1 00:00:34,000 --> 00:00:37,471 Dwarfed by the vast expanse of the open ocean, 2 00:00:37,640 --> 00:00:41,190 the biggest animal that has ever lived on our planet. 3 00:00:48,000 --> 00:00:52,791 A blue whale, 30 metres long and weighing over 200 tonnes. 4 00:00:52,960 --> 00:00:56,510 It's far bigger than even the biggest dinosaur. 5 00:00:58,160 --> 00:01:01,312 Its tongue weighs as much as an elephant. 6 00:01:01,480 --> 00:01:03,472 Its heart is the size of a car, 7 00:01:03,640 --> 00:01:06,838 and some of its blood vessels are so wide 8 00:01:07,000 --> 00:01:08,992 that you could swim down them. 9 00:01:10,600 --> 00:01:12,319 Its tail alone 10 00:01:12,480 --> 00:01:15,791 is the width of a small aircraft's wings. 11 00:01:33,040 --> 00:01:36,272 Its streamlining, close to perfection, 12 00:01:36,440 --> 00:01:38,557 enables it to cruise at 20 knots. 13 00:01:38,720 --> 00:01:41,918 It's one of the fastest animals in the sea. 14 00:01:45,960 --> 00:01:48,156 The ocean's largest inhabitant 15 00:01:48,320 --> 00:01:51,711 feeds almost exclusively on one of the smallest — 16 00:01:51,880 --> 00:01:55,317 krill, a crustacean just a few centimetres long. 17 00:01:59,000 --> 00:02:00,912 Gathered in a shoal, 18 00:02:01,160 --> 00:02:03,152 krill stain the sea red, 19 00:02:03,320 --> 00:02:07,314 and a single blue whale in a day can consume 40 million of them. 20 00:02:15,960 --> 00:02:18,953 Despite the enormous size of blue whales, 21 00:02:19,120 --> 00:02:21,112 we know very little about them. 22 00:02:21,280 --> 00:02:24,273 Their migration routes are still a mystery, 23 00:02:24,440 --> 00:02:27,558 and we have absolutely no idea where they go to breed. 24 00:02:31,240 --> 00:02:33,232 They are a dramatic reminder 25 00:02:33,400 --> 00:02:35,392 of how much we still have to learn 26 00:02:35,560 --> 00:02:38,951 about the ocean and the creatures that live there. 27 00:02:42,080 --> 00:02:44,276 Our planet is a blue planet. 28 00:02:44,440 --> 00:02:47,672 Over 70 per cent of it is covered by the sea. 29 00:02:50,000 --> 00:02:53,516 The Pacific Ocean alone covers half the globe. 30 00:02:53,680 --> 00:02:56,878 You can fly across it non—stop for 12 hours 31 00:02:57,040 --> 00:03:00,192 and still see nothing more than a speck of land. 32 00:03:01,400 --> 00:03:02,993 This series will reveal 33 00:03:03,160 --> 00:03:06,358 the complete natural history of our ocean planet 34 00:03:06,520 --> 00:03:10,753 from its familiar shores to the mysteries of its deepest seas. 35 00:03:22,000 --> 00:03:23,992 By volume, the ocean makes up 36 00:03:24,160 --> 00:03:27,232 97 per cent of the earth's inhabitable space, 37 00:03:27,400 --> 00:03:30,040 and the sheer quantity of its marine life 38 00:03:30,200 --> 00:03:32,874 far exceeds that which inhabits the land. 39 00:03:55,240 --> 00:03:59,598 But life in the ocean is not evenly spread. It's regulated 40 00:03:59,760 --> 00:04:02,753 by the path of currents carrying nutrients, 41 00:04:02,920 --> 00:04:04,991 and the varying power of the sun. 42 00:04:05,920 --> 00:04:10,870 In this first programme, we will see how these two forces interact 43 00:04:11,040 --> 00:04:13,032 to control the distribution of life 44 00:04:13,200 --> 00:04:16,591 from the coral seas to the polar wastes. 45 00:05:11,040 --> 00:05:13,999 The sheer physical power of the ocean 46 00:05:14,160 --> 00:05:15,958 dominates our planet. 47 00:05:31,760 --> 00:05:35,390 It profoundly influences the weather of all the world. 48 00:05:35,560 --> 00:05:40,191 Water vapour rising from it forms the clouds and generates the storms 49 00:05:40,360 --> 00:05:42,829 that ultimately will drench the land. 50 00:06:02,000 --> 00:06:04,993 The great waves that roar in towards the shores 51 00:06:05,160 --> 00:06:08,153 are dramatic demonstrations of its power. 52 00:06:22,960 --> 00:06:25,680 Waves originate far out at sea. 53 00:06:25,840 --> 00:06:29,277 There, even gentle breezes can cause ripples, 54 00:06:29,440 --> 00:06:31,716 and ripples grow into swells. 55 00:06:41,640 --> 00:06:44,235 Out in the open ocean, unimpeded by land, 56 00:06:44,400 --> 00:06:47,120 such swells can become gigantic. 57 00:07:09,200 --> 00:07:13,194 It's only when an ocean swell eventually reaches shallow water 58 00:07:13,360 --> 00:07:15,352 that it starts to break. 59 00:07:22,360 --> 00:07:26,354 As it approaches the coast, the water at the bottom of the swell 60 00:07:26,520 --> 00:07:29,080 is slowed by contact with the seabed. 61 00:07:29,240 --> 00:07:32,233 The top of the swell, still travelling fast, 62 00:07:32,400 --> 00:07:35,199 starts to roll over and so the wave breaks. 