1 00:00:00,000 --> 00:00:04,120 (DEEP BREATHING) 2 00:00:09,440 --> 00:00:11,560 DAVID ATTENBOROUGH: Much of our planet 3 00:00:11,680 --> 00:00:14,400 still remains unexplored... 4 00:00:16,920 --> 00:00:20,280 ...for most of it is covered by water. 5 00:00:22,960 --> 00:00:24,960 Every journey below the surface 6 00:00:25,080 --> 00:00:28,280 can reveal something extraordinary. 7 00:00:31,200 --> 00:00:36,680 More than 1,000 new species are discovered here every year. 8 00:00:50,960 --> 00:00:56,160 The ocean is home to 80% of all animal life 9 00:00:56,280 --> 00:00:58,480 on Planet Earth. 10 00:01:06,480 --> 00:01:08,680 But today, 11 00:01:08,800 --> 00:01:11,880 thriving in this varied world 12 00:01:12,000 --> 00:01:16,760 sometimes demands the most surprising behaviour. 13 00:01:37,800 --> 00:01:40,520 The shallow seas of the tropics. 14 00:01:44,000 --> 00:01:47,120 This may look like a paradise... 15 00:01:50,120 --> 00:01:52,600 ...but beneath the surface, 16 00:01:52,720 --> 00:01:54,280 it is an arena 17 00:01:54,400 --> 00:01:57,360 for constant life-and-death struggles, 18 00:01:57,480 --> 00:02:01,760 Where not everything is quite as it seems. 19 00:02:11,120 --> 00:02:13,800 A predatory lionfish... 20 00:02:17,520 --> 00:02:20,920 ...on the hunt for shrimp and small fish. 21 00:02:29,360 --> 00:02:33,680 With so many places for its prey to hide, 22 00:02:33,800 --> 00:02:37,280 the lionfish has to be patient. 23 00:02:43,720 --> 00:02:47,240 This shrimp appears tempting. 24 00:02:48,960 --> 00:02:51,400 As the lionfish closes in, 25 00:02:51,520 --> 00:02:53,840 it fans out its fins 26 00:02:53,960 --> 00:02:56,280 to disorientate its prey. 27 00:03:08,960 --> 00:03:11,840 The hunter becomes the hunted... 28 00:03:18,240 --> 00:03:20,320 ...tricked by one of the shallow sea's 29 00:03:20,440 --> 00:03:23,400 most extraordinary predators... 30 00:03:27,040 --> 00:03:29,800 ...a clown frogfish. 31 00:03:32,600 --> 00:03:36,000 On its head, it carries a fishing rod, 32 00:03:36,120 --> 00:03:38,360 a modified dorsal fin 33 00:03:38,480 --> 00:03:43,360 baited with a lure, easily mistaken for a shrimp. 34 00:03:53,520 --> 00:03:56,200 But when the fish stop biting, 35 00:03:56,320 --> 00:03:58,840 it's time to pack the rod away 36 00:03:58,960 --> 00:04:00,640 and move on. 37 00:04:04,520 --> 00:04:09,840 And for a frogfish, that takes time. 38 00:04:20,840 --> 00:04:22,920 Rather than swim, 39 00:04:23,040 --> 00:04:24,960 frogfish walk. 40 00:04:27,080 --> 00:04:30,720 Its fins have, in effect, become feet. 41 00:04:40,640 --> 00:04:44,320 It may not look pretty, but what appears to be coral 42 00:04:44,440 --> 00:04:49,160 living on its skin is actually camouflage. 43 00:05:03,000 --> 00:05:04,880 As every good angler knows, 44 00:05:05,000 --> 00:05:08,640 picking the right spot is important. 45 00:05:14,160 --> 00:05:17,480 Jigging the rod sends out pressure waves 46 00:05:17,600 --> 00:05:20,800 to attract the attention of possible prey. 47 00:05:28,960 --> 00:05:32,000 These dragonets are certainly interested. 48 00:05:44,360 --> 00:05:45,960 Almost there. 49 00:05:56,360 --> 00:05:58,080 (GULPS) 50 00:06:01,280 --> 00:06:04,040 Hook, line and sinker. 51 00:06:15,840 --> 00:06:17,680 Like all shallow seas, 52 00:06:17,800 --> 00:06:21,560 the cold waters off the coast of North America 53 00:06:21,680 --> 00:06:25,680 benefit from the intensity of the sunshine. 54 00:06:33,080 --> 00:06:36,760 Here, that fuels one of the fastest-growing organisms 55 00:06:36,880 --> 00:06:38,280 on the planet... 56 00:06:40,000 --> 00:06:41,960 ...giant kelp. 57 00:06:44,880 --> 00:06:47,880 Towering forests can eventually reach 58 00:06:48,000 --> 00:06:50,880 the height of a 12-storey building. 59 00:07:04,360 --> 00:07:09,080 These forests are nurseries for young horn sharks. 