1 00:00:43,310 --> 00:00:45,379 David Attenborough: Dwarfed by the vast expanse 2 00:00:45,413 --> 00:00:46,931 of the open ocean, 3 00:00:46,965 --> 00:00:50,827 the biggest animal that has ever lived on our planet. 4 00:00:56,724 --> 00:01:01,758 A blue whale, 30 meters long and weighing over 200 tons. 5 00:01:01,793 --> 00:01:06,724 It's far bigger than even the biggest dinosaur. 6 00:01:06,758 --> 00:01:09,689 Its tongue weighs as much as an elephant. 7 00:01:09,724 --> 00:01:12,724 Its heart is the size of a car, 8 00:01:12,758 --> 00:01:15,827 and some of its blood vessels are so wide 9 00:01:15,862 --> 00:01:19,655 that you could swim down them. 10 00:01:19,689 --> 00:01:24,758 Its tail alone is the width of a small aircraft's wings. 11 00:01:41,862 --> 00:01:44,758 Its streamlining, close to perfection, 12 00:01:44,793 --> 00:01:47,793 enables it to cruise at 20 knots. 13 00:01:47,827 --> 00:01:50,758 It's one of the fastest animals in the sea. 14 00:01:54,827 --> 00:01:56,827 The ocean's largest inhabitant 15 00:01:56,862 --> 00:02:00,758 feeds almost exclusively on one of the smallest-- 16 00:02:00,793 --> 00:02:04,482 krill, a crustacean just a few centimeters long. 17 00:02:07,862 --> 00:02:10,068 Gathered in a shoal, 18 00:02:10,103 --> 00:02:11,896 krill stain the sea red, 19 00:02:11,931 --> 00:02:17,068 and a single blue whale in a day can consume 40 million of them. 20 00:02:24,862 --> 00:02:27,862 Despite the enormous size of blue whales, 21 00:02:27,896 --> 00:02:29,862 we know very little about them. 22 00:02:29,896 --> 00:02:32,862 Their migration routes are still a mystery, 23 00:02:32,896 --> 00:02:37,137 and we have absolutely no idea where they go to breed. 24 00:02:39,862 --> 00:02:41,827 They are a dramatic reminder 25 00:02:41,862 --> 00:02:45,379 of how much we still have to learn about the ocean 26 00:02:45,413 --> 00:02:48,413 and the creatures that live there. 27 00:02:50,827 --> 00:02:53,689 Our planet is a blue planet. 28 00:02:53,724 --> 00:02:58,827 Over 70% of it is covered by the sea. 29 00:02:58,862 --> 00:03:02,827 The Pacific Ocean alone covers half the globe. 30 00:03:02,862 --> 00:03:05,931 You can fly across it nonstop for 12 hours 31 00:03:05,965 --> 00:03:09,827 and still see nothing more than a speck of land. 32 00:03:09,862 --> 00:03:11,965 This series will reveal 33 00:03:12,000 --> 00:03:14,931 the complete natural history of our ocean planet 34 00:03:14,965 --> 00:03:16,862 from its familiar shores 35 00:03:16,896 --> 00:03:20,551 to the mysteries of its deepest seas. 36 00:03:31,068 --> 00:03:32,379 By volume, 37 00:03:32,413 --> 00:03:34,413 the ocean makes up 97% 38 00:03:34,448 --> 00:03:35,931 of the Earth's inhabitable space, 39 00:03:35,965 --> 00:03:38,896 and the sheer quantity of marine life it contains 40 00:03:38,931 --> 00:03:42,448 far exceeds that which inhabits the land. 41 00:04:04,482 --> 00:04:07,551 But life in the ocean is not evenly spread. 42 00:04:07,586 --> 00:04:09,034 It's regulated 43 00:04:09,068 --> 00:04:12,241 by the path of currents carrying nutrients, 44 00:04:12,275 --> 00:04:15,241 and the varying power of the sun. 45 00:04:15,275 --> 00:04:18,655 In this first program, we will see 46 00:04:18,689 --> 00:04:20,172 how these two forces interact 47 00:04:20,206 --> 00:04:22,172 to control the distribution of life 48 00:04:22,206 --> 00:04:26,551 from the coral seas to the polar wastes. 49 00:05:20,275 --> 00:05:23,206 The sheer physical power of the ocean 50 00:05:23,241 --> 00:05:27,241 dominates our planet. 51 00:05:41,241 --> 00:05:44,965 It profoundly influences the weather of all the world. 52 00:05:45,000 --> 00:05:47,862 Water vapor rising from it forms the clouds 53 00:05:47,896 --> 00:05:49,551 and generates the storms 54 00:05:49,586 --> 00:05:52,448 that ultimately will drench the land. 55 00:06:11,310 --> 00:06:12,827 Can you feel it? 56 00:06:12,931 --> 00:06:14,655 You're exactly where you're meant to be right now. 57 00:06:17,241 --> 00:06:19,034 You and me, we could do anything. 58 00:06:19,137 --> 00:06:21,551 Us against the world. 59 00:06:21,655 --> 00:06:24,413 Welcome to the Theatre des Vampires. 60 00:06:24,517 --> 00:06:26,689 You have no idea what I'm capable of. 61 00:06:26,793 --> 00:06:29,310 My word means something. 62 00:06:29,413 --> 00:06:30,827 We need you... 63 00:06:30,931 --> 00:06:32,586 ...to lead the revival of humanity. 64 00:06:32,689 --> 00:06:34,620 You deserve a happy ending. 65 00:06:35,689 --> 00:06:37,517 Well, guess this is it, then. 66 00:06:42,206 --> 00:06:44,965 The great waves that roar in towards the shores 67 00:06:45,000 --> 00:06:49,000 are dramatic demonstrations of its power. 68 00:07:03,034 --> 00:07:05,827 Waves originate far out at sea. 69 00:07:05,862 --> 00:07:08,793 There, even gentle breezes can cause ripples, 70 00:07:08,827 --> 00:07:12,655 and ripples grow into swells. 71 00:07:21,620 --> 00:07:24,344 Out in the open ocean, unimpeded by land, 72 00:07:24,379 --> 00:07:27,137 such swells can become gigantic. 73 00:07:48,896 --> 00:07:52,827 It's only when an ocean swell eventually reaches shallow water 74 00:07:52,862 --> 00:07:56,965 that it starts to break. 