 --> 00:06:05,620 The currents travelling through our oceans bring life to seas 47 00:06:05,620 --> 00:06:08,700 that would otherwise be marine deserts. 48 00:06:13,140 --> 00:06:17,380 The Galapagos Islands lie in the path of one of them, 49 00:06:17,380 --> 00:06:19,700 the deep-flowing Cromwell Current 50 00:06:19,700 --> 00:06:22,660 that runs for 6,000 miles across the Pacific. 51 00:06:26,740 --> 00:06:29,380 As it approaches Fernandina Island, 52 00:06:29,380 --> 00:06:32,660 it rises and delivers nutrients into its shallows. 53 00:06:46,060 --> 00:06:51,180 And it also brings life to this otherwise barren island. 54 00:07:08,580 --> 00:07:10,580 Iguanas. 55 00:07:12,180 --> 00:07:14,220 There are thousands of them. 56 00:07:21,780 --> 00:07:26,020 And yet there's nothing on the island for these vegetarians to eat. 57 00:07:28,660 --> 00:07:31,140 Or... 58 00:07:31,140 --> 00:07:32,380 ..almost nothing. 59 00:07:34,780 --> 00:07:39,460 Cormorants bring seaweed ashore with which to make their nests. 60 00:07:41,100 --> 00:07:44,020 But what is building material for a cormorant 61 00:07:44,020 --> 00:07:46,540 is food for an iguana. 62 00:07:46,540 --> 00:07:48,300 SQUAWKS 63 00:07:52,460 --> 00:07:55,300 Both these species evolved here, 64 00:07:55,300 --> 00:07:58,100 but that doesn't necessarily make them good neighbours. 65 00:08:03,180 --> 00:08:04,660 No matter. 66 00:08:04,660 --> 00:08:07,260 He knows where there's more elsewhere. 67 00:08:09,300 --> 00:08:10,940 He's a marine iguana... 68 00:08:16,220 --> 00:08:18,460 ..the only lizard in the world 69 00:08:18,460 --> 00:08:20,260 that gets its food from the sea. 70 00:08:33,220 --> 00:08:35,900 The seaweed on which he totally relies 71 00:08:35,900 --> 00:08:38,300 only grows in abundance here 72 00:08:38,300 --> 00:08:41,820 because of the nutrients brought by the Cromwell Current. 73 00:08:48,660 --> 00:08:52,620 Once in the water, he has just 30 minutes to find food. 74 00:09:01,020 --> 00:09:02,900 Any longer than that, 75 00:09:02,900 --> 00:09:05,820 and his muscles will seize up and he'll drown... 76 00:09:07,220 --> 00:09:11,180 ..for, like most reptiles, he can't handle the cold. 77 00:09:20,180 --> 00:09:24,020 Chilly water isn't a problem for a warm-blooded cormorant. 78 00:09:25,700 --> 00:09:28,140 She can swim in it all day, 79 00:09:28,140 --> 00:09:30,580 but can only hold her breath for a few minutes. 80 00:09:37,900 --> 00:09:39,940 He, on the other hand, 81 00:09:39,940 --> 00:09:42,540 completes his whole half-hour trip 82 00:09:42,540 --> 00:09:44,740 on one single breath. 83 00:09:46,620 --> 00:09:49,060 His flat face and sharp teeth 84 00:09:49,060 --> 00:09:52,300 make him an efficient seaweed-cropping machine, 85 00:09:52,300 --> 00:09:54,940 but with the clock ticking, he must eat fast. 86 00:09:59,540 --> 00:10:02,020 The cormorant, having caught its fish... 87 00:10:02,860 --> 00:10:04,500 ..goes back to the surface. 88 00:10:07,100 --> 00:10:09,060 One last mouthful, 89 00:10:09,060 --> 00:10:12,180 and it's also time for the iguana to head for home. 90 00:10:15,620 --> 00:10:19,220 But to stop his muscles from seizing up in the cold water, 91 00:10:19,220 --> 00:10:20,940 he must get back quickly. 92 00:10:25,420 --> 00:10:27,860 So he could do without the attentions 93 00:10:27,860 --> 00:10:29,860 of an inquisitive sea lion. 94 00:10:53,060 --> 00:10:55,500 Dry land is now just 30 metres away, 95 00:10:56,900 --> 00:10:59,820 but the biggest hurdle is still to come. 96 00:11:09,580 --> 00:11:12,540 The surging water now fights against him. 97 00:11:19,700 --> 00:11:23,500 He's out, but he's stayed in the cold so long 98 00:11:23,500 --> 00:11:25,140 that he's lost his strength. 99 00:12:06,460 --> 00:12:08,300 And he's made it. 100 00:12:11,100 --> 00:12:14,980 Few reptiles on the planet have to work harder for a meal 101 00:12:14,980 --> 00:12:16,540 than he does. 102 00:12:19,180 --> 00:12:22,860 And, tomorrow, he'll have to do it all over again... 103 00:12:25,460 --> 00:12:27,700 ..unless next time... 104 00:12:27,700 --> 00:12:29,540 ..he can outwit his neighbour. 105 00:12:35,500 --> 00:12:38,460 Over 100,000 marine iguanas live on Fernandina... 106 00:12:40,940 --> 00:12:44,780 ..and each owes its existence to the Cromwell Current 107 00:12:44,780 --> 00:12:46,860 that brings nutrients to these shores. 108 00:12:49,460 --> 00:12:53,100 But there is another, much bigger, current 109 00:12:53,100 --> 00:12:57,340 which carries water from the Pacific into the Indian Ocean. 