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These are the user uploaded subtitles that are being translated: 1 00:00:00,000 --> 00:00:00,033 Edited at https://subtitletools.com 2 00:00:08,400 --> 00:00:10,320 As dusk gives way to twilight, 3 00:00:10,320 --> 00:00:13,760 the encroaching darkness is lit by life. 4 00:00:17,880 --> 00:00:24,000 These dancing lights around me are produced by fireflies - 5 00:00:24,000 --> 00:00:28,360 creatures that have the strange ability to produce light. 6 00:00:28,360 --> 00:00:30,120 They bioluminesce. 7 00:00:33,880 --> 00:00:36,560 And fireflies are not alone. 8 00:00:36,560 --> 00:00:39,240 Scientists are finding ever more strange and wonderful 9 00:00:39,240 --> 00:00:42,480 glowing life forms all around the world. 10 00:00:47,560 --> 00:00:50,480 Living light has always fascinated me. 11 00:00:50,480 --> 00:00:54,360 And the discovery of more and more luminous creatures raises more 12 00:00:54,360 --> 00:00:56,240 and more questions. 13 00:00:56,240 --> 00:01:00,720 Why? What is the light for? And how is it made? 14 00:01:03,400 --> 00:01:04,640 In recent years, 15 00:01:04,640 --> 00:01:08,000 scientists have begun to find answers to those questions. 16 00:01:08,000 --> 00:01:09,560 And in doing so, 17 00:01:09,560 --> 00:01:13,600 they've taken us into a world that is utterly unlike our own. 18 00:01:19,760 --> 00:01:23,840 However astonishing these images look, they are all real. 19 00:01:28,360 --> 00:01:32,200 With help from new cameras, one designed just for this film, 20 00:01:32,200 --> 00:01:34,920 we can reveal this extraordinary phenomenon 21 00:01:34,920 --> 00:01:36,880 as it has never been seen before. 22 00:01:54,840 --> 00:01:58,080 Bioluminescence holds many mysteries. 23 00:01:58,080 --> 00:02:02,480 But we do know that fireflies use it to attract the opposite sex. 24 00:02:16,960 --> 00:02:22,840 Each species has its own flash code and WE can join in the conversation. 25 00:02:29,600 --> 00:02:34,560 I'm going to use this rod to fish for fireflies. 26 00:02:35,800 --> 00:02:39,720 It's the actual rod used by the scientist who was the first 27 00:02:39,720 --> 00:02:43,360 to decipher the various call signs of fireflies. 28 00:02:43,360 --> 00:02:48,120 And there are 15 different species, at least, around here. 29 00:02:48,120 --> 00:02:50,480 Each with its own signal. 30 00:02:50,480 --> 00:02:55,200 Biologist Jim Lloyd used the rod to imitate male fireflies 31 00:02:55,200 --> 00:02:59,200 and so decode their various light patterns. 32 00:02:59,200 --> 00:03:03,720 He discovered that the call sign consisted partly in 33 00:03:03,720 --> 00:03:06,920 the actual flight path of the species concerned. 34 00:03:06,920 --> 00:03:09,080 There are, for example, 35 00:03:09,080 --> 00:03:13,360 some fireflies which move steadily horizontally, like that. 36 00:03:13,360 --> 00:03:15,760 And there are others which 37 00:03:15,760 --> 00:03:19,360 turn their light on as they climb, like that. 38 00:03:20,920 --> 00:03:25,840 But in addition to the flight path, they flash a particular signal. 39 00:03:25,840 --> 00:03:27,800 It's rather like Morse code. 40 00:03:28,920 --> 00:03:31,640 So I should be able to use this light myself. 41 00:03:33,440 --> 00:03:37,040 There is a female amongst these leaves here, 42 00:03:37,040 --> 00:03:39,880 which will emit a single flash. 43 00:03:39,880 --> 00:03:46,440 And the male of her species waits for precisely four seconds, 44 00:03:46,440 --> 00:03:49,560 and then answers back with a flash. 45 00:03:49,560 --> 00:03:54,160 Whereupon she immediately gives another flash, like that. 46 00:03:55,400 --> 00:03:59,440 And the male then knows that he is going to be a welcome visitor. 47 00:04:01,520 --> 00:04:04,560 But the message has recently been shown to be more than 48 00:04:04,560 --> 00:04:06,560 a simple signal for sex. 49 00:04:08,040 --> 00:04:11,320 A female judges the quality of a male's genes 50 00:04:11,320 --> 00:04:14,960 by the precision of his timing and the brightness of his light. 51 00:04:20,960 --> 00:04:25,680 She encourages her chosen suitor by directing her lanterns towards him. 52 00:04:36,960 --> 00:04:40,960 And it seems this male sent out all the right signals. 53 00:04:45,720 --> 00:04:47,360 We are now discovering that 54 00:04:47,360 --> 00:04:50,200 this language of light even has local dialects. 55 00:04:55,360 --> 00:04:59,040 Throughout the summer months, from Florida to southern Canada, 56 00:04:59,040 --> 00:05:03,600 gardens, fields and forests sparkle with these mating messages. 57 00:05:08,080 --> 00:05:10,120 Time-lapse photography reveals 58 00:05:10,120 --> 00:05:12,920 the extraordinary extent of this courtship. 59 00:05:18,880 --> 00:05:22,000 Some species flash only at dusk. 60 00:05:24,160 --> 00:05:27,320 Others prefer the forest canopy for their light show. 61 00:05:32,240 --> 00:05:36,680 Some species make their flashes more conspicuous by choosing 62 00:05:36,680 --> 00:05:39,280 the very darkest places in which to display. 63 00:05:40,320 --> 00:05:45,160 I can see virtually nothing here, except the flashes. 64 00:05:47,680 --> 00:05:51,040 And this particular species has another trick, too. 65 00:05:52,040 --> 00:05:54,760 It synchronises the displays. 66 00:05:54,760 --> 00:05:57,400 Individuals flash together. 67 00:06:01,840 --> 00:06:04,600 Each individual is triggered by its neighbour, 68 00:06:04,600 --> 00:06:08,600 and soon waves of light pulse through the woods. 69 00:06:14,960 --> 00:06:17,520 Speeded up, the wave becomes clearer. 70 00:06:26,520 --> 00:06:27,800 Between the waves, 71 00:06:27,800 --> 00:06:32,080 an impressed female can respond with two flashes of her own. 72 00:06:34,440 --> 00:06:36,080 And the males home in on her. 73 00:06:38,840 --> 00:06:40,760 But she can only choose one. 74 00:06:45,240 --> 00:06:49,360 These displays peak for just a few nights in June, 75 00:06:49,360 --> 00:06:53,160 which could explain why they were only recently discovered. 76 00:06:55,040 --> 00:06:58,680 Why they all flash together is still a mystery. 77 00:07:06,960 --> 00:07:11,080 It's surprising how little we know about bioluminescence. 78 00:07:12,440 --> 00:07:14,880 Fireflies are perhaps the best understood 79 00:07:14,880 --> 00:07:19,520 but some living light is still very perplexing indeed. 80 00:07:19,520 --> 00:07:23,720 With dawn, the sexual signals of the fireflies are drowned 81 00:07:23,720 --> 00:07:26,040 by the increasing flood of light. 82 00:07:26,040 --> 00:07:28,800 The flies take refuge in the undergrowth, 83 00:07:28,800 --> 00:07:32,560 away from the sharp-eyed predators of the day. 84 00:07:32,560 --> 00:07:34,040 But right now, 85 00:07:34,040 --> 00:07:38,680 light is being produced by life in the soil under my feet. 86 00:07:42,360 --> 00:07:47,000 The threads of certain fungi form a glowing underground network. 