Cicadas: The dormant army beneath your feet - Rose Eveleth
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0:07 - 0:09If you live on the east coast of the United States,
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0:09 - 0:11you spent the last 17 years of your life
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0:11 - 0:12walking,
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0:12 - 0:13eating,
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0:13 - 0:13and sleeping
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0:13 - 0:16above a dormant army of insects.
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0:16 - 0:19These are the cicadas.
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0:19 - 0:20Every 17 years,
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0:20 - 0:21billions of them emerge from the ground
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0:21 - 0:23to do three things:
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0:23 - 0:23molt,
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0:23 - 0:24mate,
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0:24 - 0:25and die.
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0:25 - 0:29There are fifteen different broods of cicadas out there,
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0:29 - 0:30grouped by when they'll emerge from the ground.
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0:30 - 0:32Some of these broods are on a 13-year cycle,
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0:32 - 0:35others are on a 17-year clock.
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0:35 - 0:36Either way, the cicadas live underground
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0:36 - 0:37for most of their lives,
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0:37 - 0:39feeding on the juices of plant roots.
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0:39 - 0:40When it's time to emerge,
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0:40 - 0:42the adults will begin to burrow their way
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0:42 - 0:43out of the ground
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0:43 - 0:44and up to the surface,
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0:44 - 0:46where they will live for just a few weeks.
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0:46 - 0:47During these weeks, though,
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0:47 - 0:50everybody will know the cicadas have arrived.
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0:50 - 0:51There will be billions of them,
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0:51 - 0:53and they're loud.
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0:53 - 0:54Male cicadas band together
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0:54 - 0:55to call for female mates,
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0:55 - 0:57and their collective chorus can reach
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0:57 - 0:58up to 100 decibels,
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0:58 - 1:00as loud as a chain saw.
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1:00 - 1:02In fact, if you happen to be using a chain saw
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1:02 - 1:03or a lawn mower,
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1:03 - 1:05male cicadas will flock to you,
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1:05 - 1:07thinking that you're one of them.
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1:07 - 1:08Now, like most things in nature,
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1:08 - 1:11the cicadas don't arrive without a posse.
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1:11 - 1:14There are all sort of awesome and gross predators and parasites
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1:14 - 1:16that come along with the buzzing bugs.
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1:16 - 1:18Take the fungus massospora for example.
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1:18 - 1:20This little white fungus buries itself
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1:20 - 1:22in the cicada's abdomen and eats the bug alive,
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1:22 - 1:24leaving behind its spores.
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1:24 - 1:25When those spores rupture,
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1:25 - 1:28they burst out of the still-alive cicada,
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1:28 - 1:30turning the bug into a flying salt shaker of death,
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1:30 - 1:32raining spores down upon
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1:32 - 1:34its unsuspecting cicada neighbors.
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1:34 - 1:35But while we know pretty precisely
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1:35 - 1:37when the cicadas will arrive and fade away,
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1:37 - 1:40we're still not totally certain of why.
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1:40 - 1:42There are certain advantages
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1:42 - 1:44to having your entire species emerge at once, of course.
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1:44 - 1:47The sheer number of cicadas coming out of the ground
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1:47 - 1:48is so overwhelming to predators,
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1:48 - 1:50it is essentially guaranteed
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1:50 - 1:52that a few bugs will survive and reproduce.
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1:52 - 1:55And since cicadas emerge every 13 or 17 years,
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1:55 - 1:57longer than the lifespan of many of their predators,
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1:57 - 1:58the animals that eat them
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1:58 - 2:00don't learn to depend on their availability.
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2:00 - 2:03But why 13 and 17 years
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2:03 - 2:04instead of 16,
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2:04 - 2:04or 18,
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2:04 - 2:05or 12?
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2:05 - 2:08Well, that part no one really knows.
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2:08 - 2:10It's possible the number just happened by chance,
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2:10 - 2:13or, perhaps, cicadas really love prime numbers.
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2:13 - 2:15Eventually, the cicadas will mate and slowly die off,
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2:15 - 2:17their call fading into the distance.
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2:17 - 2:19The eggs that they lay will begin the cycle again,
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2:19 - 2:21their cicada babies burrowing into the earth,
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2:21 - 2:22feeding on plant juice,
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2:22 - 2:23and waiting for their turn
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2:23 - 2:24to darken the skies
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2:24 - 2:26and fill the air with their songs.
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2:26 - 2:28In 17 years, they'll be ready.
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2:29 - 2:30Will you?
- Title:
- Cicadas: The dormant army beneath your feet - Rose Eveleth
- Description:
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View full lesson: http://ed.ted.com/lessons/cicadas-the-dormant-army-beneath-your-feet-rose-eveleth
Every 13 or 17 years, billions of cicadas emerge from the ground to molt, mate and die. Adult cicadas only live a few weeks above ground, but you'd be hard pressed to ignore them -- they are extremely loud! Rose Eveleth explains everything you need to know about these noisy insects, admitting that there's still some things we just don't understand.
Lesson by Rose Eveleth, animation by Eli Enigenburg.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 02:46
Krystian Aparta commented on English subtitles for Cicadas: The dormant army beneath your feet - Rose Eveleth | ||
Krystian Aparta edited English subtitles for Cicadas: The dormant army beneath your feet - Rose Eveleth | ||
TED edited English subtitles for Cicadas: The dormant army beneath your feet - Rose Eveleth | ||
Jenny Zurawell edited English subtitles for Cicadas: The dormant army beneath your feet - Rose Eveleth | ||
Jessica Ruby approved English subtitles for Cicadas: The dormant army beneath your feet - Rose Eveleth | ||
Jessica Ruby accepted English subtitles for Cicadas: The dormant army beneath your feet - Rose Eveleth | ||
Jessica Ruby edited English subtitles for Cicadas: The dormant army beneath your feet - Rose Eveleth | ||
Jessica Ruby edited English subtitles for Cicadas: The dormant army beneath your feet - Rose Eveleth |
Krystian Aparta
The English transcript was updated on 3/9/2016.