110 00:13:00,620 --> 00:13:05,500 On this great journey, it travels through the islands of Indonesia, 111 00:13:05,500 --> 00:13:08,220 bringing together life from both oceans. 112 00:13:15,700 --> 00:13:19,900 A third of all the world's reef fish live here. 113 00:13:23,660 --> 00:13:26,740 Some call it the Coral Triangle, 114 00:13:26,740 --> 00:13:29,820 the most diverse marine region on Earth. 115 00:13:38,180 --> 00:13:41,980 The variety here is dazzling, not just of coral, 116 00:13:41,980 --> 00:13:43,860 but of animals of all kinds. 117 00:13:54,300 --> 00:13:58,700 Few are stranger than the flamboyant cuttlefish. 118 00:14:02,140 --> 00:14:05,780 This is a male, just five centimetres long. 119 00:14:10,980 --> 00:14:15,340 Swimming against the current isn't easy when you're small, 120 00:14:15,340 --> 00:14:18,100 so, instead, he prefers to walk... 121 00:14:20,020 --> 00:14:22,060 ..very, very slowly. 122 00:14:26,540 --> 00:14:29,380 He's a master of camouflage. 123 00:14:29,380 --> 00:14:32,020 But, right now, he wants to be noticed. 124 00:14:35,220 --> 00:14:37,300 He's looking for a mate. 125 00:14:38,860 --> 00:14:41,980 His potential partner is a giant, by comparison, 126 00:14:41,980 --> 00:14:43,500 four times his size. 127 00:14:48,780 --> 00:14:50,900 When it comes to courtship, 128 00:14:50,900 --> 00:14:53,540 being flamboyant isn't enough. 129 00:14:59,660 --> 00:15:01,820 To win her over, he must dazzle. 130 00:15:09,220 --> 00:15:12,620 His aim is to deposit a packet of sperm 131 00:15:12,620 --> 00:15:14,620 inside her mouth. 132 00:15:17,940 --> 00:15:20,180 Close... 133 00:15:20,180 --> 00:15:21,580 ..but no cigar. 134 00:15:27,300 --> 00:15:29,700 He'll have to turn up the dazzle. 135 00:15:36,620 --> 00:15:38,100 Take two. 136 00:15:42,900 --> 00:15:44,140 Bingo! 137 00:15:54,700 --> 00:15:57,020 His job is done. 138 00:15:57,020 --> 00:16:00,180 Now she must find somewhere to lay their eggs. 139 00:16:03,340 --> 00:16:06,220 An old shell will do nicely 140 00:16:06,220 --> 00:16:09,020 if she can slip past the present occupant. 141 00:16:14,220 --> 00:16:17,860 She fastens her eggs to the underside of the shell, 142 00:16:17,860 --> 00:16:19,980 where they'll be safe from predators. 143 00:16:33,700 --> 00:16:38,300 The current that brings so much life to the Coral Triangle 144 00:16:38,300 --> 00:16:41,900 now washes the eggs with clean, oxygenated water. 145 00:16:48,740 --> 00:16:52,380 After just three weeks, they start to hatch. 146 00:16:57,060 --> 00:16:59,220 Smaller than a human fingernail, 147 00:16:59,220 --> 00:17:02,500 the hatchlings are now carried by the current 148 00:17:02,500 --> 00:17:04,460 to other parts of the reef. 149 00:17:12,580 --> 00:17:15,020 And, in just a few months, 150 00:17:15,020 --> 00:17:19,140 this young male will be ready to find a female of his own. 151 00:17:25,180 --> 00:17:28,140 By a stroke of cosmic good fortune, 152 00:17:28,140 --> 00:17:30,380 the Earth has a satellite... 153 00:17:30,380 --> 00:17:35,020 ..the moon, which orbits our planet every 27 days. 154 00:17:38,700 --> 00:17:43,780 Its gravitational pull drags our oceans across the planet... 155 00:17:46,420 --> 00:17:48,700 ..and so gives us the tides. 156 00:17:53,940 --> 00:17:57,180 Unlike currents that stir the open ocean, 157 00:17:57,180 --> 00:18:00,300 the tides have their greatest impact on the coasts, 158 00:18:00,300 --> 00:18:04,860 flushing them with nutrients from both sea and land. 159 00:18:07,540 --> 00:18:10,980 And nowhere are they more violent and dramatic than here... 160 00:18:13,180 --> 00:18:16,220 ..Norway's Saltstraumen strait. 161 00:18:18,500 --> 00:18:20,140 Every six hours, 162 00:18:20,140 --> 00:18:22,580 nearly half a billion tonnes of water 163 00:18:22,580 --> 00:18:26,700 are forced through a channel just 150 metres wide. 164 00:18:28,860 --> 00:18:32,300 Its very narrowness accelerates the water... 165 00:18:33,740 --> 00:18:38,220 ..making this the strongest tidal pull in the world. 166 00:18:53,020 --> 00:18:55,700 Most animals caught here would be swept away. 167 00:18:59,220 --> 00:19:02,100 But not these tidal specialists. 168 00:19:02,100 --> 00:19:05,140 Eiders are one of the few ducks 169 00:19:05,140 --> 00:19:09,100 that depend totally on the ocean for their survival. 170 00:19:11,740 --> 00:19:14,380 And they're the only kind strong enough 171 00:19:14,380 --> 00:19:17,620 to live permanently in these racing waters. 172 00:19:25,140 --> 00:19:28,380 But there is food here, and in great quantity, 173 00:19:28,380 --> 00:19:30,020 for any that can gather it... 174 00:19:31,620 --> 00:19:33,060 ..mussels. 