63 00:08:07,000 --> 00:08:10,914 The ocean never rests. Huge currents, such as the Gulf Stream, 64 00:08:11,080 --> 00:08:14,835 keep its waters constantly on the move all round the globe. 65 00:08:15,000 --> 00:08:17,993 It's these currents more than any other factor 66 00:08:18,160 --> 00:08:22,313 that control the distribution of nutrients and life in the seas. 67 00:08:24,800 --> 00:08:28,316 A tiny island lost in the midst of the Pacific. 68 00:08:28,480 --> 00:08:30,472 It's the tip of a huge mountain 69 00:08:30,640 --> 00:08:34,316 that rises from the sea floor thousands of metres below. 70 00:08:39,560 --> 00:08:42,758 The nearest land is 300 miles away. 71 00:08:46,800 --> 00:08:49,474 Isolated sea mounts like this one 72 00:08:49,640 --> 00:08:52,280 create oases where life can flourish 73 00:08:52,440 --> 00:08:55,990 in the comparatively empty expanses of the open ocean. 74 00:09:04,600 --> 00:09:08,389 But all the creatures that swim beside it would not be here 75 00:09:08,560 --> 00:09:10,711 were it not for one key factor — 76 00:09:11,880 --> 00:09:13,678 the deep ocean currents. 77 00:09:18,800 --> 00:09:22,794 Far below the surface, they collide with the island's flanks 78 00:09:22,960 --> 00:09:25,111 and are deflected upwards, 79 00:09:25,280 --> 00:09:29,240 bringing with them from the depths a rich soup of nutrients. 80 00:09:31,000 --> 00:09:35,313 Such up—wellings attract great concentrations of life. 81 00:09:43,240 --> 00:09:46,233 Most of the fish here are permanent residents 82 00:09:46,400 --> 00:09:50,189 feeding on plankton — tiny floating plants and animals 83 00:09:50,360 --> 00:09:53,831 nourished by the richness brought up from the depths, 84 00:09:54,000 --> 00:09:56,879 and they attract visitors from the open ocean. 85 00:09:58,160 --> 00:09:59,480 Tuna. 86 00:10:25,320 --> 00:10:28,313 The plankton feeders are easy targets. 87 00:10:39,000 --> 00:10:42,676 All this action attracts even larger predators. 88 00:10:45,440 --> 00:10:46,794 Sharks. 89 00:10:51,400 --> 00:10:53,198 Hundreds of sharks. 90 00:10:55,680 --> 00:10:59,356 These silky sharks are normally ocean—going species, 91 00:10:59,520 --> 00:11:02,319 but the sea mounts in the eastern Pacific 92 00:11:02,480 --> 00:11:04,915 like Cocos, Mapelo and the Galapagos, 93 00:11:05,080 --> 00:11:09,233 attract silkies in huge groups up to 500 strong. 94 00:11:13,240 --> 00:11:16,597 Silkies seem to specialise in taking injured fish 95 00:11:16,760 --> 00:11:18,911 and constantly circle sea mounts 96 00:11:19,080 --> 00:11:21,800 on the look out for the chance to do so. 97 00:11:26,720 --> 00:11:29,189 But silkies are not the only visitors. 98 00:11:33,000 --> 00:11:37,040 Hammerheads gather in some of the largest shark shoals 99 00:11:37,200 --> 00:11:39,351 to be found anywhere in the ocean. 100 00:11:39,520 --> 00:11:43,355 Sometimes, thousands will circle over a single sea mount. 101 00:11:48,160 --> 00:11:50,800 But these sharks are not here for food. 102 00:11:50,960 --> 00:11:53,111 They have come for another reason. 103 00:11:56,000 --> 00:12:00,040 Some of the locals provide a cleaning service. 104 00:12:03,400 --> 00:12:05,676 Following the last El Niño year, 105 00:12:05,840 --> 00:12:10,392 when a rise in water temperatures gave many sharks fungal infections, 106 00:12:10,560 --> 00:12:13,598 the number of hammerheads visiting the sea mounts 107 00:12:13,760 --> 00:12:15,558 reached record levels. 108 00:12:26,000 --> 00:12:28,754 Nutrients also well up to the surface 109 00:12:28,920 --> 00:12:31,230 along the coasts of the continents. 110 00:12:32,800 --> 00:12:36,635 This is Natal on South Africa's eastern seaboard. 111 00:12:36,800 --> 00:12:38,280 It's June, 112 00:12:38,440 --> 00:12:42,116 and just off—shore, strange black patches have appeared. 113 00:12:45,640 --> 00:12:49,077 They look like immense oil slicks up to a mile long. 114 00:12:51,360 --> 00:12:53,795 But this is a living slick: 115 00:12:53,960 --> 00:12:58,113 millions and millions of sardines on a marine migration 116 00:12:58,280 --> 00:13:00,272 that in terms of sheer biomass, 117 00:13:00,440 --> 00:13:04,195 rivals that of the wildebeest on the grasslands of Africa. 118 00:13:07,680 --> 00:13:11,469 These fish live mostly in the cold waters south of the Cape, 119 00:13:11,640 --> 00:13:14,712 but each year the coastal currents reverse. 120 00:13:14,880 --> 00:13:18,840 The warm Agulhas current that flows down from the north 121 00:13:19,000 --> 00:13:22,072 has been displaced by cold water from the south, 122 00:13:22,240 --> 00:13:24,709 and that has brought up rich nutrients. 