60 00:07:12,880 --> 00:07:14,840 As the sun begins to set, 61 00:07:14,960 --> 00:07:18,080 they leave their daytime shelter 62 00:07:18,200 --> 00:07:21,960 and set off into the heart of the kelp forest 63 00:07:22,080 --> 00:07:23,640 to find food. 64 00:07:34,080 --> 00:07:35,840 Barely half a metre long, 65 00:07:35,960 --> 00:07:39,840 this little shark is extremely vulnerable. 66 00:07:46,320 --> 00:07:48,240 There are monsters here. 67 00:07:49,480 --> 00:07:54,960 A giant sea bass weighing over 200 kilograms... 68 00:07:58,320 --> 00:08:01,800 ...and wolf eels with big teeth 69 00:08:01,920 --> 00:08:05,440 that can crush little red sea urchins. 70 00:08:08,000 --> 00:08:11,920 But the biggest danger comes from other sharks... 71 00:08:15,440 --> 00:08:17,120 ...houndsharks... 72 00:08:22,120 --> 00:08:26,160 ...and huge broadnose sevengills. 73 00:08:37,600 --> 00:08:39,400 In this forest, 74 00:08:39,520 --> 00:08:42,520 it pays to keep a low profile. 75 00:09:15,840 --> 00:09:18,240 An angel shark... 76 00:09:21,640 --> 00:09:23,320 ...one of the most deadly sharks 77 00:09:23,440 --> 00:09:25,680 in the kelp forest, 78 00:09:25,800 --> 00:09:28,840 and certainly the best camouflaged. 79 00:09:39,880 --> 00:09:43,720 An angel shark will lie in wait for days... 80 00:09:54,280 --> 00:09:58,240 ...but this one has already attracted 81 00:09:58,360 --> 00:10:00,040 too much attention. 82 00:10:06,520 --> 00:10:09,240 It's not welcome here. 83 00:10:10,280 --> 00:10:11,800 (GULPS) 84 00:10:15,920 --> 00:10:18,160 Now the coast is clear. 85 00:10:26,200 --> 00:10:30,280 But angel sharks hunt around the clock. 86 00:10:40,480 --> 00:10:43,920 Openings for breathing called spiracles 87 00:10:44,040 --> 00:10:47,520 blow out sand that helps cover its body. 88 00:10:54,920 --> 00:10:57,120 The trap is set. 89 00:11:09,000 --> 00:11:11,600 Staying close to the seabed 90 00:11:11,720 --> 00:11:15,200 is a good way to avoid most predators. 91 00:12:04,760 --> 00:12:07,680 Faster than the blink of an eye. 92 00:12:11,120 --> 00:12:13,200 But it's not over yet. 93 00:12:26,040 --> 00:12:28,920 Horn sharks have a secret weapon. 94 00:12:34,840 --> 00:12:36,480 Sharp spikes keep them 95 00:12:36,600 --> 00:12:39,000 very much off the menu for most. 96 00:12:45,480 --> 00:12:47,960 So this young horn shark... 97 00:12:49,480 --> 00:12:51,080 ...can hunt in safety... 98 00:12:53,360 --> 00:12:54,840 ...for now. 99 00:13:22,200 --> 00:13:26,880 Violent Winter storms batter these kelp forests. 100 00:13:34,120 --> 00:13:37,240 The plants can be ripped from the seafloor... 101 00:13:40,640 --> 00:13:43,920 ...and carried away far out to sea. 102 00:13:55,680 --> 00:14:00,720 The open ocean is a vast, featureless desert. 103 00:14:05,200 --> 00:14:07,520 Even a small piece of drifting kelp 104 00:14:07,640 --> 00:14:09,800 can become valuable. 105 00:14:19,960 --> 00:14:23,800 It's just what these fish have been searching for. 106 00:14:26,560 --> 00:14:30,160 Here, shelter, Where eggs can be laid unobtrusively, 107 00:14:30,280 --> 00:14:31,640 is rare... 108 00:14:33,600 --> 00:14:35,200 ...so they make the most of it. 109 00:14:38,240 --> 00:14:42,400 Each female produces up to 1,000 eggs, 110 00:14:42,520 --> 00:14:45,520 and the males rush in to fertilise them. 111 00:14:56,320 --> 00:15:01,520 All this activity attracts the attention of blue sharks. 112 00:15:04,320 --> 00:15:07,720 They can travel thousands of miles through the ocean 113 00:15:07,840 --> 00:15:09,840 in search of food. 114 00:15:14,080 --> 00:15:17,000 And they may not have eaten for weeks. 115 00:15:19,160 --> 00:15:21,200 It seems that they're in luck. 116 00:15:29,800 --> 00:15:32,920 But these fish are no easy meal. 117 00:15:40,000 --> 00:15:42,040 They are flying fish. 118 00:16:41,280 --> 00:16:43,680 The blue shark, however, 119 00:16:43,800 --> 00:16:46,280 are not here for the fish. 120 00:16:49,400 --> 00:16:53,120 They have come for the caviar. 