1 00:00:34,287 --> 00:00:37,757 Dwarfed by the vast expanse of the open ocean, 2 00:00:37,927 --> 00:00:41,476 the biggest animal that has ever lived on our planet. 3 00:00:48,287 --> 00:00:53,077 A blue whale, 30 metres long and weighing over 200 tonnes. 4 00:00:53,247 --> 00:00:56,796 it's far bigger than even the biggest dinosaur. 5 00:00:58,447 --> 00:01:01,598 its tongue weighs as much as an elephant. 6 00:01:01,767 --> 00:01:03,758 its heart is the size of a car, 7 00:01:03,927 --> 00:01:07,124 and some of its blood vessels are so wide 8 00:01:07,287 --> 00:01:09,278 that you could swim down them. 9 00:01:10,887 --> 00:01:12,605 its tail alone 10 00:01:12,767 --> 00:01:16,077 is the width of a small aircraft's wings. 11 00:01:33,327 --> 00:01:36,558 its streamlining, close to perfection, 12 00:01:36,727 --> 00:01:38,843 enables it to cruise at 20 knots. 13 00:01:39,007 --> 00:01:42,204 it's one of the fastest animals in the sea. 14 00:01:46,247 --> 00:01:48,442 The ocean's largest inhabitant 15 00:01:48,607 --> 00:01:51,997 feeds almost exclusively on one of the smallest - 16 00:01:52,167 --> 00:01:55,603 krill, a crustacean just a few centimetres long. 17 00:01:59,287 --> 00:02:01,198 Gathered in a shoal, 18 00:02:01,447 --> 00:02:03,438 krill stain the sea red, 19 00:02:03,607 --> 00:02:07,600 and a single blue whale in a day can consume 40 million of them. 20 00:02:16,247 --> 00:02:19,239 Despite the enormous size of blue whales, 21 00:02:19,407 --> 00:02:21,398 we know very little about them. 22 00:02:21,567 --> 00:02:24,559 Their migration routes are still a mystery, 23 00:02:24,727 --> 00:02:27,844 and we have absolutely no idea where they go to breed. 24 00:02:31,527 --> 00:02:33,518 They are a dramatic reminder 25 00:02:33,687 --> 00:02:35,678 of how much we still have to learn 26 00:02:35,847 --> 00:02:39,237 about the ocean and the creatures that live there. 27 00:02:42,367 --> 00:02:44,562 0ur planet is a blue planet. 28 00:02:44,727 --> 00:02:47,958 0ver 70 per cent of it is covered by the sea. 29 00:02:50,287 --> 00:02:53,802 The Pacific 0cean alone covers half the globe. 30 00:02:53,967 --> 00:02:57,164 You can fly across it non-stop for 12 hours 31 00:02:57,327 --> 00:03:00,478 and still see nothing more than a speck of land. 32 00:03:01,687 --> 00:03:03,279 This series will reveal 33 00:03:03,447 --> 00:03:06,644 the complete natural history of our ocean planet 34 00:03:06,807 --> 00:03:11,039 from its familiar shores to the mysteries of its deepest seas. 35 00:03:22,287 --> 00:03:24,278 By volume, the ocean makes up 36 00:03:24,447 --> 00:03:27,519 97 per cent of the earth's inhabitable space, 37 00:03:27,687 --> 00:03:30,326 and the sheer quantity of its marine life 38 00:03:30,487 --> 00:03:33,160 far exceeds that which inhabits the land. 39 00:03:55,527 --> 00:03:59,884 But life in the ocean is not evenly spread. it's regulated 40 00:04:00,047 --> 00:04:03,039 by the path of currents carrying nutrients, 41 00:04:03,207 --> 00:04:05,277 and the varying power of the sun. 42 00:04:06,207 --> 00:04:11,156 in this first programme, we will see how these two forces interact 43 00:04:11,327 --> 00:04:13,318 to control the distribution of life 44 00:04:13,487 --> 00:04:16,877 from the coral seas to the polar wastes. 45 00:05:11,327 --> 00:05:14,285 The sheer physical power of the ocean 46 00:05:14,447 --> 00:05:16,244 dominates our planet. 47 00:05:32,047 --> 00:05:35,676 it profoundly influences the weather of all the world. 48 00:05:35,847 --> 00:05:40,477 Water vapour rising from it forms the clouds and generates the storms 49 00:05:40,647 --> 00:05:43,115 that ultimately will drench the land. 50 00:06:02,287 --> 00:06:05,279 The great waves that roar in towards the shores 51 00:06:05,447 --> 00:06:08,439 are dramatic demonstrations of its power. 52 00:06:23,247 --> 00:06:25,966 Waves originate far out at sea. 53 00:06:26,127 --> 00:06:29,563 There, even gentle breezes can cause ripples, 54 00:06:29,727 --> 00:06:32,002 and ripples grow into swells. 55 00:06:41,927 --> 00:06:44,521 0ut in the open ocean, unimpeded by land, 56 00:06:44,687 --> 00:06:47,406 such swells can become gigantic. 57 00:07:09,487 --> 00:07:13,480 it's only when an ocean swell eventually reaches shallow water 58 00:07:13,647 --> 00:07:15,638 that it starts to break. 59 00:07:22,647 --> 00:07:26,640 As it approaches the coast, the water at the bottom of the swell 60 00:07:26,807 --> 00:07:29,367 is slowed by contact with the seabed. 61 00:07:29,527 --> 00:07:32,519 The top of the swell, still travelling fast, 62 00:07:32,687 --> 00:07:35,485 starts to roll over and so the wave breaks. 