1 00:00:36,454 --> 00:00:40,071 Dwarfed by the vast expanse of the open ocean, 2 00:00:40,249 --> 00:00:43,948 the biggest animal that has ever lived on our planet. 3 00:00:51,049 --> 00:00:56,042 A blue whale, 30 metres long and weighing over 200 tonnes. 4 00:00:56,220 --> 00:00:59,919 it's far bigger than even the biggest dinosaur. 5 00:01:01,641 --> 00:01:04,925 its tongue weighs as much as an elephant. 6 00:01:05,102 --> 00:01:07,177 its heart is the size of a car, 7 00:01:07,353 --> 00:01:10,686 and some of its blood vessels are so wide 8 00:01:10,856 --> 00:01:12,932 that you could swim down them. 9 00:01:14,609 --> 00:01:16,400 its tail alone 10 00:01:16,569 --> 00:01:20,020 is the width of a small aircraft's wings. 11 00:01:38,003 --> 00:01:41,371 its streamlining, close to perfection, 12 00:01:41,547 --> 00:01:43,753 enables it to cruise at 20 knots. 13 00:01:43,924 --> 00:01:47,257 it's one of the fastest animals in the sea. 14 00:01:51,472 --> 00:01:53,760 The ocean's largest inhabitant 15 00:01:53,932 --> 00:01:57,466 feeds almost exclusively on one of the smallest - 16 00:01:57,643 --> 00:02:01,225 krill, a crustacean just a few centimetres long. 17 00:02:05,066 --> 00:02:07,058 Gathered in a shoal, 18 00:02:07,318 --> 00:02:09,393 krill stain the sea red, 19 00:02:09,569 --> 00:02:13,732 and a single blue whale in a day can consume 40 million of them. 20 00:02:22,746 --> 00:02:25,866 Despite the enormous size of blue whales, 21 00:02:26,041 --> 00:02:28,116 we know very little about them. 22 00:02:28,292 --> 00:02:31,412 Their migration routes are still a mystery, 23 00:02:31,587 --> 00:02:34,836 and we have absolutely no idea where they go to breed. 24 00:02:38,676 --> 00:02:40,751 They are a dramatic reminder 25 00:02:40,927 --> 00:02:43,003 of how much we still have to learn 26 00:02:43,179 --> 00:02:46,713 about the ocean and the creatures that live there. 27 00:02:49,976 --> 00:02:52,265 0ur planet is a blue planet. 28 00:02:52,437 --> 00:02:55,805 0ver 70 per cent of it is covered by the sea. 29 00:02:58,233 --> 00:03:01,897 The Pacific 0cean alone covers half the globe. 30 00:03:02,069 --> 00:03:05,402 You can fly across it non-stop for 12 hours 31 00:03:05,572 --> 00:03:08,857 and still see nothing more than a speck of land. 32 00:03:10,117 --> 00:03:11,777 This series will reveal 33 00:03:11,952 --> 00:03:15,285 the complete natural history of our ocean planet 34 00:03:15,455 --> 00:03:19,867 from its familiar shores to the mysteries of its deepest seas. 35 00:03:31,593 --> 00:03:33,668 By volume, the ocean makes up 36 00:03:33,844 --> 00:03:37,047 97 per cent of the earth's inhabitable space, 37 00:03:37,222 --> 00:03:39,973 and the sheer quantity of its marine life 38 00:03:40,141 --> 00:03:42,928 far exceeds that which inhabits the land. 39 00:04:06,245 --> 00:04:10,787 But life in the ocean is not evenly spread. it's regulated 40 00:04:10,957 --> 00:04:14,076 by the path of currents carrying nutrients, 41 00:04:14,251 --> 00:04:16,409 and the varying power of the sun. 42 00:04:17,379 --> 00:04:22,538 in this first programme, we will see how these two forces interact 43 00:04:22,716 --> 00:04:24,792 to control the distribution of life 44 00:04:24,968 --> 00:04:28,502 from the coral seas to the polar wastes. 45 00:05:25,266 --> 00:05:28,349 The sheer physical power of the ocean 46 00:05:28,518 --> 00:05:30,392 dominates our planet. 47 00:05:46,866 --> 00:05:50,649 it profoundly influences the weather of all the world. 48 00:05:50,828 --> 00:05:55,654 Water vapour rising from it forms the clouds and generates the storms 49 00:05:55,832 --> 00:05:58,404 that ultimately will drench the land. 50 00:06:18,391 --> 00:06:21,510 The great waves that roar in towards the shores 51 00:06:21,685 --> 00:06:24,805 are dramatic demonstrations of its power. 52 00:06:40,242 --> 00:06:43,076 Waves originate far out at sea. 53 00:06:43,244 --> 00:06:46,826 There, even gentle breezes can cause ripples, 54 00:06:46,997 --> 00:06:49,369 and ripples grow into swells. 55 00:06:59,715 --> 00:07:02,420 0ut in the open ocean, unimpeded by land, 56 00:07:02,593 --> 00:07:05,427 such swells can become gigantic. 57 00:07:28,447 --> 00:07:32,609 it's only when an ocean swell eventually reaches shallow water 58 00:07:32,783 --> 00:07:34,859 that it starts to break. 59 00:07:42,166 --> 00:07:46,328 As it approaches the coast, the water at the bottom of the swell 60 00:07:46,502 --> 00:07:49,171 is slowed by contact with the seabed. 61 00:07:49,338 --> 00:07:52,457 The top of the swell, still travelling fast, 62 00:07:52,632 --> 00:07:55,549 starts to roll over and so the wave breaks. 