[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:08.46,0:00:11.09,Default,,0000,0000,0000,,Communicating underwater is challenging.
Dialogue: 0,0:00:11.09,0:00:16.65,Default,,0000,0000,0000,,Light and odors don't travel well,\Nso it's hard for animals to see or smell.
Dialogue: 0,0:00:16.65,0:00:21.84,Default,,0000,0000,0000,,But sound moves about four times\Nfaster in water than in air,
Dialogue: 0,0:00:21.84,0:00:23.44,Default,,0000,0000,0000,,so in this dark environment,
Dialogue: 0,0:00:23.44,0:00:28.35,Default,,0000,0000,0000,,marine mammals often rely\Non vocalization to communicate.
Dialogue: 0,0:00:28.35,0:00:32.06,Default,,0000,0000,0000,,That's why a chorus of sounds fills\Nthe ocean.
Dialogue: 0,0:00:32.06,0:00:32.82,Default,,0000,0000,0000,,Clicks,
Dialogue: 0,0:00:32.82,0:00:33.52,Default,,0000,0000,0000,,pulses,
Dialogue: 0,0:00:33.52,0:00:34.54,Default,,0000,0000,0000,,whistles,
Dialogue: 0,0:00:34.54,0:00:35.43,Default,,0000,0000,0000,,groans,
Dialogue: 0,0:00:35.43,0:00:36.28,Default,,0000,0000,0000,,boings,
Dialogue: 0,0:00:36.28,0:00:37.08,Default,,0000,0000,0000,,cries,
Dialogue: 0,0:00:37.08,0:00:39.79,Default,,0000,0000,0000,,and trills, to name a few.
Dialogue: 0,0:00:39.79,0:00:42.29,Default,,0000,0000,0000,,But the most famous parts of this\Nunderwater symphony
Dialogue: 0,0:00:42.29,0:00:48.11,Default,,0000,0000,0000,,are the evocative melodies, or songs,\Ncomposed by the world's largest mammals,
Dialogue: 0,0:00:48.11,0:00:50.74,Default,,0000,0000,0000,,whales.
Dialogue: 0,0:00:50.74,0:00:54.60,Default,,0000,0000,0000,,Whale songs are one of the most\Nsophisticated communication systems
Dialogue: 0,0:00:54.60,0:00:56.47,Default,,0000,0000,0000,,in the animal kingdom.
Dialogue: 0,0:00:56.47,0:00:59.18,Default,,0000,0000,0000,,Only a few species are known to sing.
Dialogue: 0,0:00:59.18,0:00:59.92,Default,,0000,0000,0000,,Blue,
Dialogue: 0,0:00:59.92,0:01:00.83,Default,,0000,0000,0000,,fin,
Dialogue: 0,0:01:00.83,0:01:01.70,Default,,0000,0000,0000,,bowhead
Dialogue: 0,0:01:01.70,0:01:03.18,Default,,0000,0000,0000,,minke whales,
Dialogue: 0,0:01:03.18,0:01:06.28,Default,,0000,0000,0000,,and of course humpback whales.
Dialogue: 0,0:01:06.28,0:01:08.03,Default,,0000,0000,0000,,These are all baleen whales
Dialogue: 0,0:01:08.03,0:01:12.92,Default,,0000,0000,0000,,which use hairy baleen plates\Ninstead of teeth to trap their prey.
Dialogue: 0,0:01:12.92,0:01:16.32,Default,,0000,0000,0000,,Meanwhile, toothed whales do use\Necholocation,
Dialogue: 0,0:01:16.32,0:01:19.18,Default,,0000,0000,0000,,and they and other species\Nof baleen whales
Dialogue: 0,0:01:19.18,0:01:23.87,Default,,0000,0000,0000,,make social sounds, such as \Ncries and whistles, to communicate.
Dialogue: 0,0:01:23.87,0:01:28.29,Default,,0000,0000,0000,,But those vocalizations \Nlack the complexity of songs.
Dialogue: 0,0:01:28.29,0:01:29.99,Default,,0000,0000,0000,,So how do they do it?
Dialogue: 0,0:01:29.99,0:01:34.99,Default,,0000,0000,0000,,Land mammals like us generate sound\Nby moving air over our vocal cords
Dialogue: 0,0:01:34.99,0:01:38.11,Default,,0000,0000,0000,,when we exhale,\Ncausing them to vibrate.
