1 00:00:18,393 --> 00:00:19,728 [Tom Hiddleston] The night. 2 00:00:24,399 --> 00:00:30,364 A shadowy world that hides more than half the animals on our planet. 3 00:00:33,617 --> 00:00:38,747 Until now, cameras only offered a glimpse into their lives. 4 00:00:41,792 --> 00:00:44,878 But with next-generation technology, 5 00:00:44,962 --> 00:00:49,883 we can see the night as clear as day. 6 00:00:56,557 --> 00:01:00,811 With cameras a hundred times more sensitive than the human eye... 7 00:01:04,105 --> 00:01:06,942 we can now capture the beauty of night... 8 00:01:09,361 --> 00:01:10,487 in color. 9 00:01:15,325 --> 00:01:17,202 Alien landscapes. 10 00:01:20,247 --> 00:01:24,877 Strange creatures brought to life by the darkness. 11 00:01:27,713 --> 00:01:30,215 Unseen behaviors. 12 00:01:37,306 --> 00:01:40,767 Now we can follow the lives of animals 13 00:01:41,643 --> 00:01:44,104 in Earth's last true wilderness. 14 00:01:46,565 --> 00:01:47,566 The night. 15 00:02:11,632 --> 00:02:16,887 Evening is falling over the tropical islands of Indonesia. 16 00:02:22,309 --> 00:02:24,686 And hidden beneath the waves... 17 00:02:26,605 --> 00:02:31,610 lie some of the planet's most pristine underwater worlds. 18 00:02:39,868 --> 00:02:41,078 Coral reefs... 19 00:02:47,042 --> 00:02:50,087 our seas' treasure troves of life. 20 00:02:53,507 --> 00:02:58,637 Across the world, they cover less than one percent of the seabed... 21 00:03:01,265 --> 00:03:05,519 but support over a third of life in our oceans. 22 00:03:14,403 --> 00:03:18,073 The reef is a bustling undersea city... 23 00:03:20,742 --> 00:03:24,538 with creatures of all shapes and sizes busy feeding. 24 00:03:29,543 --> 00:03:33,046 Humphead parrotfish, the reef's bulldozers, 25 00:03:33,130 --> 00:03:35,674 munch coral with birdlike beaks... 26 00:03:41,972 --> 00:03:45,809 while hawksbill turtles snack on the softer sponges 27 00:03:45,893 --> 00:03:48,228 that grow beneath the hard corals. 28 00:03:59,072 --> 00:04:04,620 For the ingenious, food can be found in the most unlikely of places. 29 00:04:08,332 --> 00:04:12,503 Small cleaner wrasse offer an intimate service. 30 00:04:13,504 --> 00:04:18,175 As they nibble food stuck in their neighbors' mouths. 31 00:04:29,603 --> 00:04:32,314 Evening is rush hour on the reef, 32 00:04:33,065 --> 00:04:37,569 with the residents making the most of the light while it lasts. 33 00:04:50,082 --> 00:04:52,376 But this busy world... 34 00:04:54,211 --> 00:04:55,796 is about to change. 35 00:05:05,722 --> 00:05:08,600 Because there is another side to coral reefs... 36 00:05:11,520 --> 00:05:16,233 that only emerges when the sun goes down. 37 00:05:28,871 --> 00:05:31,081 With the latest filming techniques... 38 00:05:33,250 --> 00:05:36,086 we can see into this hidden realm... 39 00:05:37,504 --> 00:05:44,511 and witness the drama of the world's coral reefs at night. 40 00:05:58,942 --> 00:06:04,531 As darkness falls, smaller fish shoal together for safety in numbers. 41 00:06:08,785 --> 00:06:13,874 The beginning of night is the most dangerous time on the reef. 42 00:06:20,547 --> 00:06:21,757 Cornetfish. 43 00:06:22,591 --> 00:06:26,595 A meter long and armed with a rifle-like snout. 44 00:06:28,639 --> 00:06:31,350 The reef's nocturnal marksman. 