Dead stuff: The secret ingredient in our food chain - John C. Moore

833,322 views ใƒป 2014-03-20

TED-Ed


ืื ื ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ืœืžื˜ื” ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ.

ืชืจื’ื•ื: Ido Dekkers ืขืจื™ื›ื”: Tal Dekkers
00:07
If someone called you scum,
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ืื ืžื™ืฉื”ื• ื”ื™ื” ืงื•ืจื ืœื›ื ืจืคืฉ
00:09
you'd probably be offended,
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ื›ื ืจืื” ื”ื™ื™ืชื ื ืขืœื‘ื™ื,
00:11
but scientifically,
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ืื‘ืœ ืžื“ืขื™ืช,
00:12
they might not be far off.
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ืื•ืœื™ ื”ื ืœื ื™ื”ื™ื• ืจื—ื•ืงื™ื.
00:14
Have you ever thought about
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ื”ืื ืื™ ืคืขื ื—ืฉื‘ืชื ืขืœ
00:15
where your food comes from?
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ืžืื™ืคื” ืžื’ื™ืข ื”ืื•ื›ืœ ืื•ืชื• ืืชื ืื•ื›ืœื™ื?
00:17
You might say it comes from
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ืืชื ืื•ืœื™ ืชื’ื™ื“ื• ืฉื”ื•ื ืžื’ื™ืข
00:18
plants, animals, or even fungi,
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ืžืฆืžื—ื™ื, ื—ื™ื•ืช, ืื• ืืคื™ืœื• ืคื˜ืจื™ื•ืช,
00:20
but you'd probably rather not
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ืื‘ืœ ืื•ืœื™ ืœื ืชืจืฆื•
00:21
think about the rotting organisms and poop
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ืœื—ืฉื•ื‘ ืขืœ ื”ืื•ืจื’ื ื™ื–ืžื™ื ื”ื ืจืงื‘ื™ื ื•ื”ืงืงื™
00:23
that feed those plants, animals, and fungi.
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ืฉืžืื›ื™ืœื™ื ืืช ื”ืฆืžื—ื™ื, ื”ื—ื™ื•ืช ื•ื”ืคื˜ืจื™ื•ืช.
00:26
So really, you and most of the matter in your body
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ืื– ื‘ืืžืช, ืืชื ื•ืจื•ื‘ ื”ื—ื•ืžืจ ื‘ื’ื•ืฃ ืฉืœื›ื
00:29
are just two or three degrees of separation
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ื”ื ืจืง ืฉืชื™ื™ื ืื• ืฉืœื•ืฉ ื“ืจื’ื•ืช ื”ืคืจื“ื”
00:31
from things like pond scum.
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ื‘ื™ืŸ ื“ื‘ืจื™ื ื›ืžื• ืจืคืฉ ื‘ืฉืœื•ืœื™ื•ืช.
00:34
All species in an ecosystem,
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ื›ืœ ื”ืžื™ื ื™ื ื‘ืžืขืจื›ืช ื”ืืงื•ืœื•ื’ื™ืช,
00:36
from the creatures in a coral reef
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ืžื™ืฆื•ืจื™ื ื‘ืฉื•ื ื™ื•ืช ืืœืžื•ื’ื™ื
00:38
to the fish in a lake
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ืœื“ื’ื™ื ื‘ืื’ื
00:39
to the lions on the savannah,
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ืœืืจื™ื•ืช ื‘ืกื•ื•ื ื”,
00:40
are directly or indirectly
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ืžื•ื–ื ื™ื ื™ืฉื™ืจื•ืช ืื• ื‘ืขืงื™ืคื™ืŸ
00:42
nourished by dead stuff.
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ื‘ื—ื•ืžืจ ืžืช.
00:44
Most of the organic matter in our bodies,
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ืจื•ื‘ ื”ื—ื•ืžืจ ื”ืื•ืจื’ื ื™ ื‘ื’ื•ืฃ ืฉืœื ื•.
00:46
if we trace it back far enough,
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ืื ื ืขืงื•ื‘ ืื—ืจื™ื• ืจื—ื•ืง ืžืกืคื™ืง,
00:48
comes from CO2 and water
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ืžื’ื™ืข ืžืคื—ืžืŸ ื“ื• ื—ืžืฆื ื™ ื•ืžื™ื
00:50
through photosynthesis.
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ื“ืจืš ืคื•ื˜ื•ืกื™ื ื˜ื–ื”.
00:52
Plants use the energy from sunlight
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ืฆืžื—ื™ื ืžืฉืชืžืฉื™ื ื‘ืื ืจื’ื™ืช ืื•ืจ ื”ืฉืžืฉ