63 00:08:28,702 --> 00:08:32,782 The ocean never rests. Huge currents, such as the Gulf Stream, 64 00:08:32,956 --> 00:08:36,869 keep its waters constantly on the move all round the globe. 65 00:08:37,042 --> 00:08:40,162 it's these currents more than any other factor 66 00:08:40,337 --> 00:08:44,665 that control the distribution of nutrients and life in the seas. 67 00:08:47,259 --> 00:08:50,923 A tiny island lost in the midst of the Pacific. 68 00:08:51,095 --> 00:08:53,171 it's the tip of a huge mountain 69 00:08:53,347 --> 00:08:57,178 that rises from the sea floor thousands of metres below. 70 00:09:02,646 --> 00:09:05,979 The nearest land is 300 miles away. 71 00:09:10,194 --> 00:09:12,980 isolated sea mounts like this one 72 00:09:13,154 --> 00:09:15,905 create oases where life can flourish 73 00:09:16,073 --> 00:09:19,773 in the comparatively empty expanses of the open ocean. 74 00:09:28,750 --> 00:09:32,699 But all the creatures that swim beside it would not be here 75 00:09:32,878 --> 00:09:35,120 were it not for one key factor - 76 00:09:36,339 --> 00:09:38,213 the deep ocean currents. 77 00:09:43,553 --> 00:09:47,716 Far below the surface, they collide with the island's flanks 78 00:09:47,890 --> 00:09:50,131 and are deflected upwards, 79 00:09:50,309 --> 00:09:54,436 bringing with them from the depths a rich soup of nutrients. 80 00:09:56,272 --> 00:10:00,767 Such up-wellings attract great concentrations of life. 81 00:10:09,032 --> 00:10:12,151 Most of the fish here are permanent residents 82 00:10:12,326 --> 00:10:16,275 feeding on plankton - tiny floating plants and animals 83 00:10:16,454 --> 00:10:20,072 nourished by the richness brought up from the depths, 84 00:10:20,249 --> 00:10:23,249 and they attract visitors from the open ocean. 85 00:10:24,586 --> 00:10:25,961 Tuna. 86 00:10:52,900 --> 00:10:56,019 The plankton feeders are easy targets. 87 00:11:07,161 --> 00:11:10,992 All this action attracts even larger predators. 88 00:11:13,875 --> 00:11:15,285 Sharks. 89 00:11:20,088 --> 00:11:21,961 Hundreds of sharks. 90 00:11:24,550 --> 00:11:28,381 These silky sharks are normally ocean-going species, 91 00:11:28,553 --> 00:11:31,470 but the sea mounts in the eastern Pacific 92 00:11:31,639 --> 00:11:34,176 like Cocos, Mapelo and the Galapagos, 93 00:11:34,349 --> 00:11:38,678 attract silkies in huge groups up to 500 strong. 94 00:11:42,856 --> 00:11:46,355 Silkies seem to specialise in taking injured fish 95 00:11:46,526 --> 00:11:48,767 and constantly circle sea mounts 96 00:11:48,944 --> 00:11:51,779 on the look out for the chance to do so. 97 00:11:56,909 --> 00:11:59,482 But silkies are not the only visitors. 98 00:12:03,456 --> 00:12:07,666 Hammerheads gather in some of the largest shark shoals 99 00:12:07,834 --> 00:12:10,075 to be found anywhere in the ocean. 100 00:12:10,253 --> 00:12:14,250 Sometimes, thousands will circle over a single sea mount. 101 00:12:19,260 --> 00:12:22,011 But these sharks are not here for food. 102 00:12:22,179 --> 00:12:24,420 They have come for another reason. 103 00:12:27,433 --> 00:12:31,644 Some of the locals provide a cleaning service. 104 00:12:35,147 --> 00:12:37,519 Following the last El Nino year, 105 00:12:37,691 --> 00:12:42,435 when a rise in water temperatures gave many sharks fungal infections, 106 00:12:42,612 --> 00:12:45,778 the number of hammerheads visiting the sea mounts 107 00:12:45,948 --> 00:12:47,821 reached record levels. 108 00:12:58,708 --> 00:13:01,578 Nutrients also well up to the surface 109 00:13:01,752 --> 00:13:04,159 along the coasts of the continents. 110 00:13:05,797 --> 00:13:09,794 This is Natal on South Africa's eastern seaboard. 111 00:13:09,967 --> 00:13:11,508 it's june, 112 00:13:11,676 --> 00:13:15,507 and just off-shore, strange black patches have appeared. 113 00:13:19,182 --> 00:13:22,764 They look like immense oil slicks up to a mile long. 114 00:13:25,145 --> 00:13:27,683 But this is a living slick: 115 00:13:27,856 --> 00:13:32,184 millions and millions of sardines on a marine migration 116 00:13:32,359 --> 00:13:34,435 that in terms of sheer biomass, 117 00:13:34,611 --> 00:13:38,525 rivals that of the wildebeest on the grasslands of Africa. 118 00:13:42,159 --> 00:13:46,108 These fish live mostly in the cold waters south of the Cape, 119 00:13:46,287 --> 00:13:49,490 but each year the coastal currents reverse. 120 00:13:49,665 --> 00:13:53,792 The warm Agulhas current that flows down from the north 121 00:13:53,960 --> 00:13:57,162 has been displaced by cold water from the south, 122 00:13:57,337 --> 00:13:59,910 and that has brought up rich nutrients. 