45 00:06:37,064 --> 00:06:40,234 With large, light-sensitive eyes... 46 00:06:42,236 --> 00:06:45,072 they line up on the school of fish... 47 00:06:50,160 --> 00:06:54,456 and let fire with deadly precision. 48 00:06:55,040 --> 00:06:56,708 [whooshes] 49 00:07:05,133 --> 00:07:09,763 They trap their prey in their syringe-like mouth. 50 00:07:13,559 --> 00:07:15,686 [whoosh] 51 00:07:15,769 --> 00:07:19,398 And pick off fish one at a time. 52 00:07:32,703 --> 00:07:34,621 As they swallow their prize... 53 00:07:35,497 --> 00:07:37,082 all that's left of the catch... 54 00:07:39,710 --> 00:07:42,087 is a puff of scales. 55 00:07:48,385 --> 00:07:52,973 But cornetfish aren't the only hunters lurking in the darkness. 56 00:07:58,061 --> 00:08:01,899 The reef's residents hide deep in cracks and crevices... 57 00:08:02,941 --> 00:08:07,779 because bigger, deadlier predators are now emerging. 58 00:08:09,865 --> 00:08:14,244 And each stalks the night reef in its own way. 59 00:08:32,596 --> 00:08:39,144 This whitetip reef shark will devour fish that linger too long above the reef. 60 00:08:42,481 --> 00:08:44,816 And she's not alone. 61 00:08:48,612 --> 00:08:53,534 A stingray, every little fish's nightmare. 62 00:08:56,036 --> 00:09:03,001 For his victims, the night appears almost pitch black. 63 00:09:05,629 --> 00:09:07,673 They can't see him coming. 64 00:09:10,717 --> 00:09:12,177 But our cameras reveal... 65 00:09:13,512 --> 00:09:15,514 how he stalks the reef. 66 00:09:17,933 --> 00:09:20,686 He uses electroreceptors... 67 00:09:21,728 --> 00:09:26,149 not eyesight, to sense the movement of fish hiding in the coral... 68 00:09:28,735 --> 00:09:31,280 or crabs buried in the sand. 69 00:09:34,867 --> 00:09:36,285 [water whooshes] 70 00:09:36,368 --> 00:09:40,873 Wings up to two meters wide trap them on the seabed. 71 00:09:47,754 --> 00:09:52,217 Flushing away the sand exposes the victim... 72 00:09:54,011 --> 00:09:55,637 [water whooshes] 73 00:09:59,850 --> 00:10:02,186 ...before his vacuum-like mouth... 74 00:10:02,269 --> 00:10:03,312 [whooshes] 75 00:10:07,524 --> 00:10:08,734 ...gobbles them up. 76 00:10:28,420 --> 00:10:30,839 With so many predators about at night... 77 00:10:30,923 --> 00:10:32,132 [whooshes] 78 00:10:34,551 --> 00:10:36,428 ...it's best to keep your head down. 79 00:10:48,690 --> 00:10:50,359 But despite the dangers... 80 00:10:52,569 --> 00:10:58,283 one colorful little fish is about to leave the safety of the reef. 81 00:11:02,829 --> 00:11:04,373 A mandarinfish. 82 00:11:07,876 --> 00:11:09,127 And this male... 83 00:11:09,837 --> 00:11:12,464 is on the lookout for love. 84 00:11:15,926 --> 00:11:21,932 Tonight, he's hoping to court up to eight females in under an hour. 85 00:11:25,394 --> 00:11:31,316 But to find them, he's going to have to move very carefully. 86 00:11:43,662 --> 00:11:46,164 Through the darkness, he spies... 87 00:11:47,791 --> 00:11:49,001 a female... 88 00:11:50,252 --> 00:11:55,507 having her evening meal of tiny, shrimp-like copepods. 89 00:11:58,927 --> 00:12:01,722 But she's as picky about her lovers... 90 00:12:04,600 --> 00:12:07,603 as she is about her food. 91 00:12:17,154 --> 00:12:21,575 To win her affections, the male now spreads his fins... 92 00:12:23,327 --> 00:12:28,457 to appear as big and irresistible as possible. 93 00:12:36,048 --> 00:12:37,883 She's impressed. 