87 00:07:56,160 --> 00:08:00,560 But why would a fungus shine in the permanent darkness of the soil? 88 00:08:00,560 --> 00:08:02,560 We simply don't know. 89 00:08:04,560 --> 00:08:08,240 And for years, fungus bioluminescence, 90 00:08:08,240 --> 00:08:11,680 like much other living light, was written off as a beautiful 91 00:08:11,680 --> 00:08:14,480 by-product of evolution with no function. 92 00:08:17,640 --> 00:08:21,760 But some species only glow above ground and only at night, 93 00:08:21,760 --> 00:08:24,680 when their intense green light is very obvious. 94 00:08:29,400 --> 00:08:32,600 If it was just a biochemical accident then surely 95 00:08:32,600 --> 00:08:34,880 they would shine all the time. 96 00:08:34,880 --> 00:08:37,320 The glow certainly attracts insects 97 00:08:37,320 --> 00:08:40,960 and the theory is that these visitors spread the fungal spores. 98 00:08:53,840 --> 00:08:56,960 So here, too, just as with fireflies, 99 00:08:56,960 --> 00:08:59,760 we're learning new things all the time. 100 00:09:05,360 --> 00:09:09,200 But much living light remains a beautiful enigma. 101 00:09:12,200 --> 00:09:13,920 And throughout history, 102 00:09:13,920 --> 00:09:17,680 stories of bioluminescence were often thought to be pure fiction. 103 00:09:19,960 --> 00:09:24,960 In the 1870s, Jules Verne, the French science-fiction novelist, 104 00:09:24,960 --> 00:09:29,280 wrote this in his book, 20,000 Leagues Under The Sea. 105 00:09:30,800 --> 00:09:34,960 "At seven o'clock in the evening, our ship, half-immersed, 106 00:09:34,960 --> 00:09:38,120 "was sailing in a sea of milk. 107 00:09:38,120 --> 00:09:41,880 "At first sight, the ocean seemed lactified. 108 00:09:41,880 --> 00:09:45,720 "The whole sky seemed black by contrast with 109 00:09:45,720 --> 00:09:48,640 "the whiteness of the waters." 110 00:09:48,640 --> 00:09:51,240 Jules Verne may have based this story 111 00:09:51,240 --> 00:09:53,680 on a myth told to him by sailors. 112 00:09:53,680 --> 00:09:58,080 But in 1995, the captain of a British vessel wrote 113 00:09:58,080 --> 00:10:01,840 a real-life account in his ship's log. 114 00:10:01,840 --> 00:10:05,080 "At 18:00 hours on a clear moonless night, 115 00:10:05,080 --> 00:10:09,240 "while 150 miles east of the Somalian coast, 116 00:10:09,240 --> 00:10:12,880 "a whitish glow was observed on the horizon. 117 00:10:12,880 --> 00:10:17,920 "And after 15 minutes of steaming, the ship was completely surrounded 118 00:10:17,920 --> 00:10:24,160 "by a sea of milky white colour with a fairly uniform luminescence. 119 00:10:24,160 --> 00:10:27,200 "And it appeared as though the ship was sailing over 120 00:10:27,200 --> 00:10:31,240 "a field of snow or gliding over the clouds." 121 00:10:34,880 --> 00:10:37,640 Reports like this are rarer than the supposed sightings 122 00:10:37,640 --> 00:10:39,760 of the Loch Ness Monster. 123 00:10:39,760 --> 00:10:42,400 And there was no photographic evidence. 124 00:10:45,320 --> 00:10:49,400 Some scientists, including marine biologist Steven Haddock, 125 00:10:49,400 --> 00:10:53,200 were curious, and sought confirmation from above. 126 00:10:55,600 --> 00:10:58,560 We wondered if you could find one of these ship reports where 127 00:10:58,560 --> 00:11:01,360 they record sailing through one of these milky seas, 128 00:11:01,360 --> 00:11:04,440 and actually find the corresponding satellite data that cover 129 00:11:04,440 --> 00:11:07,240 that area at that same time. 130 00:11:07,240 --> 00:11:10,680 So we looked at the satellite from the ship report in 1995 131 00:11:10,680 --> 00:11:13,600 and it was somewhat of a eureka moment. 132 00:11:13,600 --> 00:11:16,680 We cleaned up the noisy sensor image from the camera, 133 00:11:16,680 --> 00:11:20,960 we mapped it onto the ship track, and this 300km feature 134 00:11:20,960 --> 00:11:25,320 emerged on the map matching exactly with what the ship had reported. 135 00:11:25,320 --> 00:11:28,240 So it was really an amazing moment. 136 00:11:28,240 --> 00:11:31,640 We were able to document the full extent of the milky sea over 137 00:11:31,640 --> 00:11:35,160 three successive nights as it rotated with the currents. 138 00:11:35,160 --> 00:11:39,040 So satellite images from the space age validated 139 00:11:39,040 --> 00:11:41,520 a piece of maritime folklore. 140 00:11:43,360 --> 00:11:46,080 On rare occasions, the oceans do glow. 141 00:11:49,240 --> 00:11:50,920 But what was causing a glow 142 00:11:50,920 --> 00:11:53,520 so bright that it could be seen from space? 143 00:11:55,280 --> 00:11:59,560 The answer can be found at the back of a neglected fridge. 144 00:12:05,600 --> 00:12:10,440 Left for a couple of days, this sea bream starts to glow. 145 00:12:19,520 --> 00:12:23,200 The fish itself has no light-producing ability. 146 00:12:24,520 --> 00:12:28,760 The glow is, in fact, produced by bacteria that are found 147 00:12:28,760 --> 00:12:32,920 in almost all seawater when they start to feed on decaying fish. 148 00:12:34,360 --> 00:12:38,480 On rare occasions when currents and temperatures cause a large bloom of 149 00:12:38,480 --> 00:12:43,840 algae in the ocean, these very same bacteria also feed on dying algae. 150 00:12:45,400 --> 00:12:47,880 Once they reach a critical concentration, 151 00:12:47,880 --> 00:12:51,000 their secretions trigger others to glow. 152 00:12:53,120 --> 00:12:55,880 They were glowing in such numbers that they can be 153 00:12:55,880 --> 00:12:57,960 detected by a satellite in orbit. 154 00:13:08,160 --> 00:13:11,760 Bacteria are among the most ancient forms of life, 155 00:13:11,760 --> 00:13:15,560 so they may have been the very first living things to glow. 156 00:13:15,560 --> 00:13:18,120 But why they did so is still debated. 157 00:13:19,520 --> 00:13:23,440 Today some animals have stolen the genes of the bacteria, 158 00:13:23,440 --> 00:13:25,840 and incorporated them into their own DNA. 159 00:13:27,320 --> 00:13:30,760 Others have simply kidnapped the bacteria themselves. 160 00:13:39,760 --> 00:13:42,160 These lights are made by captives, 161 00:13:42,160 --> 00:13:46,560 which are farmed in special organs below the eyes of flashlight fish. 162 00:13:56,040 --> 00:13:59,400 They have harnessed the bacterial glow for many purposes. 163 00:14:02,240 --> 00:14:06,720 We can only see them because our special cameras use infrared light. 164 00:14:08,360 --> 00:14:11,640 But to a predator, the fish look like this. 165 00:14:13,200 --> 00:14:16,840 A confusion of lights which makes it hard to pick a single target. 166 00:14:25,480 --> 00:14:29,200 Just before they change direction, the fish give a quick blink. 167 00:14:37,680 --> 00:14:39,960 These lights have other functions, too. 168 00:14:41,920 --> 00:14:45,080 They act as headlights to illuminate the sea floor 169 00:14:45,080 --> 00:14:47,000 as the fish search for food. 170 00:14:56,280 --> 00:15:00,440 They may even help a fish to flirt with the opposite sex. 171 00:15:07,840 --> 00:15:09,720 Unlike their captive bacteria, 172 00:15:09,720 --> 00:15:14,400 flashlight fish use living light for functions we now understand. 