121 00:17:07,840 --> 00:17:10,840 But flying fish lay so many eggs 122 00:17:10,960 --> 00:17:14,360 that the sharks' feasts hardly make an impact. 123 00:17:22,440 --> 00:17:24,760 And in a few months' time, 124 00:17:24,880 --> 00:17:28,160 a new generation will take to the skies. 125 00:17:41,440 --> 00:17:43,600 Floating islands of weed 126 00:17:43,720 --> 00:17:45,720 are always attractive to creatures 127 00:17:45,840 --> 00:17:49,160 looking for shelter out in the big blue. 128 00:17:51,520 --> 00:17:53,000 But in today's ocean 129 00:17:53,120 --> 00:17:55,760 they're being replaced by something else. 130 00:18:01,160 --> 00:18:02,360 Plastic. 131 00:18:04,560 --> 00:18:09,640 12 million tonnes of it end up in the ocean every year. 132 00:18:13,000 --> 00:18:15,040 The deadliest kind 133 00:18:15,160 --> 00:18:18,240 are discarded fishing lines and nets. 134 00:18:22,200 --> 00:18:25,720 Each year, it's likely over half a million animals 135 00:18:25,840 --> 00:18:30,480 are ensnared and killed by these ghost nets. 136 00:18:40,120 --> 00:18:41,800 But some animals 137 00:18:41,920 --> 00:18:43,920 are learning how to take advantage 138 00:18:44,040 --> 00:18:46,080 of the plastic rafts... 139 00:18:48,120 --> 00:18:52,760 ...and use them for shelter or even as a home. 140 00:18:56,080 --> 00:18:58,520 This male Columbus crab, 141 00:18:58,640 --> 00:19:00,800 barely bigger than your thumbnail, 142 00:19:00,920 --> 00:19:02,760 is a castaway. 143 00:19:06,560 --> 00:19:08,120 Clinging to his net, 144 00:19:08,240 --> 00:19:12,000 he may have been drifting on ocean currents for months. 145 00:19:15,160 --> 00:19:16,880 Now fully grown, 146 00:19:17,000 --> 00:19:19,360 he needs to find a partner. 147 00:19:21,520 --> 00:19:22,960 But Where? 148 00:19:24,120 --> 00:19:28,160 (HIGH-PITCHED WHISTLING AND CLICKING) 149 00:19:31,280 --> 00:19:33,760 Certainly not here, 150 00:19:33,880 --> 00:19:36,200 alone on the net. 151 00:19:45,840 --> 00:19:48,440 Columbus crabs are not good swimmers, 152 00:19:48,560 --> 00:19:50,720 so this male is marooned. 153 00:20:00,520 --> 00:20:03,120 Perhaps a passing loggerhead turtle 154 00:20:03,240 --> 00:20:05,720 could be the chance to hitch a lift. 155 00:20:57,000 --> 00:20:58,320 Made it. 156 00:21:00,880 --> 00:21:04,200 But there is more than one passenger here. 157 00:21:05,760 --> 00:21:08,440 A female Columbus crab. 158 00:21:16,120 --> 00:21:19,400 They waste no time in getting acquainted... 159 00:21:23,440 --> 00:21:25,280 ...and start to mate. 160 00:21:33,480 --> 00:21:35,840 This pair may well stay together 161 00:21:35,960 --> 00:21:38,240 for the rest of their lives. 162 00:21:48,160 --> 00:21:53,320 The turtle, after all, makes an excellent home. 163 00:22:01,200 --> 00:22:05,880 In return, the crabs provide an on board grooming service. 164 00:22:37,040 --> 00:22:42,360 Finding a partner in the vast ocean is not easy. 165 00:22:49,280 --> 00:22:52,880 Dawn in the Sea of Cortez. 166 00:23:16,560 --> 00:23:18,760 Mobula rays. 167 00:23:39,080 --> 00:23:42,640 They're gathering here, most likely, to breed. 168 00:23:47,680 --> 00:23:50,280 No-one is sure why they leap, 169 00:23:50,400 --> 00:23:52,360 but the loud splashes 170 00:23:52,480 --> 00:23:55,320 certainly seem to attract more rays. 171 00:23:55,440 --> 00:23:57,560 (THUNDEROUS SPLASHING) 172 00:23:59,800 --> 00:24:01,960 Other creatures, however, 173 00:24:02,080 --> 00:24:04,000 are also listening. 174 00:24:12,600 --> 00:24:14,360 (HIGH-PITCHED WHISTLING AND CLICKING) 175 00:24:14,480 --> 00:24:17,560 Orca have heard the splashes. 176 00:24:25,240 --> 00:24:29,080 (HIGH-PITCHED WHISTLING AND CLICKING) 177 00:24:39,080 --> 00:24:43,680 This female specialises in hunting rays. 178 00:24:50,120 --> 00:24:54,120 But today she is teaching two youngsters 179 00:24:54,240 --> 00:24:58,760 the finer points of mobula ray hunting. 