1 00:00:23,648 --> 00:00:26,276 There's something magical about dolphins. 2 00:00:30,947 --> 00:00:32,866 They appear so friendly. 3 00:00:35,410 --> 00:00:37,162 Yet so otherworldly. 4 00:00:41,207 --> 00:00:43,251 They're clearly intelligent. 5 00:00:46,713 --> 00:00:47,797 And agile. 6 00:00:56,765 --> 00:01:00,643 But we've still barely glimpsed beneath the surface. 7 00:01:05,940 --> 00:01:08,818 Now we can immerse ourselves in their world, 8 00:01:09,486 --> 00:01:12,655 we're discovering just how sophisticated they are. 9 00:01:21,414 --> 00:01:23,041 And the deeper we look, 10 00:01:24,292 --> 00:01:25,835 the more like us they seem. 11 00:01:52,695 --> 00:01:56,116 Born into a world where he can't even breathe, 12 00:01:57,784 --> 00:01:59,744 a young Atlantic spotted dolphin 13 00:01:59,828 --> 00:02:02,747 has a lot to learn about surviving at sea. 14 00:02:06,835 --> 00:02:09,712 A good thing he has someone to show him the way. 15 00:02:13,883 --> 00:02:14,717 Mom. 16 00:02:19,514 --> 00:02:22,642 And a wider group of family and friends. 17 00:02:38,992 --> 00:02:40,869 They'll help teach him 18 00:02:41,661 --> 00:02:43,163 how to find food… 19 00:02:45,248 --> 00:02:47,792 and how to avoid danger. 20 00:02:54,257 --> 00:02:56,634 But dolphin society is complicated. 21 00:02:58,094 --> 00:02:59,762 The greatest challenge 22 00:02:59,846 --> 00:03:01,973 is learning how to fit in. 23 00:03:15,028 --> 00:03:17,322 These warm, shallow waters 24 00:03:17,405 --> 00:03:19,866 are also home to another species. 25 00:03:21,784 --> 00:03:23,578 Bottlenose dolphins. 26 00:03:31,211 --> 00:03:35,465 This might seem the perfect place for a mother to raise her newborn calf… 27 00:03:37,592 --> 00:03:38,551 but even here, 28 00:03:39,260 --> 00:03:41,054 life isn't easy. 29 00:03:49,354 --> 00:03:50,980 They're being followed. 30 00:03:55,735 --> 00:03:57,153 A group of males, 31 00:03:58,071 --> 00:03:59,572 looking for a mate. 32 00:04:02,784 --> 00:04:05,620 They could attack the baby to get to Mom. 33 00:04:17,966 --> 00:04:20,134 More dolphins join the chase. 34 00:04:28,351 --> 00:04:31,271 Mom does all she can to protect her calf. 35 00:04:39,195 --> 00:04:40,280 Eventually, 36 00:04:40,905 --> 00:04:42,282 she fights them off. 37 00:04:45,660 --> 00:04:47,704 But her baby is nowhere to be seen. 38 00:04:58,006 --> 00:05:01,134 Alone, he stands little chance. 39 00:05:25,908 --> 00:05:28,328 Reunited with Mom… 40 00:05:30,496 --> 00:05:32,040 and her allies, 41 00:05:33,416 --> 00:05:37,503 the calf a little wiser in the ways of the world. 42 00:05:39,088 --> 00:05:43,676 But his lessons in becoming a dolphin have only just begun. 43 00:05:57,857 --> 00:06:01,235 Dolphins are air-breathing mammals, like us. 44 00:06:03,946 --> 00:06:07,033 Their ancestors once lived on dry land, 45 00:06:08,659 --> 00:06:10,912 but 50 million years ago, 46 00:06:10,995 --> 00:06:13,122 they did something amazing. 47 00:06:14,832 --> 00:06:16,125 Left the land 48 00:06:16,209 --> 00:06:19,253 to enter a life aquatic. 49 00:06:24,133 --> 00:06:25,802 While one branch of the family 50 00:06:25,885 --> 00:06:29,514 became huge, filter-feeding baleen whales… 51 00:06:31,933 --> 00:06:34,685 they turned into streamlined, 52 00:06:34,769 --> 00:06:36,896 quick-thinking predators. 