173 00:15:17,520 --> 00:15:20,160 But how is the light made? 174 00:15:20,160 --> 00:15:22,520 While it might appear magic, 175 00:15:22,520 --> 00:15:26,840 it's actually a straightforward chemical reaction that happens 176 00:15:26,840 --> 00:15:32,680 when a substance is mixed with a particular enzyme, like this. 177 00:15:38,000 --> 00:15:40,280 Hey, presto, light. 178 00:15:43,040 --> 00:15:47,600 The exact chemical formula varies according to the species. 179 00:15:47,600 --> 00:15:53,280 The reaction is very similar to that with which bacteria produce energy. 180 00:15:53,280 --> 00:15:57,160 Indeed, it could well be that the first luminescence was 181 00:15:57,160 --> 00:15:59,520 a by-product of that process. 182 00:16:00,840 --> 00:16:04,520 An evolutionary accident that has been co-opted by the fish to 183 00:16:04,520 --> 00:16:06,680 help them survive. 184 00:16:08,400 --> 00:16:11,680 The chemicals involved are quite harmless. 185 00:16:11,680 --> 00:16:15,680 In fact, you can actually buy a lollipop which, 186 00:16:15,680 --> 00:16:20,280 when you put it in hot water, glows. 187 00:16:21,440 --> 00:16:28,120 But to be truthful, I don't really find that very appetising. 188 00:16:28,120 --> 00:16:32,120 Perhaps, at the back of my mind, there's a memory of those 189 00:16:32,120 --> 00:16:35,640 bacteria on rotting fish, which tells me 190 00:16:35,640 --> 00:16:39,000 that things that glow aren't all that nice to eat. 191 00:16:41,640 --> 00:16:44,920 Bacteria may have been the first living lights, 192 00:16:44,920 --> 00:16:48,520 but then many other organisms also developed the ability. 193 00:16:49,920 --> 00:16:52,520 From jellyfish to fungi and insects, 194 00:16:52,520 --> 00:16:57,160 bioluminescence has evolved independently over 50 times, 195 00:16:57,160 --> 00:17:01,200 and is now produced by thousands of different species. 196 00:17:03,920 --> 00:17:06,720 And defence seems to be a common function. 197 00:17:12,360 --> 00:17:15,280 Millipedes are found across the globe. 198 00:17:15,280 --> 00:17:17,200 Many are active during the day, 199 00:17:17,200 --> 00:17:19,760 scuttling across the damp forest floor. 200 00:17:21,320 --> 00:17:25,960 They can do this with impunity, because they are deadly poisonous. 201 00:17:25,960 --> 00:17:29,160 Their bright colours are a clear message to predators - 202 00:17:29,160 --> 00:17:33,240 "Do not eat me. I am laced with cyanide." 203 00:17:40,560 --> 00:17:43,880 But what about millipedes that are active at night? 204 00:17:46,520 --> 00:17:50,640 They are no less toxic than those that are active during the day. 205 00:17:52,960 --> 00:17:57,720 But, of course, colours at night are no warning at all. 206 00:17:57,720 --> 00:18:01,120 Could it be that luminescence is a way 207 00:18:01,120 --> 00:18:04,720 of warning off night-time predators? 208 00:18:05,960 --> 00:18:08,920 These extraordinary millipedes are only found 209 00:18:08,920 --> 00:18:11,040 in the high mountains of California. 210 00:18:12,160 --> 00:18:15,440 Their bioluminescence has never been filmed before. 211 00:18:17,680 --> 00:18:21,680 They can't be sending signals to one another, because they're blind. 212 00:18:24,040 --> 00:18:27,360 Their living light evolved separately from bacteria, 213 00:18:27,360 --> 00:18:31,400 from a chemical process that helps millipedes conserve water 214 00:18:31,400 --> 00:18:33,600 in dry environments. 215 00:18:33,600 --> 00:18:36,840 But since the millipedes already contain cyanide, 216 00:18:36,840 --> 00:18:38,800 the light evolved a function. 217 00:18:40,960 --> 00:18:44,440 To my eyes, he doesn't look very bright. 218 00:18:44,440 --> 00:18:49,000 But my eyes are not the eyes of a night-time predator, 219 00:18:49,000 --> 00:18:52,200 or indeed of our specialist camera. 220 00:18:52,200 --> 00:18:54,240 And to both of them, 221 00:18:54,240 --> 00:18:58,200 this could look very bright indeed and be a real warning. 222 00:19:00,080 --> 00:19:03,200 When scientists made clay models of these millipedes, 223 00:19:03,200 --> 00:19:04,880 half of which glowed, 224 00:19:04,880 --> 00:19:09,000 nocturnal predators were more likely to attack those that didn't glow. 225 00:19:14,280 --> 00:19:17,680 This simple experiment produced a clear result. 226 00:19:17,680 --> 00:19:21,760 Living light can act as a warning. 227 00:19:24,800 --> 00:19:28,280 But proving the function of bioluminescence is not always 228 00:19:28,280 --> 00:19:31,480 so easy, as a recent discovery has shown. 229 00:19:36,480 --> 00:19:41,760 These, surely, are like creatures from science-fiction. 230 00:19:41,760 --> 00:19:44,400 Luminous earthworms. 231 00:19:44,400 --> 00:19:45,920 A few years ago, 232 00:19:45,920 --> 00:19:50,920 a lady living in the Loire Valley in central France went out during the 233 00:19:50,920 --> 00:19:55,240 evening to look for her dog which was digging a hole in the garden. 234 00:19:55,240 --> 00:20:00,200 And in the bottom of the hole, the soil was glowing. 235 00:20:00,200 --> 00:20:04,480 It was these earthworms. She could hardly believe her eyes. 236 00:20:04,480 --> 00:20:07,360 And she went and told people what she had seen 237 00:20:07,360 --> 00:20:09,280 and few people would believe her. 238 00:20:09,280 --> 00:20:13,360 The species of worm was already known, it lived over quite 239 00:20:13,360 --> 00:20:17,480 a lot of France, but no-one had ever seen it glow before. 240 00:20:17,480 --> 00:20:21,320 Perhaps that's because few people went out in the middle of the night 241 00:20:21,320 --> 00:20:24,400 digging a hole, especially without a light. 242 00:20:24,400 --> 00:20:28,880 But eventually, science recognised these creatures. 243 00:20:28,880 --> 00:20:33,160 But why should they luminesce in the darkness of the soil? 244 00:20:34,280 --> 00:20:36,440 Nobody knew. 245 00:20:39,520 --> 00:20:44,720 This blue light had gone unnoticed by science until 2010, 246 00:20:44,720 --> 00:20:49,200 when biologist Marcel Koken first saw their eerie glow. 247 00:20:51,880 --> 00:20:55,680 We are trying to find out why this animal produces light. 248 00:20:55,680 --> 00:20:59,360 A thing living underground. Why produce light? 249 00:20:59,360 --> 00:21:02,040 No use for it, apparently. 250 00:21:02,040 --> 00:21:05,960 Is it just a by-product of some internal chemistry? 251 00:21:05,960 --> 00:21:08,920 Or could the glow be used to frighten off attackers? 252 00:21:10,160 --> 00:21:14,560 These ground beetles are voracious predators and they love earthworms. 253 00:21:17,000 --> 00:21:20,560 The worms look like ordinary ones until the light goes out. 254 00:21:21,960 --> 00:21:23,680 Our special camera gives us 255 00:21:23,680 --> 00:21:26,600 a privileged view of what's happening in the dark. 256 00:21:31,840 --> 00:21:35,000 Marcel's experiments have shown that the worms can 257 00:21:35,000 --> 00:21:37,440 control their brightness. 