94 00:12:48,477 --> 00:12:54,149 But to mate, it's now time for an even bolder move... 95 00:12:56,151 --> 00:12:59,404 and to use the darkness to their advantage. 96 00:13:05,202 --> 00:13:08,413 With fish that would eat their eggs hiding amongst the coral... 97 00:13:14,378 --> 00:13:18,340 the new couple rise above the reef... 98 00:13:20,050 --> 00:13:23,971 to spawn in a dazzling courtship dance. 99 00:13:40,529 --> 00:13:42,656 With their nighttime display over... 100 00:13:43,866 --> 00:13:46,660 the couple retreat to the safety of the coral... 101 00:13:49,913 --> 00:13:51,623 but not for long. 102 00:13:55,252 --> 00:13:58,172 With up to seven more females to find... 103 00:14:00,215 --> 00:14:04,469 this Casanova is off to brave the dark 104 00:14:04,553 --> 00:14:07,931 in search of his next dancing partner. 105 00:14:20,569 --> 00:14:22,070 As the night draws on... 106 00:14:23,113 --> 00:14:27,284 the darkness triggers one of nature's most astonishing hidden wonders... 107 00:14:33,207 --> 00:14:38,545 an event that will bring a magical change to the reef. 108 00:14:43,050 --> 00:14:48,639 From the ocean depths, an army of tiny animals is emerging... 109 00:14:51,391 --> 00:14:54,311 as if from an alien world. 110 00:14:58,857 --> 00:15:03,111 It's the greatest migration of creatures anywhere on the planet, 111 00:15:03,987 --> 00:15:07,491 and it happens every night in our oceans. 112 00:15:11,036 --> 00:15:14,665 Over a billion tons of planktonic life 113 00:15:14,748 --> 00:15:19,169 rise from the depths to feed in the surface waters. 114 00:15:28,762 --> 00:15:32,558 These creatures, some no bigger than a grain of rice... 115 00:15:34,059 --> 00:15:36,728 are the lifeblood of the ocean. 116 00:15:42,067 --> 00:15:45,946 With ingenious forms of luminescence and propulsion... 117 00:15:49,867 --> 00:15:54,079 they capture morsels of food adrift in the dark. 118 00:16:16,143 --> 00:16:20,105 Some creatures live entirely in this hidden world. 119 00:16:23,609 --> 00:16:26,612 Others, like this mantis shrimp larvae, 120 00:16:27,196 --> 00:16:31,450 spend only the first part of their lives in this alien existence 121 00:16:32,034 --> 00:16:35,621 and will return to live on the reef once they grow. 122 00:16:58,519 --> 00:17:00,812 This rising tide of life... 123 00:17:01,522 --> 00:17:07,277 now triggers the coral reef to undergo a magical transformation. 124 00:17:13,367 --> 00:17:16,994 Seemingly dormant rocks come to life. 125 00:17:43,522 --> 00:17:49,695 Coral reefs are made up of colossal colonies of tiny animals. 126 00:17:51,446 --> 00:17:54,992 By day, the reef absorbs energy from the sun. 127 00:17:58,036 --> 00:17:59,246 But at night... 128 00:18:01,999 --> 00:18:06,044 these animals spread their tentacles to become hunters... 129 00:18:07,713 --> 00:18:10,841 of a microscopic nocturnal realm. 130 00:18:18,515 --> 00:18:20,851 For the tiny animals drifting in... 131 00:18:22,769 --> 00:18:29,776 this colorful garden has turned into a deadly wall of millions of mouths. 132 00:18:52,591 --> 00:18:57,471 This nighttime feast provides corals with the nutrients 133 00:18:57,554 --> 00:18:59,681 that are essential for the reef to grow. 134 00:19:03,602 --> 00:19:08,440 And we now know, as coral reefs struggle with rising sea temperatures, 135 00:19:09,024 --> 00:19:13,779 this nighttime feeding is more vital than ever for their survival. 