53 00:06:39,774 --> 00:06:44,445 Today, over 40 species of dolphin hunt the oceans of the world. 54 00:06:50,034 --> 00:06:51,953 From tropical waters… 55 00:06:55,915 --> 00:06:57,834 to polar seas, 56 00:06:59,419 --> 00:07:03,548 and even in rivers thousands of miles inland, 57 00:07:05,466 --> 00:07:07,260 wherever there is prey, 58 00:07:08,386 --> 00:07:11,806 there's a dolphin with a clever way of catching it. 59 00:07:21,441 --> 00:07:24,902 Orca are the largest members of the family. 60 00:07:27,155 --> 00:07:29,824 They can grow nearly 30 feet long 61 00:07:30,366 --> 00:07:33,119 and weigh seven tons. 62 00:07:37,790 --> 00:07:41,461 Each needs to catch over 100 lb. of food a day. 63 00:07:43,713 --> 00:07:45,798 Not easy in the polar winter. 64 00:07:46,924 --> 00:07:49,218 Unless you know where to look. 65 00:08:02,690 --> 00:08:04,609 During the coldest months, 66 00:08:04,692 --> 00:08:07,945 their favorite prey shelters in protected fjords. 67 00:08:13,743 --> 00:08:14,660 Herring. 68 00:08:15,995 --> 00:08:19,081 In their billions. 69 00:08:31,344 --> 00:08:33,930 Tracking down their exact location 70 00:08:34,013 --> 00:08:35,181 can be tricky. 71 00:08:39,560 --> 00:08:41,521 Catching them is even harder. 72 00:08:50,988 --> 00:08:53,282 Led by an experienced female, 73 00:08:54,408 --> 00:08:58,621 the family pod home in on the vast shoal. 74 00:09:02,250 --> 00:09:04,544 As long as the herring keep formation, 75 00:09:05,920 --> 00:09:07,713 they're hard to single out. 76 00:09:18,891 --> 00:09:20,768 But the orca have a plan. 77 00:09:24,063 --> 00:09:26,274 With pulsing calls, 78 00:09:27,233 --> 00:09:29,485 and by flashing their white bellies… 79 00:09:32,405 --> 00:09:35,366 they herd the herring into the shallows. 80 00:09:50,464 --> 00:09:54,302 In the panic, the fish form tighter and tighter shoals. 81 00:10:04,353 --> 00:10:05,980 Until finally, 82 00:10:06,063 --> 00:10:08,608 the orca can strike. 83 00:10:19,785 --> 00:10:24,123 Smashing their tail flukes creates powerful pressure waves. 84 00:10:29,170 --> 00:10:31,756 A barrage of knockout blows. 85 00:10:39,555 --> 00:10:41,432 Once the fish are stunned, 86 00:10:42,224 --> 00:10:44,977 the orca can eat at leisure. 87 00:11:09,043 --> 00:11:13,297 Dolphins maximize their hunting success by working as a team. 88 00:11:15,216 --> 00:11:17,134 And out in the open ocean, 89 00:11:17,218 --> 00:11:19,512 they operate on an epic scale. 90 00:11:25,059 --> 00:11:28,229 A stampede of spinner dolphins. 91 00:11:30,523 --> 00:11:34,193 A super pod over a thousand strong. 92 00:11:51,085 --> 00:11:54,046 They make such an effective hunting force, 93 00:11:54,755 --> 00:11:57,842 they can afford plenty of downtime. 94 00:12:11,605 --> 00:12:13,441 Two hundred miles east of Brazil, 95 00:12:14,608 --> 00:12:17,153 this archipelago is a favorite stop-off 96 00:12:17,236 --> 00:12:19,196 for Atlantic spinner dolphins. 97 00:12:22,908 --> 00:12:25,369 They head for the island's shallow bays. 98 00:12:28,581 --> 00:12:32,418 The first arrivals are in high spirits. 99 00:12:47,933 --> 00:12:51,061 The Olympic gymnasts of the dolphin family. 100 00:12:52,396 --> 00:12:55,357 They can leap ten feet 101 00:12:56,233 --> 00:12:58,277 and spin seven times. 