75 00:08:01,931 --> 00:08:04,206 As it approaches the coast, 76 00:08:04,241 --> 00:08:05,896 the water at the bottom of the swell 77 00:08:05,931 --> 00:08:08,931 is slowed by contact with the seabed. 78 00:08:08,965 --> 00:08:11,862 The top of the swell, still traveling fast, 79 00:08:11,896 --> 00:08:13,620 starts to roll over, 80 00:08:13,655 --> 00:08:15,551 and so the wave breaks. 81 00:08:45,241 --> 00:08:48,103 The ocean never rests. 82 00:08:48,137 --> 00:08:50,896 Huge currents, such as the Gulf Stream, 83 00:08:50,931 --> 00:08:54,896 keep its waters constantly on the move all 'round the globe. 84 00:08:54,931 --> 00:08:57,206 It's these currents, more than any other factor, 85 00:08:57,241 --> 00:08:59,620 that control the distribution of nutrients 86 00:08:59,655 --> 00:09:03,448 and life in the seas. 87 00:09:03,482 --> 00:09:08,448 A tiny island lost in the midst of the Pacific. 88 00:09:08,482 --> 00:09:10,379 It's the tip of a huge mountain 89 00:09:10,413 --> 00:09:12,689 that rises precipitously from the sea floor 90 00:09:12,724 --> 00:09:14,517 thousands of meters below. 91 00:09:18,965 --> 00:09:23,068 The nearest land is 300 miles away. 92 00:09:26,965 --> 00:09:28,896 Isolated seamounts like this one 93 00:09:28,931 --> 00:09:31,965 create oases where life can flourish 94 00:09:32,000 --> 00:09:36,172 in the comparatively empty expanses of the open ocean. 95 00:09:45,000 --> 00:09:48,724 But all the creatures that swim beside it would not be here 96 00:09:48,758 --> 00:09:51,965 were it not for one key factor-- 97 00:09:52,000 --> 00:09:54,793 the deep ocean currents. 98 00:09:58,758 --> 00:10:02,965 Far below the surface, they collide with the island's flanks 99 00:10:03,000 --> 00:10:05,206 and are deflected upwards, 100 00:10:05,241 --> 00:10:06,517 bringing with them from the depths 101 00:10:06,551 --> 00:10:10,965 a rich soup of nutrients. 102 00:10:11,000 --> 00:10:15,172 Such upwellings attract great concentrations of life. 103 00:10:23,137 --> 00:10:26,413 Most of the fish here are permanent residents 104 00:10:26,448 --> 00:10:27,827 feeding on the plankton-- 105 00:10:27,862 --> 00:10:30,172 the tiny floating plants and animals 106 00:10:30,206 --> 00:10:31,448 that are nourished by the richness 107 00:10:31,482 --> 00:10:33,172 brought up from the depths-- 108 00:10:33,206 --> 00:10:36,896 and they in turn attract visitors from the open ocean. 109 00:10:36,931 --> 00:10:39,931 Tuna. 110 00:11:04,965 --> 00:11:08,586 The plankton feeders are easy targets. 111 00:11:18,965 --> 00:11:23,310 All this action attracts even larger predators. 112 00:11:25,275 --> 00:11:27,931 Sharks. 113 00:11:30,931 --> 00:11:34,965 Hundreds of sharks. 114 00:11:35,000 --> 00:11:39,275 These silky sharks are normally ocean-going species, 115 00:11:39,310 --> 00:11:41,965 but the seamounts in the Eastern Pacific, 116 00:11:42,000 --> 00:11:44,965 like Cocos, Malpelo, and the Galapagos, 117 00:11:45,000 --> 00:11:47,931 attract silkies in huge groups 118 00:11:47,965 --> 00:11:49,965 up to 500 strong. 119 00:11:53,068 --> 00:11:56,551 Silkies seem to specialize in taking injured fish 120 00:11:56,586 --> 00:11:58,931 and constantly circle seamounts 121 00:11:58,965 --> 00:12:02,827 on the lookout for the chance to do so. 122 00:12:06,275 --> 00:12:09,172 But silkies are not the only visitors. 123 00:12:12,620 --> 00:12:17,000 Hammerheads gather in some of the largest shark shoals 124 00:12:17,034 --> 00:12:19,034 to be found anywhere in the ocean. 125 00:12:19,068 --> 00:12:24,206 Sometimes, thousands will circle over a single seamount. 126 00:12:27,379 --> 00:12:30,379 But these sharks are not here for food. 127 00:12:30,413 --> 00:12:33,689 They have come for another reason. 128 00:12:36,344 --> 00:12:40,482 Some of the locals provide a cleaning service. 129 00:12:43,448 --> 00:12:45,724 Following the last El Niño year, 130 00:12:45,758 --> 00:12:47,482 when a rise in water temperatures 131 00:12:47,517 --> 00:12:50,620 caused many sharks to suffer from fungal infections, 132 00:12:50,655 --> 00:12:53,379 the number of hammerheads visiting the seamounts 133 00:12:53,413 --> 00:12:56,413 reached record levels. 134 00:13:06,344 --> 00:13:09,034 Nutrients also well up to the surface 135 00:13:09,068 --> 00:13:12,793 along the coasts of the continents. 136 00:13:12,827 --> 00:13:16,965 This is Natal on South Africa's Eastern seaboard. 137 00:13:17,000 --> 00:13:19,241 It's June, and just offshore, 138 00:13:19,275 --> 00:13:22,586 strange black patches have appeared. 139 00:13:25,620 --> 00:13:31,689 They look like immense oil slicks up to a mile long. 140 00:13:31,724 --> 00:13:34,275 But this is a living slick-- 141 00:13:34,310 --> 00:13:35,724 millions and millions 142 00:13:35,758 --> 00:13:37,724 of sardines on a marine migration 143 00:13:37,758 --> 00:13:39,758 that, in terms of sheer biomass, 144 00:13:39,793 --> 00:13:44,620 rivals that of the wildebeest on the grasslands of Africa. 