123 00:14:00,090 --> 00:14:03,540 They in turn have created a bloom of plankton, 124 00:14:04,385 --> 00:14:07,136 and the sardines are now feasting on it. 125 00:14:16,519 --> 00:14:18,595 As the sardines travel north, 126 00:14:18,771 --> 00:14:21,724 a whole caravan of predators follow them. 127 00:14:25,318 --> 00:14:28,484 Thousands of Cape gannets track the sardines. 128 00:14:28,654 --> 00:14:31,856 They nested off the Cape and timed their breeding 129 00:14:32,032 --> 00:14:34,403 so that their newly-fledged chicks 130 00:14:34,575 --> 00:14:37,148 can join them in pursuing the shoals. 131 00:14:43,999 --> 00:14:48,744 Below water, hundreds of sharks have also joined the caravan. 132 00:14:51,714 --> 00:14:54,667 These are bronze whaler sharks, 133 00:14:54,841 --> 00:14:58,920 a cold water species that normally lives much further south. 134 00:15:04,182 --> 00:15:06,554 These three-metre sharks 135 00:15:06,726 --> 00:15:10,094 cut such great swathes through the sardine shoals 136 00:15:10,270 --> 00:15:13,057 that their tracks are visible from the air. 137 00:15:13,231 --> 00:15:15,306 Harried by packs of predators 138 00:15:15,483 --> 00:15:18,602 and swept in by the action of the waves, 139 00:15:18,777 --> 00:15:22,062 the sardine shoals are penned close to the shore. 140 00:15:39,793 --> 00:15:45,000 Common dolphin are coming in from the open ocean to join the feast. 141 00:16:00,143 --> 00:16:02,218 There are over a thousand of them 142 00:16:02,395 --> 00:16:04,470 in this one school. 143 00:16:12,111 --> 00:16:17,151 When they catch up with the sardines, the action really begins. 144 00:16:21,368 --> 00:16:25,495 Working together, they drive the shoal towards the surface. 145 00:16:33,878 --> 00:16:38,171 it's easier for the dolphins to snatch fish up here. 146 00:16:52,726 --> 00:16:55,680 Now the sardines have no escape. 147 00:17:07,196 --> 00:17:09,272 Thanks to the dolphins, 148 00:17:09,448 --> 00:17:13,694 the sardines have come within the diving range of the gannets. 149 00:17:25,377 --> 00:17:28,294 Hundreds of white arrows shoot into the sea, 150 00:17:28,463 --> 00:17:32,080 leaving long trails of bubbles behind each dive. 151 00:17:44,809 --> 00:17:47,513 Next to join the frenzy are the sharks. 152 00:18:00,154 --> 00:18:03,938 Sharks get very excited when dolphins are around. 153 00:18:04,116 --> 00:18:06,274 They can feed particularly well 154 00:18:06,451 --> 00:18:09,321 once the dolphins have driven the sardines 155 00:18:09,495 --> 00:18:12,365 into more compact groups near the surface. 156 00:18:16,042 --> 00:18:19,991 As the frenzy continues, walls of bubbles drift upwards. 157 00:18:22,839 --> 00:18:25,508 They are being released by the dolphins 158 00:18:25,675 --> 00:18:27,750 working together in teams. 159 00:18:30,220 --> 00:18:32,011 They use the bubbles 160 00:18:32,180 --> 00:18:35,429 to corral the sardines into ever tighter groups. 161 00:18:38,893 --> 00:18:41,929 The sardines seldom cross the wall of bubbles 162 00:18:42,104 --> 00:18:44,180 and crowd closer together. 163 00:18:47,692 --> 00:18:49,565 Bubble netting in this way, 164 00:18:49,735 --> 00:18:53,946 enables the dolphins to grab every last trapped sardine. 165 00:19:05,873 --> 00:19:08,992 just when the feasting seems to be almost over, 166 00:19:09,167 --> 00:19:11,041 a Bryde's whale. 167 00:19:15,547 --> 00:19:17,955 The survivors head on northwards, 168 00:19:18,133 --> 00:19:21,050 and the caravan of predators follows them. 169 00:19:29,475 --> 00:19:33,342 Nutrients can also be brought up, though less predictably, 170 00:19:33,520 --> 00:19:35,596 by rough weather. 171 00:19:40,484 --> 00:19:44,267 Particularly near the poles, huge storms stir the depths 172 00:19:44,445 --> 00:19:46,852 and enrich the surface waters, 173 00:19:47,031 --> 00:19:49,106 and here, in the South Atlantic, 174 00:19:49,282 --> 00:19:52,034 the seas are the roughest on the planet. 175 00:19:55,746 --> 00:19:57,821 And very rich seas they are, too, 176 00:19:57,998 --> 00:20:01,448 for here, the cold Falklands current from the south 177 00:20:01,626 --> 00:20:04,661 meets the warm Brazil current from the north, 178 00:20:04,836 --> 00:20:07,623 and at their junction is food in abundance. 179 00:20:09,465 --> 00:20:13,248 These black-browed albatross are duck-diving for krill 180 00:20:13,427 --> 00:20:16,213 that has been driven up to the surface. 181 00:20:19,431 --> 00:20:21,305 Like all albatross, 182 00:20:21,475 --> 00:20:25,554 black-brows are wanderers across the face of the open ocean. 183 00:20:41,198 --> 00:20:44,531 A feeding assembly on this scale is a rare sight. 