180 00:25:07,080 --> 00:25:10,240 (HIGH-PITCHED WHISTLING AND CLICKING) 181 00:25:10,360 --> 00:25:14,480 The rays are fast and can outmanoeuvre an orca. 182 00:25:23,240 --> 00:25:26,480 She knows she needs to herd the prey 183 00:25:26,600 --> 00:25:27,880 into a tight group. 184 00:25:32,480 --> 00:25:36,240 But she can't do that on her own. 185 00:25:36,360 --> 00:25:38,040 It'll take teamwork. 186 00:25:40,360 --> 00:25:42,640 And that is today's lesson. 187 00:25:50,880 --> 00:25:54,400 The young orca are quick to catch on. 188 00:25:58,880 --> 00:26:01,320 The rays are surrounded. 189 00:26:05,800 --> 00:26:07,280 They dive... 190 00:26:11,320 --> 00:26:13,600 ...only to be forced back up again 191 00:26:13,720 --> 00:26:16,360 by the experienced female. 192 00:26:19,880 --> 00:26:20,840 And now, 193 00:26:20,960 --> 00:26:24,160 with the exhausted rays trapped against the surface... 194 00:26:25,560 --> 00:26:27,040 ...she attacks. 195 00:26:33,160 --> 00:26:36,760 (HIGH-PITCHED WHISTLING) 196 00:26:40,440 --> 00:26:44,520 And the young ones follow her lead. 197 00:26:53,400 --> 00:26:58,560 This family are the only orca known to hunt rays like this. 198 00:27:00,440 --> 00:27:02,760 And they are lethally efficient. 199 00:27:08,160 --> 00:27:12,240 But it appears that school is over for today. 200 00:27:13,720 --> 00:27:17,080 For a few battle-scarred survivors, 201 00:27:17,200 --> 00:27:19,520 it's a lucky reprieve. 202 00:27:30,160 --> 00:27:34,800 With the orca gone, the rays can resume their courtship. 203 00:27:43,280 --> 00:27:47,280 And they do so in astounding numbers. 204 00:27:56,280 --> 00:28:00,800 Tens of thousands of rays in a single shoal. 205 00:28:15,880 --> 00:28:19,720 Vast areas of our ocean are yet to be explored. 206 00:28:21,840 --> 00:28:25,920 The least known parts of it are its great depths. 207 00:28:27,400 --> 00:28:30,400 (INDISTINCT RADIO CHATTER) 208 00:28:32,800 --> 00:28:36,720 Only highly specialised vessels can take you there. 209 00:28:42,080 --> 00:28:46,360 As you descend, the sunlight rapidly fades. 210 00:28:52,960 --> 00:28:58,000 200 metres down, you enter the twilight zone. 211 00:29:05,080 --> 00:29:06,920 An alien world 212 00:29:07,040 --> 00:29:11,280 inhabited by creatures beyond imagination. 213 00:29:32,960 --> 00:29:35,360 The siphonophore, 214 00:29:35,480 --> 00:29:38,880 with a cloak of lethal stinging tentacles. 215 00:29:52,000 --> 00:29:55,800 Siphonophores repeatedly clone themselves, 216 00:29:55,920 --> 00:29:58,560 and so grow to immense lengths. 217 00:30:03,480 --> 00:30:06,520 This one measures 45 metres 218 00:30:06,640 --> 00:30:09,520 and is the longest animal ever recorded. 219 00:30:14,080 --> 00:30:16,880 With such deadly predators around, 220 00:30:17,000 --> 00:30:20,720 creatures here go to great lengths to hide. 221 00:30:30,920 --> 00:30:32,880 A glass squid. 222 00:30:34,920 --> 00:30:37,080 Completely transparent, 223 00:30:37,200 --> 00:30:39,880 except for its eyes... 224 00:30:43,360 --> 00:30:45,040 ...and stomach. 225 00:30:47,040 --> 00:30:50,840 So it is extremely difficult to find in the gloom. 226 00:31:12,080 --> 00:31:14,640 Below 1,000 metres, 227 00:31:14,760 --> 00:31:18,480 all traces of sunlight have disappeared. 228 00:31:20,800 --> 00:31:24,560 This is the midnight zone. 229 00:31:29,920 --> 00:31:32,920 Catching food in the perpetual darkness 230 00:31:33,040 --> 00:31:34,440 is not easy. 231 00:31:47,960 --> 00:31:49,720 (GULPS) 232 00:31:51,120 --> 00:31:52,840 (GULPS) 233 00:31:55,480 --> 00:31:57,280 The gulper eel. 234 00:32:05,720 --> 00:32:08,160 Its giant, extendable mouth 235 00:32:08,280 --> 00:32:11,920 can engulf prey larger than its own body. 236 00:32:35,040 --> 00:32:36,880 Two miles down, 237 00:32:37,000 --> 00:32:40,720 you finally reach the ocean floor. 