175 00:19:34,660 --> 00:19:39,860 They filter out particles of food brought to them by the tide. 176 00:19:41,020 --> 00:19:43,380 And eider ducks love mussels. 177 00:19:46,740 --> 00:19:48,900 The challenge is reaching them. 178 00:20:06,460 --> 00:20:08,820 Eiders seem to be the only creatures 179 00:20:08,820 --> 00:20:12,060 that can hold their own in the fast-flowing water... 180 00:20:15,020 --> 00:20:17,300 ..so they have the mussels all to themselves. 181 00:20:20,020 --> 00:20:23,020 They swallow them whole, shell and all. 182 00:20:27,180 --> 00:20:31,020 Each eider duck eats hundreds of mussels a day... 183 00:20:32,220 --> 00:20:35,820 ..a year-round feast that no others can reach. 184 00:20:47,420 --> 00:20:50,460 The tides here owe their power 185 00:20:50,460 --> 00:20:53,260 to the unique geography of the coastline. 186 00:20:54,300 --> 00:20:56,940 But, elsewhere in our oceans, 187 00:20:56,940 --> 00:21:01,340 the lay of the land influences tides in a very different way. 188 00:21:04,380 --> 00:21:06,300 Here in the Bahamas, 189 00:21:06,300 --> 00:21:10,660 wide, shallow sandbanks mean the tide moves gently 190 00:21:10,660 --> 00:21:13,420 over the sea floor... 191 00:21:13,420 --> 00:21:15,980 ..turning what would be a sandy desert 192 00:21:15,980 --> 00:21:18,460 into a rich underwater habitat. 193 00:21:22,060 --> 00:21:26,380 This is the home of garden eels and razorfish. 194 00:21:30,660 --> 00:21:35,340 And fresh food arrives for them from deeper waters twice a day. 195 00:21:38,180 --> 00:21:40,220 Life seems unhurried and gentle... 196 00:21:43,060 --> 00:21:46,020 ..but there is trouble in paradise. 197 00:21:46,020 --> 00:21:49,140 WHISTLING AND CLICKING 198 00:21:49,140 --> 00:21:52,780 These bottlenose dolphins eat razorfish, 199 00:21:52,780 --> 00:21:55,860 and they're not so easily fooled by vanishing tricks. 200 00:22:01,620 --> 00:22:05,580 They scan the sand with echolocating clicks 201 00:22:05,580 --> 00:22:09,860 to discover exactly where the razorfish are hiding. 202 00:22:09,860 --> 00:22:11,940 CLICKING CONTINUES 203 00:22:25,940 --> 00:22:29,180 But knowing where they are is not the same as catching them. 204 00:22:35,500 --> 00:22:38,100 The more the dolphins dig, 205 00:22:38,100 --> 00:22:40,140 the deeper the razorfish burrow. 206 00:22:43,780 --> 00:22:46,420 But it's clearly not deep enough. 207 00:22:55,980 --> 00:22:59,020 Blowing jets of water into the sand 208 00:22:59,020 --> 00:23:02,900 exposes even the most hard-to-reach razorfish. 209 00:23:06,540 --> 00:23:10,700 Before long, the dolphins have had enough and they move on. 210 00:23:13,060 --> 00:23:15,900 It looks as if they have picked the sand clean... 211 00:23:21,180 --> 00:23:23,180 ..but here, at least, 212 00:23:23,180 --> 00:23:26,100 there really are plenty more fish in the sea. 213 00:23:36,420 --> 00:23:40,260 Closer to the land, the same tides bring nourishment 214 00:23:40,260 --> 00:23:43,660 to one of the most threatened of coastal habitats... 215 00:23:44,660 --> 00:23:46,540 ..mangrove forests. 216 00:23:48,060 --> 00:23:50,220 Part land... 217 00:23:50,220 --> 00:23:52,020 ..part sea. 218 00:23:53,860 --> 00:23:56,700 Mangroves are the only trees 219 00:23:56,700 --> 00:23:59,780 capable of surviving in salt water 220 00:23:59,780 --> 00:24:03,980 and are specially adapted to it coming and going twice every day. 221 00:24:11,580 --> 00:24:14,980 As sea water floods in, fish come with it. 222 00:24:16,380 --> 00:24:18,460 Here in the flooded forests, 223 00:24:18,460 --> 00:24:21,900 they can find both food and shelter. 224 00:24:28,420 --> 00:24:31,860 Stingrays ride on the incoming tide. 225 00:24:39,300 --> 00:24:42,580 Other commuters follow. 226 00:24:42,580 --> 00:24:45,980 Young lemon sharks, still far from full-grown, 227 00:24:45,980 --> 00:24:47,900 are looking for food. 228 00:25:02,940 --> 00:25:05,340 When the tide is at its highest, 229 00:25:05,340 --> 00:25:07,580 even adult lemon sharks 230 00:25:07,580 --> 00:25:09,420 can get into the mangroves. 231 00:25:12,500 --> 00:25:16,380 A three-metre female moves cautiously into the shallows. 232 00:25:19,580 --> 00:25:22,020 She can't stay here for long, 233 00:25:22,020 --> 00:25:24,660 but, then, she hasn't come here to hunt. 234 00:25:31,100 --> 00:25:33,860 She's come to give birth... 235 00:25:35,380 --> 00:25:38,060 ..returning to the very place where she was born. 236 00:25:41,940 --> 00:25:45,340 She has nourished the pups inside her body 237 00:25:45,340 --> 00:25:47,620 with a placenta, as we do. 238 00:25:54,460 --> 00:25:57,980 The mangroves provide an ideal nursery for them, 239 00:25:57,980 --> 00:26:01,220 and placing them here gives them an excellent start, 240 00:26:01,220 --> 00:26:04,300 but that is the end of her parental care. 241 00:26:06,300 --> 00:26:10,380 She has to return to deeper water before the tide goes out. 242 00:26:14,700 --> 00:26:17,460 Her young must now fend for themselves. 