184 00:20:44,701 --> 00:20:48,947 Most of the time, the birds of the open sea are widely dispersed, 185 00:20:49,121 --> 00:20:53,782 but these feeding grounds are close to an albatross breeding colony, 186 00:20:53,959 --> 00:20:55,867 and a very special one. 187 00:21:05,343 --> 00:21:07,418 This is Steeple jason, 188 00:21:07,594 --> 00:21:10,797 a remote island in the far west of the Falklands. 189 00:21:10,972 --> 00:21:14,175 it has the largest albatross colony in the world. 190 00:21:23,065 --> 00:21:26,314 There are almost half a million albatross here, 191 00:21:26,484 --> 00:21:30,647 an astonishing demonstration of how fertile the ocean can be 192 00:21:30,821 --> 00:21:32,897 and how much food it can give 193 00:21:33,073 --> 00:21:36,358 even to creatures that do not actually live in it. 194 00:22:02,971 --> 00:22:05,047 Nutrients by themselves 195 00:22:05,223 --> 00:22:08,592 are not enough to generate these vast assemblies. 196 00:22:08,768 --> 00:22:11,970 The heat and light from the sun is also essential 197 00:22:12,145 --> 00:22:15,596 for the growth of the microscopic floating plants - 198 00:22:15,773 --> 00:22:18,015 the phytoplankton. 199 00:22:21,903 --> 00:22:26,860 And it's the phytoplankton that is the basis of all life in the ocean. 200 00:22:33,537 --> 00:22:37,700 Every evening, the disappearance of the sun below the horizon 201 00:22:37,874 --> 00:22:40,791 triggers the largest migration of life 202 00:22:40,960 --> 00:22:43,035 that takes place on our planet. 203 00:22:50,509 --> 00:22:53,960 0ne thousand million tonnes of sea creatures 204 00:22:54,137 --> 00:22:58,300 ascend from the deep ocean to search for food near the surface. 205 00:23:05,563 --> 00:23:09,725 They graze on the phytoplankton under cover of darkness. 206 00:23:09,899 --> 00:23:12,604 Even so, they are far from safe. 207 00:23:12,777 --> 00:23:15,101 0ther marine hunters follow them, 208 00:23:15,279 --> 00:23:18,647 some travelling up from hundreds of metres below. 209 00:24:19,997 --> 00:24:21,574 At dawn, 210 00:24:21,748 --> 00:24:25,959 the whole procession returns to the safety of the dark depths. 211 00:24:32,381 --> 00:24:37,208 The moon, too, has a great influence on life in the oceans. 212 00:24:38,636 --> 00:24:40,925 its gravitational pull 213 00:24:41,097 --> 00:24:44,679 creates the daily advances and retreats of the tide. 214 00:24:56,859 --> 00:24:59,978 But the moon has more than a daily cycle. 215 00:25:00,153 --> 00:25:04,565 Each month, it waxes and wanes as it travels round the earth, 216 00:25:04,740 --> 00:25:08,737 and this monthly cycle also triggers events in the ocean. 217 00:25:12,121 --> 00:25:14,742 The Pacific coast of Costa Rica 218 00:25:14,915 --> 00:25:16,991 on a very special night. 219 00:25:17,167 --> 00:25:21,543 it's just after midnight and the tide is coming in. 220 00:25:25,924 --> 00:25:28,545 The moon is in its last quarter, 221 00:25:28,718 --> 00:25:31,920 exactly half way between full and new. 222 00:25:34,430 --> 00:25:37,217 For weeks, the beach has been empty, 223 00:25:37,391 --> 00:25:39,467 but that is about to change. 224 00:25:39,643 --> 00:25:43,889 At high tide, turtles start to emerge from the surf. 225 00:25:49,317 --> 00:25:52,436 At first, they come in ones and twos, 226 00:25:52,611 --> 00:25:54,604 but within an hour, 227 00:25:54,780 --> 00:25:57,899 they are appearing all along the beach. 228 00:26:03,412 --> 00:26:06,495 They are all female Ridley's turtles, 229 00:26:06,664 --> 00:26:08,740 and over the next six days or so, 230 00:26:08,916 --> 00:26:12,415 400,000 will visit this one beach 231 00:26:12,586 --> 00:26:14,661 to lay their eggs in the sand. 232 00:26:22,844 --> 00:26:27,552 At the peak time, 5,000 are coming and going every hour. 233 00:26:27,723 --> 00:26:30,593 The top of the beach gets so crowded 234 00:26:30,767 --> 00:26:34,514 that they have to clamber over one another to find a patch 235 00:26:34,686 --> 00:26:36,762 where they can dig a nest hole. 236 00:26:42,067 --> 00:26:45,898 A quarter of the world's population of Ridley's turtles 237 00:26:46,070 --> 00:26:49,770 come to this one beach on a few key nights each year. 238 00:26:49,948 --> 00:26:52,024 The rest of the time, 239 00:26:52,200 --> 00:26:55,403 they are widely distributed through the ocean, 240 00:26:56,037 --> 00:26:58,112 most, hundreds of miles away. 241 00:26:58,288 --> 00:27:03,163 This mass nesting is called an arribada. How it's co-ordinated 242 00:27:03,334 --> 00:27:05,410 is a mystery, 243 00:27:05,586 --> 00:27:07,911 but we do know that arribadas start 244 00:27:08,088 --> 00:27:11,622 when the moon is either in its first or last quarter. 