238 00:32:45,840 --> 00:32:49,400 We know more about the surface of Mars. 239 00:32:54,640 --> 00:32:56,360 The pressure of the water 240 00:32:56,480 --> 00:33:00,720 is 300 times greater than at the surface, 241 00:33:00,840 --> 00:33:03,400 and it's freezing cold. 242 00:33:05,480 --> 00:33:10,600 Yet, amazingly, there are animals living here. 243 00:33:15,840 --> 00:33:18,520 Muusoctopus robustus, 244 00:33:18,640 --> 00:33:22,120 nicknamed the pearl octopus. 245 00:33:25,080 --> 00:33:28,120 Breeding in these extreme conditions 246 00:33:28,240 --> 00:33:31,000 poses a particular problem for these animals. 247 00:33:34,640 --> 00:33:37,000 At these low temperatures, 248 00:33:37,120 --> 00:33:38,800 this female's eggs 249 00:33:38,920 --> 00:33:42,000 could take over ten years to develop. 250 00:33:51,000 --> 00:33:55,280 So she travels to a very special place. 251 00:34:09,360 --> 00:34:12,160 This is the largest known gathering 252 00:34:12,280 --> 00:34:14,600 of octopus in the world. 253 00:34:24,680 --> 00:34:28,800 She joins 20,000 other females... 254 00:34:30,680 --> 00:34:33,200 ...all here to lay their eggs. 255 00:34:40,000 --> 00:34:43,320 Water, heated deep in the Earth's crust, 256 00:34:43,440 --> 00:34:46,840 rises through cracks in the seabed... 257 00:34:48,760 --> 00:34:53,840 ...raising the temperature to as much as ten degrees Celsius. 258 00:34:55,560 --> 00:34:58,240 A deep-sea thermal spa. 259 00:35:03,520 --> 00:35:06,360 This warmth significantly speeds up 260 00:35:06,480 --> 00:35:09,200 the development of their eggs. 261 00:35:09,320 --> 00:35:13,640 Even so, they will still take nearly two years to hatch. 262 00:35:16,040 --> 00:35:17,920 Once a female is settled, 263 00:35:18,040 --> 00:35:20,600 she won't move from her spot... 264 00:35:22,440 --> 00:35:24,880 ...not even to feed. 265 00:35:35,800 --> 00:35:40,200 She will constantly tend to her brood, 266 00:35:40,320 --> 00:35:43,320 keeping them clean 267 00:35:43,440 --> 00:35:47,240 and oxygenating them with jets of water. 268 00:35:51,680 --> 00:35:53,400 Pearl octopus mothers 269 00:35:53,520 --> 00:35:56,720 must surely be amongst the most devoted. 270 00:36:14,160 --> 00:36:16,440 After almost two years, 271 00:36:16,560 --> 00:36:19,400 the ordeal takes its toll. 272 00:36:26,680 --> 00:36:29,360 But the vigil is almost over. 273 00:37:27,480 --> 00:37:32,440 The last of the brood are gently encouraged to leave. 274 00:37:40,560 --> 00:37:43,520 But this will be a final act. 275 00:37:45,280 --> 00:37:47,640 Like all the mothers here, 276 00:37:47,760 --> 00:37:51,680 this octopus is starved and exhausted. 277 00:37:54,720 --> 00:37:57,400 Her life will soon be over. 278 00:38:15,760 --> 00:38:18,560 But this devotion means that her offspring 279 00:38:18,680 --> 00:38:21,360 are among the largest and most developed 280 00:38:21,480 --> 00:38:24,040 of any octopus, 281 00:38:24,160 --> 00:38:26,720 and have the best chance of survival 282 00:38:26,840 --> 00:38:29,800 in the demanding world of the deep. 283 00:38:46,240 --> 00:38:49,120 We are finding more of these strange hot springs 284 00:38:49,240 --> 00:38:50,600 every year. 285 00:38:53,720 --> 00:38:58,560 (BUBBLING) 286 00:39:01,720 --> 00:39:05,720 In some places, they can be astonishingly violent. 287 00:39:07,120 --> 00:39:09,280 Superheated water, 288 00:39:09,400 --> 00:39:14,040 hot enough to melt lead, spouts from the sea floor. 289 00:39:15,840 --> 00:39:18,160 Dissolved minerals condense around them 290 00:39:18,280 --> 00:39:23,520 to form towering chimneys known as hydrothermal vents. 291 00:39:27,760 --> 00:39:29,040 They are home 292 00:39:29,160 --> 00:39:30,840 to unique communities of animals 293 00:39:30,960 --> 00:39:35,640 that all rely on the nutrients in the scalding water. 