243 00:26:21,140 --> 00:26:25,620 The pups instinctively take refuge among the roots of the mangroves. 244 00:26:28,700 --> 00:26:32,220 They're so small, they can swim deep 245 00:26:32,220 --> 00:26:34,100 into this tangled labyrinth. 246 00:26:45,580 --> 00:26:47,740 With the tide fast receding, 247 00:26:47,740 --> 00:26:49,780 even they need to find a place 248 00:26:49,780 --> 00:26:52,020 where they won't be left high and dry. 249 00:26:53,740 --> 00:26:55,540 A place like this... 250 00:26:56,900 --> 00:27:00,740 ..a permanent pool in the heart of the mangrove forest. 251 00:27:07,500 --> 00:27:10,180 Only the smallest sharks can get here, 252 00:27:10,180 --> 00:27:12,540 and only at the highest tides. 253 00:27:19,700 --> 00:27:22,700 The pups will spend the next two years here 254 00:27:22,700 --> 00:27:26,340 perfecting the skills that make them one of the ocean's top hunters. 255 00:27:31,380 --> 00:27:33,660 And it seems... 256 00:27:33,660 --> 00:27:35,460 ..that there's a lot to learn. 257 00:27:42,060 --> 00:27:43,500 Got one! 258 00:27:49,540 --> 00:27:54,260 All life at the coasts has to move to the daily rhythm of the tides, 259 00:27:55,620 --> 00:27:58,660 but tides are not the same throughout the year. 260 00:28:04,540 --> 00:28:10,380 Every month, when our planet, the moon and the sun are all aligned, 261 00:28:10,380 --> 00:28:12,980 the increased gravitational pull 262 00:28:12,980 --> 00:28:15,900 produces particularly high tides. 263 00:28:17,500 --> 00:28:21,100 And this triggers a truly extraordinary event 264 00:28:21,100 --> 00:28:23,660 on one particular reef in the central Pacific. 265 00:28:30,500 --> 00:28:33,460 Thousands of resident surgeonfish 266 00:28:33,460 --> 00:28:36,820 begin to assemble on these high tides. 267 00:28:41,300 --> 00:28:45,540 And they are being followed by one of the largest fish in the sea... 268 00:28:52,260 --> 00:28:54,100 ..manta rays. 269 00:29:03,580 --> 00:29:08,500 The rays spend their year moving between coral islands. 270 00:29:10,940 --> 00:29:15,060 But it's only now, when the tide is at its highest 271 00:29:15,060 --> 00:29:17,860 and the surgeonfish have gathered, that they appear 272 00:29:17,860 --> 00:29:19,980 on this particular reef. 273 00:29:23,580 --> 00:29:25,860 Their timing is so perfect 274 00:29:25,860 --> 00:29:28,620 that they rarely have to wait more than an hour 275 00:29:28,620 --> 00:29:30,460 for the event to begin. 276 00:29:56,900 --> 00:30:01,340 At the precise moment when the tide is at its highest, 277 00:30:01,340 --> 00:30:03,540 the surgeonfish begin to spawn. 278 00:30:06,220 --> 00:30:09,260 They release billions of eggs and sperm into the water. 279 00:30:14,460 --> 00:30:17,180 Breeding in this way gives their fertilised eggs 280 00:30:17,180 --> 00:30:20,340 the best chance of being carried on the tide 281 00:30:20,340 --> 00:30:22,860 away from predators that haunt the reef. 282 00:30:26,580 --> 00:30:28,140 All except one. 283 00:30:31,820 --> 00:30:33,820 The mantas move in. 284 00:30:51,540 --> 00:30:54,140 They gorge on the eggs, 285 00:30:54,140 --> 00:30:57,060 filtering them out using specially adapted gills. 286 00:30:59,500 --> 00:31:02,700 If the mantas had arrived just an hour later, 287 00:31:02,700 --> 00:31:05,260 there would have been nothing here for them to eat. 288 00:31:12,700 --> 00:31:16,300 No-one knows how the mantas are so perfectly in tune 289 00:31:16,300 --> 00:31:18,140 with the rhythm of the tides. 290 00:31:24,340 --> 00:31:28,460 But they appear without fail whenever the surgeonfish spawn. 291 00:31:36,780 --> 00:31:38,620 Most of the eggs, however, 292 00:31:38,620 --> 00:31:41,260 are carried out into the open ocean 293 00:31:41,260 --> 00:31:43,900 before the mantas are able to eat them all. 294 00:32:00,260 --> 00:32:06,020 The rhythms of coastal life are influenced by another ocean force. 295 00:32:09,740 --> 00:32:14,180 Winds blowing over the sea so batter the surface 296 00:32:14,180 --> 00:32:17,020 that it begins to rise and fall. 297 00:32:19,060 --> 00:32:20,860 These swells may travel far 298 00:32:20,860 --> 00:32:23,940 and reach the shores of even the most sheltered bays. 299 00:32:25,540 --> 00:32:27,820 As they approach shallower water, 300 00:32:27,820 --> 00:32:29,620 they turn into waves. 