245 00:27:19,305 --> 00:27:23,384 Forty million eggs are laid in just a few days. 246 00:27:23,558 --> 00:27:27,342 By synchronising their nesting, the females ensure 247 00:27:27,520 --> 00:27:30,853 that six weeks later, their hatchlings will emerge 248 00:27:31,023 --> 00:27:33,098 in such enormous numbers 249 00:27:33,274 --> 00:27:35,765 that predators are overwhelmed, 250 00:27:35,943 --> 00:27:41,067 and a significant proportion of baby turtles will make it to the water. 251 00:27:43,366 --> 00:27:47,066 But why do the females use a cue from the moon 252 00:27:47,244 --> 00:27:49,651 to help synchronise their nesting? 253 00:27:49,829 --> 00:27:51,905 Part of the answer to that 254 00:27:52,081 --> 00:27:55,414 becomes clear at dawn on the following morning. 255 00:28:16,851 --> 00:28:21,346 The day shift of predators are arriving for their first meals. 256 00:28:26,733 --> 00:28:28,809 Vultures have learnt 257 00:28:28,985 --> 00:28:33,397 that the returning tide can wash freshly laid eggs out of the sand. 258 00:28:35,907 --> 00:28:39,073 The risk of eggs being exposed by the surf 259 00:28:39,243 --> 00:28:42,446 may be partly why turtle arribadas tend to occur 260 00:28:42,621 --> 00:28:45,740 around the last or first quarter of the moon. 261 00:28:49,460 --> 00:28:54,417 it's on such days as this when the moon is neither full nor new, 262 00:28:54,589 --> 00:28:58,586 that the tides are weakest and the sea is likely to be calmer. 263 00:29:13,854 --> 00:29:19,013 So it's easier for the female turtles to make their way through the surf, 264 00:29:19,192 --> 00:29:22,311 and harder for eggs to be washed out of the sand 265 00:29:22,486 --> 00:29:24,395 and taken by vultures. 266 00:29:36,413 --> 00:29:40,576 The moon's monthly cycle and its influence on the tides 267 00:29:40,750 --> 00:29:43,075 triggers many events in the ocean, 268 00:29:43,252 --> 00:29:47,000 from the spawning of the corals on the Great Barrier reef 269 00:29:47,172 --> 00:29:49,248 to the breeding cycles of fish, 270 00:29:49,424 --> 00:29:51,665 but there's an even longer rhythm 271 00:29:51,842 --> 00:29:54,547 that has the most profound effect of all - 272 00:29:54,720 --> 00:29:56,795 the annual cycle of the sun. 273 00:29:59,015 --> 00:30:01,719 The sun's position relative to the earth 274 00:30:01,892 --> 00:30:03,968 changes through the year, 275 00:30:04,144 --> 00:30:06,848 and it's this that produces the seasons. 276 00:30:07,021 --> 00:30:08,894 in the north, spring comes 277 00:30:09,064 --> 00:30:12,018 as the sun begins to rise higher in the sky. 278 00:30:12,859 --> 00:30:15,396 0ff the coast of north west America, 279 00:30:15,569 --> 00:30:20,029 the seas are transformed by the increasing strength of the sun. 280 00:30:25,160 --> 00:30:28,659 Here in Alaska, the coastal waters turn green 281 00:30:28,830 --> 00:30:31,403 with a sudden bloom of phytoplankton. 282 00:30:34,543 --> 00:30:37,745 Herring that have spent the winter far out to sea 283 00:30:37,920 --> 00:30:42,665 time their return to the shallow waters to coincide with this bloom. 284 00:30:42,841 --> 00:30:44,964 They come in vast numbers 285 00:30:45,134 --> 00:30:49,427 and initiate one of the most productive food chains in all the oceans. 286 00:31:04,984 --> 00:31:08,683 Humpback whales are at the top of that food chain. 287 00:31:08,862 --> 00:31:10,937 They have spent the winter 288 00:31:11,113 --> 00:31:14,564 breeding in the warmer tropical waters off Hawaii, 289 00:31:14,741 --> 00:31:16,817 but there was little food there. 290 00:31:16,993 --> 00:31:19,069 This herring bonanza 291 00:31:19,245 --> 00:31:22,660 provides the majority of their food for the year. 292 00:31:43,347 --> 00:31:45,838 Stellar and Californian sea lions 293 00:31:46,016 --> 00:31:50,724 also return from the open ocean each year to feast off the herring. 294 00:32:01,528 --> 00:32:05,442 The herring, however, have not come here for food. 295 00:32:05,615 --> 00:32:08,781 They are about to breed. Nothing deters them 296 00:32:08,951 --> 00:32:12,236 as they head for even shallower waters. 297 00:32:13,955 --> 00:32:16,030 Now the waters are so shallow 298 00:32:16,207 --> 00:32:18,163 that glaucous-winged gulls 299 00:32:18,333 --> 00:32:21,499 can snatch live fish from just below the surface. 300 00:32:33,595 --> 00:32:36,512 in spite of these attacks, the herring swim on 301 00:32:36,681 --> 00:32:38,887 until they reach the vegetation 302 00:32:39,058 --> 00:32:41,809 that the females need if they are to lay. 303 00:32:48,190 --> 00:32:51,475 Each female produces around 20,000 eggs, 304 00:32:51,651 --> 00:32:54,058 and they're very sticky. 