145 00:13:48,034 --> 00:13:50,206 These fish live for most of the time 146 00:13:50,241 --> 00:13:52,620 in the cold waters south of the cape, 147 00:13:52,655 --> 00:13:55,517 but each year, the coastal currents reverse. 148 00:13:55,551 --> 00:13:57,068 The warm Agulhas current 149 00:13:57,103 --> 00:13:59,586 that usually flows down from the north 150 00:13:59,620 --> 00:14:02,586 has been displaced by cold water coming up from the south, 151 00:14:02,620 --> 00:14:05,275 and that has brought up rich nutrients. 152 00:14:05,310 --> 00:14:09,379 They in turn have created a bloom of plankton, 153 00:14:09,413 --> 00:14:12,896 and the sardines are now feasting on it. 154 00:14:20,275 --> 00:14:23,275 As the sardines travel north, 155 00:14:23,310 --> 00:14:26,896 a whole caravan of predators follow them. 156 00:14:29,275 --> 00:14:32,620 Thousands of Cape gannets track the sardines. 157 00:14:32,655 --> 00:14:35,310 They nested off the Cape and timed their breeding 158 00:14:35,344 --> 00:14:38,206 so that their newly fledged chicks can join them 159 00:14:38,241 --> 00:14:41,241 in pursuing the shoals. 160 00:14:47,413 --> 00:14:52,482 Below water, hundreds of sharks have also joined the caravan. 161 00:14:54,344 --> 00:14:57,275 These are bronze whaler sharks, 162 00:14:57,310 --> 00:15:00,000 a cold-water species that normally lives 163 00:15:00,034 --> 00:15:02,344 much further south. 164 00:15:06,379 --> 00:15:09,172 These three-meter sharks 165 00:15:09,206 --> 00:15:12,413 cut such great swathes through the sardine shoals 166 00:15:12,448 --> 00:15:15,379 that their tracks are clearly visible from the air. 167 00:15:15,413 --> 00:15:18,137 Harried by packs of predators 168 00:15:18,172 --> 00:15:20,344 and swept in by the action of the waves, 169 00:15:20,379 --> 00:15:24,275 the sardine shoals are penned close to the shore. 170 00:15:40,965 --> 00:15:44,448 Common dolphin are coming in from the open ocean 171 00:15:44,482 --> 00:15:46,068 to join the feast. 172 00:16:00,379 --> 00:16:02,586 There are over a thousand of them 173 00:16:02,620 --> 00:16:04,758 in this one school. 174 00:16:11,931 --> 00:16:14,413 When they catch up with the sardines, 175 00:16:14,448 --> 00:16:16,896 the action really begins. 176 00:16:20,827 --> 00:16:25,275 Working together, they drive the shoal towards the surface. 177 00:16:32,517 --> 00:16:37,000 It's easier for the dolphins to snatch fish up here. 178 00:16:50,482 --> 00:16:54,655 Now the sardines have no escape. 179 00:17:04,517 --> 00:17:06,965 Thanks to the dolphins, 180 00:17:07,000 --> 00:17:11,137 the sardines have come within the diving range of the gannets. 181 00:17:22,517 --> 00:17:25,482 Hundreds of white arrows shoot into the sea, 182 00:17:25,517 --> 00:17:28,758 leaving long trails of bubbles behind each dive. 183 00:17:40,896 --> 00:17:44,310 Next to join the frenzy are the sharks. 184 00:17:55,586 --> 00:17:59,344 Sharks get very excited when dolphins are around. 185 00:17:59,379 --> 00:18:02,379 That may be because they can feed particularly well 186 00:18:02,413 --> 00:18:04,586 once the dolphins have driven the sardines 187 00:18:04,620 --> 00:18:07,724 into more compact groups near the surface. 188 00:18:10,275 --> 00:18:12,758 As the frenzy continues, 189 00:18:12,793 --> 00:18:17,310 walls of bubbles drift upwards. 190 00:18:17,344 --> 00:18:20,034 They are being released by the dolphins, 191 00:18:20,068 --> 00:18:24,551 working together in teams. 192 00:18:24,586 --> 00:18:26,275 They use the bubbles 193 00:18:26,310 --> 00:18:29,827 to corral the sardines into ever tighter groups. 194 00:18:32,689 --> 00:18:35,586 The sardines seldom cross the wall of bubbles 195 00:18:35,620 --> 00:18:38,586 and crowd closer together. 196 00:18:41,344 --> 00:18:43,000 Bubble netting in this way 197 00:18:43,034 --> 00:18:47,586 enables the dolphins to grab every last trapped sardine. 198 00:18:58,655 --> 00:19:01,620 Just when the feasting seems to be almost over, 199 00:19:01,655 --> 00:19:03,724 a Bryde's whale. 200 00:19:07,724 --> 00:19:10,655 The survivors head on northwards, 201 00:19:10,689 --> 00:19:14,137 and the caravan of predators follows them. 202 00:19:22,793 --> 00:19:24,586 Nutrients can also be brought up, 203 00:19:24,620 --> 00:19:27,896 though less predictably, by rough weather. 204 00:19:32,551 --> 00:19:34,758 Particularly near the Poles, 205 00:19:34,793 --> 00:19:37,000 huge storms stir the depths 206 00:19:37,034 --> 00:19:38,896 and enrich the surface waters. 207 00:19:38,931 --> 00:19:40,793 And here in the South Atlantic, 208 00:19:40,827 --> 00:19:43,758 the seas are the roughest on the planet. 209 00:19:45,827 --> 00:19:48,931 And very rich seas they are, too, 210 00:19:48,965 --> 00:19:51,896 for here, the cold Falklands Current from the south 211 00:19:51,931 --> 00:19:54,689 meets the warm Brazil Current from the north, 212 00:19:54,724 --> 00:19:58,586 and at their junction, there is food in abundance. 213 00:20:00,551 --> 00:20:04,241 These black-browed albatross are duck diving for krill 214 00:20:04,275 --> 00:20:07,206 that has been driven up to the surface. 215 00:20:10,379 --> 00:20:13,172 Like all albatross, black-brows are wanderers 216 00:20:13,206 --> 00:20:15,448 across the face of the open ocean. 