123 00:13:24,880 --> 00:13:28,191 They in turn have created a bloom of plankton, 124 00:13:29,000 --> 00:13:31,640 and the sardines are now feasting on it. 125 00:13:40,640 --> 00:13:42,632 As the sardines travel north, 126 00:13:42,800 --> 00:13:45,634 a whole caravan of predators follow them. 127 00:13:49,080 --> 00:13:52,118 Thousands of Cape gannets track the sardines. 128 00:13:52,280 --> 00:13:55,352 They nested off the Cape and timed their breeding 129 00:13:55,520 --> 00:13:57,796 so that their newly—fledged chicks 130 00:13:57,960 --> 00:14:00,429 can join them in pursuing the shoals. 131 00:14:07,000 --> 00:14:11,552 Below water, hundreds of sharks have also joined the caravan. 132 00:14:14,400 --> 00:14:17,234 These are bronze whaler sharks, 133 00:14:17,400 --> 00:14:21,314 a cold water species that normally lives much further south. 134 00:14:26,360 --> 00:14:28,636 These three—metre sharks 135 00:14:28,800 --> 00:14:32,032 cut such great swathes through the sardine shoals 136 00:14:32,200 --> 00:14:34,874 that their tracks are visible from the air. 137 00:14:35,040 --> 00:14:37,032 Harried by packs of predators 138 00:14:37,200 --> 00:14:40,193 and swept in by the action of the waves, 139 00:14:40,360 --> 00:14:43,512 the sardine shoals are penned close to the shore. 140 00:15:00,520 --> 00:15:05,515 Common dolphin are coming in from the open ocean to join the feast. 141 00:15:20,040 --> 00:15:22,032 There are over a thousand of them 142 00:15:22,200 --> 00:15:24,192 in this one school. 143 00:15:31,520 --> 00:15:36,356 When they catch up with the sardines, the action really begins. 144 00:15:40,400 --> 00:15:44,360 Working together, they drive the shoal towards the surface. 145 00:15:52,400 --> 00:15:56,519 It's easier for the dolphins to snatch fish up here. 146 00:16:10,480 --> 00:16:13,314 Now the sardines have no escape. 147 00:16:24,360 --> 00:16:26,352 Thanks to the dolphins, 148 00:16:26,520 --> 00:16:30,594 the sardines have come within the diving range of the gannets. 149 00:16:41,800 --> 00:16:44,599 Hundreds of white arrows shoot into the sea, 150 00:16:44,760 --> 00:16:48,231 leaving long trails of bubbles behind each dive. 151 00:17:00,440 --> 00:17:03,035 Next to join the frenzy are the sharks. 152 00:17:15,160 --> 00:17:18,790 Sharks get very excited when dolphins are around. 153 00:17:18,960 --> 00:17:21,031 They can feed particularly well 154 00:17:21,200 --> 00:17:23,954 once the dolphins have driven the sardines 155 00:17:24,120 --> 00:17:26,874 into more compact groups near the surface. 156 00:17:30,400 --> 00:17:34,189 As the frenzy continues, walls of bubbles drift upwards. 157 00:17:36,920 --> 00:17:39,480 They are being released by the dolphins 158 00:17:39,640 --> 00:17:41,632 working together in teams. 159 00:17:44,000 --> 00:17:45,719 They use the bubbles 160 00:17:45,880 --> 00:17:48,998 to corral the sardines into ever tighter groups. 161 00:17:52,320 --> 00:17:55,233 The sardines seldom cross the wall of bubbles 162 00:17:55,400 --> 00:17:57,392 and crowd closer together. 163 00:18:00,760 --> 00:18:02,558 Bubble netting in this way, 164 00:18:02,720 --> 00:18:06,760 enables the dolphins to grab every last trapped sardine. 165 00:18:18,200 --> 00:18:21,193 Just when the feasting seems to be almost over, 166 00:18:21,360 --> 00:18:23,158 a Bryde's whale. 167 00:18:27,480 --> 00:18:29,790 The survivors head on northwards, 168 00:18:29,960 --> 00:18:32,759 and the caravan of predators follows them. 169 00:18:40,840 --> 00:18:44,550 Nutrients can also be brought up, though less predictably, 170 00:18:44,720 --> 00:18:46,712 by rough weather. 171 00:18:51,400 --> 00:18:55,030 Particularly near the poles, huge storms stir the depths 172 00:18:55,200 --> 00:18:57,510 and enrich the surface waters, 173 00:18:57,680 --> 00:18:59,672 and here, in the South Atlantic, 174 00:18:59,840 --> 00:19:02,480 the seas are the roughest on the planet. 175 00:19:06,040 --> 00:19:08,032 And very rich seas they are, too, 176 00:19:08,200 --> 00:19:11,511 for here, the cold Falklands current from the south 177 00:19:11,680 --> 00:19:14,593 meets the warm Brazil current from the north, 178 00:19:14,760 --> 00:19:17,434 and at their junction is food in abundance. 179 00:19:19,200 --> 00:19:22,830 These black—browed albatross are duck—diving for krill 180 00:19:23,000 --> 00:19:25,674 that has been driven up to the surface. 181 00:19:28,760 --> 00:19:30,558 Like all albatross, 182 00:19:30,720 --> 00:19:34,634 black—brows are wanderers across the face of the open ocean. 183 00:19:49,640 --> 00:19:52,838 A feeding assembly on this scale is a rare sight. 