63 00:08:07,287 --> 00:08:11,200 The ocean never rests. Huge currents, such as the Gulf Stream, 64 00:08:11,367 --> 00:08:15,121 keep its waters constantly on the move all round the globe. 65 00:08:15,287 --> 00:08:18,279 it's these currents more than any other factor 66 00:08:18,447 --> 00:08:22,599 that control the distribution of nutrients and life in the seas. 67 00:08:25,087 --> 00:08:28,602 A tiny island lost in the midst of the Pacific. 68 00:08:28,767 --> 00:08:30,758 it's the tip of a huge mountain 69 00:08:30,927 --> 00:08:34,602 that rises from the sea floor thousands of metres below. 70 00:08:39,847 --> 00:08:43,044 The nearest land is 300 miles away. 71 00:08:47,087 --> 00:08:49,760 isolated sea mounts like this one 72 00:08:49,927 --> 00:08:52,566 create oases where life can flourish 73 00:08:52,727 --> 00:08:56,276 in the comparatively empty expanses of the open ocean. 74 00:09:04,887 --> 00:09:08,675 But all the creatures that swim beside it would not be here 75 00:09:08,847 --> 00:09:10,997 were it not for one key factor - 76 00:09:12,167 --> 00:09:13,964 the deep ocean currents. 77 00:09:19,087 --> 00:09:23,080 Far below the surface, they collide with the island's flanks 78 00:09:23,247 --> 00:09:25,397 and are deflected upwards, 79 00:09:25,567 --> 00:09:29,526 bringing with them from the depths a rich soup of nutrients. 80 00:09:31,287 --> 00:09:35,599 Such up-wellings attract great concentrations of life. 81 00:09:43,527 --> 00:09:46,519 Most of the fish here are permanent residents 82 00:09:46,687 --> 00:09:50,475 feeding on plankton - tiny floating plants and animals 83 00:09:50,647 --> 00:09:54,117 nourished by the richness brought up from the depths, 84 00:09:54,287 --> 00:09:57,165 and they attract visitors from the open ocean. 85 00:09:58,447 --> 00:09:59,766 Tuna. 86 00:10:25,607 --> 00:10:28,599 The plankton feeders are easy targets. 87 00:10:39,287 --> 00:10:42,962 All this action attracts even larger predators. 88 00:10:45,727 --> 00:10:47,080 Sharks. 89 00:10:51,687 --> 00:10:53,484 Hundreds of sharks. 90 00:10:55,967 --> 00:10:59,642 These silky sharks are normally ocean-going species, 91 00:10:59,807 --> 00:11:02,605 but the sea mounts in the eastern Pacific 92 00:11:02,767 --> 00:11:05,201 like Cocos, Mapelo and the Galapagos, 93 00:11:05,367 --> 00:11:09,519 attract silkies in huge groups up to 500 strong. 94 00:11:13,527 --> 00:11:16,883 Silkies seem to specialise in taking injured fish 95 00:11:17,047 --> 00:11:19,197 and constantly circle sea mounts 96 00:11:19,367 --> 00:11:22,086 on the look out for the chance to do so. 97 00:11:27,007 --> 00:11:29,475 But silkies are not the only visitors. 98 00:11:33,287 --> 00:11:37,326 Hammerheads gather in some of the largest shark shoals 99 00:11:37,487 --> 00:11:39,637 to be found anywhere in the ocean. 100 00:11:39,807 --> 00:11:43,641 Sometimes, thousands will circle over a single sea mount. 101 00:11:48,447 --> 00:11:51,086 But these sharks are not here for food. 102 00:11:51,247 --> 00:11:53,397 They have come for another reason. 103 00:11:56,287 --> 00:12:00,326 Some of the locals provide a cleaning service. 104 00:12:03,687 --> 00:12:05,962 Following the last El Nino year, 105 00:12:06,127 --> 00:12:10,678 when a rise in water temperatures gave many sharks fungal infections, 106 00:12:10,847 --> 00:12:13,884 the number of hammerheads visiting the sea mounts 107 00:12:14,047 --> 00:12:15,844 reached record levels. 108 00:12:26,287 --> 00:12:29,040 Nutrients also well up to the surface 109 00:12:29,207 --> 00:12:31,516 along the coasts of the continents. 110 00:12:33,087 --> 00:12:36,921 This is Natal on South Africa's eastern seaboard. 111 00:12:37,087 --> 00:12:38,566 it's june, 112 00:12:38,727 --> 00:12:42,402 and just off-shore, strange black patches have appeared. 113 00:12:45,927 --> 00:12:49,363 They look like immense oil slicks up to a mile long. 114 00:12:51,647 --> 00:12:54,081 But this is a living slick: 115 00:12:54,247 --> 00:12:58,399 millions and millions of sardines on a marine migration 116 00:12:58,567 --> 00:13:00,558 that in terms of sheer biomass, 117 00:13:00,727 --> 00:13:04,481 rivals that of the wildebeest on the grasslands of Africa. 118 00:13:07,967 --> 00:13:11,755 These fish live mostly in the cold waters south of the Cape, 119 00:13:11,927 --> 00:13:14,999 but each year the coastal currents reverse. 120 00:13:15,167 --> 00:13:19,126 The warm Agulhas current that flows down from the north 121 00:13:19,287 --> 00:13:22,359 has been displaced by cold water from the south, 122 00:13:22,527 --> 00:13:24,995 and that has brought up rich nutrients. 