301 00:32:34,100 --> 00:32:36,700 A shoal of hardyheads, 302 00:32:36,700 --> 00:32:40,100 close to the beach of Australia's Lizard Island. 303 00:32:42,020 --> 00:32:46,980 The clearness of these glassy waters shows that they lack nutrients. 304 00:32:48,540 --> 00:32:52,420 But the gentle waves expose food hidden in the sand, 305 00:32:52,420 --> 00:32:54,980 and that's what the hardyheads are looking for. 306 00:33:10,900 --> 00:33:13,420 Packs of trevally are on the hunt. 307 00:33:22,060 --> 00:33:24,460 The hardyheads stick together. 308 00:33:25,460 --> 00:33:27,100 There's safety in numbers. 309 00:33:28,580 --> 00:33:30,740 But they're vulnerable, nonetheless. 310 00:33:41,900 --> 00:33:44,820 They're so small, they can swim in the shallowest waters... 311 00:33:53,300 --> 00:33:56,540 ..even in the body of the waves themselves, 312 00:33:56,540 --> 00:33:58,780 out of the reach of their enemies. 313 00:34:03,900 --> 00:34:06,700 But trevally aren't their only concern. 314 00:34:16,180 --> 00:34:18,260 Blacktip reef sharks. 315 00:34:19,740 --> 00:34:23,780 They are bigger and more powerful than trevally... 316 00:34:25,580 --> 00:34:27,860 ..but not as fast or as agile. 317 00:34:32,940 --> 00:34:35,740 The hardyheads are well aware of them, 318 00:34:35,740 --> 00:34:38,380 but, so long as they stay just out of reach, 319 00:34:38,380 --> 00:34:39,820 they have little to fear. 320 00:34:54,300 --> 00:34:57,780 But now the sharks and the trevally join forces. 321 00:35:02,940 --> 00:35:05,780 Together, they enter the shallows, 322 00:35:05,780 --> 00:35:07,860 each looking for a chance to attack. 323 00:35:25,900 --> 00:35:27,780 The trevally make the first move... 324 00:35:29,580 --> 00:35:33,420 ..and the hardyheads take refuge again in the waves. 325 00:35:34,500 --> 00:35:36,900 And this is what the sharks have been waiting for. 326 00:35:41,380 --> 00:35:45,620 Surging forwards, they chase the hardyheads out of the water... 327 00:35:46,660 --> 00:35:50,900 ..beaching themselves in a daring bid to hoover up their prey. 328 00:35:55,420 --> 00:35:57,820 The hardyheads that escape the sharks 329 00:35:57,820 --> 00:35:59,660 swim back out to deeper water... 330 00:36:01,860 --> 00:36:04,140 ..but into the mouths of the trevally. 331 00:36:15,300 --> 00:36:18,740 Now the receding waves help to pull the sharks back 332 00:36:18,740 --> 00:36:20,580 into deeper water. 333 00:36:51,260 --> 00:36:54,740 In the chaos, the sea birds get their chance. 334 00:36:59,820 --> 00:37:02,220 It's a feeding frenzy... 335 00:37:02,220 --> 00:37:04,860 ..in only ten centimetres of water. 336 00:37:17,820 --> 00:37:21,900 The power of waves is dramatically evident 337 00:37:21,900 --> 00:37:23,540 when they crash onto our shores. 338 00:37:26,860 --> 00:37:32,260 But the biggest of all start far away from land, out at sea. 339 00:37:32,260 --> 00:37:34,740 THUNDER CRASHES 340 00:37:34,740 --> 00:37:38,660 Great storms blowing over the surface of the ocean 341 00:37:38,660 --> 00:37:41,300 raise towering walls of water. 342 00:37:44,900 --> 00:37:48,940 Such giant swells can travel for thousands of miles. 343 00:37:51,460 --> 00:37:53,580 As they approach land, 344 00:37:53,580 --> 00:37:58,180 the shallowing sea floor begins to drag on their undersides, 345 00:37:58,180 --> 00:38:00,300 and they topple forward... 346 00:38:00,300 --> 00:38:01,740 ..and break. 347 00:38:05,580 --> 00:38:09,820 This stirring of the ocean produces great riches. 348 00:38:13,620 --> 00:38:15,740 The Falkland Islands are surrounded 349 00:38:15,740 --> 00:38:17,980 by some of the stormiest waters on Earth... 350 00:38:22,060 --> 00:38:26,500 ..ideal hunting grounds for rockhopper penguins. 351 00:38:28,300 --> 00:38:30,380 It's the breeding season 352 00:38:30,380 --> 00:38:32,020 and, for the last two weeks, 353 00:38:32,020 --> 00:38:34,820 the males have been incubating the eggs by themselves. 354 00:38:37,740 --> 00:38:40,700 They're confined to the nest with nothing to eat, 355 00:38:40,700 --> 00:38:43,300 while the females are out at sea collecting food. 356 00:38:48,060 --> 00:38:51,940 All across the colony, eggs are starting to hatch. 357 00:38:53,940 --> 00:38:57,540 This male now has two youngsters to care for. 358 00:39:00,860 --> 00:39:05,100 But he has no food to give them, and he can't leave them unprotected. 359 00:39:06,700 --> 00:39:09,180 He can do nothing but wait. 360 00:39:23,180 --> 00:39:26,740 are now heading for home with food in their crops. 361 00:39:30,700 --> 00:39:32,300 There's just one problem. 362 00:39:33,620 --> 00:39:36,580 The colony sits at the top of huge cliffs. 