217 00:20:30,172 --> 00:20:33,896 A feeding assembly on this scale is a rare sight. 218 00:20:33,931 --> 00:20:36,241 Most of the time, the birds of the open sea 219 00:20:36,275 --> 00:20:38,206 are widely dispersed. 220 00:20:38,241 --> 00:20:41,000 But these feeding grounds are close to 221 00:20:41,034 --> 00:20:44,724 an albatross breeding colony, and a very special one. 222 00:20:53,965 --> 00:20:56,241 This is Steeple Jason, 223 00:20:56,275 --> 00:20:59,379 a remote island in the far west of the Falklands. 224 00:20:59,413 --> 00:21:02,379 It has the largest albatross colony in the world. 225 00:21:09,620 --> 00:21:14,137 There are almost half a million albatross here, 226 00:21:14,172 --> 00:21:18,103 an astonishing demonstration of how fertile the ocean can be 227 00:21:18,137 --> 00:21:20,034 and how much food it can give 228 00:21:20,068 --> 00:21:23,551 even to creatures that do not actually live in it. 229 00:21:48,896 --> 00:21:51,344 Nutrients by themselves are not enough 230 00:21:51,379 --> 00:21:54,137 to generate these vast assemblies. 231 00:21:54,172 --> 00:21:56,758 The heat and light that the sun brings every day 232 00:21:56,793 --> 00:21:59,241 is also essential for the growth 233 00:21:59,275 --> 00:22:03,586 of the microscopic floating plants, the phytoplankton. 234 00:22:07,137 --> 00:22:09,206 And it's the phytoplankton 235 00:22:09,241 --> 00:22:12,758 that is the basis of all life in the ocean. 236 00:22:17,965 --> 00:22:19,344 Every evening, 237 00:22:19,379 --> 00:22:22,172 the disappearance of the sun below the horizon 238 00:22:22,206 --> 00:22:24,655 triggers the largest migration of life 239 00:22:24,689 --> 00:22:27,655 that takes place on our planet. 240 00:22:34,310 --> 00:22:37,758 One thousand million tons of sea creatures 241 00:22:37,793 --> 00:22:39,758 ascend from the deep ocean 242 00:22:39,793 --> 00:22:42,827 to search for food near the surface. 243 00:22:48,827 --> 00:22:52,758 They graze on the phytoplankton under cover of darkness. 244 00:22:52,793 --> 00:22:55,758 Even so, they are far from safe. 245 00:22:55,793 --> 00:22:58,551 Other marine hunters follow them, 246 00:22:58,586 --> 00:23:01,965 some traveling up from hundreds of meters below. 247 00:24:00,620 --> 00:24:03,793 At dawn, the whole procession returns 248 00:24:03,827 --> 00:24:06,103 to the safety of the dark depths. 249 00:24:12,793 --> 00:24:18,275 The moon, too, has a great influence on life in the oceans. 250 00:24:18,310 --> 00:24:20,827 Its gravitational pull creates 251 00:24:20,862 --> 00:24:24,586 the daily advances and retreats of the tide. 252 00:24:35,689 --> 00:24:39,137 But the moon has more than a daily cycle. 253 00:24:39,172 --> 00:24:43,379 Each month, it waxes and wanes as it travels round the Earth. 254 00:24:43,413 --> 00:24:47,793 And this monthly cycle also triggers events in the ocean. 255 00:24:50,413 --> 00:24:53,379 The Pacific coast of Costa Rica 256 00:24:53,413 --> 00:24:56,482 on a very special night. 257 00:24:56,517 --> 00:25:00,068 It's just after midnight, and the tide is coming in. 258 00:25:03,689 --> 00:25:06,275 The moon is in its last quarter, 259 00:25:06,310 --> 00:25:10,689 exactly halfway between full and new. 260 00:25:11,827 --> 00:25:14,620 For weeks, the beach has been empty, 261 00:25:14,655 --> 00:25:16,689 but that is about to change. 262 00:25:16,724 --> 00:25:21,275 At high tide, turtles start to emerge from the surf. 263 00:25:25,724 --> 00:25:29,241 At first, they come in ones and twos, 264 00:25:29,275 --> 00:25:31,275 but within an hour, 265 00:25:31,310 --> 00:25:35,241 they are appearing all along the beach. 266 00:25:39,689 --> 00:25:43,310 They are all female ridley's turtles, 267 00:25:43,344 --> 00:25:44,896 and over the next six days or so, 268 00:25:44,931 --> 00:25:48,448 400,000 will visit this one beach 269 00:25:48,482 --> 00:25:52,241 to lay their eggs in the sand. 270 00:25:58,241 --> 00:26:02,965 At the peak time, 5,000 are coming and going every hour. 271 00:26:03,000 --> 00:26:05,448 The top of the beach gets so crowded 272 00:26:05,482 --> 00:26:08,275 that they have to clamber over one another 273 00:26:08,310 --> 00:26:09,655 to find a bare patch 274 00:26:09,689 --> 00:26:12,000 where they can dig a nest hole. 275 00:26:15,586 --> 00:26:20,034 A quarter of the world's population of ridley's turtles 276 00:26:20,068 --> 00:26:24,310 come to this one beach on a few key nights each year. 277 00:26:24,344 --> 00:26:26,275 The rest of the time, 278 00:26:26,310 --> 00:26:27,793 they are widely distributed through the ocean, 279 00:26:27,827 --> 00:26:30,103 searching for food, 280 00:26:30,137 --> 00:26:32,275 most, hundreds of miles away from here. 281 00:26:32,310 --> 00:26:35,310 This mass nesting is called an arribada. 282 00:26:35,344 --> 00:26:37,931 How it's coordinated is a mystery, 283 00:26:37,965 --> 00:26:40,965 but we do know that arribadas start 284 00:26:41,000 --> 00:26:43,655 when the moon is either in its first or its last quarter. 