123 00:13:25,167 --> 00:13:28,477 They in turn have created a bloom of plankton, 124 00:13:29,287 --> 00:13:31,926 and the sardines are now feasting on it. 125 00:13:40,927 --> 00:13:42,918 As the sardines travel north, 126 00:13:43,087 --> 00:13:45,920 a whole caravan of predators follow them. 127 00:13:49,367 --> 00:13:52,404 Thousands of Cape gannets track the sardines. 128 00:13:52,567 --> 00:13:55,639 They nested off the Cape and timed their breeding 129 00:13:55,807 --> 00:13:58,082 so that their newly-fledged chicks 130 00:13:58,247 --> 00:14:00,715 can join them in pursuing the shoals. 131 00:14:07,287 --> 00:14:11,838 Below water, hundreds of sharks have also joined the caravan. 132 00:14:14,687 --> 00:14:17,520 These are bronze whaler sharks, 133 00:14:17,687 --> 00:14:21,600 a cold water species that normally lives much further south. 134 00:14:26,647 --> 00:14:28,922 These three-metre sharks 135 00:14:29,087 --> 00:14:32,318 cut such great swathes through the sardine shoals 136 00:14:32,487 --> 00:14:35,160 that their tracks are visible from the air. 137 00:14:35,327 --> 00:14:37,318 Harried by packs of predators 138 00:14:37,487 --> 00:14:40,479 and swept in by the action of the waves, 139 00:14:40,647 --> 00:14:43,798 the sardine shoals are penned close to the shore. 140 00:15:00,807 --> 00:15:05,801 Common dolphin are coming in from the open ocean to join the feast. 141 00:15:20,327 --> 00:15:22,318 There are over a thousand of them 142 00:15:22,487 --> 00:15:24,478 in this one school. 143 00:15:31,807 --> 00:15:36,642 When they catch up with the sardines, the action really begins. 144 00:15:40,687 --> 00:15:44,646 Working together, they drive the shoal towards the surface. 145 00:15:52,687 --> 00:15:56,805 it's easier for the dolphins to snatch fish up here. 146 00:16:10,767 --> 00:16:13,600 Now the sardines have no escape. 147 00:16:24,647 --> 00:16:26,638 Thanks to the dolphins, 148 00:16:26,807 --> 00:16:30,880 the sardines have come within the diving range of the gannets. 149 00:16:42,087 --> 00:16:44,885 Hundreds of white arrows shoot into the sea, 150 00:16:45,047 --> 00:16:48,517 leaving long trails of bubbles behind each dive. 151 00:17:00,727 --> 00:17:03,321 Next to join the frenzy are the sharks. 152 00:17:15,447 --> 00:17:19,076 Sharks get very excited when dolphins are around. 153 00:17:19,247 --> 00:17:21,317 They can feed particularly well 154 00:17:21,487 --> 00:17:24,240 once the dolphins have driven the sardines 155 00:17:24,407 --> 00:17:27,160 into more compact groups near the surface. 156 00:17:30,687 --> 00:17:34,475 As the frenzy continues, walls of bubbles drift upwards. 157 00:17:37,207 --> 00:17:39,767 They are being released by the dolphins 158 00:17:39,927 --> 00:17:41,918 working together in teams. 159 00:17:44,287 --> 00:17:46,005 They use the bubbles 160 00:17:46,167 --> 00:17:49,284 to corral the sardines into ever tighter groups. 161 00:17:52,607 --> 00:17:55,519 The sardines seldom cross the wall of bubbles 162 00:17:55,687 --> 00:17:57,678 and crowd closer together. 163 00:18:01,047 --> 00:18:02,844 Bubble netting in this way, 164 00:18:03,007 --> 00:18:07,046 enables the dolphins to grab every last trapped sardine. 165 00:18:18,487 --> 00:18:21,479 just when the feasting seems to be almost over, 166 00:18:21,647 --> 00:18:23,444 a Bryde's whale. 167 00:18:27,767 --> 00:18:30,076 The survivors head on northwards, 168 00:18:30,247 --> 00:18:33,045 and the caravan of predators follows them. 169 00:18:41,127 --> 00:18:44,836 Nutrients can also be brought up, though less predictably, 170 00:18:45,007 --> 00:18:46,998 by rough weather. 171 00:18:51,687 --> 00:18:55,316 Particularly near the poles, huge storms stir the depths 172 00:18:55,487 --> 00:18:57,796 and enrich the surface waters, 173 00:18:57,967 --> 00:18:59,958 and here, in the South Atlantic, 174 00:19:00,127 --> 00:19:02,766 the seas are the roughest on the planet. 175 00:19:06,327 --> 00:19:08,318 And very rich seas they are, too, 176 00:19:08,487 --> 00:19:11,797 for here, the cold Falklands current from the south 177 00:19:11,967 --> 00:19:14,879 meets the warm Brazil current from the north, 178 00:19:15,047 --> 00:19:17,720 and at their junction is food in abundance. 179 00:19:19,487 --> 00:19:23,116 These black-browed albatross are duck-diving for krill 180 00:19:23,287 --> 00:19:25,960 that has been driven up to the surface. 181 00:19:29,047 --> 00:19:30,844 Like all albatross, 182 00:19:31,007 --> 00:19:34,920 black-brows are wanderers across the face of the open ocean. 183 00:19:49,927 --> 00:19:53,124 A feeding assembly on this scale is a rare sight. 