258 00:21:37,440 --> 00:21:41,200 When the beetle touches part of the worm, its light gets brighter. 259 00:21:43,960 --> 00:21:47,400 So it could be that in case a predator tries to bite it, 260 00:21:47,400 --> 00:21:50,240 it lights up, that scares the predator. 261 00:21:50,240 --> 00:21:53,120 The predator goes off and the earthworm can escape. 262 00:21:54,400 --> 00:21:57,480 The beetle bites, and the worm's entire body 263 00:21:57,480 --> 00:22:00,400 bursts into light as it struggles to break free. 264 00:22:01,480 --> 00:22:04,160 But the beetle doesn't seem put off by the glow. 265 00:22:08,440 --> 00:22:11,680 If this is defence, it isn't working here. 266 00:22:13,480 --> 00:22:15,880 Marcel is still looking for the function. 267 00:22:18,000 --> 00:22:21,760 Perhaps other predators are put off or perhaps the worms use 268 00:22:21,760 --> 00:22:23,240 light to find each other. 269 00:22:27,240 --> 00:22:32,080 So it seems that this beautiful glow has a function which 270 00:22:32,080 --> 00:22:33,840 we still don't understand. 271 00:22:36,280 --> 00:22:40,320 The world of living light is full of mysteries. 272 00:22:40,320 --> 00:22:42,840 The French worms went unnoticed for so long 273 00:22:42,840 --> 00:22:46,200 because they produce their eerie light underground. 274 00:22:48,800 --> 00:22:50,400 But there are rare occasions 275 00:22:50,400 --> 00:22:53,920 when luminous life is all about revealing yourself. 276 00:23:03,400 --> 00:23:05,720 May 2015. 277 00:23:05,720 --> 00:23:09,360 While the southern aurora illuminates the night sky above, 278 00:23:09,360 --> 00:23:12,960 the sea below produces a strange blue glow. 279 00:23:22,400 --> 00:23:25,640 Each wave causes a ripple of intense colour. 280 00:23:39,080 --> 00:23:42,040 The animals in the bay notice it first. 281 00:23:44,200 --> 00:23:47,000 Wading birds are attracted to small crustaceans 282 00:23:47,000 --> 00:23:48,400 caught in the glow. 283 00:23:52,040 --> 00:23:55,600 Each movement alerts others to this rare spectacle. 284 00:23:55,600 --> 00:23:59,160 People gather to marvel at this once-in-a-lifetime event. 285 00:24:03,520 --> 00:24:04,920 That is amazing! 286 00:24:04,920 --> 00:24:07,960 I've never seen anything like this before in my life. 287 00:24:10,200 --> 00:24:11,240 That's wicked. 288 00:24:14,960 --> 00:24:18,480 LAUGHTER 289 00:24:25,560 --> 00:24:29,600 It may look like something from Willy Wonka's chocolate factory, 290 00:24:29,600 --> 00:24:31,480 but the phenomenon is real. 291 00:24:32,920 --> 00:24:36,960 A mass bloom of microscopic organisms caused by a rare 292 00:24:36,960 --> 00:24:40,560 combination of climate and nutrients. 293 00:24:40,560 --> 00:24:45,800 Under this microscope, I've got a drop of ordinary seawater. 294 00:24:45,800 --> 00:24:50,240 And it's full of tiny organisms, invisible to the naked eye, 295 00:24:50,240 --> 00:24:51,640 called dinoflagellates. 296 00:24:52,840 --> 00:24:55,760 And if I disturb them in some way, 297 00:24:55,760 --> 00:25:00,560 they combine two chemicals in their body to produce a flash of light. 298 00:25:00,560 --> 00:25:02,120 Watch. 299 00:25:18,880 --> 00:25:20,800 Dinoflagellates are one of the 300 00:25:20,800 --> 00:25:23,400 biggest single-celled organisms known. 301 00:25:25,240 --> 00:25:28,640 They are 1,000 times bigger than bacteria. 302 00:25:28,640 --> 00:25:30,600 They are neither animal nor plant, 303 00:25:30,600 --> 00:25:33,160 but have characteristics of them both, 304 00:25:33,160 --> 00:25:37,040 and when conditions are right in the sea, as they were in Tasmania, 305 00:25:37,040 --> 00:25:39,440 they bloom in enormous numbers. 306 00:25:42,560 --> 00:25:46,040 Bioluminescent tides like this one are certainly rare. 307 00:25:49,800 --> 00:25:54,920 However, dinoflagellates are found in huge numbers all over the world. 308 00:25:54,920 --> 00:25:59,480 They are among the most widespread of all bioluminescent life. 309 00:25:59,480 --> 00:26:01,040 Wherever they exist, 310 00:26:01,040 --> 00:26:05,120 these single-celled creatures highlight anything that moves. 311 00:26:08,800 --> 00:26:13,600 But why do dinoflagellates behave in this way? 312 00:26:13,600 --> 00:26:17,280 It's certainly not to entertain us, though it obviously does. 313 00:26:17,280 --> 00:26:20,240 Well, it could be that it is a kind of burglar alarm - 314 00:26:20,240 --> 00:26:23,360 that when a shrimp or some other animal 315 00:26:23,360 --> 00:26:26,440 that feeds on the dinoflagellates by filtering them out, 316 00:26:26,440 --> 00:26:28,560 comes along and starts to feed, 317 00:26:28,560 --> 00:26:31,360 it is, in doing so, illuminating itself. 318 00:26:34,800 --> 00:26:38,840 So that attracts the attention of perhaps bigger fish that might 319 00:26:38,840 --> 00:26:40,280 feed on the shrimp. 320 00:26:42,600 --> 00:26:46,600 Just as a flashing burglar alarm alerts the police to a thief, 321 00:26:46,600 --> 00:26:50,360 the dinoflagellates expose their attacker to its enemies. 322 00:26:55,680 --> 00:26:59,560 The shrimp is revealed to a cuttlefish, with fatal results. 323 00:27:03,840 --> 00:27:07,840 And so the cuttlefish can hunt in total darkness. 324 00:27:09,000 --> 00:27:12,600 But while the dinoflagellates' light can work in this way, 325 00:27:12,600 --> 00:27:15,360 it is still debated if that's why they do it. 326 00:27:19,000 --> 00:27:22,400 Whatever the reason, the magic created by their light can be 327 00:27:22,400 --> 00:27:25,240 one of nature's most magical spectacles. 328 00:27:41,920 --> 00:27:45,320 Bow-riding dolphins are revealed as dazzling outlines. 329 00:27:52,840 --> 00:27:57,120 Whenever these lights appear, the way life in the ocean hunts 330 00:27:57,120 --> 00:27:59,000 and hides is transformed. 331 00:28:00,120 --> 00:28:03,320 Perhaps dolphins are guided to their prey by the light 332 00:28:03,320 --> 00:28:04,760 of the dinoflagellates. 333 00:28:17,760 --> 00:28:22,640 Only now has it become possible to film these scenes with such clarity. 334 00:28:22,640 --> 00:28:26,600 But every night, spectacular light shows like this play out 335 00:28:26,600 --> 00:28:29,720 somewhere in the vastness of the oceans. 336 00:28:45,360 --> 00:28:49,720 While exactly how dinoflagellates use bioluminescence remains 337 00:28:49,720 --> 00:28:52,320 unproven, there are other instances 338 00:28:52,320 --> 00:28:56,400 when the burglar alarm effect has been clearly demonstrated. 339 00:29:04,320 --> 00:29:06,760 Caribbean coral reefs are some of the 340 00:29:06,760 --> 00:29:09,200 most well-dived waters in the world... 341 00:29:10,520 --> 00:29:11,560 ..by day. 342 00:29:23,320 --> 00:29:27,120 At night, it's a different world. 343 00:29:29,240 --> 00:29:32,320 A crab searches for a tasty morsel. 344 00:29:35,840 --> 00:29:38,560 This is just what it's looking for, the delicate 345 00:29:38,560 --> 00:29:42,200 tentacles of a brittle star, a relative of starfish. 346 00:29:53,040 --> 00:29:57,520 But the brittle star has a surprisingly effective defence. 