184 00:19:53,000 --> 00:19:57,074 Most of the time, the birds of the open sea are widely dispersed, 185 00:19:57,240 --> 00:20:01,712 but these feeding grounds are close to an albatross breeding colony, 186 00:20:01,880 --> 00:20:03,712 and a very special one. 187 00:20:12,800 --> 00:20:14,792 This is Steeple Jason, 188 00:20:14,960 --> 00:20:18,032 a remote island in the far west of the Falklands. 189 00:20:18,200 --> 00:20:21,272 It has the largest albatross colony in the world. 190 00:20:29,800 --> 00:20:32,918 There are almost half a million albatross here, 191 00:20:33,080 --> 00:20:37,074 an astonishing demonstration of how fertile the ocean can be 192 00:20:37,240 --> 00:20:39,232 and how much food it can give 193 00:20:39,400 --> 00:20:42,552 even to creatures that do not actually live in it. 194 00:21:08,080 --> 00:21:10,072 Nutrients by themselves 195 00:21:10,240 --> 00:21:13,472 are not enough to generate these vast assemblies. 196 00:21:13,640 --> 00:21:16,712 The heat and light from the sun is also essential 197 00:21:16,880 --> 00:21:20,191 for the growth of the microscopic floating plants — 198 00:21:20,360 --> 00:21:22,511 the phytoplankton. 199 00:21:26,240 --> 00:21:30,996 And it's the phytoplankton that is the basis of all life in the ocean. 200 00:21:37,400 --> 00:21:41,394 Every evening, the disappearance of the sun below the horizon 201 00:21:41,560 --> 00:21:44,359 triggers the largest migration of life 202 00:21:44,520 --> 00:21:46,512 that takes place on our planet. 203 00:21:53,680 --> 00:21:56,991 One thousand million tonnes of sea creatures 204 00:21:57,160 --> 00:22:01,154 ascend from the deep ocean to search for food near the surface. 205 00:22:08,120 --> 00:22:12,114 They graze on the phytoplankton under cover of darkness. 206 00:22:12,280 --> 00:22:14,875 Even so, they are far from safe. 207 00:22:15,040 --> 00:22:17,271 Other marine hunters follow them, 208 00:22:17,440 --> 00:22:20,672 some travelling up from hundreds of metres below. 209 00:23:19,520 --> 00:23:21,034 At dawn, 210 00:23:21,200 --> 00:23:25,240 the whole procession returns to the safety of the dark depths. 211 00:23:31,400 --> 00:23:36,031 The moon, too, has a great influence on life in the oceans. 212 00:23:37,400 --> 00:23:39,596 Its gravitational pull 213 00:23:39,760 --> 00:23:43,197 creates the daily advances and retreats of the tide. 214 00:23:54,880 --> 00:23:57,873 But the moon has more than a daily cycle. 215 00:23:58,040 --> 00:24:02,273 Each month, it waxes and wanes as it travels round the earth, 216 00:24:02,440 --> 00:24:06,275 and this monthly cycle also triggers events in the ocean. 217 00:24:09,520 --> 00:24:12,035 The Pacific coast of Costa Rica 218 00:24:12,200 --> 00:24:14,192 on a very special night. 219 00:24:14,360 --> 00:24:18,559 It's just after midnight and the tide is coming in. 220 00:24:22,760 --> 00:24:25,275 The moon is in its last quarter, 221 00:24:25,440 --> 00:24:28,512 exactly half way between full and new. 222 00:24:30,920 --> 00:24:33,594 For weeks, the beach has been empty, 223 00:24:33,760 --> 00:24:35,752 but that is about to change. 224 00:24:35,920 --> 00:24:39,994 At high tide, turtles start to emerge from the surf. 225 00:24:45,200 --> 00:24:48,193 At first, they come in ones and twos, 226 00:24:48,360 --> 00:24:50,272 but within an hour, 227 00:24:50,440 --> 00:24:53,433 they are appearing all along the beach. 228 00:24:58,720 --> 00:25:01,679 They are all female Ridley's turtles, 229 00:25:01,840 --> 00:25:03,832 and over the next six days or so, 230 00:25:04,000 --> 00:25:07,357 400,000 willvisit this one beach 231 00:25:07,520 --> 00:25:09,512 to lay their eggs in the sand. 232 00:25:17,360 --> 00:25:21,877 At the peak time, 5,000 are coming and going every hour. 233 00:25:22,040 --> 00:25:24,794 The top of the beach gets so crowded 234 00:25:24,960 --> 00:25:28,556 that they have to clamber over one another to find a patch 235 00:25:28,720 --> 00:25:30,712 where they can dig a nest hole. 236 00:25:35,800 --> 00:25:39,476 A quarter of the world's population of Ridley's turtles 237 00:25:39,640 --> 00:25:43,190 come to this one beach on a few key nights each year. 238 00:25:43,360 --> 00:25:45,352 The rest of the time, 239 00:25:45,520 --> 00:25:48,592 they are widely distributed through the ocean, 240 00:25:49,200 --> 00:25:51,192 most, hundreds of miles away. 241 00:25:51,360 --> 00:25:56,037 This mass nesting is called an arribada. How it's co—ordinated 242 00:25:56,200 --> 00:25:58,192 is a mystery, 243 00:25:58,360 --> 00:26:00,591 but we do know that arribadas start 244 00:26:00,760 --> 00:26:04,151 when the moon is either in its first or last quarter. 