184 00:19:53,287 --> 00:19:57,360 Most of the time, the birds of the open sea are widely dispersed, 185 00:19:57,527 --> 00:20:01,998 but these feeding grounds are close to an albatross breeding colony, 186 00:20:02,167 --> 00:20:03,998 and a very special one. 187 00:20:13,087 --> 00:20:15,078 This is Steeple jason, 188 00:20:15,247 --> 00:20:18,319 a remote island in the far west of the Falklands. 189 00:20:18,487 --> 00:20:21,559 it has the largest albatross colony in the world. 190 00:20:30,087 --> 00:20:33,204 There are almost half a million albatross here, 191 00:20:33,367 --> 00:20:37,360 an astonishing demonstration of how fertile the ocean can be 192 00:20:37,527 --> 00:20:39,518 and how much food it can give 193 00:20:39,687 --> 00:20:42,838 even to creatures that do not actually live in it. 194 00:21:08,367 --> 00:21:10,358 Nutrients by themselves 195 00:21:10,527 --> 00:21:13,758 are not enough to generate these vast assemblies. 196 00:21:13,927 --> 00:21:16,999 The heat and light from the sun is also essential 197 00:21:17,167 --> 00:21:20,477 for the growth of the microscopic floating plants - 198 00:21:20,647 --> 00:21:22,797 the phytoplankton. 199 00:21:26,527 --> 00:21:31,282 And it's the phytoplankton that is the basis of all life in the ocean. 200 00:21:37,687 --> 00:21:41,680 Every evening, the disappearance of the sun below the horizon 201 00:21:41,847 --> 00:21:44,645 triggers the largest migration of life 202 00:21:44,807 --> 00:21:46,798 that takes place on our planet. 203 00:21:53,967 --> 00:21:57,277 0ne thousand million tonnes of sea creatures 204 00:21:57,447 --> 00:22:01,440 ascend from the deep ocean to search for food near the surface. 205 00:22:08,407 --> 00:22:12,400 They graze on the phytoplankton under cover of darkness. 206 00:22:12,567 --> 00:22:15,161 Even so, they are far from safe. 207 00:22:15,327 --> 00:22:17,557 0ther marine hunters follow them, 208 00:22:17,727 --> 00:22:20,958 some travelling up from hundreds of metres below. 209 00:23:19,807 --> 00:23:21,320 At dawn, 210 00:23:21,487 --> 00:23:25,526 the whole procession returns to the safety of the dark depths. 211 00:23:31,687 --> 00:23:36,317 The moon, too, has a great influence on life in the oceans. 212 00:23:37,687 --> 00:23:39,882 its gravitational pull 213 00:23:40,047 --> 00:23:43,483 creates the daily advances and retreats of the tide. 214 00:23:55,167 --> 00:23:58,159 But the moon has more than a daily cycle. 215 00:23:58,327 --> 00:24:02,559 Each month, it waxes and wanes as it travels round the earth, 216 00:24:02,727 --> 00:24:06,561 and this monthly cycle also triggers events in the ocean. 217 00:24:09,807 --> 00:24:12,321 The Pacific coast of Costa Rica 218 00:24:12,487 --> 00:24:14,478 on a very special night. 219 00:24:14,647 --> 00:24:18,845 it's just after midnight and the tide is coming in. 220 00:24:23,047 --> 00:24:25,561 The moon is in its last quarter, 221 00:24:25,727 --> 00:24:28,799 exactly half way between full and new. 222 00:24:31,207 --> 00:24:33,880 For weeks, the beach has been empty, 223 00:24:34,047 --> 00:24:36,038 but that is about to change. 224 00:24:36,207 --> 00:24:40,280 At high tide, turtles start to emerge from the surf. 225 00:24:45,487 --> 00:24:48,479 At first, they come in ones and twos, 226 00:24:48,647 --> 00:24:50,558 but within an hour, 227 00:24:50,727 --> 00:24:53,719 they are appearing all along the beach. 228 00:24:59,007 --> 00:25:01,965 They are all female Ridley's turtles, 229 00:25:02,127 --> 00:25:04,118 and over the next six days or so, 230 00:25:04,287 --> 00:25:07,643 400,000 will visit this one beach 231 00:25:07,807 --> 00:25:09,798 to lay their eggs in the sand. 232 00:25:17,647 --> 00:25:22,163 At the peak time, 5,000 are coming and going every hour. 233 00:25:22,327 --> 00:25:25,080 The top of the beach gets so crowded 234 00:25:25,247 --> 00:25:28,842 that they have to clamber over one another to find a patch 235 00:25:29,007 --> 00:25:30,998 where they can dig a nest hole. 236 00:25:36,087 --> 00:25:39,762 A quarter of the world's population of Ridley's turtles 237 00:25:39,927 --> 00:25:43,476 come to this one beach on a few key nights each year. 238 00:25:43,647 --> 00:25:45,638 The rest of the time, 239 00:25:45,807 --> 00:25:48,879 they are widely distributed through the ocean, 240 00:25:49,487 --> 00:25:51,478 most, hundreds of miles away. 241 00:25:51,647 --> 00:25:56,323 This mass nesting is called an arribada. How it's co-ordinated 242 00:25:56,487 --> 00:25:58,478 is a mystery, 243 00:25:58,647 --> 00:26:00,877 but we do know that arribadas start 244 00:26:01,047 --> 00:26:04,437 when the moon is either in its first or last quarter. 