347 00:30:00,160 --> 00:30:04,840 When disturbed, it unleashes a dazzling weapon, raising the alarm. 348 00:30:07,200 --> 00:30:10,000 Having been revealed, the crab makes a run for it. 349 00:30:16,200 --> 00:30:20,560 And the normally well camouflaged crustacean becomes easy prey 350 00:30:20,560 --> 00:30:23,120 for the octopus, even in the gloom. 351 00:30:25,520 --> 00:30:29,000 Scientists have only recently proved the light helps the 352 00:30:29,000 --> 00:30:33,400 brittle star drive off predators or, better still, to get them eaten. 353 00:30:40,320 --> 00:30:43,960 It's in the open water, where there's nowhere to hide, that the 354 00:30:43,960 --> 00:30:46,640 burglar alarm defence is most effective. 355 00:30:48,000 --> 00:30:52,160 Fish hunt small invertebrates silhouetted against the night sky. 356 00:30:54,200 --> 00:30:58,160 Ostracods, tiny crustaceans no bigger than a grain of sand, 357 00:30:58,160 --> 00:30:59,480 emerge from the reef. 358 00:31:01,880 --> 00:31:05,480 Cardinal fish are common predators of the small and unwary. 359 00:31:07,200 --> 00:31:09,440 But when they strike an ostracod, 360 00:31:09,440 --> 00:31:11,640 they get more than they bargained for. 361 00:31:14,080 --> 00:31:17,560 The ostracod discharges a bioluminescent flash bomb, 362 00:31:17,560 --> 00:31:20,160 one of the brightest forms of living light. 363 00:31:20,160 --> 00:31:22,800 And the cardinal fish quickly spits it out. 364 00:31:27,320 --> 00:31:30,240 The light is so bright that it shines through 365 00:31:30,240 --> 00:31:34,320 the body of the fish, temporarily blinding it, and this normally 366 00:31:34,320 --> 00:31:37,560 invisible fish becomes an easy target for a predator. 367 00:31:48,000 --> 00:31:50,720 Ostracods, with their flash bomb defence, 368 00:31:50,720 --> 00:31:53,000 are found throughout the world's oceans. 369 00:31:59,520 --> 00:32:01,240 But in the Caribbean, 370 00:32:01,240 --> 00:32:04,680 they employ their glow to attract as well as to repel. 371 00:32:07,960 --> 00:32:10,960 It's something that researchers Gretchen Gerrish 372 00:32:10,960 --> 00:32:12,920 and Trevor Rivers are studying. 373 00:32:12,920 --> 00:32:15,960 The spectacular mating display of ostracods. 374 00:32:17,600 --> 00:32:20,800 But they can't even begin to work until the moon has set. 375 00:32:22,320 --> 00:32:26,120 A fully moonlit night is not dark in the eyes of an organism that 376 00:32:26,120 --> 00:32:30,600 depends on their own light that they create, and so darkness truly 377 00:32:30,600 --> 00:32:35,080 is just a starlit sky, no moon present in the sky at all. 378 00:32:45,160 --> 00:32:48,880 Diving without torches in near total darkness, Gretchen 379 00:32:48,880 --> 00:32:52,960 and Trevor are entering a world that few people ever witness. 380 00:32:56,200 --> 00:32:59,440 You are immersed in darkness, you are immersed in water. 381 00:33:00,600 --> 00:33:04,000 And you see streaming stars floating past you and they're being 382 00:33:04,000 --> 00:33:08,080 produced by these tiny crustaceans that we barely understand. 383 00:33:09,480 --> 00:33:12,840 By releasing small amounts of glowing liquid as they swim, 384 00:33:12,840 --> 00:33:16,360 male ostracods leave a trail of lights in their wake. 385 00:33:18,000 --> 00:33:22,200 The series of precisely timed dots tell the female where 386 00:33:22,200 --> 00:33:24,520 he will be in exactly half a second. 387 00:33:26,960 --> 00:33:31,640 But as one male starts to display, another and another join him. 388 00:33:38,560 --> 00:33:39,960 And as they synchronise, 389 00:33:39,960 --> 00:33:43,960 they fan out into this firework-like display of light. 390 00:33:48,480 --> 00:33:51,760 It's one of the most awe-inspiring things I've ever seen. 391 00:34:02,240 --> 00:34:06,600 With every research trip, Trevor and Gretchen discover new species, 392 00:34:06,600 --> 00:34:09,560 each with its own light language. 393 00:34:24,200 --> 00:34:27,680 Ostracods and fireflies use bioluminescence 394 00:34:27,680 --> 00:34:29,600 to find potential mates. 395 00:34:29,600 --> 00:34:33,440 And it can be an efficient means of getting your message across, 396 00:34:33,440 --> 00:34:36,360 but it's not foolproof. 397 00:34:36,360 --> 00:34:38,600 Those messages can be hacked. 398 00:34:40,480 --> 00:34:43,920 There's a love cheat in this situation. 399 00:34:43,920 --> 00:34:48,880 There's also a female of a particular species here that, 400 00:34:48,880 --> 00:34:53,280 when she sees the males of a different species fly past, 401 00:34:53,280 --> 00:34:57,760 answers with their particular call sign, and that attracts them. 402 00:34:57,760 --> 00:35:01,760 And when they arrive, instead of mating with them, 403 00:35:01,760 --> 00:35:04,160 she has her own dastardly way with them. 404 00:35:07,160 --> 00:35:10,680 She mimics the flash patterns of other species. 405 00:35:14,680 --> 00:35:17,640 An unsuspecting male is lured in. 406 00:35:33,560 --> 00:35:38,960 Fireflies contain toxins thought to protect them against most predators. 407 00:35:38,960 --> 00:35:41,640 But this femme fatale is not put off. 408 00:35:43,840 --> 00:35:46,480 And she eats him alive. 409 00:35:46,480 --> 00:35:49,360 In fact, it may be the toxins that she is after. 410 00:35:51,200 --> 00:35:54,280 She can't produce such chemicals herself. 411 00:35:54,280 --> 00:36:00,040 So she tricks and then devours males of different species to obtain them. 412 00:36:05,040 --> 00:36:09,080 If she can't get males to come to her, she goes after them. 413 00:36:11,520 --> 00:36:15,640 And a good place to look for one is on a spider's web. 414 00:36:20,920 --> 00:36:23,040 A male firefly is ensnared. 415 00:36:23,040 --> 00:36:25,640 As the spider venom takes effect, 416 00:36:25,640 --> 00:36:28,360 his flashing turns to a constant glow. 417 00:36:35,080 --> 00:36:38,760 The femme fatale is alerted by the dim glow, 418 00:36:38,760 --> 00:36:43,240 and she flies straight onto the web to steal the spider's catch. 419 00:36:45,080 --> 00:36:47,400 As the spider struggles to keep its prey, 420 00:36:47,400 --> 00:36:49,680 she dazzles it with her lantern. 421 00:36:57,440 --> 00:37:00,960 Using her light, the firefly can clearly see the spider 422 00:37:00,960 --> 00:37:02,240 and avoid the web. 423 00:37:07,000 --> 00:37:09,920 The confused spider loses out. 424 00:37:17,840 --> 00:37:22,600 Predation turns out to be one area where light-making life 425 00:37:22,600 --> 00:37:24,520 has been very creative. 426 00:37:29,720 --> 00:37:32,440 Like a scene from the surface of an alien planet, 427 00:37:32,440 --> 00:37:36,400 these termite mounds have lodgers living in their walls. 428 00:37:44,480 --> 00:37:48,040 The luminous larvae of click beetles wait in burrows. 429 00:37:56,320 --> 00:38:00,040 Insects are drawn to their death by the green glow, 430 00:38:00,040 --> 00:38:01,760 like moths to a flame. 