102 00:13:11,123 --> 00:13:12,750 It looks a lot of fun. 103 00:13:15,044 --> 00:13:18,214 But it's thought there's more to these acrobatics. 104 00:13:26,096 --> 00:13:28,182 Perhaps they're communicating, 105 00:13:28,265 --> 00:13:30,768 greeting other dolphins entering the bay. 106 00:13:45,825 --> 00:13:47,618 With safety in numbers, 107 00:13:48,452 --> 00:13:50,621 the spinners can relax. 108 00:14:02,466 --> 00:14:04,677 But they can't switch off completely, 109 00:14:05,427 --> 00:14:07,012 or they would drown. 110 00:14:08,389 --> 00:14:11,767 So they shut down one side of their brain at a time… 111 00:14:13,853 --> 00:14:16,272 with one eye on where they're going. 112 00:14:18,190 --> 00:14:20,818 Sleep swimming at half speed. 113 00:14:27,616 --> 00:14:29,994 While older dolphins rest, 114 00:14:31,370 --> 00:14:33,998 the younger ones play. 115 00:14:56,478 --> 00:14:58,480 A game of seaweed catch. 116 00:15:28,218 --> 00:15:30,387 It seems simple enough. 117 00:15:33,807 --> 00:15:37,353 But this is surprisingly sophisticated play. 118 00:15:39,563 --> 00:15:41,649 Manipulating objects, 119 00:15:43,025 --> 00:15:46,111 copying moves and, most importantly, 120 00:15:46,195 --> 00:15:47,780 understanding each other. 121 00:15:48,864 --> 00:15:54,453 A skill every young dolphin must master as it grows. 122 00:16:00,334 --> 00:16:02,211 By a year old, 123 00:16:02,294 --> 00:16:06,674 an Atlantic spotted calf is almost fluent in dolphin. 124 00:16:22,189 --> 00:16:25,609 Much can be communicated through body language and touch. 125 00:16:27,695 --> 00:16:29,780 A flipper rub reassures, 126 00:16:30,781 --> 00:16:32,282 like holding hands. 127 00:16:35,369 --> 00:16:39,373 But some things can only be said with sound. 128 00:16:42,960 --> 00:16:44,962 His mom repeats a unique call. 129 00:16:48,799 --> 00:16:50,300 Her signature whistle. 130 00:16:53,429 --> 00:16:55,764 It helps him to find her in a crowd. 131 00:17:00,602 --> 00:17:02,896 And once he's learned to copy it, 132 00:17:02,980 --> 00:17:04,857 he can call her by her name. 133 00:17:08,027 --> 00:17:11,572 Now it's time to experiment with a whistle of his own. 134 00:17:16,452 --> 00:17:17,745 Like children, 135 00:17:17,828 --> 00:17:20,664 dolphins take years learning to speak. 136 00:17:23,125 --> 00:17:25,085 And once they start talking… 137 00:17:28,255 --> 00:17:30,841 …they never let up. 138 00:17:38,223 --> 00:17:42,186 But a dolphin's sonic skills go way beyond words. 139 00:17:48,108 --> 00:17:51,904 The local bottlenose are searching for food on the sea floor. 140 00:17:54,073 --> 00:17:56,033 There doesn't appear to be much here. 141 00:17:57,826 --> 00:18:01,997 But they can see things we can't. 142 00:18:09,338 --> 00:18:12,424 They fire a stream of high-pitched clicks. 143 00:18:13,634 --> 00:18:16,595 Five hundred per second. 144 00:18:24,645 --> 00:18:26,647 And interpret the echoes 145 00:18:26,730 --> 00:18:29,566 to pinpoint fish hiding in the sand. 146 00:18:52,381 --> 00:18:55,801 Echolocation is an extraordinary sixth sense… 147 00:18:57,845 --> 00:19:03,142 that allows dolphins to hunt in the most unlikely of places. 148 00:19:15,112 --> 00:19:16,405 A muddy estuary, 149 00:19:17,447 --> 00:19:20,033 and the tide is dropping. 