245 00:26:11,807 --> 00:26:15,720 Forty million eggs are laid in just a few days. 246 00:26:15,887 --> 00:26:19,516 By synchronising their nesting, the females ensure 247 00:26:19,687 --> 00:26:22,884 that six weeks later, their hatchlings will emerge 248 00:26:23,047 --> 00:26:25,038 in such enormous numbers 249 00:26:25,207 --> 00:26:27,596 that predators are overwhelmed, 250 00:26:27,767 --> 00:26:32,682 and a significant proportion of baby turtles will make it to the water. 251 00:26:34,887 --> 00:26:38,436 But why do the females use a cue from the moon 252 00:26:38,607 --> 00:26:40,916 to help synchronise their nesting? 253 00:26:41,087 --> 00:26:43,078 Part of the answer to that 254 00:26:43,247 --> 00:26:46,444 becomes clear at dawn on the following morning. 255 00:27:07,007 --> 00:27:11,319 The day shift of predators are arriving for their first meals. 256 00:27:16,487 --> 00:27:18,478 Vultures have learnt 257 00:27:18,647 --> 00:27:22,879 that the returning tide can wash freshly laid eggs out of the sand. 258 00:27:25,287 --> 00:27:28,324 The risk of eggs being exposed by the surf 259 00:27:28,487 --> 00:27:31,559 may be partly why turtle arribadas tend to occur 260 00:27:31,727 --> 00:27:34,719 around the last or first quarter of the moon. 261 00:27:38,287 --> 00:27:43,042 it's on such days as this when the moon is neither full nor new, 262 00:27:43,207 --> 00:27:47,041 that the tides are weakest and the sea is likely to be calmer. 263 00:28:01,687 --> 00:28:06,636 So it's easier for the female turtles to make their way through the surf, 264 00:28:06,807 --> 00:28:09,799 and harder for eggs to be washed out of the sand 265 00:28:09,967 --> 00:28:11,798 and taken by vultures. 266 00:28:23,327 --> 00:28:27,320 The moon's monthly cycle and its influence on the tides 267 00:28:27,487 --> 00:28:29,717 triggers many events in the ocean, 268 00:28:29,887 --> 00:28:33,482 from the spawning of the corals on the Great Barrier reef 269 00:28:33,647 --> 00:28:35,638 to the breeding cycles of fish, 270 00:28:35,807 --> 00:28:37,957 but there's an even longer rhythm 271 00:28:38,127 --> 00:28:40,721 that has the most profound effect of all - 272 00:28:40,887 --> 00:28:42,878 the annual cycle of the sun. 273 00:28:45,007 --> 00:28:47,601 The sun's position relative to the earth 274 00:28:47,767 --> 00:28:49,758 changes through the year, 275 00:28:49,927 --> 00:28:52,521 and it's this that produces the seasons. 276 00:28:52,687 --> 00:28:54,484 in the north, spring comes 277 00:28:54,647 --> 00:28:57,480 as the sun begins to rise higher in the sky. 278 00:28:58,287 --> 00:29:00,721 0ff the coast of north west America, 279 00:29:00,887 --> 00:29:05,165 the seas are transformed by the increasing strength of the sun. 280 00:29:10,087 --> 00:29:13,443 Here in Alaska, the coastal waters turn green 281 00:29:13,607 --> 00:29:16,075 with a sudden bloom of phytoplankton. 282 00:29:19,087 --> 00:29:22,159 Herring that have spent the winter far out to sea 283 00:29:22,327 --> 00:29:26,878 time their return to the shallow waters to coincide with this bloom. 284 00:29:27,047 --> 00:29:29,083 They come in vast numbers 285 00:29:29,247 --> 00:29:33,365 and initiate one of the most productive food chains in all the oceans. 286 00:29:48,287 --> 00:29:51,836 Humpback whales are at the top of that food chain. 287 00:29:52,007 --> 00:29:53,998 They have spent the winter 288 00:29:54,167 --> 00:29:57,477 breeding in the warmer tropical waters off Hawaii, 289 00:29:57,647 --> 00:29:59,638 but there was little food there. 290 00:29:59,807 --> 00:30:01,798 This herring bonanza 291 00:30:01,967 --> 00:30:05,243 provides the majority of their food for the year. 292 00:30:25,087 --> 00:30:27,476 Stellar and Californian sea lions 293 00:30:27,647 --> 00:30:32,163 also return from the open ocean each year to feast off the herring. 294 00:30:42,527 --> 00:30:46,281 The herring, however, have not come here for food. 295 00:30:46,447 --> 00:30:49,484 They are about to breed. Nothing deters them 296 00:30:49,647 --> 00:30:52,798 as they head for even shallower waters. 297 00:30:54,447 --> 00:30:56,438 Now the waters are so shallow 298 00:30:56,607 --> 00:30:58,484 that glaucous-winged gulls 299 00:30:58,647 --> 00:31:01,684 can snatch live fish from just below the surface. 300 00:31:13,287 --> 00:31:16,085 in spite of these attacks, the herring swim on 301 00:31:16,247 --> 00:31:18,363 until they reach the vegetation 302 00:31:18,527 --> 00:31:21,166 that the females need if they are to lay. 303 00:31:27,287 --> 00:31:30,438 Each female produces around 20,000 eggs, 304 00:31:30,607 --> 00:31:32,916 and they're very sticky. 