305 00:32:58,115 --> 00:33:02,361 After the females have spawned, the males release their sperm 306 00:33:02,535 --> 00:33:04,610 in vast, milky clouds. 307 00:33:09,749 --> 00:33:13,959 Soon, the excesses of the herrings' sexual spree 308 00:33:14,127 --> 00:33:17,745 creates a thick white scum on the surface. 309 00:33:19,215 --> 00:33:21,290 Through the season, 310 00:33:21,466 --> 00:33:25,000 curds of sperm clog the shores for hundreds of miles 311 00:33:25,178 --> 00:33:29,009 from British Columbia in the south to Alaska in the north. 312 00:33:35,436 --> 00:33:39,896 After a few days, this gigantic spawning comes to an end, 313 00:33:40,064 --> 00:33:43,184 and the herring head back out to deeper waters, 314 00:33:43,359 --> 00:33:45,849 leaving behind them fertilised eggs 315 00:33:46,028 --> 00:33:49,396 plastered on every rock and strand of vegetation. 316 00:34:00,456 --> 00:34:05,876 They time the spawning so that two weeks later, when the eggs hatch, 317 00:34:06,043 --> 00:34:10,336 the annual plankton bloom will be at its height, and the fish fry 318 00:34:10,505 --> 00:34:12,581 will have plenty to eat. 319 00:34:12,757 --> 00:34:15,164 in the meantime, these eggs provide food 320 00:34:15,342 --> 00:34:18,793 for armies of different animals below and above the surface. 321 00:34:27,060 --> 00:34:31,638 Millions of birds arrive to collect a share of the herrings' bounty. 322 00:34:31,814 --> 00:34:33,889 Some of it is easily gathered, 323 00:34:34,066 --> 00:34:37,765 for millions of eggs have been washed up onto the shore. 324 00:34:38,694 --> 00:34:40,770 This encapsulated energy 325 00:34:40,946 --> 00:34:44,729 is particularly valuable to migrating birds. 326 00:34:44,907 --> 00:34:47,065 These surfbirds are on their way 327 00:34:47,243 --> 00:34:51,904 to their breeding grounds in the Arctic and come down to refuel. 328 00:34:52,080 --> 00:34:55,282 Stranded herring eggs are just what they need. 329 00:34:57,417 --> 00:34:59,540 Bonaparte gulls collect the eggs 330 00:34:59,711 --> 00:35:01,999 just below the surface of the water. 331 00:35:04,840 --> 00:35:08,789 Further out in the bay, huge flocks of ducks have gathered. 332 00:35:08,968 --> 00:35:11,007 They're mostly surf scoters - 333 00:35:11,178 --> 00:35:15,341 diving ducks that can feed off the bottom several metres down. 334 00:35:19,351 --> 00:35:22,470 There are such huge quantities of eggs, 335 00:35:22,646 --> 00:35:24,721 that even a big animal like a bear 336 00:35:24,897 --> 00:35:27,352 finds it worthwhile to collect them. 337 00:35:30,819 --> 00:35:34,269 The spawning of the herring is a crucial event 338 00:35:34,447 --> 00:35:37,649 in the lives of many animals all along the coast. 339 00:35:37,824 --> 00:35:41,275 The whole event coincides with the plankton bloom, 340 00:35:41,452 --> 00:35:44,322 and within three short weeks, it's all over. 341 00:35:49,584 --> 00:35:54,043 The migratory birds leave to continue their journey north. 342 00:36:01,885 --> 00:36:06,048 They will not come back until the herring also return next year. 343 00:36:12,518 --> 00:36:14,843 As the herring spawning finishes, 344 00:36:15,020 --> 00:36:18,353 other migrants are starting to arrive offshore. 345 00:36:20,858 --> 00:36:22,732 Grey whales. 346 00:36:27,655 --> 00:36:29,897 They have followed the sun north, 347 00:36:30,074 --> 00:36:32,399 and they too are seeking the food 348 00:36:32,576 --> 00:36:35,695 generated by the bloom of the phytoplankton. 349 00:36:38,497 --> 00:36:42,993 Krill are feeding off it, and these whales are feeding on the krill, 350 00:36:43,168 --> 00:36:47,247 skimming it from the surface with the filter plates of baleen 351 00:36:47,421 --> 00:36:49,579 that hang from their upper jaws. 352 00:36:51,091 --> 00:36:54,210 Grey whales make one of the longest migrations 353 00:36:54,385 --> 00:36:56,424 of any marine mammal - 354 00:36:56,595 --> 00:36:59,264 a round trip of 12,000 miles or so 355 00:36:59,431 --> 00:37:02,550 from their breeding grounds off Mexico 356 00:37:02,725 --> 00:37:07,053 along the entire coast of North America up to the Arctic 0cean. 357 00:37:09,897 --> 00:37:11,973 They travel close to the coast, 358 00:37:12,149 --> 00:37:15,980 with the males and non-breeding females leading the way. 359 00:37:16,152 --> 00:37:20,943 The last to start are cows that have just given birth. 360 00:37:21,114 --> 00:37:25,277 They have to wait until their calves are sufficiently strong 361 00:37:25,451 --> 00:37:27,574 to tackle such an immense journey. 362 00:37:28,829 --> 00:37:31,746 Their progress is necessarily slow. 363 00:37:31,915 --> 00:37:34,072 The mothers stay with their young, 364 00:37:34,250 --> 00:37:37,867 and even a strong calf only travels at a couple of knots. 