245 00:26:11,520 --> 00:26:15,434 Forty million eggs are laid in just a few days. 246 00:26:15,600 --> 00:26:19,230 By synchronising their nesting, the females ensure 247 00:26:19,400 --> 00:26:22,598 that six weeks later, their hatchlings will emerge 248 00:26:22,760 --> 00:26:24,752 in such enormous numbers 249 00:26:24,920 --> 00:26:27,310 that predators are overwhelmed, 250 00:26:27,480 --> 00:26:32,396 and a significant proportion of baby turtles will make it to the water. 251 00:26:34,600 --> 00:26:38,150 But why do the females use a cue from the moon 252 00:26:38,320 --> 00:26:40,630 to help synchronise their nesting? 253 00:26:40,800 --> 00:26:42,792 Part of the answer to that 254 00:26:42,960 --> 00:26:46,158 becomes clear at dawn on the following morning. 255 00:27:06,720 --> 00:27:11,033 The day shift of predators are arriving for their first meals. 256 00:27:16,200 --> 00:27:18,192 Vultures have learnt 257 00:27:18,360 --> 00:27:22,593 that the returning tide can wash freshly laid eggs out of the sand. 258 00:27:25,000 --> 00:27:28,038 The risk of eggs being exposed by the surf 259 00:27:28,200 --> 00:27:31,272 may be partly why turtle arribadas tend to occur 260 00:27:31,440 --> 00:27:34,433 around the last or first quarter of the moon. 261 00:27:38,000 --> 00:27:42,756 It's on such days as this when the moon is neither full nor new, 262 00:27:42,920 --> 00:27:46,755 that the tides are weakest and the sea is likely to be calmer. 263 00:28:01,400 --> 00:28:06,350 So it's easier for the female turtles to make their way through the surf, 264 00:28:06,520 --> 00:28:09,513 and harder for eggs to be washed out of the sand 265 00:28:09,680 --> 00:28:11,512 and taken by vultures. 266 00:28:23,040 --> 00:28:27,034 The moon's monthly cycle and its influence on the tides 267 00:28:27,200 --> 00:28:29,431 triggers many events in the ocean, 268 00:28:29,600 --> 00:28:33,196 from the spawning of the corals on the Great Barrier reef 269 00:28:33,360 --> 00:28:35,352 to the breeding cycles of fish, 270 00:28:35,520 --> 00:28:37,671 but there's an even longer rhythm 271 00:28:37,840 --> 00:28:40,435 that has the most profound effect of all— 272 00:28:40,600 --> 00:28:42,592 the annual cycle of the sun. 273 00:28:44,720 --> 00:28:47,315 The sun's position relative to the earth 274 00:28:47,480 --> 00:28:49,472 changes through the year, 275 00:28:49,640 --> 00:28:52,235 and it's this that produces the seasons. 276 00:28:52,400 --> 00:28:54,198 In the north, spring comes 277 00:28:54,360 --> 00:28:57,194 as the sun begins to rise higher in the sky. 278 00:28:58,000 --> 00:29:00,435 Off the coast of north west America, 279 00:29:00,600 --> 00:29:04,879 the seas are transformed by the increasing strength of the sun. 280 00:29:09,800 --> 00:29:13,157 Here in Alaska, the coastal waters turn green 281 00:29:13,320 --> 00:29:15,789 with a sudden bloom of phytoplankton. 282 00:29:18,800 --> 00:29:21,872 Herring that have spent the winter far out to sea 283 00:29:22,040 --> 00:29:26,592 time their return to the shallow waters to coincide with this bloom. 284 00:29:26,760 --> 00:29:28,797 They come in vast numbers 285 00:29:28,960 --> 00:29:33,079 and initiate one of the most productive food chains in all the oceans. 286 00:29:48,000 --> 00:29:51,550 Humpback whales are at the top of that food chain. 287 00:29:51,720 --> 00:29:53,712 They have spent the winter 288 00:29:53,880 --> 00:29:57,191 breeding in the warmer tropical waters off Hawaii, 289 00:29:57,360 --> 00:29:59,352 but there was little food there. 290 00:29:59,520 --> 00:30:01,512 This herring bonanza 291 00:30:01,680 --> 00:30:04,957 provides the majority of their food for the year. 292 00:30:24,800 --> 00:30:27,190 Stellar and Californian sea lions 293 00:30:27,360 --> 00:30:31,877 also return from the open ocean each year to feast off the herring. 294 00:30:42,240 --> 00:30:45,995 The herring, however, have not come here for food. 295 00:30:46,160 --> 00:30:49,198 They are about to breed. Nothing deters them 296 00:30:49,360 --> 00:30:52,512 as they head for even shallower waters. 297 00:30:54,160 --> 00:30:56,152 Now the waters are so shallow 298 00:30:56,320 --> 00:30:58,198 that glaucous—winged gulls 299 00:30:58,360 --> 00:31:01,398 can snatch live fish from just below the surface. 300 00:31:13,000 --> 00:31:15,799 In spite of these attacks, the herring swim on 301 00:31:15,960 --> 00:31:18,077 until they reach the vegetation 302 00:31:18,240 --> 00:31:20,880 that the females need if they are to lay. 303 00:31:27,000 --> 00:31:30,152 Each female produces around 20,000 eggs, 304 00:31:30,320 --> 00:31:32,630 and they're very sticky. 