305 00:31:36,807 --> 00:31:40,880 After the females have spawned, the males release their sperm 306 00:31:41,047 --> 00:31:43,038 in vast, milky clouds. 307 00:31:47,967 --> 00:31:52,006 Soon, the excesses of the herrings' sexual spree 308 00:31:52,167 --> 00:31:55,637 creates a thick white scum on the surface. 309 00:31:57,047 --> 00:31:59,038 Through the season, 310 00:31:59,207 --> 00:32:02,597 curds of sperm clog the shores for hundreds of miles 311 00:32:02,767 --> 00:32:06,442 from British Columbia in the south to Alaska in the north. 312 00:32:12,607 --> 00:32:16,885 After a few days, this gigantic spawning comes to an end, 313 00:32:17,047 --> 00:32:20,039 and the herring head back out to deeper waters, 314 00:32:20,207 --> 00:32:22,596 leaving behind them fertilised eggs 315 00:32:22,767 --> 00:32:25,998 plastered on every rock and strand of vegetation. 316 00:32:36,607 --> 00:32:41,806 They time the spawning so that two weeks later, when the eggs hatch, 317 00:32:41,967 --> 00:32:46,085 the annual plankton bloom will be at its height, and the fish fry 318 00:32:46,247 --> 00:32:48,238 will have plenty to eat. 319 00:32:48,407 --> 00:32:50,716 in the meantime, these eggs provide food 320 00:32:50,887 --> 00:32:54,197 for armies of different animals below and above the surface. 321 00:33:02,127 --> 00:33:06,518 Millions of birds arrive to collect a share of the herrings' bounty. 322 00:33:06,687 --> 00:33:08,678 Some of it is easily gathered, 323 00:33:08,847 --> 00:33:12,396 for millions of eggs have been washed up onto the shore. 324 00:33:13,287 --> 00:33:15,278 This encapsulated energy 325 00:33:15,447 --> 00:33:19,076 is particularly valuable to migrating birds. 326 00:33:19,247 --> 00:33:21,317 These surfbirds are on their way 327 00:33:21,487 --> 00:33:25,958 to their breeding grounds in the Arctic and come down to refuel. 328 00:33:26,127 --> 00:33:29,199 Stranded herring eggs are just what they need. 329 00:33:31,247 --> 00:33:33,283 Bonaparte gulls collect the eggs 330 00:33:33,447 --> 00:33:35,642 just below the surface of the water. 331 00:33:38,367 --> 00:33:42,155 Further out in the bay, huge flocks of ducks have gathered. 332 00:33:42,327 --> 00:33:44,283 They're mostly surf scoters - 333 00:33:44,447 --> 00:33:48,440 diving ducks that can feed off the bottom several metres down. 334 00:33:52,287 --> 00:33:55,279 There are such huge quantities of eggs, 335 00:33:55,447 --> 00:33:57,438 that even a big animal like a bear 336 00:33:57,607 --> 00:33:59,962 finds it worthwhile to collect them. 337 00:34:03,287 --> 00:34:06,597 The spawning of the herring is a crucial event 338 00:34:06,767 --> 00:34:09,839 in the lives of many animals all along the coast. 339 00:34:10,007 --> 00:34:13,317 The whole event coincides with the plankton bloom, 340 00:34:13,487 --> 00:34:16,240 and within three short weeks, it's all over. 341 00:34:21,287 --> 00:34:25,565 The migratory birds leave to continue their journey north. 342 00:34:33,087 --> 00:34:37,080 They will not come back until the herring also return next year. 343 00:34:43,287 --> 00:34:45,517 As the herring spawning finishes, 344 00:34:45,687 --> 00:34:48,884 other migrants are starting to arrive offshore. 345 00:34:51,287 --> 00:34:53,084 Grey whales. 346 00:34:57,807 --> 00:34:59,957 They have followed the sun north, 347 00:35:00,127 --> 00:35:02,357 and they too are seeking the food 348 00:35:02,527 --> 00:35:05,519 generated by the bloom of the phytoplankton. 349 00:35:08,207 --> 00:35:12,519 Krill are feeding off it, and these whales are feeding on the krill, 350 00:35:12,687 --> 00:35:16,600 skimming it from the surface with the filter plates of baleen 351 00:35:16,767 --> 00:35:18,837 that hang from their upper jaws. 352 00:35:20,287 --> 00:35:23,279 Grey whales make one of the longest migrations 353 00:35:23,447 --> 00:35:25,403 of any marine mammal - 354 00:35:25,567 --> 00:35:28,127 a round trip of 12,000 miles or so 355 00:35:28,287 --> 00:35:31,279 from their breeding grounds off Mexico 356 00:35:31,447 --> 00:35:35,599 along the entire coast of North America up to the Arctic 0cean. 357 00:35:38,327 --> 00:35:40,318 They travel close to the coast, 358 00:35:40,487 --> 00:35:44,162 with the males and non-breeding females leading the way. 359 00:35:44,327 --> 00:35:48,923 The last to start are cows that have just given birth. 360 00:35:49,087 --> 00:35:53,080 They have to wait until their calves are sufficiently strong 361 00:35:53,247 --> 00:35:55,283 to tackle such an immense journey. 362 00:35:56,487 --> 00:35:59,285 Their progress is necessarily slow. 363 00:35:59,447 --> 00:36:01,517 The mothers stay with their young, 364 00:36:01,687 --> 00:36:05,157 and even a strong calf only travels at a couple of knots. 