365 00:37:39,754 --> 00:37:42,161 They stick even closer to the shore, 366 00:37:42,339 --> 00:37:44,415 often within just 200 metres. 367 00:37:48,428 --> 00:37:50,219 Killer whales. 368 00:37:50,387 --> 00:37:54,550 They have learnt that grey whales follow traditional routes. 369 00:37:54,724 --> 00:37:56,800 The killers have no trouble 370 00:37:56,976 --> 00:38:00,724 in overtaking the calf and its devoted mother. 371 00:38:04,774 --> 00:38:08,059 Normally, they continually call to one another, 372 00:38:08,235 --> 00:38:10,607 but now they have fallen silent. 373 00:38:10,779 --> 00:38:12,854 The grey whale and her calf 374 00:38:13,030 --> 00:38:16,150 have no idea that they've been targeted. 375 00:38:36,966 --> 00:38:41,627 Catching up with the grey whales is the easy part for the killers. 376 00:38:41,803 --> 00:38:43,463 They have to be cautious 377 00:38:43,638 --> 00:38:46,971 for they are only about half the size of the mother. 378 00:38:50,602 --> 00:38:53,935 She can inflict real damage with her tail. 379 00:39:03,529 --> 00:39:05,853 But the killers are after her calf. 380 00:39:06,031 --> 00:39:10,074 As long as the mother can keep it on the move, it will be safe, 381 00:39:10,242 --> 00:39:13,492 and she does her best to hurry it along. 382 00:39:15,997 --> 00:39:21,037 At first, the killers avoid getting too close but just stay alongside. 383 00:39:21,209 --> 00:39:26,203 They know that the calf, going at this speed, will eventually tire. 384 00:39:36,638 --> 00:39:38,926 After three hours of being harried, 385 00:39:39,098 --> 00:39:42,549 the calf becomes too exhausted to swim any further. 386 00:39:42,726 --> 00:39:44,802 The mother has to stop. 387 00:39:44,978 --> 00:39:48,512 This is the moment the killers have been waiting for. 388 00:39:48,940 --> 00:39:53,186 They start to try and force themselves between mother and calf. 389 00:40:14,835 --> 00:40:19,247 A calf separated from its mother will not be able to defend itself. 390 00:40:19,422 --> 00:40:22,541 Time and again, the black fins of the killers 391 00:40:22,716 --> 00:40:25,005 appear between the grey whales. 392 00:40:36,477 --> 00:40:38,553 At last the killers succeed, 393 00:40:38,729 --> 00:40:41,848 and now they've got the calf on its own, 394 00:40:42,023 --> 00:40:44,099 they change their tactics. 395 00:40:44,275 --> 00:40:47,809 They leap right onto the calf, and try to push it under. 396 00:40:59,203 --> 00:41:01,279 They are trying to drown it. 397 00:41:11,880 --> 00:41:14,999 The calf snatches a desperate breath. 398 00:41:28,101 --> 00:41:31,220 The mother becomes increasingly agitated. 399 00:41:31,396 --> 00:41:35,309 Frantically, she tries to push her calf back to the surface 400 00:41:35,482 --> 00:41:37,558 so that it can breathe. 401 00:41:39,986 --> 00:41:41,978 But now it's so exhausted 402 00:41:42,154 --> 00:41:45,357 that it has to be supported by its mother's body. 403 00:42:02,921 --> 00:42:04,996 The killers won't give up. 404 00:42:05,172 --> 00:42:09,335 Like a pack of wolves, they take turns in harassing the whales. 405 00:42:30,943 --> 00:42:33,611 Now, the whole pod is involved. 406 00:42:44,203 --> 00:42:46,954 0ne of them takes a bite. 407 00:43:00,299 --> 00:43:03,714 Soon, the sea is reddened with the calf's blood, 408 00:43:03,885 --> 00:43:07,005 and the killers close in for the final act. 409 00:43:29,239 --> 00:43:31,112 The calf is dead. 410 00:43:35,577 --> 00:43:37,653 After a six-hour hunt, 411 00:43:37,829 --> 00:43:41,162 the killer whales have finally won their prize. 412 00:43:46,836 --> 00:43:48,912 The mother, bereft, 413 00:43:49,088 --> 00:43:52,254 has to continue her migration north on her own. 414 00:43:56,844 --> 00:43:59,963 She leaves behind the carcass of a calf 415 00:44:00,138 --> 00:44:03,921 that she cherished for 13 months in her womb, 416 00:44:04,100 --> 00:44:07,634 for which she delayed her own journey to find food. 417 00:44:10,688 --> 00:44:15,017 The 15 killer whales spent over six hours trying to kill the calf, 418 00:44:15,192 --> 00:44:17,398 but having succeeded, 419 00:44:17,569 --> 00:44:22,526 they've eaten nothing more than its lower jaw and its tongue. 420 00:44:30,829 --> 00:44:35,075 Valuable food like this will not go to waste in the ocean. 421 00:44:35,249 --> 00:44:38,783 Before long, the carcass will sink to the very bottom 422 00:44:38,961 --> 00:44:40,704 of this deep sea, 423 00:44:40,879 --> 00:44:43,998 but even there its flesh will not be wasted. 424 00:44:46,925 --> 00:44:50,922 0ver a mile down, in the total darkness of the deep ocean, 425 00:44:51,095 --> 00:44:53,383 the body of another grey whale, 426 00:44:53,555 --> 00:44:55,097 a 30-tonne adult. 