305 00:31:36,520 --> 00:31:40,594 After the females have spawned, the males release their sperm 306 00:31:40,760 --> 00:31:42,752 in vast, milky clouds. 307 00:31:47,680 --> 00:31:51,720 Soon, the excesses of the herrings' sexual spree 308 00:31:51,880 --> 00:31:55,351 creates a thick white scum on the surface. 309 00:31:56,760 --> 00:31:58,752 Through the season, 310 00:31:58,920 --> 00:32:02,311 curds of sperm clog the shores for hundreds of miles 311 00:32:02,480 --> 00:32:06,156 from British Columbia in the south to Alaska in the north. 312 00:32:12,320 --> 00:32:16,599 After a few days, this gigantic spawning comes to an end, 313 00:32:16,760 --> 00:32:19,753 and the herring head back out to deeper waters, 314 00:32:19,920 --> 00:32:22,310 leaving behind them fertilised eggs 315 00:32:22,480 --> 00:32:25,712 plastered on every rock and strand of vegetation. 316 00:32:36,320 --> 00:32:41,520 They time the spawning so that two weeks later, when the eggs hatch, 317 00:32:41,680 --> 00:32:45,799 the annual plankton bloom will be at its height, and the fish fry 318 00:32:45,960 --> 00:32:47,952 will have plenty to eat. 319 00:32:48,120 --> 00:32:50,430 In the meantime, these eggs provide food 320 00:32:50,600 --> 00:32:53,911 for armies of different animals below and above the surface. 321 00:33:01,840 --> 00:33:06,232 Millions of birds arrive to collect a share of the herrings' bounty. 322 00:33:06,400 --> 00:33:08,392 Some of it is easily gathered, 323 00:33:08,560 --> 00:33:12,110 for millions of eggs have been washed up onto the shore. 324 00:33:13,000 --> 00:33:14,992 This encapsulated energy 325 00:33:15,160 --> 00:33:18,790 is particularly valuable to migrating birds. 326 00:33:18,960 --> 00:33:21,031 These surfbirds are on their way 327 00:33:21,200 --> 00:33:25,672 to their breeding grounds in the Arctic and come down to refuel. 328 00:33:25,840 --> 00:33:28,912 Stranded herring eggs are just what they need. 329 00:33:30,960 --> 00:33:32,997 Bonaparte gulls collect the eggs 330 00:33:33,160 --> 00:33:35,356 just below the surface of the water. 331 00:33:38,080 --> 00:33:41,869 Further out in the bay, huge flocks of ducks have gathered. 332 00:33:42,040 --> 00:33:43,997 They're mostly surf scoters — 333 00:33:44,160 --> 00:33:48,154 diving ducks that can feed off the bottom several metres down. 334 00:33:52,000 --> 00:33:54,993 There are such huge quantities of eggs, 335 00:33:55,160 --> 00:33:57,152 that even a big animal like a bear 336 00:33:57,320 --> 00:33:59,676 finds it worthwhile to collect them. 337 00:34:03,000 --> 00:34:06,311 The spawning of the herring is a crucial event 338 00:34:06,480 --> 00:34:09,552 in the lives of many animals all along the coast. 339 00:34:09,720 --> 00:34:13,031 The whole event coincides with the plankton bloom, 340 00:34:13,200 --> 00:34:15,954 and within three short weeks, it's all over. 341 00:34:21,000 --> 00:34:25,279 The migratory birds leave to continue their journey north. 342 00:34:32,800 --> 00:34:36,794 They will not come back until the herring also return next year. 343 00:34:43,000 --> 00:34:45,231 As the herring spawning finishes, 344 00:34:45,400 --> 00:34:48,598 other migrants are starting to arrive offshore. 345 00:34:51,000 --> 00:34:52,798 Grey whales. 346 00:34:57,520 --> 00:34:59,671 They have followed the sun north, 347 00:34:59,840 --> 00:35:02,071 and they too are seeking the food 348 00:35:02,240 --> 00:35:05,233 generated by the bloom of the phytoplankton. 349 00:35:07,920 --> 00:35:12,233 Krill are feeding off it, and these whales are feeding on the krill, 350 00:35:12,400 --> 00:35:16,314 skimming it from the surface with the filter plates of baleen 351 00:35:16,480 --> 00:35:18,551 that hang from their upper jaws. 352 00:35:20,000 --> 00:35:22,993 Grey whales make one of the longest migrations 353 00:35:23,160 --> 00:35:25,117 of any marine mammal— 354 00:35:25,280 --> 00:35:27,840 a round trip of 12,000 miles or so 355 00:35:28,000 --> 00:35:30,993 from their breeding grounds off Mexico 356 00:35:31,160 --> 00:35:35,313 along the entire coast of North America up to the Arctic Ocean. 357 00:35:38,040 --> 00:35:40,032 They travel close to the coast, 358 00:35:40,200 --> 00:35:43,876 with the males and non—breeding females leading the way. 359 00:35:44,040 --> 00:35:48,637 The last to start are cows that have just given birth. 360 00:35:48,800 --> 00:35:52,794 They have to wait until their calves are sufficiently strong 361 00:35:52,960 --> 00:35:54,997 to tackle such an immense journey. 362 00:35:56,200 --> 00:35:58,999 Their progress is necessarily slow. 363 00:35:59,160 --> 00:36:01,231 The mothers stay with their young, 364 00:36:01,400 --> 00:36:04,871 and even a strong calf only travels at a couple of knots. 