365 00:36:06,967 --> 00:36:09,276 They stick even closer to the shore, 366 00:36:09,447 --> 00:36:11,438 often within just 200 metres. 367 00:36:15,287 --> 00:36:17,005 Killer whales. 368 00:36:17,167 --> 00:36:21,160 They have learnt that grey whales follow traditional routes. 369 00:36:21,327 --> 00:36:23,318 The killers have no trouble 370 00:36:23,487 --> 00:36:27,082 in overtaking the calf and its devoted mother. 371 00:36:30,967 --> 00:36:34,118 Normally, they continually call to one another, 372 00:36:34,287 --> 00:36:36,562 but now they have fallen silent. 373 00:36:36,727 --> 00:36:38,718 The grey whale and her calf 374 00:36:38,887 --> 00:36:41,879 have no idea that they've been targeted. 375 00:37:01,847 --> 00:37:06,318 Catching up with the grey whales is the easy part for the killers. 376 00:37:06,487 --> 00:37:08,079 They have to be cautious 377 00:37:08,247 --> 00:37:11,444 for they are only about half the size of the mother. 378 00:37:14,927 --> 00:37:18,124 She can inflict real damage with her tail. 379 00:37:27,327 --> 00:37:29,557 But the killers are after her calf. 380 00:37:29,727 --> 00:37:33,606 As long as the mother can keep it on the move, it will be safe, 381 00:37:33,767 --> 00:37:36,884 and she does her best to hurry it along. 382 00:37:39,287 --> 00:37:44,122 At first, the killers avoid getting too close but just stay alongside. 383 00:37:44,287 --> 00:37:49,077 They know that the calf, going at this speed, will eventually tire. 384 00:37:59,087 --> 00:38:01,282 After three hours of being harried, 385 00:38:01,447 --> 00:38:04,757 the calf becomes too exhausted to swim any further. 386 00:38:04,927 --> 00:38:06,918 The mother has to stop. 387 00:38:07,087 --> 00:38:10,477 This is the moment the killers have been waiting for. 388 00:38:10,887 --> 00:38:14,960 They start to try and force themselves between mother and calf. 389 00:38:35,727 --> 00:38:39,959 A calf separated from its mother will not be able to defend itself. 390 00:38:40,127 --> 00:38:43,119 Time and again, the black fins of the killers 391 00:38:43,287 --> 00:38:45,482 appear between the grey whales. 392 00:38:56,487 --> 00:38:58,478 At last the killers succeed, 393 00:38:58,647 --> 00:39:01,639 and now they've got the calf on its own, 394 00:39:01,807 --> 00:39:03,798 they change their tactics. 395 00:39:03,967 --> 00:39:07,357 They leap right onto the calf, and try to push it under. 396 00:39:18,287 --> 00:39:20,278 They are trying to drown it. 397 00:39:30,447 --> 00:39:33,439 The calf snatches a desperate breath. 398 00:39:46,007 --> 00:39:48,999 The mother becomes increasingly agitated. 399 00:39:49,167 --> 00:39:52,921 Frantically, she tries to push her calf back to the surface 400 00:39:53,087 --> 00:39:55,078 so that it can breathe. 401 00:39:57,407 --> 00:39:59,318 But now it's so exhausted 402 00:39:59,487 --> 00:40:02,559 that it has to be supported by its mother's body. 403 00:40:19,407 --> 00:40:21,398 The killers won't give up. 404 00:40:21,567 --> 00:40:25,560 Like a pack of wolves, they take turns in harassing the whales. 405 00:40:46,287 --> 00:40:48,847 Now, the whole pod is involved. 406 00:40:59,007 --> 00:41:01,646 0ne of them takes a bite. 407 00:41:14,447 --> 00:41:17,723 Soon, the sea is reddened with the calf's blood, 408 00:41:17,887 --> 00:41:20,879 and the killers close in for the final act. 409 00:41:42,207 --> 00:41:44,004 The calf is dead. 410 00:41:48,287 --> 00:41:50,278 After a six-hour hunt, 411 00:41:50,447 --> 00:41:53,644 the killer whales have finally won their prize. 412 00:41:59,087 --> 00:42:01,078 The mother, bereft, 413 00:42:01,247 --> 00:42:04,284 has to continue her migration north on her own. 414 00:42:08,687 --> 00:42:11,679 She leaves behind the carcass of a calf 415 00:42:11,847 --> 00:42:15,476 that she cherished for 13 months in her womb, 416 00:42:15,647 --> 00:42:19,037 for which she delayed her own journey to find food. 417 00:42:21,967 --> 00:42:26,119 The 15 killer whales spent over six hours trying to kill the calf, 418 00:42:26,287 --> 00:42:28,403 but having succeeded, 419 00:42:28,567 --> 00:42:33,322 they've eaten nothing more than its lower jaw and its tongue. 420 00:42:41,287 --> 00:42:45,360 Valuable food like this will not go to waste in the ocean. 421 00:42:45,527 --> 00:42:48,917 Before long, the carcass will sink to the very bottom 422 00:42:49,087 --> 00:42:50,759 of this deep sea, 423 00:42:50,927 --> 00:42:53,919 but even there its flesh will not be wasted. 424 00:42:56,727 --> 00:43:00,561 0ver a mile down, in the total darkness of the deep ocean, 425 00:43:00,727 --> 00:43:02,922 the body of another grey whale, 426 00:43:03,087 --> 00:43:04,566 a 30-tonne adult. 