363 00:39:39,700 --> 00:39:43,100 The waves that make feeding so good here 364 00:39:43,100 --> 00:39:46,100 have now become major obstacles. 365 00:39:48,380 --> 00:39:50,420 Timing is vital. 366 00:40:04,620 --> 00:40:06,260 Go too early... 367 00:40:07,300 --> 00:40:09,780 ..and they could be smashed against the rocks. 368 00:40:16,020 --> 00:40:18,940 Too late... 369 00:40:18,940 --> 00:40:21,060 ..and they will be carried back out to sea. 370 00:40:27,380 --> 00:40:29,780 Hooked claws now help to get purchase 371 00:40:29,780 --> 00:40:31,420 on the slippery rocks. 372 00:40:34,900 --> 00:40:36,740 But they're not out of trouble yet. 373 00:40:41,700 --> 00:40:44,820 Success depends on both judgment... 374 00:40:44,820 --> 00:40:46,260 ..and luck. 375 00:41:06,380 --> 00:41:10,220 Time and again, the waves drag her back in. 376 00:41:16,540 --> 00:41:18,540 She has to persevere. 377 00:41:18,540 --> 00:41:23,060 The lives of her chicks depend on her safe return. 378 00:41:55,060 --> 00:41:57,140 Finally... 379 00:41:57,140 --> 00:41:59,140 ..she's made it. 380 00:42:08,540 --> 00:42:11,300 They're not called rockhoppers for nothing. 381 00:42:16,940 --> 00:42:19,180 With one more jump, she's home. 382 00:42:22,620 --> 00:42:24,380 And just in time. 383 00:42:29,540 --> 00:42:31,900 Her chicks are desperately hungry. 384 00:42:39,660 --> 00:42:42,700 This is their first proper meal. 385 00:42:42,700 --> 00:42:44,700 CHICK CHEEPS 386 00:42:52,660 --> 00:42:56,940 The oceans have sustained life on our planet for millions of years. 387 00:43:01,740 --> 00:43:06,260 But, today, there's growing evidence that this is changing. 388 00:43:12,300 --> 00:43:14,340 As our climate warms, 389 00:43:14,340 --> 00:43:17,860 polar ice sheets are melting at an alarming rate. 390 00:43:21,900 --> 00:43:26,460 In the Arctic alone, 14,000 tonnes of fresh water 391 00:43:26,460 --> 00:43:29,580 are emptying into the sea every second. 392 00:43:37,500 --> 00:43:40,900 This is slowing the flow of currents around the globe. 393 00:43:43,820 --> 00:43:47,020 And, if the atmosphere continues to warm, 394 00:43:47,020 --> 00:43:50,700 ocean circulation could eventually stop altogether. 395 00:43:59,740 --> 00:44:02,860 Our seas would then stagnate, 396 00:44:02,860 --> 00:44:05,620 threatening the life within them. 397 00:44:09,380 --> 00:44:12,060 And there are places in the oceans today 398 00:44:12,060 --> 00:44:14,820 where this is already beginning to happen. 399 00:44:23,620 --> 00:44:25,420 The Gulf of Thailand. 400 00:44:32,740 --> 00:44:35,780 Eden's whales have lived here for generations. 401 00:44:39,380 --> 00:44:41,900 But the world around them is changing. 402 00:44:51,220 --> 00:44:54,820 Today, agricultural pollution flowing from the land... 403 00:44:57,540 --> 00:45:00,340 ..is beginning to suffocate this sea. 404 00:45:10,540 --> 00:45:13,780 Many fish now stay closer to the surface, 405 00:45:13,780 --> 00:45:17,660 where the waters still contain enough oxygen to survive. 406 00:45:22,140 --> 00:45:25,580 Eden's whales depend on these fish. 407 00:45:27,540 --> 00:45:30,060 They swallow huge quantities of water 408 00:45:30,060 --> 00:45:32,220 before filtering out their prey. 409 00:45:37,540 --> 00:45:41,580 It takes a lot of energy to drive their 15-tonne bulk 410 00:45:41,580 --> 00:45:43,420 through the water. 411 00:45:46,180 --> 00:45:48,500 And, with so few fish, 412 00:45:48,500 --> 00:45:51,460 the rewards from feeding like this are barely worth it. 413 00:45:54,060 --> 00:45:56,580 So, to survive here, 414 00:45:56,580 --> 00:45:59,660 the whales have developed a new hunting technique... 415 00:46:04,420 --> 00:46:07,620 ..one that requires almost no effort. 416 00:46:10,780 --> 00:46:13,660 They simply open their mouths... 417 00:46:13,660 --> 00:46:15,060 ..and wait. 418 00:46:20,420 --> 00:46:22,860 The panicked fish jump right in. 419 00:46:30,380 --> 00:46:32,300 Swimming alongside, 420 00:46:32,300 --> 00:46:35,780 another whale scares even more into the open jaws. 421 00:46:47,820 --> 00:46:50,700 With this ingenious new technique, 422 00:46:50,700 --> 00:46:54,420 Eden's whales have found a way to survive the pressures 423 00:46:54,420 --> 00:46:55,740 they now face. 424 00:46:58,220 --> 00:47:02,260 All across the planet, animals are having to adapt 425 00:47:02,260 --> 00:47:04,100 to a changing world. 426 00:47:05,980 --> 00:47:09,580 But the speed of these changes will be too fast for many. 427 00:47:14,980 --> 00:47:20,340 If we could only halt our unrestrained plunder of the ocean, 428 00:47:20,340 --> 00:47:22,940 its habitats and species would recover. 