Dialogue: 0,0:01:38.11,0:01:42.26,Default,,0000,0000,0000,,Baleen whales have a U-shaped fold\Nof tissue between their lungs
Dialogue: 0,0:01:42.26,0:01:47.49,Default,,0000,0000,0000,,and their large inflatable organs\Ncalled laryngeal sacs.
Dialogue: 0,0:01:47.49,0:01:49.70,Default,,0000,0000,0000,,We don't know this for sure
Dialogue: 0,0:01:49.70,0:01:53.12,Default,,0000,0000,0000,,because it's essentially impossible\Nto observe the internal organs
Dialogue: 0,0:01:53.12,0:01:55.10,Default,,0000,0000,0000,,of a living, singing whale,
Dialogue: 0,0:01:55.10,0:01:57.33,Default,,0000,0000,0000,,but we think that when a whale sings,
Dialogue: 0,0:01:57.33,0:02:00.11,Default,,0000,0000,0000,,muscular contractions in the throat\Nand chest
Dialogue: 0,0:02:00.11,0:02:06.02,Default,,0000,0000,0000,,move air from the lungs across\Nthe U-fold and into the laryngeal sacs,
Dialogue: 0,0:02:06.02,0:02:08.48,Default,,0000,0000,0000,,causing the U-fold to vibrate.
Dialogue: 0,0:02:08.48,0:02:14.16,Default,,0000,0000,0000,,The resulting sound resonates in the sacs\Nlike a choir singing in a cathedral
Dialogue: 0,0:02:14.16,0:02:19.19,Default,,0000,0000,0000,,making songs loud enough to propagate\Nup to thousands of kilometers away.
Dialogue: 0,0:02:19.19,0:02:21.76,Default,,0000,0000,0000,,Whales don't have to exhale to sing.
Dialogue: 0,0:02:21.76,0:02:25.33,Default,,0000,0000,0000,,Instead, the air is recycled \Nback into the lungs,
Dialogue: 0,0:02:25.33,0:02:27.98,Default,,0000,0000,0000,,creating sound once more.
Dialogue: 0,0:02:27.98,0:02:31.76,Default,,0000,0000,0000,,One reason whale songs are so fascinating\Nis their pattern.
Dialogue: 0,0:02:31.76,0:02:36.62,Default,,0000,0000,0000,,Units, like moans, cries, and chirps\Nare arranged in phrases.
Dialogue: 0,0:02:36.62,0:02:39.67,Default,,0000,0000,0000,,Repeated phrases \Nare assembled into themes.
Dialogue: 0,0:02:39.67,0:02:44.55,Default,,0000,0000,0000,,Multiple themes repeated in a predictable\Npattern create a song.
Dialogue: 0,0:02:44.55,0:02:47.12,Default,,0000,0000,0000,,This hierarchical structure \Nis a kind of grammar.
Dialogue: 0,0:02:47.12,0:02:50.84,Default,,0000,0000,0000,,Whale songs are extremely variable\Nin duration,
Dialogue: 0,0:02:50.84,0:02:54.14,Default,,0000,0000,0000,,and whales can repeat them over and over.
Dialogue: 0,0:02:54.14,0:02:59.95,Default,,0000,0000,0000,,In one recorded session,\Na humpback whale sang for 22 hours.
Dialogue: 0,0:02:59.95,0:03:01.56,Default,,0000,0000,0000,,And why do they do it?
Dialogue: 0,0:03:01.56,0:03:05.16,Default,,0000,0000,0000,,We don't yet know the exact purpose,\Nbut we can speculate.
Dialogue: 0,0:03:05.16,0:03:09.32,Default,,0000,0000,0000,,Given that the singers are males and \Nthey mostly sing during the mating season,
Dialogue: 0,0:03:09.32,0:03:12.27,Default,,0000,0000,0000,,songs might be used to attract females.
Dialogue: 0,0:03:12.27,0:03:17.04,Default,,0000,0000,0000,,Or perhaps they're territorial,\Nused to deter other males.