294 00:39:45,400 --> 00:39:48,000 Some suggest that vents like these 295 00:39:48,120 --> 00:39:51,240 could be the places Where life on Earth first began 296 00:39:51,360 --> 00:39:53,360 4 billion years ago. 297 00:40:00,920 --> 00:40:04,320 And there is now evidence of hydrothermal vents 298 00:40:04,440 --> 00:40:07,720 on the moons of Jupiter and Saturn. 299 00:40:09,320 --> 00:40:12,120 Could they, too, be supporting life? 300 00:40:16,800 --> 00:40:20,800 Here on Earth, the influence of these vents 301 00:40:20,920 --> 00:40:24,120 extends far beyond their chimneys. 302 00:40:26,120 --> 00:40:29,080 The essential nutrients carried in these plumes 303 00:40:29,200 --> 00:40:31,560 can rise all the way to the surface, 304 00:40:31,680 --> 00:40:33,960 two miles above. 305 00:40:39,520 --> 00:40:42,000 Here, they stimulate the rapid growth 306 00:40:42,120 --> 00:40:46,880 of tiny marine plants on an astronomic scale. 307 00:40:53,760 --> 00:40:56,880 This phytoplankton is so abundant 308 00:40:57,000 --> 00:41:01,400 that it produces half of all the oxygen on Earth. 309 00:41:19,760 --> 00:41:24,680 It's also food for a host of minute animals - 310 00:41:24,800 --> 00:41:27,160 zooplankton. 311 00:41:29,800 --> 00:41:33,360 Together, they are the basis of the food chains 312 00:41:33,480 --> 00:41:36,160 that sustain nearly all life in the ocean. 313 00:41:42,200 --> 00:41:45,160 In the Pacific waters off South America, 314 00:41:45,280 --> 00:41:50,480 they feed anchovy that gather here in billions. 315 00:42:04,040 --> 00:42:07,960 This is one of the world's most productive ecosystems. 316 00:42:19,920 --> 00:42:23,680 These South American sea lions are on the hunt. 317 00:42:43,520 --> 00:42:47,840 But the anchovy shoal has already been located... 318 00:42:47,960 --> 00:42:51,280 (ENGINE RUMBLES) 319 00:42:53,520 --> 00:42:56,920 ...by the planet's most efficient hunters. 320 00:43:00,520 --> 00:43:04,800 A net over half a mile long encircles the shoal. 321 00:43:07,920 --> 00:43:10,920 It can trap over a million fish. 322 00:43:12,920 --> 00:43:16,680 (SEA BIRDS CAW) 323 00:43:22,680 --> 00:43:25,720 But the sea lions aren't about to go hungry. 324 00:43:28,000 --> 00:43:31,800 They have learnt to look for holes in the net. 325 00:43:41,640 --> 00:43:44,080 Why waste energy 326 00:43:44,200 --> 00:43:48,600 when food comes to you as easily as this? 327 00:43:54,560 --> 00:43:58,400 As more and more sea lions arrive, 328 00:43:58,520 --> 00:44:00,880 some change their tactics. 329 00:44:09,240 --> 00:44:11,560 They line up on both sides of the net... 330 00:44:13,320 --> 00:44:14,840 ...and wait. 331 00:44:20,440 --> 00:44:22,520 (SEA LIONS BARK) 332 00:44:30,160 --> 00:44:31,760 As the net tightens, 333 00:44:31,880 --> 00:44:35,480 the anchovy panic and rush for the surface. 334 00:44:37,840 --> 00:44:41,480 (SEA LIONS BARK) 335 00:44:41,600 --> 00:44:43,040 This is the moment 336 00:44:43,160 --> 00:44:45,440 the sea lions have been waiting for. 337 00:44:59,680 --> 00:45:01,960 It's such an effective way of hunfing 338 00:45:02,080 --> 00:45:03,480 that the sea lions here 339 00:45:03,600 --> 00:45:06,080 are changing their natural behaviour... 340 00:45:09,600 --> 00:45:13,000 ...and are raiding the fishing nets 341 00:45:13,120 --> 00:45:15,040 in their thousands. 342 00:45:18,520 --> 00:45:21,280 (BARKING) 343 00:45:23,520 --> 00:45:25,640 With the net almost drawn in, 344 00:45:25,760 --> 00:45:28,840 the fishermen beat out a warning signal. 345 00:45:28,960 --> 00:45:31,600 (CLANGS SIDE OF BOAT) 346 00:45:31,720 --> 00:45:32,760 (SEA LIONS BARK) 347 00:45:32,880 --> 00:45:34,320 Time is up. 348 00:45:44,840 --> 00:45:46,360 (CLANGS SIDE OF BOAT) 349 00:45:49,680 --> 00:45:53,840 (SEA LIONS BARK) 350 00:46:03,960 --> 00:46:08,800 In the confusion, not everyone manages to escape. 351 00:46:08,920 --> 00:46:12,320 (SEA LIONS WAIL) 352 00:46:16,840 --> 00:46:21,080 The trapped sea lions are in danger of being drowned. 