429 00:47:25,820 --> 00:47:28,460 And, at a time when our overexploited lands 430 00:47:28,460 --> 00:47:30,700 are already failing us, 431 00:47:30,700 --> 00:47:33,700 this has never been more important for humanity. 432 00:47:54,660 --> 00:47:58,300 The volcanic island of Fernandina in the Galapagos 433 00:47:58,300 --> 00:48:01,060 is home to two incredible lizards... 434 00:48:03,420 --> 00:48:07,660 ..the land iguana and the marine iguana. 435 00:48:09,460 --> 00:48:12,180 There are two parts to their story 436 00:48:12,180 --> 00:48:14,940 that cameraman, Richard Wollocombe, has wanted to film 437 00:48:14,940 --> 00:48:18,620 since he first came to these islands 25 years ago, 438 00:48:19,860 --> 00:48:22,900 and, on A Perfect Planet, he got his chance. 439 00:48:27,620 --> 00:48:29,820 Driven by powerful currents, 440 00:48:29,820 --> 00:48:34,140 the cold Pacific Ocean slams into Fernandina's shores. 441 00:48:40,780 --> 00:48:44,220 The marine iguanas must brave these waters every day. 442 00:48:49,100 --> 00:48:52,100 Their journey through the big surf is what Richard and the team 443 00:48:52,100 --> 00:48:54,340 are here to film... 444 00:48:54,340 --> 00:48:56,220 ..but from underwater. 445 00:48:57,220 --> 00:48:59,580 It looks fairly benign from the surface here, 446 00:48:59,580 --> 00:49:02,300 but, underneath, it's really shallow, 447 00:49:02,300 --> 00:49:06,140 and there's all these really sharp rocks with lots of jagged edges. 448 00:49:06,140 --> 00:49:08,580 So if we were taken by the wave, 449 00:49:08,580 --> 00:49:11,460 it would cut us up really badly, I think. 450 00:49:16,140 --> 00:49:17,980 Whose idea was this? 451 00:49:17,980 --> 00:49:19,740 Ha-ha, ha-ha. 452 00:49:20,780 --> 00:49:23,020 I'm a glutton for punishment, did you know? 453 00:49:26,860 --> 00:49:29,940 The waves are certainly punishing. 454 00:49:30,940 --> 00:49:33,220 With these dangerous conditions, 455 00:49:33,220 --> 00:49:37,420 extra protection is clearly needed for Richard and dive buddy Rafael. 456 00:49:38,340 --> 00:49:41,100 So what better than surf helmets? 457 00:49:49,420 --> 00:49:53,740 It isn't long before Richard realises what he's up against. 458 00:49:56,740 --> 00:49:59,780 The relentless churning of the water makes it difficult 459 00:49:59,780 --> 00:50:02,220 to stay the right way up... 460 00:50:02,220 --> 00:50:03,860 ..let alone film the iguanas. 461 00:50:09,540 --> 00:50:13,180 In between the waves, the iguanas briefly appear. 462 00:50:17,860 --> 00:50:20,740 But Richard barely has time to line up a shot... 463 00:50:21,860 --> 00:50:24,980 ..before the iguana disappears behind another wave. 464 00:50:32,460 --> 00:50:34,100 In the violent surge, 465 00:50:34,100 --> 00:50:36,940 the iguanas have learned to hang on to the rocks... 466 00:50:38,380 --> 00:50:42,620 ..a trick Richard is quick to copy to avoid being swept away. 467 00:50:44,500 --> 00:50:47,460 That, however, only leaves one hand to film with. 468 00:50:56,460 --> 00:50:59,260 But, with adrenaline carrying him through, 469 00:50:59,260 --> 00:51:03,220 Richard is able to get the perfect shots of iguanas in the surf. 470 00:51:09,580 --> 00:51:14,140 And to achieve that totally unscathed is a great relief. 471 00:51:15,140 --> 00:51:17,780 I don't need to go to the gym for months after that! 472 00:51:20,100 --> 00:51:22,300 Well done, mate. Good job. 473 00:51:25,460 --> 00:51:30,340 On the shore, land iguanas have to battle a very different force. 474 00:51:33,020 --> 00:51:38,540 Each year, they migrate up to the top of Fernandina's active volcano, 475 00:51:38,540 --> 00:51:42,900 a journey of ten days across razor-sharp lava 476 00:51:42,900 --> 00:51:45,940 before descending into its heart to lay their eggs 477 00:51:45,940 --> 00:51:47,780 in the ashy floor. 478 00:51:52,740 --> 00:51:57,020 It's this behaviour Richard and the team plan to film, 479 00:51:57,020 --> 00:52:00,860 and the scale of the expedition is one that's rarely been attempted 480 00:52:00,860 --> 00:52:02,660 in the Galapagos. 481 00:52:07,340 --> 00:52:11,620 To reach the top takes the crew ten gruelling hours. 482 00:52:21,540 --> 00:52:23,980 When they finally arrive on the rim, 483 00:52:23,980 --> 00:52:26,020 the experience doesn't disappoint. 484 00:52:28,300 --> 00:52:30,260 I can't believe it. 485 00:52:30,260 --> 00:52:32,820 It's absolutely awe-inspiring. 486 00:52:35,020 --> 00:52:38,220 I just can't believe the iguanas actually manage 487 00:52:38,220 --> 00:52:42,740 to navigate down these slopes into the bowl of this volcano. 