Dialogue: 0,0:03:17.04,0:03:21.16,Default,,0000,0000,0000,,Whales return to the same feeding\Nand breeding grounds annually,
Dialogue: 0,0:03:21.16,0:03:24.97,Default,,0000,0000,0000,,and each discrete population has\Na different song.
Dialogue: 0,0:03:24.97,0:03:31.20,Default,,0000,0000,0000,,Songs evolve over time as units\Nor phrases are added, changed, or dropped.
Dialogue: 0,0:03:31.20,0:03:35.02,Default,,0000,0000,0000,,And when males from different populations\Nare feeding within earshot,
Dialogue: 0,0:03:35.02,0:03:37.30,Default,,0000,0000,0000,,phrases are often exchanged,
Dialogue: 0,0:03:37.30,0:03:41.86,Default,,0000,0000,0000,,maybe because new songs make them more\Nattractive to breeding females.
Dialogue: 0,0:03:41.86,0:03:45.59,Default,,0000,0000,0000,,This is one of the fastest examples\Nof cultural transmission,
Dialogue: 0,0:03:45.59,0:03:49.47,Default,,0000,0000,0000,,where learned behaviors are passed\Nbetween unrelated individuals
Dialogue: 0,0:03:49.47,0:03:51.52,Default,,0000,0000,0000,,of the same species.
Dialogue: 0,0:03:51.52,0:03:54.51,Default,,0000,0000,0000,,We can eavesdrop on these songs\Nusing underwater microphones
Dialogue: 0,0:03:54.51,0:03:56.41,Default,,0000,0000,0000,,called hydrophones.
Dialogue: 0,0:03:56.41,0:04:02.01,Default,,0000,0000,0000,,These help us track species when sightings\Nor genetic samples are rare.
Dialogue: 0,0:04:02.01,0:04:04.90,Default,,0000,0000,0000,,For example, scientists have been able\Nto differentiate
Dialogue: 0,0:04:04.90,0:04:10.34,Default,,0000,0000,0000,,the elusive blue whale's populations\Nworldwide based on their songs.
Dialogue: 0,0:04:10.34,0:04:14.95,Default,,0000,0000,0000,,But the oceans are getting noisier\Nas a result of human activity.
Dialogue: 0,0:04:14.95,0:04:15.68,Default,,0000,0000,0000,,Boating,
Dialogue: 0,0:04:15.68,0:04:16.76,Default,,0000,0000,0000,,military sonar,
Dialogue: 0,0:04:16.76,0:04:18.13,Default,,0000,0000,0000,,underwater construction,
Dialogue: 0,0:04:18.13,0:04:22.16,Default,,0000,0000,0000,,and seismic surveys for oil\Nare occurring more often
Dialogue: 0,0:04:22.16,0:04:25.35,Default,,0000,0000,0000,,which may interfere \Nwith whale's communication.
Dialogue: 0,0:04:25.35,0:04:28.67,Default,,0000,0000,0000,,Some whales will avoid key feeding\Nor breeding grounds
Dialogue: 0,0:04:28.67,0:04:31.30,Default,,0000,0000,0000,,if human noise is too loud.
Dialogue: 0,0:04:31.30,0:04:34.56,Default,,0000,0000,0000,,And humpback whales have been observed\Nto reduce their singing
Dialogue: 0,0:04:34.56,0:04:38.90,Default,,0000,0000,0000,,in response to noise 200 kilometers away.
Dialogue: 0,0:04:38.90,0:04:41.56,Default,,0000,0000,0000,,Limiting human activity\Nalong migratory routes
Dialogue: 0,0:04:41.56,0:04:43.62,Default,,0000,0000,0000,,and in other critical habitats,
Dialogue: 0,0:04:43.62,0:04:46.44,Default,,0000,0000,0000,,and reducing noise pollution\Nthroughout the ocean
Dialogue: 0,0:04:46.44,0:04:49.99,Default,,0000,0000,0000,,would help ensure \Nwhales continued survival.
Dialogue: 0,0:04:49.99,0:04:52.84,Default,,0000,0000,0000,,If the whales can keep singing\Nand we can keep listening,
Dialogue: 0,0:04:52.84,0:04:56.54,Default,,0000,0000,0000,,maybe one day we'll truly understand\Nwhat they're saying.