427 00:44:55,265 --> 00:44:58,431 it settled here only a few weeks ago. 428 00:45:00,686 --> 00:45:04,019 Already, it has attracted hundreds of hagfish. 429 00:45:10,360 --> 00:45:14,689 These scavengers, over half a metre long and as thick as your arm, 430 00:45:14,864 --> 00:45:17,485 are only found in the deep sea. 431 00:45:17,658 --> 00:45:21,240 They have been attracted by the faint whiff of decay 432 00:45:21,411 --> 00:45:24,744 suffusing through the water for miles around. 433 00:45:28,166 --> 00:45:31,416 With their heads buried in the whale's flesh, 434 00:45:31,586 --> 00:45:35,417 they breathe through gill openings along their sides. 435 00:45:35,589 --> 00:45:37,996 They're very primitive creatures - 436 00:45:38,174 --> 00:45:41,293 not even true fish for they lack jaws. 437 00:45:41,468 --> 00:45:43,544 They feed, not by biting, 438 00:45:43,720 --> 00:45:47,468 but by rasping off flesh with two rows of horny teeth. 439 00:45:49,391 --> 00:45:51,384 in just a few hours, 440 00:45:51,560 --> 00:45:55,806 a hagfish can eat several times its own weight of rotting flesh. 441 00:45:59,024 --> 00:46:01,100 Next to arrive, 442 00:46:01,276 --> 00:46:03,351 a sleeper shark. 443 00:46:09,782 --> 00:46:13,115 it moves so slowly to conserve energy - 444 00:46:13,285 --> 00:46:16,570 an important strategy for so large an animal 445 00:46:16,746 --> 00:46:18,988 surviving in such a poor habitat. 446 00:46:25,753 --> 00:46:28,670 Sleeper sharks live over a mile down, 447 00:46:28,839 --> 00:46:31,294 and grow to over seven metres long. 448 00:46:34,177 --> 00:46:38,174 They can go for months without food, slowly cruising along, 449 00:46:38,347 --> 00:46:40,339 waiting for rare bonanzas 450 00:46:40,515 --> 00:46:42,388 such as this one 451 00:46:42,558 --> 00:46:44,432 to arrive from above. 452 00:46:51,357 --> 00:46:54,690 A whole range of different deep-sea scavengers 453 00:46:54,860 --> 00:46:57,979 will feast on this carcass for a long time 454 00:46:58,154 --> 00:47:01,487 before all its nutriment has been consumed. 455 00:47:02,824 --> 00:47:04,484 18 months later, 456 00:47:04,659 --> 00:47:08,988 all that is left is a perfect skeleton stripped bare. 457 00:47:11,790 --> 00:47:16,118 The sun's energy, that was captured and turned into living tissue 458 00:47:16,293 --> 00:47:18,369 by the floating phytoplankton, 459 00:47:18,545 --> 00:47:22,245 has been transferred to another link in the food chain, 460 00:47:22,423 --> 00:47:26,502 and has ended up as far away from the sun as it is possible to be - 461 00:47:26,677 --> 00:47:28,752 at the bottom of the deep sea. 462 00:47:28,928 --> 00:47:33,008 But some energy also returns from the deep. 463 00:47:39,312 --> 00:47:43,640 Millions of opalescent squid are on their way to the shallows. 464 00:47:43,815 --> 00:47:46,353 They've come up here to mate. 465 00:47:46,526 --> 00:47:50,902 As the males grab the females, their tentacles flush red. 466 00:47:53,489 --> 00:47:55,197 For most of the year, 467 00:47:55,366 --> 00:47:58,615 these squid live at a depth of around 500 metres. 468 00:47:58,785 --> 00:48:02,652 They are part of these breeding schools for a few weeks. 469 00:48:02,830 --> 00:48:06,163 just one school was estimated to contain animals 470 00:48:06,333 --> 00:48:08,740 that weigh around 4,000 tonnes. 471 00:48:20,010 --> 00:48:23,260 Wave after wave rise from the depths, 472 00:48:23,430 --> 00:48:25,755 and soon the seabed in the shallows 473 00:48:25,932 --> 00:48:30,509 is strewn with dense patches of egg capsules several metres across. 474 00:48:36,065 --> 00:48:39,267 As each female adds another capsule to the pile, 475 00:48:39,442 --> 00:48:42,775 the males fight to fertilise its contents. 476 00:48:58,749 --> 00:49:02,034 The squid make their huge journey into the shallows 477 00:49:02,210 --> 00:49:06,622 because their eggs will develop faster in the warmer water here, 478 00:49:06,797 --> 00:49:10,166 and when the young emerge, they will find more food 479 00:49:10,342 --> 00:49:13,675 more easily than they would in the ocean depths. 480 00:49:17,931 --> 00:49:20,007 Dawn the next morning, 481 00:49:20,183 --> 00:49:24,132 and the seabed for miles around is covered in egg capsules. 482 00:49:24,311 --> 00:49:27,726 The squid have all gone. Many have died, 483 00:49:27,897 --> 00:49:31,432 but some will have returned to their home in the deep. 484 00:49:31,609 --> 00:49:34,728 They will not return to the light of the sun 485 00:49:34,903 --> 00:49:39,030 until the next time they are driven up by the urge to spawn.