488 00:52:44,540 --> 00:52:47,620 More people have been into space than to the bottom 489 00:52:47,620 --> 00:52:49,820 of Fernandina's crater. 490 00:52:49,820 --> 00:52:53,260 But that is exactly where Richard and the team must go 491 00:52:53,260 --> 00:52:55,900 if they are to film the nesting iguanas. 492 00:53:00,780 --> 00:53:03,700 From their campsite at the edge of the volcano, 493 00:53:03,700 --> 00:53:07,060 it's an extremely dangerous journey down to the crater floor, 494 00:53:07,060 --> 00:53:11,540 and assistant producer Toby wants to be clear with everyone 495 00:53:11,540 --> 00:53:13,380 what is at stake. 496 00:53:31,420 --> 00:53:34,740 There's only one passable route down, 497 00:53:34,740 --> 00:53:38,780 and, as the team enter the lip of the volcano, 498 00:53:38,780 --> 00:53:41,740 the sound of rock fall is all around. 499 00:53:41,740 --> 00:53:43,740 THUNDEROUS SOUND 500 00:53:44,780 --> 00:53:46,300 WOMAN SHOUTS OUT 501 00:53:50,700 --> 00:53:54,620 Regular earthquakes make the crater walls very unstable. 502 00:53:59,700 --> 00:54:02,140 Just keeps getting better. 503 00:54:02,140 --> 00:54:06,380 Not far away, some iguanas are making their own descent, 504 00:54:06,380 --> 00:54:08,820 disturbing the loose surface as they go. 505 00:54:20,420 --> 00:54:23,580 If a creature only a sixth the size of a person 506 00:54:23,580 --> 00:54:27,180 can start a deadly avalanche of razor-sharp rocks, 507 00:54:27,180 --> 00:54:29,820 what can a whole film crew do? 508 00:54:29,820 --> 00:54:31,780 RUMBLE OF FALLING ROCKS 509 00:54:36,460 --> 00:54:40,860 It's clear the crew are going to have to be extremely cautious. 510 00:54:40,860 --> 00:54:42,780 ROCK FALL DROWNS OUT WORDS 511 00:54:45,660 --> 00:54:48,420 On the steepest slopes, the equipment needs to be 512 00:54:48,420 --> 00:54:50,020 lowered with ropes. 513 00:54:58,180 --> 00:55:02,260 With rocks falling all around, the longer they're on the slopes, 514 00:55:02,260 --> 00:55:04,740 the greater the risk of an accident. 515 00:55:09,020 --> 00:55:11,820 But, when one misstep can start an avalanche, 516 00:55:11,820 --> 00:55:13,620 hurrying is impossible. 517 00:55:16,740 --> 00:55:20,380 Finally, the prize of the crater floor is in sight. 518 00:55:20,380 --> 00:55:24,140 Look, just below there is where the iguanas are nesting. 519 00:55:24,140 --> 00:55:28,060 We're very close to it now, about an hour's walk. 520 00:55:28,060 --> 00:55:31,700 All that lies between them is a stretch of loose lava 521 00:55:31,700 --> 00:55:34,940 that has cascaded down the slopes after the last eruption. 522 00:55:37,060 --> 00:55:40,300 FALLING ROCK RUMBLING 523 00:55:48,740 --> 00:55:51,180 We're actually in the crater now, 524 00:55:51,180 --> 00:55:54,020 surrounded by these vertical walls. 525 00:55:55,780 --> 00:55:59,060 I just can't believe that we really made it down here. 526 00:56:00,100 --> 00:56:03,820 Sometimes I doubted that, you know, we would actually make it. 527 00:56:07,060 --> 00:56:11,300 And there they were, iguanas, using the warm volcanic ash 528 00:56:11,300 --> 00:56:13,180 to incubate their eggs. 529 00:56:17,900 --> 00:56:22,860 For Richard, after 25 years living in the Galapagos, 530 00:56:22,860 --> 00:56:26,940 filming this unique behaviour is a lifelong dream come true. 531 00:56:29,300 --> 00:56:32,420 My, God, what an incredible place this is! 532 00:56:32,420 --> 00:56:37,100 It's such a vivid feeling to be constantly challenged 533 00:56:37,100 --> 00:56:39,060 by the forces of nature like that. 534 00:56:40,380 --> 00:56:44,220 But they have to do this every year in order to survive. 535 00:56:44,220 --> 00:56:47,820 I'll never forget, for as long as I live. 536 00:56:47,820 --> 00:56:49,940 What an adventure! What an adventure! 537 00:56:54,180 --> 00:56:55,860 Next time... 538 00:56:55,860 --> 00:56:57,820 ..a new force... 539 00:56:57,820 --> 00:56:59,500 ..humans. 540 00:56:59,500 --> 00:57:01,260 Now so dominant... 541 00:57:02,380 --> 00:57:04,500 ..we're disrupting the forces of nature... 542 00:57:06,540 --> 00:57:10,460 ..and the vital habitats life needs to survive. 543 00:57:12,020 --> 00:57:14,860 This is the most important story... 544 00:57:14,860 --> 00:57:16,700 ..of our time. 545 00:57:16,700 --> 00:57:18,820 Whose future? Our future. 546 00:57:19,980 --> 00:57:23,220 The Open University has produced a free poster 547 00:57:23,220 --> 00:57:25,460 exploring our perfect planet. 548 00:57:25,460 --> 00:57:27,060 To order, please call... 549 00:57:31,140 --> 00:57:32,700 Or go to... 550 00:57:35,820 --> 00:57:38,420 ..and follow the links to the Open University.