150 00:19:21,702 --> 00:19:25,956 Right now, heading inland could be a risky move. 151 00:19:38,677 --> 00:19:43,265 But this dolphin knows the estuary is full of fish. 152 00:19:53,901 --> 00:19:55,903 Using echolocation, 153 00:19:55,986 --> 00:20:00,616 she can navigate the silty waters and find her prey. 154 00:20:08,665 --> 00:20:10,250 Only problem is, 155 00:20:10,334 --> 00:20:13,295 at low tide they hide in the oyster beds. 156 00:20:15,214 --> 00:20:18,300 Charging in would shred her sensitive skin. 157 00:20:20,761 --> 00:20:25,098 Somehow, she needs to get the fish into the open. 158 00:20:38,820 --> 00:20:42,741 Pumping her tail, she flushes them out of hiding 159 00:20:43,825 --> 00:20:47,246 and towards the sandy banks, where it's safe to strike. 160 00:20:55,712 --> 00:20:58,840 Only a few dolphins have learned to hunt like this. 161 00:21:03,679 --> 00:21:05,764 And the technique only works 162 00:21:05,847 --> 00:21:08,058 for a few hours each day. 163 00:21:14,731 --> 00:21:17,317 When the tide begins to rise, 164 00:21:17,401 --> 00:21:19,319 the fish disperse. 165 00:21:22,698 --> 00:21:24,616 A new strategy is needed. 166 00:21:28,662 --> 00:21:30,664 She joins forces with friends 167 00:21:31,999 --> 00:21:35,460 and together they head towards wider channels. 168 00:21:39,506 --> 00:21:40,507 Then, 169 00:21:42,384 --> 00:21:43,593 they wait. 170 00:22:28,013 --> 00:22:30,223 Each time a shoal swims past, 171 00:22:30,307 --> 00:22:32,184 the dolphins attack, 172 00:22:33,852 --> 00:22:36,980 creating bow waves that wash the fish ashore. 173 00:22:54,581 --> 00:22:58,335 Through echolocation and coordination, 174 00:22:58,418 --> 00:23:01,505 they conjure a feast from the mud. 175 00:23:08,261 --> 00:23:10,263 Out in the big blue, 176 00:23:10,347 --> 00:23:13,767 dolphins must push their super senses to the limits. 177 00:23:21,108 --> 00:23:22,984 The challenge of hunting in the abyss 178 00:23:23,068 --> 00:23:27,781 has created one of the most extraordinary dolphins of all. 179 00:23:48,468 --> 00:23:51,054 Pilot whales may look strange, 180 00:23:51,763 --> 00:23:55,892 but their bulbous foreheads hold the secret to their success. 181 00:23:57,144 --> 00:24:01,231 They project long-range sonic beams hundreds of feet. 182 00:24:02,274 --> 00:24:05,777 The most powerful echolocation of any dolphin. 183 00:24:13,702 --> 00:24:16,830 It enables pilot whales to hunt shoals of squid 184 00:24:16,913 --> 00:24:19,040 over half a mile down. 185 00:24:29,426 --> 00:24:33,138 But young calves can't hold their breath long enough to follow. 186 00:24:37,517 --> 00:24:40,645 So the family take turns 187 00:24:40,729 --> 00:24:42,689 babysitting at the surface. 188 00:24:45,942 --> 00:24:48,653 Grandma is over 50 years old. 189 00:24:49,988 --> 00:24:53,325 But she still produces milk to keep the youngsters fed. 190 00:25:02,417 --> 00:25:05,879 These dolphins live up to 70 years 191 00:25:06,880 --> 00:25:09,174 and stay with the family for life. 192 00:25:10,050 --> 00:25:14,971 Possibly the longest, most loyal bonds of any animal. 193 00:25:22,437 --> 00:25:24,606 When the hunting party surfaces, 194 00:25:24,689 --> 00:25:26,691 it's clear they've had success. 