431 00:38:04,680 --> 00:38:06,880 And the beetle larvae gorge 432 00:38:06,880 --> 00:38:10,360 on the steady supply of unsuspecting victims. 433 00:38:20,560 --> 00:38:23,080 These predators work as individuals. 434 00:38:26,720 --> 00:38:30,240 There is another insect that excels in deception. 435 00:38:32,360 --> 00:38:35,600 But it works alongside thousands of its own kind. 436 00:38:39,000 --> 00:38:42,960 From outside, this cave shows no sign of the astonishing 437 00:38:42,960 --> 00:38:44,760 things that go on inside. 438 00:38:50,800 --> 00:38:54,280 The entrance is fringed with a curtain of silk, 439 00:38:54,280 --> 00:38:56,640 woven by the larvae of a kind of gnat. 440 00:38:58,560 --> 00:39:00,840 They move back and forth along the rocks, 441 00:39:00,840 --> 00:39:05,120 lowering sticky strings of saliva from the roof of the cave. 442 00:39:10,280 --> 00:39:12,280 As night falls, the walls 443 00:39:12,280 --> 00:39:16,880 and ceiling of this cavern become nature's very own planetarium. 444 00:39:27,240 --> 00:39:28,280 The trap is set. 445 00:39:31,560 --> 00:39:36,800 The cool, blue light produced in each larva's tail is the lure. 446 00:39:42,240 --> 00:39:43,680 Other insects that hatch 447 00:39:43,680 --> 00:39:48,800 and emerge in the cave instinctively fly upwards to the sky. 448 00:39:48,800 --> 00:39:52,760 But this is not a starlit sky. It's a deathtrap. 449 00:40:05,360 --> 00:40:08,640 Bioluminescence is clearly a powerful tool 450 00:40:08,640 --> 00:40:11,320 to these life forms that possess it. 451 00:40:11,320 --> 00:40:14,920 But it is only effective in darkness. 452 00:40:14,920 --> 00:40:16,120 Each dawn, 453 00:40:16,120 --> 00:40:20,120 the bright rays of the sun overwhelm the power of living light. 454 00:40:25,800 --> 00:40:28,520 For all of the wonders of bioluminescence 455 00:40:28,520 --> 00:40:31,760 in the plains and woodlands of the Earth, there is 456 00:40:31,760 --> 00:40:36,960 one place where living light is virtually the key to existence. 457 00:40:36,960 --> 00:40:40,680 The world of eternal darkness, the deep sea. 458 00:40:49,080 --> 00:40:52,640 The Western Fire is one of the world's most advanced 459 00:40:52,640 --> 00:40:54,600 deep sea research vessels. 460 00:40:56,400 --> 00:40:59,040 In the black depths there are no edges. 461 00:41:00,040 --> 00:41:02,680 No boundaries, nowhere to hide. 462 00:41:04,120 --> 00:41:07,200 Predators and prey have therefore had to develop some 463 00:41:07,200 --> 00:41:09,880 extraordinary strategies to stay alive. 464 00:41:09,880 --> 00:41:12,280 And many do so with the help of light. 465 00:41:14,600 --> 00:41:18,840 Dr Steven Haddock has spent the last 25 years studying the 466 00:41:18,840 --> 00:41:22,720 least known part of our planet, the ocean depths. 467 00:41:24,280 --> 00:41:27,360 I think people look at bioluminescence, 468 00:41:27,360 --> 00:41:31,640 this ability to make light, they think of it as a very magical thing, 469 00:41:31,640 --> 00:41:35,920 but once you see the diversity and the range of functions that 470 00:41:35,920 --> 00:41:38,640 bioluminescence serves for animals in the ocean, it is 471 00:41:38,640 --> 00:41:41,160 clear that it is a critical part of the whole ecology 472 00:41:41,160 --> 00:41:42,200 of the system. 473 00:41:42,200 --> 00:41:45,200 Until recently, it was all but impossible 474 00:41:45,200 --> 00:41:50,160 to collect living bioluminescent creatures from the deep. 475 00:41:50,160 --> 00:41:53,840 But this remote submersible, known as the Doc Ricketts, 476 00:41:53,840 --> 00:41:56,040 is equipped to do just that. 477 00:41:57,840 --> 00:41:59,840 They are trying to find new life 478 00:41:59,840 --> 00:42:03,960 and clues as to why light-making has evolved in so many forms. 479 00:42:12,320 --> 00:42:15,840 In the control room, thousands of metres above, Steve 480 00:42:15,840 --> 00:42:19,920 and the crew navigate past alien-like life forms. 481 00:42:19,920 --> 00:42:20,960 Nice. 482 00:42:23,080 --> 00:42:24,280 Wow. 483 00:42:24,280 --> 00:42:27,720 But in truth, it is us who are the aliens down here. 484 00:42:44,520 --> 00:42:47,600 Although very sophisticated, the Doc Ricketts' 485 00:42:47,600 --> 00:42:52,360 own remote cameras are not sensitive enough to record bioluminescence, 486 00:42:52,360 --> 00:42:55,840 so they use bright lights to find and film these creatures. 487 00:42:58,240 --> 00:43:01,440 To have any hope of observing their light-making powers, 488 00:43:01,440 --> 00:43:05,000 the research team needs to bring them to the surface. 489 00:43:06,440 --> 00:43:10,360 Gentle suction and remotely controlled canisters are used to 490 00:43:10,360 --> 00:43:13,120 delicately scoop up the rare sea creatures. 491 00:43:19,640 --> 00:43:20,760 Vampire squid. 492 00:43:27,880 --> 00:43:28,960 Yes! 493 00:43:30,480 --> 00:43:31,920 Viper fish. 494 00:43:35,440 --> 00:43:37,520 Perfect. 495 00:43:37,520 --> 00:43:39,160 Oh, look at that! 496 00:43:39,160 --> 00:43:40,840 And dragonfish. 497 00:43:43,160 --> 00:43:46,480 They don't just sound like something from a sailor's tale of 498 00:43:46,480 --> 00:43:49,680 fantasy monsters, they look like them, too. 499 00:43:52,160 --> 00:43:55,800 This is one of the few dragonfish that has ever been seen alive. 500 00:43:58,760 --> 00:44:02,960 And it's one of the even fewer that have been captured unharmed. 501 00:44:06,560 --> 00:44:10,120 - Yes! - Yay! - Oh, my gosh. 502 00:44:15,360 --> 00:44:18,240 Once they arrive on the ship, thousands of metres 503 00:44:18,240 --> 00:44:22,000 above their normal environment, there is no time to waste. 504 00:44:22,000 --> 00:44:25,240 The enormous pressure change is likely to cause any 505 00:44:25,240 --> 00:44:28,000 bioluminescence abilities to disappear. 506 00:44:31,280 --> 00:44:34,400 The race is on to try and observe those abilities 507 00:44:34,400 --> 00:44:36,480 and understand their functions. 508 00:44:40,680 --> 00:44:42,520 Wow. 509 00:44:49,120 --> 00:44:51,840 In some species, it seems to be defensive. 510 00:44:53,200 --> 00:44:57,240 Like the circling flashes of the Atolla jellyfish. 511 00:45:00,240 --> 00:45:04,280 Or the rippling light waves of the Beroe comb jelly. 512 00:45:15,360 --> 00:45:18,320 In other species, like this viper fish, 513 00:45:18,320 --> 00:45:22,360 light is used not only for defence, but to lure prey. 514 00:45:27,280 --> 00:45:32,040 These pyrosomes, colonies of minute translucent creatures, 515 00:45:32,040 --> 00:45:35,640 use light to communicate within the colony. 516 00:45:35,640 --> 00:45:40,040 The team's experiment shows that as one colony begins to glow, 517 00:45:40,040 --> 00:45:42,200 its neighbours light up in response. 518 00:45:44,840 --> 00:45:46,680 What could they be saying? 519 00:45:50,960 --> 00:45:54,400 Thanks to the delicate sampling methods of the Doc Ricketts, 520 00:45:54,400 --> 00:45:56,880 the team are able to observe a living 521 00:45:56,880 --> 00:46:01,200 and luminescing dragonfish, a sight few have ever witnessed. 