285 00:26:52,482 --> 00:26:56,482 Forty million eggs are laid in just a few days. 286 00:26:56,517 --> 00:27:00,241 By synchronizing their nesting in this way, the females ensure 287 00:27:00,275 --> 00:27:03,724 that six weeks later, their hatchlings will emerge 288 00:27:03,758 --> 00:27:06,724 in such enormous numbers that predators on the beach 289 00:27:06,758 --> 00:27:08,241 are overwhelmed, 290 00:27:08,275 --> 00:27:10,793 and a significant proportion of the baby turtles 291 00:27:10,827 --> 00:27:13,482 will get past them and make it to the water. 292 00:27:15,724 --> 00:27:18,689 But why do the females use a cue from the moon 293 00:27:18,724 --> 00:27:21,724 to help in synchronize their nesting? 294 00:27:21,758 --> 00:27:23,758 Part of the answer to that 295 00:27:23,793 --> 00:27:27,137 becomes clear at dawn on the following morning. 296 00:27:48,137 --> 00:27:50,000 The day shift of predators 297 00:27:50,034 --> 00:27:52,793 are arriving for their first meals. 298 00:27:57,068 --> 00:28:00,758 Vultures have learnt that the returning tide 299 00:28:00,793 --> 00:28:05,379 can wash freshly laid eggs out of the sand. 300 00:28:05,413 --> 00:28:09,137 The risk of eggs' being exposed by the surf 301 00:28:09,172 --> 00:28:12,862 may be part of the reason why turtle arribadas tend to occur 302 00:28:12,896 --> 00:28:16,275 around the last or first quarter of the moon. 303 00:28:19,172 --> 00:28:21,689 It's on such days as this, 304 00:28:21,724 --> 00:28:24,206 when the moon is neither full nor new, 305 00:28:24,241 --> 00:28:25,724 that the tides are weakest 306 00:28:25,758 --> 00:28:28,482 and the sea is likely to be calmer. 307 00:28:42,241 --> 00:28:45,724 So at these times it's easier for the female turtles 308 00:28:45,758 --> 00:28:47,137 to make their way through the surf, 309 00:28:47,172 --> 00:28:50,034 and there's less chance of their eggs' being washed 310 00:28:50,068 --> 00:28:53,000 out of the sand and being taken by the vultures. 311 00:29:04,379 --> 00:29:06,517 The moon's monthly cycle 312 00:29:06,551 --> 00:29:08,482 and its influence on the tides 313 00:29:08,517 --> 00:29:10,551 triggers many events in the ocean, 314 00:29:10,586 --> 00:29:13,482 from the spawning of the corals on the Great Barrier Reef 315 00:29:13,517 --> 00:29:15,862 to the breeding cycles of fish. 316 00:29:15,896 --> 00:29:17,931 But there's an even longer rhythm 317 00:29:17,965 --> 00:29:20,758 that has the most profound effect of all-- 318 00:29:20,793 --> 00:29:23,620 the annual cycle of the sun. 319 00:29:25,965 --> 00:29:28,724 The sun's position relative to the Earth 320 00:29:28,758 --> 00:29:30,758 changes through the year, 321 00:29:30,793 --> 00:29:33,758 and it's this that produces the seasons. 322 00:29:33,793 --> 00:29:35,793 In the North, spring comes 323 00:29:35,827 --> 00:29:39,724 as the sun begins to rise higher in the sky. 324 00:29:39,758 --> 00:29:42,137 Off the coast of Northwest America, 325 00:29:42,172 --> 00:29:43,793 the seas are transformed 326 00:29:43,827 --> 00:29:46,275 by the increasing strength of the sunshine. 327 00:29:50,862 --> 00:29:54,517 Here in Alaska, the coastal waters turn green 328 00:29:54,551 --> 00:29:57,517 with a sudden bloom of phytoplankton. 329 00:30:00,517 --> 00:30:03,482 Herring that have spent the winter far out to sea 330 00:30:03,517 --> 00:30:06,344 time their return to the shallow waters 331 00:30:06,379 --> 00:30:08,482 to coincide with this bloom. 332 00:30:08,517 --> 00:30:10,862 They come in vast numbers and initiate 333 00:30:10,896 --> 00:30:14,482 one of the most productive food chains in all the oceans. 334 00:30:29,517 --> 00:30:32,758 Humpback whales are at the top of that food chain. 335 00:30:32,793 --> 00:30:34,310 They have spent the winter 336 00:30:34,344 --> 00:30:36,896 breeding in the warmer tropical waters off Hawaii, 337 00:30:36,931 --> 00:30:39,586 but there was little food for them there. 338 00:30:39,620 --> 00:30:43,172 This herring bonanza provides the vast majority 339 00:30:43,206 --> 00:30:46,241 of their food for the year. 340 00:31:06,586 --> 00:31:08,482 Stellar and Californian sea lions 341 00:31:08,517 --> 00:31:10,896 also return from the open ocean 342 00:31:10,931 --> 00:31:13,206 each year to feast off the herring. 343 00:31:23,620 --> 00:31:27,551 The herring themselves, however, have not come here for food. 344 00:31:27,586 --> 00:31:29,448 They are about to breed. 345 00:31:29,482 --> 00:31:30,793 Nothing deters them 346 00:31:30,827 --> 00:31:33,896 as they head for even shallower waters. 347 00:31:35,620 --> 00:31:37,482 Now the waters are so shallow 348 00:31:37,517 --> 00:31:39,586 that glaucous-winged gulls 349 00:31:39,620 --> 00:31:42,758 are able to snatch live fish from just below the surface. 350 00:31:53,931 --> 00:31:57,103 In spite of these attacks and losses, 351 00:31:57,137 --> 00:31:59,551 the herring swim on until they reach the vegetation 352 00:31:59,586 --> 00:32:02,413 that the females need if they are to lay. 353 00:32:08,620 --> 00:32:11,448 Each female produces around 20,000 eggs, 354 00:32:11,482 --> 00:32:15,034 and they're very sticky. 