195 00:25:32,781 --> 00:25:34,366 Time to move on. 196 00:25:35,742 --> 00:25:38,870 Grandma has a mental map of their ocean home. 197 00:25:39,996 --> 00:25:43,792 She listens for the sounds of waves crashing on islands 198 00:25:43,875 --> 00:25:46,545 and currents washing around sea mouths. 199 00:25:49,548 --> 00:25:52,342 Acoustic landmarks revealing the route. 200 00:25:59,349 --> 00:26:00,559 But sometimes, 201 00:26:01,810 --> 00:26:04,312 even these great navigators lose their way. 202 00:26:09,776 --> 00:26:10,652 Every year, 203 00:26:11,653 --> 00:26:15,282 hundreds of dolphins strand on beaches around the world. 204 00:26:16,241 --> 00:26:18,785 Pilot whales more often than most. 205 00:26:20,954 --> 00:26:23,915 It only takes one or two to go off course… 206 00:26:26,001 --> 00:26:29,546 and family members feel compelled to swim to their side. 207 00:26:33,133 --> 00:26:36,261 Sometimes, their distress calls bring hundreds more. 208 00:26:44,436 --> 00:26:46,354 Natural disasters, 209 00:26:46,438 --> 00:26:48,815 noise pollution, and ill health 210 00:26:48,898 --> 00:26:51,067 all seem to play a part. 211 00:26:53,570 --> 00:26:57,198 But the exact triggers for these events are poorly understood. 212 00:27:04,623 --> 00:27:08,126 People do all they can to keep stranded whales alive 213 00:27:08,209 --> 00:27:10,920 and try to help them back out to sea. 214 00:27:20,430 --> 00:27:23,975 The connection between humans and dolphins runs deep. 215 00:27:25,685 --> 00:27:30,106 We share a thrill-seeking side found in few other animals. 216 00:27:31,232 --> 00:27:36,237 And we express ourselves in ways that have no obvious role in survival. 217 00:27:41,034 --> 00:27:43,828 But it seems there's purpose to all this play. 218 00:27:46,289 --> 00:27:48,667 It produces a rush of hormones 219 00:27:48,750 --> 00:27:51,920 that create feelings of confidence and joy. 220 00:27:53,630 --> 00:27:56,883 Playing together heightens these emotions… 221 00:27:59,052 --> 00:28:03,014 encouraging teamwork and time spent with friends. 222 00:28:17,070 --> 00:28:20,365 Perhaps this is why dolphins seek the company of others. 223 00:28:34,754 --> 00:28:36,881 Playing with their own kind. 224 00:28:41,720 --> 00:28:42,554 With us. 225 00:28:46,558 --> 00:28:48,560 And with other animals. 226 00:29:15,336 --> 00:29:18,256 Dolphins are famous for their friendly nature. 227 00:29:20,425 --> 00:29:22,844 But they also have a darker side. 228 00:29:36,608 --> 00:29:39,944 When the ocean's top predators go hunting, 229 00:29:40,028 --> 00:29:42,071 nothing is safe. 230 00:30:01,591 --> 00:30:04,177 Southern right whales. 231 00:30:06,304 --> 00:30:08,556 Up to 80 tons. 232 00:30:10,058 --> 00:30:12,852 Ten times heavier than an orca. 233 00:30:21,319 --> 00:30:23,112 But working as a team, 234 00:30:24,072 --> 00:30:26,741 orca are almost unstoppable. 235 00:30:32,038 --> 00:30:34,457 The right whales make for the shallows 236 00:30:34,541 --> 00:30:36,543 to avoid attack from below. 237 00:30:40,880 --> 00:30:43,758 But orca don't give up easily. 238 00:30:48,012 --> 00:30:49,848 Taking turns, 239 00:30:49,931 --> 00:30:52,851 they smash into the whales' flanks, 240 00:30:52,934 --> 00:30:54,644 hitting them where it hurts. 