522 00:46:04,400 --> 00:46:05,640 Whatever their function, 523 00:46:05,640 --> 00:46:09,480 one thing unites all these types of bioluminescence - 524 00:46:09,480 --> 00:46:11,360 their otherworldly beauty. 525 00:46:17,240 --> 00:46:21,640 And this beauty is the result of an evolutionary arms race 526 00:46:21,640 --> 00:46:25,640 where light is a weapon to blind or deceive. 527 00:46:28,600 --> 00:46:33,040 In response, some animals have evolved the most sophisticated 528 00:46:33,040 --> 00:46:36,000 and bizarre eyes on the planet. 529 00:46:39,320 --> 00:46:44,120 The rare barreleye fish has eyes that can only look upwards, 530 00:46:44,120 --> 00:46:47,040 through the top of its translucent head. 531 00:46:47,040 --> 00:46:48,560 Searching for prey above. 532 00:46:51,040 --> 00:46:52,240 It is so rare, 533 00:46:52,240 --> 00:46:55,520 catching even a glimpse of it alive is a huge achievement. 534 00:47:02,040 --> 00:47:05,640 And the same is true for the cock-eyed squid. 535 00:47:05,640 --> 00:47:09,800 It has one normal eye and one strange, upward-looking eye. 536 00:47:19,160 --> 00:47:23,040 At this depth, it is too dark for human eyes. 537 00:47:23,040 --> 00:47:25,520 But the faintest light from the surface, 538 00:47:25,520 --> 00:47:30,280 half a kilometre above, can just reach this twilight zone. 539 00:47:33,280 --> 00:47:36,720 Firefly squid normally live at these depths. 540 00:47:36,720 --> 00:47:39,480 To prevent themselves from being seen from below, 541 00:47:39,480 --> 00:47:44,120 they hide themselves with light. 542 00:47:44,120 --> 00:47:46,200 It's a strange paradox. 543 00:47:46,200 --> 00:47:49,880 In this dark world, light can be used for camouflage. 544 00:47:54,560 --> 00:47:58,520 At close range, the light-emitting cells, called photophores, 545 00:47:58,520 --> 00:48:00,120 are easy to see. 546 00:48:00,120 --> 00:48:03,560 But from a distance, they break up the outline of the squid 547 00:48:03,560 --> 00:48:05,640 and it merges with the background. 548 00:48:11,520 --> 00:48:14,720 It's an elegant solution used by many creatures 549 00:48:14,720 --> 00:48:17,440 when a silhouette can be a death sentence. 550 00:48:25,680 --> 00:48:28,880 In shallower waters, the colour of the light changes 551 00:48:28,880 --> 00:48:34,000 so the squid, as it gets closer to the surface, uses green photophores. 552 00:48:44,480 --> 00:48:47,440 The lives of firefly squid are short. 553 00:48:47,440 --> 00:48:49,320 When they are only a year old, 554 00:48:49,320 --> 00:48:53,640 mated females make their final journey, to the surface to spawn. 555 00:48:58,960 --> 00:49:02,600 But even in their final moments, they are both spectacular 556 00:49:02,600 --> 00:49:03,640 and valuable. 557 00:49:12,560 --> 00:49:14,160 All along the coast here, 558 00:49:14,160 --> 00:49:17,320 these squid, which die naturally after spawning, 559 00:49:17,320 --> 00:49:19,480 are gathered as a local delicacy. 560 00:49:21,760 --> 00:49:24,560 It's largely through this fishery that we know 561 00:49:24,560 --> 00:49:27,200 anything at all about the firefly squid. 562 00:49:29,400 --> 00:49:31,440 Like so many deep sea creatures, 563 00:49:31,440 --> 00:49:34,200 their daily lives are still virtually unknown. 564 00:49:35,560 --> 00:49:40,360 What we do know is that their world is dominated by bioluminescence. 565 00:49:44,040 --> 00:49:47,160 We've come a long way from watching fireflies 566 00:49:47,160 --> 00:49:50,640 in the woodlands of Pennsylvania. 567 00:49:50,640 --> 00:49:55,160 Organisms that produce light on land may be exceptional 568 00:49:55,160 --> 00:49:56,600 but in the sea, 569 00:49:56,600 --> 00:50:00,400 creatures that do so, like these comb jellies, 570 00:50:00,400 --> 00:50:02,920 are, in fact, the norm. 571 00:50:07,520 --> 00:50:10,080 In the oceans and on land, 572 00:50:10,080 --> 00:50:14,560 living creatures of many kinds have harnessed the power of light in 573 00:50:14,560 --> 00:50:21,120 extraordinary ways, to mate, to lie, even to hide under a cloak of light. 574 00:50:25,080 --> 00:50:28,200 Yet, with the latest cameras and technology, we are 575 00:50:28,200 --> 00:50:32,560 only beginning to understand the lives of luminous creatures. 576 00:50:35,440 --> 00:50:41,720 There remain many mysteries. But what a beautiful world they create. 577 00:50:43,120 --> 00:50:47,960 And what a beautiful world awaits the scientists of the future. 578 00:51:04,200 --> 00:51:07,080 During this programme, we've had to use cameras 579 00:51:07,080 --> 00:51:09,800 that are far more sensitive than our own eyes 580 00:51:09,800 --> 00:51:14,760 and about as sensitive as many of the animals that we are showing. 581 00:51:18,000 --> 00:51:21,760 The eye is one of evolution's greatest achievements. 582 00:51:21,760 --> 00:51:25,520 And nature has certainly devised some fiendishly complex 583 00:51:25,520 --> 00:51:27,760 and sensitive examples. 584 00:51:27,760 --> 00:51:31,840 Some of which are designed specifically to see bioluminescence. 585 00:51:35,920 --> 00:51:40,520 When we enter the dark, we barely notice bioluminescence. 586 00:51:40,520 --> 00:51:42,840 But after a few minutes, physiological changes 587 00:51:42,840 --> 00:51:47,280 take place in our eyes that enable us to see living light. 588 00:51:48,320 --> 00:51:50,880 Cameras have always struggled to replicate 589 00:51:50,880 --> 00:51:52,400 what the human eye can do, 590 00:51:52,400 --> 00:51:54,920 but with special low-light cameras, 591 00:51:54,920 --> 00:51:58,000 we can now record glowing light at least as well, 592 00:51:58,000 --> 00:52:01,240 and sometimes better, than we can see it ourselves. 593 00:52:03,000 --> 00:52:07,400 But being able to film the glow is only one part of the solution. 594 00:52:07,400 --> 00:52:11,280 To really understand light on Earth, you need to be able to record 595 00:52:11,280 --> 00:52:14,080 the creature themselves as they make the light. 596 00:52:15,720 --> 00:52:17,880 This camera allows you to film 597 00:52:17,880 --> 00:52:21,040 in low-light levels in a completely new way. 598 00:52:21,040 --> 00:52:24,160 The beam of light comes in through the single lens, 599 00:52:24,160 --> 00:52:29,680 but it is then split into two, and one camera records on one 600 00:52:29,680 --> 00:52:34,960 light frequency, and the other on a different light frequency. 601 00:52:34,960 --> 00:52:38,920 One of the cameras is sensitive to infrared light, invisible to 602 00:52:38,920 --> 00:52:42,720 most animals, but which allows the camera to record in the dark. 603 00:52:43,760 --> 00:52:47,280 The second camera records only the bioluminescence, 604 00:52:47,280 --> 00:52:49,280 which is mostly blue or green. 605 00:52:50,480 --> 00:52:53,280 The two are then combined into one picture. 606 00:52:57,000 --> 00:53:00,520 And that way you can get pictures at a low-light level, 607 00:53:00,520 --> 00:53:02,960 not only of bioluminescent animals, 608 00:53:02,960 --> 00:53:06,160 but even the environment in which they are living. 