136 00:19:33,924 --> 00:19:39,555 But it's not just the tiny corals that rely on the nighttime tide of plankton. 137 00:19:43,058 --> 00:19:48,939 Other far larger creatures are gathering for the night's final feast: 138 00:19:53,735 --> 00:19:59,783 a manta ray, gliding on wings up to four meters wide. 139 00:20:02,661 --> 00:20:04,204 Though usually solitary... 140 00:20:05,747 --> 00:20:10,294 there are places in the tropical seas where the plankton is so rich, 141 00:20:10,377 --> 00:20:12,921 mantas come together to feed. 142 00:20:18,302 --> 00:20:22,556 Most astonishing, these one-ton giants 143 00:20:23,056 --> 00:20:29,188 are sustained by the tiny planktonic animals that rise in the sea at night. 144 00:20:37,487 --> 00:20:42,534 With hornlike fins, they funnel the plankton into their open mouths... 145 00:20:48,457 --> 00:20:50,918 and sift out the morsels of food. 146 00:21:01,261 --> 00:21:03,347 Now in the dead of night... 147 00:21:04,473 --> 00:21:09,853 they reveal their mastery in feeding on the night's riches. 148 00:21:35,796 --> 00:21:38,715 By barrel-rolling over and over... 149 00:21:39,591 --> 00:21:42,886 they target the greatest concentrations of plankton... 150 00:21:44,429 --> 00:21:46,932 which they then devour. 151 00:22:17,629 --> 00:22:22,759 We now know that manta rays possess the largest brains of any fish. 152 00:22:24,761 --> 00:22:29,308 But how they navigate huge distances to find food 153 00:22:29,391 --> 00:22:34,479 in the vastness of the dark ocean remains a mystery. 154 00:22:42,821 --> 00:22:47,534 It's one of many secrets still to be discovered... 155 00:22:48,118 --> 00:22:50,579 in our seas at night. 156 00:23:15,312 --> 00:23:19,149 To capture the nighttime dramas of coral reefs, 157 00:23:19,233 --> 00:23:24,071 the Earth at Night team filmed in some of the world's most pristine tropical waters. 158 00:23:28,951 --> 00:23:31,119 For cameraman David Reichert, 159 00:23:31,203 --> 00:23:36,124 the biggest challenge was filming the reef's predators hunting at night. 160 00:23:38,544 --> 00:23:43,006 Sharks and other predators can be more active at night... 161 00:23:45,843 --> 00:23:49,304 but can also be very hard to approach safely. 162 00:23:53,183 --> 00:23:55,394 [man] Filming at night is a whole new world. 163 00:23:59,898 --> 00:24:02,693 We just don't know what's gonna come out of the dark. 164 00:24:05,112 --> 00:24:06,947 We'll find out. We're about to jump in. 165 00:24:17,875 --> 00:24:21,628 [Tom Hiddleston] David had to plan his dives around the full moon, 166 00:24:21,712 --> 00:24:24,381 when strong currents wash food into the reef... 167 00:24:25,215 --> 00:24:27,968 and can make the predators more active. 168 00:24:32,139 --> 00:24:34,474 But it creates a big problem. 169 00:24:34,975 --> 00:24:38,437 Surface to divers, surface to divers. How is the current? 170 00:24:38,520 --> 00:24:43,192 -[static] -Not good. The current is too strong. 171 00:24:44,818 --> 00:24:47,321 [Reichert] We're boarding. Coming up. 172 00:24:51,658 --> 00:24:53,952 Current is ripping down there right now, 173 00:24:54,036 --> 00:24:57,789 making it almost impossible to stay put. 174 00:24:57,873 --> 00:24:59,249 Well, that was terrible. 