241 00:31:05,029 --> 00:31:07,073 The whales strike back. 242 00:31:35,018 --> 00:31:39,147 But it's only when the sounds of struggle attract more right whales 243 00:31:40,690 --> 00:31:43,693 that the orca finally back off. 244 00:31:50,533 --> 00:31:53,286 Orca's ability to take on such large prey 245 00:31:53,369 --> 00:31:55,914 earned them the nickname "whale killers," 246 00:31:56,581 --> 00:31:57,415 or 247 00:31:58,166 --> 00:31:59,375 "killer whales." 248 00:32:02,879 --> 00:32:05,298 Dolphins are not just ruthless hunters. 249 00:32:06,591 --> 00:32:10,178 They can also be surprisingly aggressive to each other. 250 00:32:24,359 --> 00:32:25,610 By six years old, 251 00:32:26,194 --> 00:32:28,154 this young spotted dolphin 252 00:32:28,237 --> 00:32:31,366 has finally developed his trademark spots. 253 00:32:37,330 --> 00:32:38,998 He's seeing less of Mom… 254 00:32:41,042 --> 00:32:44,253 and spending more time hanging out with friends. 255 00:32:48,841 --> 00:32:52,512 Building alliances is crucial in these early years. 256 00:33:02,730 --> 00:33:06,567 Dolphins form more numerous, more intense relationships 257 00:33:06,651 --> 00:33:09,821 than any other animal except us. 258 00:33:14,951 --> 00:33:18,162 As he matures, life will become more complicated. 259 00:33:22,083 --> 00:33:24,585 And he'll need all the friends he can get. 260 00:33:36,723 --> 00:33:40,309 A community of bottlenose dolphins in Western Australia 261 00:33:40,393 --> 00:33:45,314 is considered the most sophisticated dolphin society of all. 262 00:33:48,276 --> 00:33:50,945 Two thousand live in this one bay. 263 00:34:02,081 --> 00:34:04,208 During the breeding season, 264 00:34:04,292 --> 00:34:07,670 who you know becomes more important than ever. 265 00:34:09,714 --> 00:34:11,632 Males that are able to team up 266 00:34:11,716 --> 00:34:13,968 have more chance of winning a mate. 267 00:34:28,316 --> 00:34:31,194 This trio hangs out on the east side of the bay. 268 00:34:37,492 --> 00:34:41,496 They've been best friends for 20 years. 269 00:34:44,791 --> 00:34:49,253 Swimming in sync shows just how tight they are. 270 00:34:51,714 --> 00:34:55,802 And choreographed moves help impress the opposite sex. 271 00:35:02,892 --> 00:35:04,602 There's the crossover. 272 00:35:07,230 --> 00:35:08,439 The butterfly. 273 00:35:12,068 --> 00:35:13,903 The duo tail touch. 274 00:35:16,114 --> 00:35:17,949 Synchronous dives. 275 00:35:20,118 --> 00:35:21,494 Dual leaps. 276 00:35:22,954 --> 00:35:24,539 Tango moves. 277 00:35:25,206 --> 00:35:29,001 And the inverse rooster strut. 278 00:35:32,213 --> 00:35:35,967 The slicker the routine, the more attractive they seem. 279 00:35:41,514 --> 00:35:42,765 Even so, 280 00:35:42,849 --> 00:35:45,518 it often takes days to win over a female. 281 00:35:51,649 --> 00:35:54,360 And now they have competition. 282 00:35:56,487 --> 00:35:57,864 On the west side, 283 00:35:57,947 --> 00:36:00,074 rival gangs are forming. 284 00:36:03,369 --> 00:36:05,663 The east side trio needs backup. 285 00:36:08,958 --> 00:36:11,752 So they call on a wider circle of friends. 286 00:36:31,397 --> 00:36:33,191 Weaker gangs usually back down. 287 00:36:35,568 --> 00:36:37,945 But when the sides are equally matched, 288 00:36:39,322 --> 00:36:41,782 fights can cause serious injury. 289 00:37:30,039 --> 00:37:31,040 An hour later, 290 00:37:32,124 --> 00:37:33,334 it's all over. 291 00:37:38,256 --> 00:37:41,550 Through strong allegiances and tight teamwork, 292 00:37:41,634 --> 00:37:44,178 the east side friends emerge victorious 293 00:37:44,804 --> 00:37:48,599 and win the chance to father the next generation. 