609 00:53:06,160 --> 00:53:09,720 This technique, pioneered by film-maker Martin Dohrn, 610 00:53:09,720 --> 00:53:13,880 allows us to enter the world of bioluminescent creatures, 611 00:53:13,880 --> 00:53:17,280 and also to contribute to new science. 612 00:53:17,280 --> 00:53:19,400 With this type of camera, there are many things 613 00:53:19,400 --> 00:53:23,720 I see on these images which I wouldn't be able to see normally. 614 00:53:25,240 --> 00:53:29,200 In the past, scientist Marcel Koken has been unable to 615 00:53:29,200 --> 00:53:32,840 study the worm and beetle without using a light. 616 00:53:32,840 --> 00:53:35,560 But when he did, the light would frighten the beetle 617 00:53:35,560 --> 00:53:38,680 and overpower the worm's bioluminescence. 618 00:53:38,680 --> 00:53:42,560 With the help of Martin's camera, Marcel is able to observe 619 00:53:42,560 --> 00:53:47,240 and record the beetle and worm encounter for the first time. 620 00:53:47,240 --> 00:53:50,920 Having decided working with two cameras simultaneously wasn't 621 00:53:50,920 --> 00:53:55,800 already hard enough, the team decide to take them underwater. 622 00:53:55,800 --> 00:53:57,840 The objective was to film 623 00:53:57,840 --> 00:54:01,520 the beautiful mating display of ostracods - 624 00:54:01,520 --> 00:54:05,680 tiny, one millimetre long crustaceans in the dark 625 00:54:05,680 --> 00:54:10,760 swirling currents of their natural habitat. A huge challenge. 626 00:54:10,760 --> 00:54:13,840 - Martin, how was it tonight? - We had a lot of problems. 627 00:54:13,840 --> 00:54:17,800 Tonight, it went smoother. It's calmer. Much, much calmer. 628 00:54:17,800 --> 00:54:21,160 A lot of what I saw looked utterly amazing. 629 00:54:23,280 --> 00:54:26,760 Martin's beam-splitting system makes it possible to film 630 00:54:26,760 --> 00:54:30,560 the bioluminescence as well as the tiny ostracods, as they leave 631 00:54:30,560 --> 00:54:32,240 lights in their wake. 632 00:54:32,240 --> 00:54:35,200 However, the scientists are not done. 633 00:54:36,880 --> 00:54:40,880 Marine biologist Gretchen Gerrish hopes the camera will enable 634 00:54:40,880 --> 00:54:43,760 her to film groups of males that aren't flashing, 635 00:54:43,760 --> 00:54:46,800 swimming alongside the individual that is. 636 00:54:46,800 --> 00:54:49,800 Something that has only ever been seen in the lab. 637 00:54:52,360 --> 00:54:56,360 These males, known as sneakers, are invisible to a normal camera, 638 00:54:56,360 --> 00:54:58,800 because they leave no night trail. 639 00:54:58,800 --> 00:55:03,720 But our camera, nicknamed Bertha, could change all that. 640 00:55:03,720 --> 00:55:06,840 - So, how was Bertha? - Bertha is awesome. 641 00:55:06,840 --> 00:55:11,960 She was filming sneakers and you could see them swimming. 642 00:55:11,960 --> 00:55:14,200 She's a bit of a beast. 643 00:55:14,200 --> 00:55:17,240 What do you think, Trevor? Did you get any good footage? 644 00:55:17,240 --> 00:55:18,720 It was just awesome. 645 00:55:18,720 --> 00:55:20,840 This is opening the doors for so much. 646 00:55:22,040 --> 00:55:25,560 The scientists are keen to get their first look at the combined 647 00:55:25,560 --> 00:55:27,160 images from Bertha. 648 00:55:32,240 --> 00:55:35,880 The infrared does show there is a spiralling group of males, 649 00:55:35,880 --> 00:55:39,600 intent on intercepting the female, before she can reach the male 650 00:55:39,600 --> 00:55:42,400 that has done all the hard work of attracting her. 651 00:55:46,560 --> 00:55:48,680 And there are far more competing males 652 00:55:48,680 --> 00:55:51,120 than the scientists had expected. 653 00:55:52,120 --> 00:55:54,800 It's an ostracod soup. There's thousands of them. 654 00:55:55,800 --> 00:56:00,120 What, to our eyes, is a beautiful, orderly display is in fact 655 00:56:00,120 --> 00:56:02,160 an ostracod free-for-all. 656 00:56:02,160 --> 00:56:05,840 Lots of males try to cash in on the efforts of a few. 657 00:56:05,840 --> 00:56:08,560 The amount of information you could fire from this is something 658 00:56:08,560 --> 00:56:10,880 we've been trying to do for the last five years. 659 00:56:10,880 --> 00:56:12,360 Yeah, that's a paper, right there. 660 00:56:12,360 --> 00:56:14,920 What? You mean in that short clip? There's not a paper there. 661 00:56:14,920 --> 00:56:17,560 Close to it. 662 00:56:17,560 --> 00:56:21,160 But having hi-tech kit is only part of the story. 663 00:56:21,160 --> 00:56:23,960 Since much of the bioluminescence is little-known, 664 00:56:23,960 --> 00:56:27,840 just finding it is often the biggest hurdle. 665 00:56:27,840 --> 00:56:32,160 The crew are about to head out on their most ambitious shoot. 666 00:56:32,160 --> 00:56:33,600 Tonight, we're going to try 667 00:56:33,600 --> 00:56:36,920 and film something that we know is found all over the world, 668 00:56:36,920 --> 00:56:40,720 and it happens every night in every ocean, almost anywhere, 669 00:56:40,720 --> 00:56:44,120 and yet, in terms of getting information from people 670 00:56:44,120 --> 00:56:45,680 as to where we might find it, 671 00:56:45,680 --> 00:56:48,200 and when the best time is, there is nothing. 672 00:56:50,880 --> 00:56:55,880 As night falls, they head away from shore and any artificial light. 673 00:56:57,040 --> 00:57:00,840 And soon, they are sailing in the sea laced with dinoflagellates. 674 00:57:02,640 --> 00:57:04,720 These blue flashes can be seen 675 00:57:04,720 --> 00:57:08,080 in almost any ocean at night, with the lights out. 676 00:57:08,080 --> 00:57:11,080 But this alone is not what the crew came for. 677 00:57:11,080 --> 00:57:13,800 They are hoping to meet some special visitors. 678 00:57:24,320 --> 00:57:27,240 Working on a rocking boat in complete darkness with 679 00:57:27,240 --> 00:57:30,800 a prototype camera is one of the trickiest challenges Martin 680 00:57:30,800 --> 00:57:32,600 has faced in his career. 681 00:57:35,720 --> 00:57:39,840 After a week searching the dark sea, here they are. 682 00:57:39,840 --> 00:57:41,000 Dolphins. 683 00:57:49,720 --> 00:57:53,600 To be out at night, with clear skies and beautiful stars, 684 00:57:53,600 --> 00:57:57,000 and everywhere there are flashes of light, 685 00:57:57,000 --> 00:58:01,760 and when dolphins turn up, the show just gets more extraordinary still. 686 00:58:01,760 --> 00:58:05,600 It really is one of the most amazing things I've ever seen in my life. 687 00:58:07,480 --> 00:58:11,280 Scenes like this are happening across the oceans, 688 00:58:11,280 --> 00:58:15,040 yet this is one of the few times they've ever been caught on camera. 689 00:58:18,960 --> 00:58:22,200 New technologies and new ideas are creating 690 00:58:22,200 --> 00:58:26,080 a revolution in our way of seeing the world. 691 00:58:26,080 --> 00:58:29,120 And of understanding life that glows. 59408

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