365 00:36:06,680 --> 00:36:08,990 They stick even closer to the shore, 366 00:36:09,160 --> 00:36:11,152 often within just 200 metres. 367 00:36:15,000 --> 00:36:16,719 Killer whales. 368 00:36:16,880 --> 00:36:20,874 They have learnt that grey whales follow traditional routes. 369 00:36:21,040 --> 00:36:23,032 The killers have no trouble 370 00:36:23,200 --> 00:36:26,796 in overtaking the calf and its devoted mother. 371 00:36:30,680 --> 00:36:33,832 Normally, they continually call to one another, 372 00:36:34,000 --> 00:36:36,276 but now they have fallen silent. 373 00:36:36,440 --> 00:36:38,432 The grey whale and her calf 374 00:36:38,600 --> 00:36:41,593 have no idea that they've been targeted. 375 00:37:01,560 --> 00:37:06,032 Catching up with the grey whales is the easy part for the killers. 376 00:37:06,200 --> 00:37:07,793 They have to be cautious 377 00:37:07,960 --> 00:37:11,158 for they are only about half the size of the mother. 378 00:37:14,640 --> 00:37:17,838 She can inflict real damage with her tail. 379 00:37:27,040 --> 00:37:29,271 But the killers are after her calf. 380 00:37:29,440 --> 00:37:33,320 As long as the mother can keep it on the move, it will be safe, 381 00:37:33,480 --> 00:37:36,598 and she does her best to hurry it along. 382 00:37:39,000 --> 00:37:43,836 At first, the killers avoid getting too close but just stay alongside. 383 00:37:44,000 --> 00:37:48,791 They know that the calf, going at this speed, will eventually tire. 384 00:37:58,800 --> 00:38:00,996 After three hours of being harried, 385 00:38:01,160 --> 00:38:04,471 the calf becomes too exhausted to swim any further. 386 00:38:04,640 --> 00:38:06,632 The mother has to stop. 387 00:38:06,800 --> 00:38:10,191 This is the moment the killers have been waiting for. 388 00:38:10,600 --> 00:38:14,674 They start to try and force themselves between mother and calf. 389 00:38:35,440 --> 00:38:39,673 A calf separated from its mother will not be able to defend itself. 390 00:38:39,840 --> 00:38:42,833 Time and again, the black fins of the killers 391 00:38:43,000 --> 00:38:45,196 appear between the grey whales. 392 00:38:56,200 --> 00:38:58,192 At last the killers succeed, 393 00:38:58,360 --> 00:39:01,353 and now they've got the calf on its own, 394 00:39:01,520 --> 00:39:03,512 they change their tactics. 395 00:39:03,680 --> 00:39:07,071 They leap right onto the calf, and try to push it under. 396 00:39:18,000 --> 00:39:19,992 They are trying to drown it. 397 00:39:30,160 --> 00:39:33,153 The calf snatches a desperate breath. 398 00:39:45,720 --> 00:39:48,713 The mother becomes increasingly agitated. 399 00:39:48,880 --> 00:39:52,635 Frantically, she tries to push her calf back to the surface 400 00:39:52,800 --> 00:39:54,792 so that it can breathe. 401 00:39:57,120 --> 00:39:59,032 But now it's so exhausted 402 00:39:59,200 --> 00:40:02,272 that it has to be supported by its mother's body. 403 00:40:19,120 --> 00:40:21,112 The killers won't give up. 404 00:40:21,280 --> 00:40:25,274 Like a pack of wolves, they take turns in harassing the whales. 405 00:40:46,000 --> 00:40:48,560 Now, the whole pod is involved. 406 00:40:58,720 --> 00:41:01,360 One of them takes a bite. 407 00:41:14,160 --> 00:41:17,437 Soon, the sea is reddened with the calf's blood, 408 00:41:17,600 --> 00:41:20,593 and the killers close in for the final act. 409 00:41:41,920 --> 00:41:43,718 The calf is dead. 410 00:41:48,000 --> 00:41:49,992 After a six—hour hunt, 411 00:41:50,160 --> 00:41:53,358 the killer whales have finally won their prize. 412 00:41:58,800 --> 00:42:00,792 The mother, bereft, 413 00:42:00,960 --> 00:42:03,998 has to continue her migration north on her own. 414 00:42:08,400 --> 00:42:11,393 She leaves behind the carcass of a calf 415 00:42:11,560 --> 00:42:15,190 that she cherished for 13 months in her womb, 416 00:42:15,360 --> 00:42:18,751 for which she delayed her own journey to find food. 417 00:42:21,680 --> 00:42:25,833 The 15 killer whales spent over six hours trying to kill the calf, 418 00:42:26,000 --> 00:42:28,117 but having succeeded, 419 00:42:28,280 --> 00:42:33,036 they've eaten nothing more than its lower jaw and its tongue. 420 00:42:41,000 --> 00:42:45,074 Valuable food like this will not go to waste in the ocean. 421 00:42:45,240 --> 00:42:48,631 Before long, the carcass will sink to the very bottom 422 00:42:48,800 --> 00:42:50,473 of this deep sea, 423 00:42:50,640 --> 00:42:53,633 but even there its flesh will not be wasted. 424 00:42:56,440 --> 00:43:00,275 Over a mile down, in the total darkness of the deep ocean, 425 00:43:00,440 --> 00:43:02,636 the body of another grey whale, 426 00:43:02,800 --> 00:43:04,280 a 30—tonne adult. 