294 00:37:52,770 --> 00:37:54,897 Intelligence and collaboration 295 00:37:54,981 --> 00:37:58,943 have enabled dolphins to navigate life in the ocean. 296 00:38:01,362 --> 00:38:03,781 But their home is changing fast. 297 00:38:08,577 --> 00:38:12,248 Even these adaptable animals are struggling to cope. 298 00:38:18,587 --> 00:38:20,673 Our seas are becoming noisier. 299 00:38:22,800 --> 00:38:23,676 Warmer. 300 00:38:25,428 --> 00:38:26,804 And more polluted. 301 00:38:34,270 --> 00:38:35,896 Instead of seaweed, 302 00:38:35,980 --> 00:38:39,108 many dolphins now play with plastic bags. 303 00:38:49,618 --> 00:38:55,291 Swallowing trash kills over 100,000 marine mammals every year. 304 00:38:56,334 --> 00:38:58,586 And chemical contamination 305 00:38:58,669 --> 00:39:01,339 threatens their ability to reproduce. 306 00:39:04,675 --> 00:39:09,305 But industrial-scale fishing is the biggest problem dolphins face… 307 00:39:11,974 --> 00:39:14,393 rapidly depleting their vital food 308 00:39:15,019 --> 00:39:19,190 and drowning hundreds of thousands of them each year. 309 00:39:28,240 --> 00:39:31,369 However, even small changes in our actions 310 00:39:31,452 --> 00:39:33,704 can make a big difference. 311 00:39:47,385 --> 00:39:49,303 When fishermen trawl for shrimp… 312 00:39:52,056 --> 00:39:54,558 other animals are caught in their nets. 313 00:39:57,061 --> 00:40:00,564 But these fishermen now incorporate special openings 314 00:40:00,648 --> 00:40:02,858 so larger animals can escape. 315 00:40:06,153 --> 00:40:09,365 And the local bottlenose have learned to seek them out, 316 00:40:10,825 --> 00:40:14,745 using the exit holes to pick out a prize of fish. 317 00:40:31,429 --> 00:40:34,598 Entering these death traps is a risky maneuver. 318 00:40:38,769 --> 00:40:41,689 But these hungry dolphins take their chances. 319 00:40:56,495 --> 00:40:58,289 And the fishermen tolerate them. 320 00:41:01,208 --> 00:41:03,043 There's no loss to their catch. 321 00:41:08,466 --> 00:41:11,218 We still have a lot to learn about dolphins. 322 00:41:12,011 --> 00:41:15,389 And while some species are on the brink of extinction, 323 00:41:17,057 --> 00:41:20,311 new ones are still being found. 324 00:41:26,650 --> 00:41:31,906 It's long been thought there were five species of river dolphin in the world. 325 00:41:31,989 --> 00:41:35,242 Now biologists believe they've discovered a sixth. 326 00:41:37,328 --> 00:41:42,500 Only around 1,000 Araguaian river dolphins are thought to exist. 327 00:41:46,253 --> 00:41:48,005 But every day 328 00:41:48,088 --> 00:41:50,341 in this Brazilian town, 329 00:41:50,424 --> 00:41:52,760 a small number come to hang out. 330 00:41:54,887 --> 00:41:58,432 The local children can hardly wait. 331 00:42:03,687 --> 00:42:08,108 It's easy to understand their affinity with these magical animals. 332 00:42:12,696 --> 00:42:16,992 Humans and dolphins may inhabit very different worlds… 333 00:42:19,495 --> 00:42:22,998 but there's much in our nature that we share. 334 00:42:30,089 --> 00:42:32,800 A deep connection to be cherished 335 00:42:33,676 --> 00:42:36,470 for generations to come.