353 00:46:23,160 --> 00:46:27,640 (SEA LIONS WAIL) 354 00:46:31,480 --> 00:46:35,920 (SEA LIONS WAIL) 355 00:46:42,840 --> 00:46:45,800 Pups were separated from their mothers. 356 00:47:05,440 --> 00:47:08,480 (SEA LIONS WAIL) 357 00:47:35,200 --> 00:47:38,320 (WINCH CREAKS) 358 00:47:41,000 --> 00:47:45,520 (SEA LIONS WAIL) 359 00:47:50,120 --> 00:47:52,760 Then, at the last minute, 360 00:47:52,880 --> 00:47:55,400 the fishermen briefly drop their net... 361 00:48:02,560 --> 00:48:05,160 ...and the trapped sea lions can escape. 362 00:48:13,840 --> 00:48:17,080 But many are not so lucky. 363 00:48:18,960 --> 00:48:20,280 Around the world, 364 00:48:20,400 --> 00:48:25,080 millions of animals are accidentally caught and die 365 00:48:25,200 --> 00:48:27,760 in fishing nets every day. 366 00:48:30,480 --> 00:48:34,200 And this by-catch, as it's known, 367 00:48:34,320 --> 00:48:37,400 is pushing many species toward extinction. 368 00:48:42,680 --> 00:48:45,640 Animals have evolved in remarkable ways 369 00:48:45,760 --> 00:48:48,360 to the demands of life in the ocean. 370 00:48:53,120 --> 00:48:57,400 But can they now adapt to the new challenge - 371 00:48:57,520 --> 00:49:00,000 living alongside us? 372 00:49:17,360 --> 00:49:19,320 DAVID: The open ocean is home 373 00:49:19,440 --> 00:49:20,680 to some of the largest 374 00:49:20,800 --> 00:49:23,400 and most extraordinary animals on Earth. 375 00:49:24,840 --> 00:49:27,560 But here, off the Canary Islands, 376 00:49:27,680 --> 00:49:29,760 the Manet Earth team are searching 377 00:49:29,880 --> 00:49:34,200 for one of its smaller and less familiar residents. 378 00:49:34,320 --> 00:49:35,640 We're looking for a tiny creature 379 00:49:35,760 --> 00:49:36,720 called a Columbus crab, 380 00:49:36,840 --> 00:49:38,280 which is only about the size of your thumbnail, 381 00:49:38,400 --> 00:49:42,240 which live on floating objects in the open ocean. 382 00:49:42,360 --> 00:49:45,760 Columbus crabs were once only found on natural debris 383 00:49:45,880 --> 00:49:47,480 like driftwood or seaweed, 384 00:49:47,600 --> 00:49:49,760 but the oceans are changing, 385 00:49:49,880 --> 00:49:52,200 and they've been forced to adapt. 386 00:50:06,560 --> 00:50:08,880 One of the most common items they find 387 00:50:09,000 --> 00:50:11,840 is discarded fishing gear. 388 00:50:13,440 --> 00:50:15,040 Over a million tonnes 389 00:50:15,160 --> 00:50:19,840 is left adrift in the ocean each year, 390 00:50:19,960 --> 00:50:22,840 and Columbus crabs are now making their homes 391 00:50:22,960 --> 00:50:25,440 on these unnatural materials. 392 00:50:32,680 --> 00:50:34,920 Surprisingly, Columbus crabs 393 00:50:35,040 --> 00:50:37,200 are thriving on this new habitat. 394 00:50:41,080 --> 00:50:46,240 But for larger ocean creatures, these nets can be lethal. 395 00:50:48,360 --> 00:50:52,600 Loggerhead sea turtles are especially vulnerable. 396 00:50:55,800 --> 00:50:58,360 Many times they are very injured 397 00:50:58,480 --> 00:51:01,320 and many times they don't even survive. 398 00:51:02,960 --> 00:51:04,720 It's a sad situation. 399 00:51:06,880 --> 00:51:10,720 As a rule, wildlife film-makers observe natural behaviour 400 00:51:10,840 --> 00:51:12,640 and do not interfere. 401 00:51:16,560 --> 00:51:18,640 But this is far from natural. 402 00:51:19,800 --> 00:51:22,600 The team feel they must take action. 403 00:51:33,000 --> 00:51:35,720 ANDREA CASINI: Sh, Sh, Sh! 404 00:51:35,840 --> 00:51:38,320 It seems that the turtle is quite OK. 405 00:51:38,440 --> 00:51:40,720 We'll just finish to cut the plastic 406 00:51:40,840 --> 00:51:42,240 and then we release it. 407 00:51:47,920 --> 00:51:50,680 (SPEAKS INDISTINCTLY) 408 00:51:56,400 --> 00:51:58,440 (LAUGHS) 409 00:51:59,800 --> 00:52:01,240 It's a bittersweet moment, 410 00:52:01,360 --> 00:52:03,920 as this is one of eight turtles they rescued 411 00:52:04,040 --> 00:52:05,400 whilst filming here. 412 00:52:06,800 --> 00:52:09,720 This situation is not natural. 