355 00:32:17,689 --> 00:32:20,827 The males arrive soon after the females have spawned 356 00:32:20,862 --> 00:32:25,034 and release their sperm in vast, milky clouds. 357 00:32:28,896 --> 00:32:33,068 Soon, the excesses of the herrings' sexual spree 358 00:32:33,103 --> 00:32:36,689 creates a thick white scum on the surface. 359 00:32:38,241 --> 00:32:41,413 Through the season, curds of sperm clog the shores 360 00:32:41,448 --> 00:32:42,965 for hundreds of miles 361 00:32:43,000 --> 00:32:45,482 from British Columbia in the south 362 00:32:45,517 --> 00:32:47,827 all the way to Alaska in the north. 363 00:32:53,655 --> 00:32:57,793 After a few days, this gigantic spawning comes to an end, 364 00:32:57,827 --> 00:33:00,241 and the herring head back out to deeper waters, 365 00:33:00,275 --> 00:33:02,724 leaving behind them fertilized eggs 366 00:33:02,758 --> 00:33:06,896 plastered on every rock and strand of vegetation. 367 00:33:17,620 --> 00:33:19,206 They time their spawning 368 00:33:19,241 --> 00:33:22,344 so that two weeks later, when these eggs start to hatch, 369 00:33:22,379 --> 00:33:24,034 the annual plankton bloom 370 00:33:24,068 --> 00:33:25,413 will have reached its height, 371 00:33:25,448 --> 00:33:28,206 and the newborn fish fry will have plenty to eat. 372 00:33:28,241 --> 00:33:31,448 But in the meantime, all these eggs provide food 373 00:33:31,482 --> 00:33:33,586 for armies of different animals 374 00:33:33,620 --> 00:33:36,482 both below and above the surface. 375 00:33:42,689 --> 00:33:44,482 Millions of birds arrive 376 00:33:44,517 --> 00:33:47,620 to collect a share of the herrings' bounty. 377 00:33:47,655 --> 00:33:49,793 Some of it is easily gathered, 378 00:33:49,827 --> 00:33:54,034 for millions of eggs have been washed up onto the shore. 379 00:33:54,068 --> 00:33:57,137 This encapsulated energy 380 00:33:57,172 --> 00:34:00,172 is particularly valuable to migrating birds. 381 00:34:00,206 --> 00:34:02,862 These surfbirds are on their way 382 00:34:02,896 --> 00:34:05,275 to their breeding grounds in the Arctic, 383 00:34:05,310 --> 00:34:07,000 and they had to come down to refuel. 384 00:34:07,034 --> 00:34:12,172 Stranded herring eggs are just what they need. 385 00:34:12,206 --> 00:34:14,862 Bonaparte gulls collect the eggs 386 00:34:14,896 --> 00:34:16,896 just below the surface of the water. 387 00:34:19,896 --> 00:34:21,206 Farther out in the bay, 388 00:34:21,241 --> 00:34:23,241 huge flocks of ducks have gathered. 389 00:34:23,275 --> 00:34:25,482 They're mostly surf scoters-- 390 00:34:25,517 --> 00:34:27,448 diving ducks that can feed off the bottom 391 00:34:27,482 --> 00:34:29,827 several meters down. 392 00:34:33,896 --> 00:34:36,241 There are such huge quantities of eggs 393 00:34:36,275 --> 00:34:38,448 that even such a big animal as a bear 394 00:34:38,482 --> 00:34:41,034 finds it worthwhile to collect them. 395 00:34:44,275 --> 00:34:47,275 The spawning of the herring is a crucial event 396 00:34:47,310 --> 00:34:50,482 in the lives of many animals all along the coast. 397 00:34:50,517 --> 00:34:53,689 The whole event coincides with the plankton bloom, 398 00:34:53,724 --> 00:34:57,379 and within just three short weeks, it's all over. 399 00:35:02,931 --> 00:35:07,862 The migratory birds leave to continue their journey north. 400 00:35:13,965 --> 00:35:15,517 They will not come back 401 00:35:15,551 --> 00:35:19,172 until the herring also return next year. 402 00:35:24,551 --> 00:35:27,310 As the herring spawning finishes, 403 00:35:27,344 --> 00:35:32,896 other migrants are starting to arrive just offshore. 404 00:35:32,931 --> 00:35:35,068 Gray whales. 405 00:35:38,965 --> 00:35:41,068 They have followed the sun north, 406 00:35:41,103 --> 00:35:43,206 and they too are seeking the food 407 00:35:43,241 --> 00:35:46,517 that is generated by the bloom of the phytoplankton. 408 00:35:48,379 --> 00:35:51,206 Krill are feeding off it, 409 00:35:51,241 --> 00:35:53,793 and these whales are feeding on the krill, 410 00:35:53,827 --> 00:35:56,724 skimming it from the surface with the filter plates of baleen 411 00:35:56,758 --> 00:36:00,000 that hang from their upper jaws. 412 00:36:02,655 --> 00:36:05,862 Gray whales make one of the longest migrations 413 00:36:05,896 --> 00:36:07,482 undertaken by any marine mammal-- 414 00:36:07,517 --> 00:36:09,827 a round trip of 12,000 miles or so 415 00:36:09,862 --> 00:36:12,862 from their breeding grounds off Mexico 416 00:36:12,896 --> 00:36:15,068 along the entire coast of North America 417 00:36:15,103 --> 00:36:17,275 right up to the Arctic Ocean. 418 00:36:19,724 --> 00:36:21,862 They travel close to the coast, 419 00:36:21,896 --> 00:36:25,344 with the males and non-breeding females leading the way. 420 00:36:25,379 --> 00:36:28,931 The last to start are the cows that have just given birth. 421 00:36:28,965 --> 00:36:31,551 They have to wait until their newborn calves 422 00:36:31,586 --> 00:36:33,103 are sufficiently big and strong 423 00:36:33,137 --> 00:36:36,965 to tackle such an immense journey. 