427 00:43:04,440 --> 00:43:07,478 It settled here only a few weeks ago. 428 00:43:09,640 --> 00:43:12,838 Already, it has attracted hundreds of hagfish. 429 00:43:18,920 --> 00:43:23,073 These scavengers, over half a metre long and as thick as your arm, 430 00:43:23,240 --> 00:43:25,755 are only found in the deep sea. 431 00:43:25,920 --> 00:43:29,357 They have been attracted by the faint whiff of decay 432 00:43:29,520 --> 00:43:32,718 suffusing through the water for miles around. 433 00:43:36,000 --> 00:43:39,118 With their heads buried in the whale's flesh, 434 00:43:39,280 --> 00:43:42,956 they breathe through gill openings along their sides. 435 00:43:43,120 --> 00:43:45,430 They're very primitive creatures — 436 00:43:45,600 --> 00:43:48,593 not even true fish for they lack jaws. 437 00:43:48,760 --> 00:43:50,752 They feed, not by biting, 438 00:43:50,920 --> 00:43:54,516 but by rasping off flesh with two rows of horny teeth. 439 00:43:56,360 --> 00:43:58,272 In just a few hours, 440 00:43:58,440 --> 00:44:02,514 a hagfish can eat several times its own weight of rotting flesh. 441 00:44:05,600 --> 00:44:07,592 Next to arrive, 442 00:44:07,760 --> 00:44:09,752 a sleeper shark. 443 00:44:15,920 --> 00:44:19,118 It moves so slowly to conserve energy — 444 00:44:19,280 --> 00:44:22,432 an important strategy for so large an animal 445 00:44:22,600 --> 00:44:24,751 surviving in such a poor habitat. 446 00:44:31,240 --> 00:44:34,039 Sleeper sharks live over a mile down, 447 00:44:34,200 --> 00:44:36,556 and grow to over seven metres long. 448 00:44:39,320 --> 00:44:43,155 They can go for months without food, slowly cruising along, 449 00:44:43,320 --> 00:44:45,232 waiting for rare bonanzas 450 00:44:45,400 --> 00:44:47,198 such as this one 451 00:44:47,360 --> 00:44:49,158 to arrive from above. 452 00:44:55,800 --> 00:44:58,998 A whole range of different deep—sea scavengers 453 00:44:59,160 --> 00:45:02,153 will feast on this carcass for a long time 454 00:45:02,320 --> 00:45:05,518 before all its nutriment has been consumed. 455 00:45:06,800 --> 00:45:08,393 18 months later, 456 00:45:08,560 --> 00:45:12,713 all that is left is a perfect skeleton stripped bare. 457 00:45:15,400 --> 00:45:19,553 The sun's energy, that was captured and turned into living tissue 458 00:45:19,720 --> 00:45:21,712 by the floating phytoplankton, 459 00:45:21,880 --> 00:45:25,430 has been transferred to another link in the food chain, 460 00:45:25,600 --> 00:45:29,514 and has ended up as far away from the sun as it is possible to be — 461 00:45:29,680 --> 00:45:31,672 at the bottom of the deep sea. 462 00:45:31,840 --> 00:45:35,754 But some energy also returns from the deep. 463 00:45:41,800 --> 00:45:45,953 Millions of opalescent squid are on their way to the shallows. 464 00:45:46,120 --> 00:45:48,555 They've come up here to mate. 465 00:45:48,720 --> 00:45:52,919 As the males grab the females, their tentacles flush red. 466 00:45:55,400 --> 00:45:57,039 For most of the year, 467 00:45:57,200 --> 00:46:00,318 these squid live at a depth of around 500 metres. 468 00:46:00,480 --> 00:46:04,190 They are part of these breeding schools for a few weeks. 469 00:46:04,360 --> 00:46:07,558 Just one school was estimated to contain animals 470 00:46:07,720 --> 00:46:10,030 that weigh around 4,000 tonnes. 471 00:46:20,840 --> 00:46:23,958 Wave after wave rise from the depths, 472 00:46:24,120 --> 00:46:26,351 and soon the seabed in the shallows 473 00:46:26,520 --> 00:46:30,912 is strewn with dense patches of egg capsules several metres across. 474 00:46:36,240 --> 00:46:39,312 As each female adds another capsule to the pile, 475 00:46:39,480 --> 00:46:42,678 the males fight to fertilise its contents. 476 00:46:58,000 --> 00:47:01,152 The squid make their huge journey into the shallows 477 00:47:01,320 --> 00:47:05,553 because their eggs will develop faster in the warmer water here, 478 00:47:05,720 --> 00:47:08,952 and when the young emerge, they will find more food 479 00:47:09,120 --> 00:47:12,318 more easily than they would in the ocean depths. 480 00:47:16,400 --> 00:47:18,392 Dawn the next morning, 481 00:47:18,560 --> 00:47:22,349 and the seabed for miles around is covered in egg capsules. 482 00:47:22,520 --> 00:47:25,797 The squid have all gone. Many have died, 483 00:47:25,960 --> 00:47:29,351 but some will have returned to their home in the deep. 484 00:47:29,520 --> 00:47:32,513 They will not return to the light of the sun 485 00:47:32,680 --> 00:47:36,640 until the next time they are driven up by the urge to spawn.