413 00:52:09,840 --> 00:52:12,960 It's something that is being caused by human beings. 414 00:52:15,360 --> 00:52:18,360 Sadly, the crew now face dilemmas like this 415 00:52:18,480 --> 00:52:21,360 on many of their filming expeditions... 416 00:52:23,880 --> 00:52:26,040 ...including when they travelled 417 00:52:26,160 --> 00:52:28,440 to the Pacific coast of Chile 418 00:52:28,560 --> 00:52:31,360 to show how sea lions are competing for food 419 00:52:31,480 --> 00:52:33,800 with one of the biggest fisheries on Earth. 420 00:52:38,800 --> 00:52:41,480 Expedition leader Fernando Olivares 421 00:52:41,600 --> 00:52:43,760 takes the team to the fleet. 422 00:52:43,880 --> 00:52:47,280 (SEA LIONS BARK) 423 00:52:50,880 --> 00:52:53,960 Diving near fishing nets is extremely dangerous, 424 00:52:54,080 --> 00:52:57,640 so the crew must ensure they have the full cooperation 425 00:52:57,760 --> 00:52:59,360 of the fishermen. 426 00:53:24,600 --> 00:53:26,720 Pretty hazardous place to dive. 427 00:53:26,840 --> 00:53:29,160 It's just a case of trying to keep an eye on the divers, 428 00:53:29,280 --> 00:53:32,280 but the sea lions also like to go down and blow bubbles. 429 00:53:32,400 --> 00:53:34,240 So you'll think you're following the divers, 430 00:53:34,360 --> 00:53:36,040 and then a sea lion will pop up. 431 00:53:41,880 --> 00:53:43,920 Taking the utmost care, 432 00:53:44,040 --> 00:53:46,320 the divers get a close-up view 433 00:53:46,440 --> 00:53:48,800 of the sheer scale of the operation. 434 00:53:54,800 --> 00:53:57,960 This one there must have about 15 tonnes of fish in it, 435 00:53:58,080 --> 00:54:01,000 and there's eight or nine boats in this one little bay. 436 00:54:01,120 --> 00:54:03,040 And these are just the small boats. 437 00:54:03,160 --> 00:54:04,800 Out there, there are huge factory ships 438 00:54:04,920 --> 00:54:08,400 that are taking even bigger catches. 439 00:54:08,520 --> 00:54:10,520 How much fish a year from just here? 440 00:54:10,640 --> 00:54:14,960 From a million tonne a year, more or less. 441 00:54:22,600 --> 00:54:25,360 The catches are so vast, 442 00:54:25,480 --> 00:54:28,600 the sea lions have changed their natural behaviour 443 00:54:28,720 --> 00:54:31,720 to collect anchovies directly from the nets. 444 00:54:34,800 --> 00:54:38,400 But it's a risky strategy. 445 00:54:39,560 --> 00:54:44,240 The crew witnessed sea lions caught in nets multiple times. 446 00:54:44,360 --> 00:54:47,840 Whoa, it's intense, mate. There's so many in there. 447 00:54:47,960 --> 00:54:51,960 (SEA LIONS BARK) 448 00:54:53,520 --> 00:54:56,040 There's a pup stuck in the net calling to its mother, 449 00:54:56,160 --> 00:54:57,960 and its mother is just on the outside of the net, 450 00:54:58,080 --> 00:54:59,560 calling back. 451 00:55:00,640 --> 00:55:04,440 (SEA LIONS BARK) 452 00:55:05,800 --> 00:55:08,600 That is really hard to watch. 453 00:55:14,120 --> 00:55:16,640 No, the pup's really panicking now. 454 00:55:18,640 --> 00:55:22,760 Sometimes fishermen are able to release trapped sea lions... 455 00:55:24,560 --> 00:55:26,200 ...but not this time. 456 00:55:28,680 --> 00:55:31,240 The pup is in serious danger. 457 00:55:33,360 --> 00:55:37,080 Once again, the crew decide to step in. 458 00:55:43,400 --> 00:55:46,240 (SEA LIONS BARK) 459 00:55:56,280 --> 00:55:58,760 (APPLAUSE) 460 00:55:58,880 --> 00:56:02,000 (SEA LIONS BARK) 461 00:56:05,880 --> 00:56:07,360 Wow. 462 00:56:07,480 --> 00:56:09,040 (LAUGHS) 463 00:56:12,000 --> 00:56:13,600 Nice. Really nice. 464 00:56:16,120 --> 00:56:18,000 It's a relief this time... 465 00:56:20,520 --> 00:56:23,000 ...but it highlights the new realities 466 00:56:23,120 --> 00:56:28,480 of filming Wildlife in today's changing ocean.