424 00:36:37,000 --> 00:36:40,827 Their progress is necessarily slow. 425 00:36:40,862 --> 00:36:42,827 The mothers must stay alongside their young, 426 00:36:42,862 --> 00:36:46,862 and even a strong calf can only travel at a couple of knots. 427 00:36:48,655 --> 00:36:50,793 They stick even closer to the shore, 428 00:36:50,827 --> 00:36:54,310 often within just 200 meters. 429 00:36:56,827 --> 00:36:58,758 Killer whales. 430 00:36:58,793 --> 00:37:01,172 They have learnt that gray whales 431 00:37:01,206 --> 00:37:02,862 follow traditional routes. 432 00:37:02,896 --> 00:37:04,896 The killers have no trouble 433 00:37:04,931 --> 00:37:09,241 in overtaking a calf and its devoted mother. 434 00:37:11,965 --> 00:37:15,758 Normally, they continually call to one another, 435 00:37:15,793 --> 00:37:17,931 but now they have fallen silent. 436 00:37:17,965 --> 00:37:19,896 The mother gray whale and her calf 437 00:37:19,931 --> 00:37:23,206 have no idea that they've been targeted. 438 00:37:43,344 --> 00:37:45,827 Catching up with the gray whales 439 00:37:45,862 --> 00:37:47,586 is the easy part for the killers. 440 00:37:47,620 --> 00:37:48,896 They have to be cautious, 441 00:37:48,931 --> 00:37:50,827 for they're only about half the size 442 00:37:50,862 --> 00:37:53,034 of the gray whale mother. 443 00:37:56,172 --> 00:37:59,689 She can inflict real damage with her tail. 444 00:38:07,827 --> 00:38:10,586 But the killers are not after her. 445 00:38:10,620 --> 00:38:12,724 They're after her calf. 446 00:38:12,758 --> 00:38:15,275 As long as the mother can keep it on the move, it will be safe, 447 00:38:15,310 --> 00:38:18,586 and she does her best to hurry it along. 448 00:38:21,310 --> 00:38:24,275 At first, the killers avoid getting too close to the mother 449 00:38:24,310 --> 00:38:25,793 but just keep pace alongside. 450 00:38:25,827 --> 00:38:28,758 They know that the calf, going at this speed, 451 00:38:28,793 --> 00:38:31,068 will eventually tire. 452 00:38:40,310 --> 00:38:43,275 After three hours of being harried in this way, 453 00:38:43,310 --> 00:38:46,241 the calf becomes too exhausted to swim any further. 454 00:38:46,275 --> 00:38:49,275 The mother has to stop. 455 00:38:49,310 --> 00:38:52,344 This is the moment the killers have been waiting for. 456 00:38:52,379 --> 00:38:54,103 They start to try and force themselves 457 00:38:54,137 --> 00:38:56,586 between mother and calf. 458 00:39:17,413 --> 00:39:19,172 A calf separated from its mother 459 00:39:19,206 --> 00:39:21,379 will not be able to defend itself. 460 00:39:21,413 --> 00:39:24,137 Time and again, the black fins of the killers 461 00:39:24,172 --> 00:39:27,137 appear between the mottled backs of the gray whales. 462 00:39:38,379 --> 00:39:40,379 At last, the killers succeed, 463 00:39:40,413 --> 00:39:43,000 and now that they've got the calf on its own, 464 00:39:43,034 --> 00:39:44,758 they change their tactics. 465 00:39:44,793 --> 00:39:46,793 They leap right onto the calf 466 00:39:46,827 --> 00:39:49,344 and try to push it under. 467 00:40:00,758 --> 00:40:02,827 They are trying to drown it. 468 00:40:11,896 --> 00:40:14,586 The calf snatches a desperate breath. 469 00:40:27,931 --> 00:40:30,551 The mother becomes increasingly agitated. 470 00:40:30,586 --> 00:40:33,620 Frantically, she tries to push her calf back to the surface 471 00:40:33,655 --> 00:40:35,758 so that it can breathe. 472 00:40:38,551 --> 00:40:40,517 But now it's so exhausted 473 00:40:40,551 --> 00:40:44,310 that it has to be supported by its mother's body. 474 00:41:00,620 --> 00:41:03,103 The killers won't give up. 475 00:41:03,137 --> 00:41:07,310 Like a pack of wolves, they take turns in harassing the whales. 476 00:41:28,137 --> 00:41:31,137 Now the whole pod is involved. 477 00:41:41,103 --> 00:41:43,586 One of them takes a bite. 478 00:41:56,103 --> 00:41:59,103 Soon, the sea is reddened with the calf's blood, 479 00:41:59,137 --> 00:42:02,793 and the killers close in for the final act. 480 00:42:23,586 --> 00:42:26,655 The calf is dead. 481 00:42:30,206 --> 00:42:32,206 After a six-hour hunt, 482 00:42:32,241 --> 00:42:35,965 the killer whales have finally won their prize. 483 00:42:41,206 --> 00:42:43,172 The mother, bereft, 484 00:42:43,206 --> 00:42:47,206 has to continue her migration north on her own. 485 00:42:50,206 --> 00:42:53,172 She leaves behind the carcass of a calf 486 00:42:53,206 --> 00:42:57,172 that she cherished for 13 months in her womb, 487 00:42:57,206 --> 00:43:01,034 for which she delayed her own journey to find food. 488 00:43:03,965 --> 00:43:05,931 The pod of 15 killer whales 489 00:43:05,965 --> 00:43:09,206 spent over six hours trying to kill this calf, 490 00:43:09,241 --> 00:43:11,655 but now, having succeeded, 491 00:43:11,689 --> 00:43:15,551 they've eaten nothing more than its lower jaw and its tongue. 492 00:43:23,275 --> 00:43:25,172 Valuable food like this 493 00:43:25,206 --> 00:43:27,965 will not go to waste in the ocean. 494 00:43:28,000 --> 00:43:29,965 Before long, the carcass will sink 495 00:43:30,000 --> 00:43:32,896 to the very bottom of this deep sea. 496 00:43:32,931 --> 00:43:36,689 But even there, its flesh will not be wasted. 