175 00:25:00,667 --> 00:25:01,752 Yeah... 176 00:25:03,212 --> 00:25:05,297 [Reichert] There's more action, more things to film, 177 00:25:05,380 --> 00:25:07,132 more life when the currents are up... 178 00:25:07,216 --> 00:25:08,800 [male diver] Still too strong. 179 00:25:08,884 --> 00:25:11,512 [Reichert] But we are struggling just to be there. 180 00:25:11,595 --> 00:25:13,055 That's kinda the game we're playing. 181 00:25:16,683 --> 00:25:22,397 [Tom Hiddleston] Over the coming nights, as the full moon wanes, the currents ease. 182 00:25:24,691 --> 00:25:29,613 But although it makes diving easier, the reefs are empty. 183 00:25:32,533 --> 00:25:33,534 [male diver] Yeah. 184 00:25:33,617 --> 00:25:38,205 Yeah, current kinda died, and then, uh, I guess that was-- 185 00:25:38,288 --> 00:25:39,706 Yeah, everybody just went home. 186 00:25:39,790 --> 00:25:41,250 -Yeah. -Yeah. 187 00:25:42,626 --> 00:25:45,379 [Tom Hiddleston] As the team searched for the right conditions... 188 00:25:45,462 --> 00:25:48,340 they discover they have to hit a tiny window... 189 00:25:49,383 --> 00:25:52,177 when the water slackens between currents. 190 00:26:00,602 --> 00:26:02,104 [Reichert] It's tough to film like that, 191 00:26:02,187 --> 00:26:06,483 because it can be maybe 6:00 p.m. right when the sun sets, 192 00:26:06,567 --> 00:26:11,363 but then as soon as we miss that window, suddenly it's 4:00 a.m. 193 00:26:11,446 --> 00:26:12,906 So we get in these terrible schedules 194 00:26:12,990 --> 00:26:18,161 where we having to, like, wait all night for a 40-minute dive. 195 00:26:18,745 --> 00:26:21,832 [yawns] Gimme a cup of tea. 196 00:26:21,915 --> 00:26:23,166 [exhales deeply] 197 00:26:24,960 --> 00:26:27,921 [Tom Hiddleston] With perseverance and many sleepless nights... 198 00:26:28,964 --> 00:26:32,009 David and the team finally begin to capture 199 00:26:32,092 --> 00:26:35,220 the new behaviors they've been searching for. 200 00:26:36,263 --> 00:26:39,766 [Reichert] I've never seen these cornet fish attack like that before. 201 00:26:40,642 --> 00:26:42,728 You don't win 'em all, but I think we won that one. 202 00:26:47,316 --> 00:26:51,403 [Tom Hiddleston] Each predator had their own way of stalking their prey. 203 00:26:53,447 --> 00:26:58,285 Moray eels were venturing into the reef to hunt. 204 00:26:58,368 --> 00:27:00,954 [Reichert] The moray was, like, working the top of the reef. 205 00:27:02,372 --> 00:27:05,459 And there was, like, a little hole that it kinda went down through. 206 00:27:13,050 --> 00:27:14,843 Sure enough, there was a little fish down there, 207 00:27:14,927 --> 00:27:16,053 and the moray came down there. 208 00:27:17,221 --> 00:27:18,305 Well, there it is. 209 00:27:23,101 --> 00:27:24,353 And then, boom. 210 00:27:26,563 --> 00:27:28,315 [whooshes] 211 00:27:28,398 --> 00:27:31,693 Got it! Right in front of the camera. Right in the hole too. That was good. 212 00:27:36,490 --> 00:27:38,992 There's a lot going on on these reefs. 213 00:27:39,952 --> 00:27:43,288 You start to see this really vibrant community down there 214 00:27:43,372 --> 00:27:45,999 that seems to just come alive at night. 215 00:27:50,295 --> 00:27:54,091 [Tom Hiddleston] The crew had managed to capture unique new insights 216 00:27:54,174 --> 00:27:57,678 into this magical underwater world.