427 00:43:04,727 --> 00:43:07,764 it settled here only a few weeks ago. 428 00:43:09,927 --> 00:43:13,124 Already, it has attracted hundreds of hagfish. 429 00:43:19,207 --> 00:43:23,359 These scavengers, over half a metre long and as thick as your arm, 430 00:43:23,527 --> 00:43:26,041 are only found in the deep sea. 431 00:43:26,207 --> 00:43:29,643 They have been attracted by the faint whiff of decay 432 00:43:29,807 --> 00:43:33,004 suffusing through the water for miles around. 433 00:43:36,287 --> 00:43:39,404 With their heads buried in the whale's flesh, 434 00:43:39,567 --> 00:43:43,242 they breathe through gill openings along their sides. 435 00:43:43,407 --> 00:43:45,716 They're very primitive creatures - 436 00:43:45,887 --> 00:43:48,879 not even true fish for they lack jaws. 437 00:43:49,047 --> 00:43:51,038 They feed, not by biting, 438 00:43:51,207 --> 00:43:54,802 but by rasping off flesh with two rows of horny teeth. 439 00:43:56,647 --> 00:43:58,558 in just a few hours, 440 00:43:58,727 --> 00:44:02,800 a hagfish can eat several times its own weight of rotting flesh. 441 00:44:05,887 --> 00:44:07,878 Next to arrive, 442 00:44:08,047 --> 00:44:10,038 a sleeper shark. 443 00:44:16,207 --> 00:44:19,404 it moves so slowly to conserve energy - 444 00:44:19,567 --> 00:44:22,718 an important strategy for so large an animal 445 00:44:22,887 --> 00:44:25,037 surviving in such a poor habitat. 446 00:44:31,527 --> 00:44:34,325 Sleeper sharks live over a mile down, 447 00:44:34,487 --> 00:44:36,842 and grow to over seven metres long. 448 00:44:39,607 --> 00:44:43,441 They can go for months without food, slowly cruising along, 449 00:44:43,607 --> 00:44:45,518 waiting for rare bonanzas 450 00:44:45,687 --> 00:44:47,484 such as this one 451 00:44:47,647 --> 00:44:49,444 to arrive from above. 452 00:44:56,087 --> 00:44:59,284 A whole range of different deep-sea scavengers 453 00:44:59,447 --> 00:45:02,439 will feast on this carcass for a long time 454 00:45:02,607 --> 00:45:05,804 before all its nutriment has been consumed. 455 00:45:07,087 --> 00:45:08,679 18 months later, 456 00:45:08,847 --> 00:45:12,999 all that is left is a perfect skeleton stripped bare. 457 00:45:15,687 --> 00:45:19,839 The sun's energy, that was captured and turned into living tissue 458 00:45:20,007 --> 00:45:21,998 by the floating phytoplankton, 459 00:45:22,167 --> 00:45:25,716 has been transferred to another link in the food chain, 460 00:45:25,887 --> 00:45:29,800 and has ended up as far away from the sun as it is possible to be - 461 00:45:29,967 --> 00:45:31,958 at the bottom of the deep sea. 462 00:45:32,127 --> 00:45:36,040 But some energy also returns from the deep. 463 00:45:42,087 --> 00:45:46,239 Millions of opalescent squid are on their way to the shallows. 464 00:45:46,407 --> 00:45:48,841 They've come up here to mate. 465 00:45:49,007 --> 00:45:53,205 As the males grab the females, their tentacles flush red. 466 00:45:55,687 --> 00:45:57,325 For most of the year, 467 00:45:57,487 --> 00:46:00,604 these squid live at a depth of around 500 metres. 468 00:46:00,767 --> 00:46:04,476 They are part of these breeding schools for a few weeks. 469 00:46:04,647 --> 00:46:07,844 just one school was estimated to contain animals 470 00:46:08,007 --> 00:46:10,316 that weigh around 4,000 tonnes. 471 00:46:21,127 --> 00:46:24,244 Wave after wave rise from the depths, 472 00:46:24,407 --> 00:46:26,637 and soon the seabed in the shallows 473 00:46:26,807 --> 00:46:31,198 is strewn with dense patches of egg capsules several metres across. 474 00:46:36,527 --> 00:46:39,599 As each female adds another capsule to the pile, 475 00:46:39,767 --> 00:46:42,964 the males fight to fertilise its contents. 476 00:46:58,287 --> 00:47:01,438 The squid make their huge journey into the shallows 477 00:47:01,607 --> 00:47:05,839 because their eggs will develop faster in the warmer water here, 478 00:47:06,007 --> 00:47:09,238 and when the young emerge, they will find more food 479 00:47:09,407 --> 00:47:12,604 more easily than they would in the ocean depths. 480 00:47:16,687 --> 00:47:18,678 Dawn the next morning, 481 00:47:18,847 --> 00:47:22,635 and the seabed for miles around is covered in egg capsules. 482 00:47:22,807 --> 00:47:26,083 The squid have all gone. Many have died, 483 00:47:26,247 --> 00:47:29,637 but some will have returned to their home in the deep. 484 00:47:29,807 --> 00:47:32,799 They will not return to the light of the sun 485 00:47:32,967 --> 00:47:36,926 until the next time they are driven up by the urge to spawn.