497 00:43:38,758 --> 00:43:40,310 Over a mile down, 498 00:43:40,344 --> 00:43:42,931 in the total darkness of the deep ocean, 499 00:43:42,965 --> 00:43:46,931 the body of another gray whale, a 30-ton adult. 500 00:43:46,965 --> 00:43:51,724 It settled here only a few weeks ago. 501 00:43:51,758 --> 00:43:56,620 Already, it has attracted hundreds of hagfish. 502 00:44:01,172 --> 00:44:04,413 These scavengers, over half a meter long 503 00:44:04,448 --> 00:44:08,379 and as thick as your arm, are only found in the deep sea. 504 00:44:08,413 --> 00:44:11,413 They have been attracted by the faint whiff of decay 505 00:44:11,448 --> 00:44:16,000 suffusing through the water for miles around. 506 00:44:18,413 --> 00:44:21,379 With their heads buried in the whale's flesh, 507 00:44:21,413 --> 00:44:23,448 they breathe through gill openings 508 00:44:23,482 --> 00:44:25,344 along the sides of their bodies. 509 00:44:25,379 --> 00:44:27,413 They're very primitive creatures-- 510 00:44:27,448 --> 00:44:31,413 not even true fish, for they lack jaws. 511 00:44:31,448 --> 00:44:34,103 They feed, not by biting, 512 00:44:34,137 --> 00:44:37,275 but by rasping off flesh with two rows of horny teeth. 513 00:44:39,103 --> 00:44:41,275 In just a few hours, a hagfish can eat 514 00:44:41,310 --> 00:44:42,827 several times its own weight 515 00:44:42,862 --> 00:44:45,862 of rotting flesh. 516 00:44:48,000 --> 00:44:52,241 Next to arrive, a sleeper shark. 517 00:44:58,448 --> 00:45:01,482 It moves so slowly to conserve energy-- 518 00:45:01,517 --> 00:45:04,034 an important strategy for so large an animal 519 00:45:04,068 --> 00:45:07,482 surviving in such a poor habitat. 520 00:45:13,517 --> 00:45:16,482 Sleeper sharks live over a mile down 521 00:45:16,517 --> 00:45:20,586 and grow to over seven meters long. 522 00:45:20,620 --> 00:45:23,620 They can go for months without food, 523 00:45:23,655 --> 00:45:26,379 slowly cruising along the bottom, 524 00:45:26,413 --> 00:45:29,206 waiting for rare bonanzas such as this one 525 00:45:29,241 --> 00:45:31,862 to arrive from above. 526 00:45:38,034 --> 00:45:41,448 A whole range of different deep-sea scavengers 527 00:45:41,482 --> 00:45:44,482 will feast on this carcass for a long time 528 00:45:44,517 --> 00:45:47,689 before all its nutriment has been consumed. 529 00:45:49,379 --> 00:45:51,000 18 months later, 530 00:45:51,034 --> 00:45:54,586 all that is left is a perfect skeleton stripped bare. 531 00:45:57,551 --> 00:45:59,551 The sun's energy, that was captured 532 00:45:59,586 --> 00:46:03,172 and turned into living tissue by the floating phytoplankton, 533 00:46:03,206 --> 00:46:05,551 has been transferred from one link to another 534 00:46:05,586 --> 00:46:07,482 in the food chain and has ended up 535 00:46:07,517 --> 00:46:08,931 as far away from the sun 536 00:46:08,965 --> 00:46:11,448 as it's possible to be on this planet-- 537 00:46:11,482 --> 00:46:14,586 at the bottom of the deep sea. 538 00:46:14,620 --> 00:46:18,724 But some energy also returns from the deep. 539 00:46:23,689 --> 00:46:25,689 Millions of opalescent squid 540 00:46:25,724 --> 00:46:28,551 are on their way to the shallows. 541 00:46:28,586 --> 00:46:31,551 They've come up here to mate. 542 00:46:31,586 --> 00:46:35,241 As the males grab the females, their tentacles flush red. 543 00:46:37,551 --> 00:46:39,551 For most of the year, 544 00:46:39,586 --> 00:46:41,896 these squid live at a depth of around 500 meters. 545 00:46:41,931 --> 00:46:44,034 They only come together 546 00:46:44,068 --> 00:46:46,413 in these great breeding schools for a few weeks. 547 00:46:46,448 --> 00:46:49,448 Just one school was estimated to contain animals 548 00:46:49,482 --> 00:46:52,896 that weigh around 4,000 tons. 549 00:47:03,172 --> 00:47:06,137 Wave after wave rise from the depths, 550 00:47:06,172 --> 00:47:07,931 and soon the seabed in the shallows 551 00:47:07,965 --> 00:47:10,551 is strewn with dense patches of egg capsules 552 00:47:10,586 --> 00:47:12,689 several meters across. 553 00:47:17,793 --> 00:47:21,655 As each female adds another capsule to the pile, 554 00:47:21,689 --> 00:47:24,896 the males fight to fertilize its contents. 555 00:47:40,655 --> 00:47:43,655 The squid make their huge journey into the shallows 556 00:47:43,689 --> 00:47:47,172 because their eggs will develop faster in the warmer water here, 557 00:47:47,206 --> 00:47:48,758 and when the young emerge, 558 00:47:48,793 --> 00:47:51,000 they will find more food more easily 559 00:47:51,034 --> 00:47:54,586 than they would in the ocean depths. 560 00:47:58,241 --> 00:48:00,655 Dawn the next morning, 561 00:48:00,689 --> 00:48:04,724 and the seabed for miles around is covered in egg capsules. 562 00:48:04,758 --> 00:48:07,172 The squid themselves have all gone. 563 00:48:07,206 --> 00:48:08,931 Many will have died, 564 00:48:08,965 --> 00:48:11,827 but some will have returned to their home in the deep. 565 00:48:11,862 --> 00:48:14,689 They will not return to the light of the sun 566 00:48:14,724 --> 00:48:19,896 until the next time they are driven up by the urge to spawn.