00:54
to transform carbon dioxide and water from the environment
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ื›ื“ื™ ืœืฉื ื•ืช ืคื—ืžืŸ ื“ื• ื—ืžืฆื ื™ ื•ืžื™ื ืžื”ืกื‘ื™ื‘ื”
00:57
into glucose and oxygen.
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ืœื’ืœื•ืงื•ื– ื•ื—ืžืฆืŸ.
00:59
That glucose is then transformed
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ื”ื’ืœื•ืงื•ื– ื”ื–ื” ื”ื•ืคืš
01:01
into more complex organic molecules
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ืœืžื•ืœืงื•ืœื•ืช ืื•ืจื’ื ื™ื•ืช ืžื•ืจื›ื‘ื•ืช ื™ื•ืชืจ
01:02
to form leaves, stems, roots, fruit, and so on.
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ื›ื“ื™ ืœื™ืฆื•ืจ ืขืœื™ื, ื’ื‘ืขื•ืœื™ื, ืฉื•ืจืฉื™ื, ืคื™ืจื•ืช, ื•ื›ืš ื”ืœืื”.
01:06
The energy stored in these organic molecules
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ื”ืื ืจื’ื™ื” ืฉืืฆื•ืจื” ื‘ืžื•ืœืงื•ืœื•ืช ื”ืื•ืจื’ื ื™ื•ืช ื”ืืœื”
01:08
supports the food chains with which we're familiar.
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ืชื•ืžื›ืช ื‘ืฉืจืฉืจืื•ืช ื”ืžื–ื•ืŸ ืื•ืชืŸ ืื ื• ืžื›ื™ืจื™ื.
01:11
You've probably seen illustrations like this
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ื›ื ืจืื” ืจืื™ืชื ืฆื™ื•ืจื™ื ื›ืžื• ื–ื”
01:13
or this.
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ืื• ื–ื”.
01:15
These green food chains
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ืฉืจืฉืจืื•ืช ื”ืื•ื›ืœ ื”ื™ืจื•ืงื•ืช ื”ืืœื”
01:16
start with living plants at their base.
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ืžืชื—ื™ืœื•ืช ืขื ืฆืžื—ื™ื ื—ื™ื™ื ื‘ื‘ืกื™ืกืŸ.
01:19
But in real-life terrestrial ecosystems,
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ืื‘ืœ ื‘ืžืขืจื›ื•ืช ืืงื•ืœื•ื’ื™ื•ืช ื™ื‘ืฉืชื™ื•ืช ื‘ื—ื™ื™ื ื”ืืžื™ืชื™ื™ื,
01:22
less than 10% of plant matter
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ืคื—ื•ืช ืž 10% ืžื”ื—ื•ืžืจ ื”ืฆืžื—ื™
01:23
is eaten while it's still alive.
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ื ืื›ืœ ื‘ืขื•ื“ื• ื—ื™.
01:26
What about the other 90?
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ืžื” ืขื ืฉืืจ 90 ื”ืื—ื•ื–ื™ื?
01:27
Well, just look at the ground
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ื•ื‘ื›ืŸ, ื‘ื•ืื• ื ื‘ื™ื˜ ื‘ืงืจืงืข
01:29
on an autumn day.
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ื‘ื™ื•ื ืกืชื•ื™.
01:30
Living plants shed dead body parts:
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ืฆืžื—ื™ื ื—ื™ื™ื ืžืฉื™ืœื™ื ื—ืœืงื™ ื’ื•ืฃ ืžืชื™ื:
01:32
fallen leaves, broken branches,
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ืขืœื™ื ืฉื ืคืœื•, ืขื ืคื™ื ืฉื‘ื•ืจื™ื,
01:33
and even underground roots.
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ื•ืืคื™ืœื• ืฉื•ืจืฉื™ื ืชืช ืงืจืงืขื™ื™ื.
01:35
Many plants are lucky enough
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ืœื”ืจื‘ื” ืฆืžื—ื™ื ื™ืฉ ืžื–ืœ
01:36
to go their whole lives without being eaten,
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ืœืขื‘ื•ืจ ืืช ื›ืœ ื—ื™ื™ื”ื ื‘ืœื™ ืœื”ืื›ืœ,
01:38
eventually dying and leaving remains.
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ื”ื ืžืชื™ื ืœื‘ืกื•ืฃ ื•ืžืฉืื™ืจื™ื ืฉืืจื™ื•ืช.
01:41
All of these uneaten, undigested, and dead plant parts,
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ื›ืœ ื—ืœืงื™ ื”ืฆืžื—ื™ื ื”ืžืชื™ื ืฉืœื ื ืื›ืœื• ืื• ืขื•ื›ืœื•,
01:44
that 90% of terrestrial plant matter?
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90% ืžื”ื—ื•ืžืจ ื”ืฆืžื—ื™ ื”ื™ื‘ืฉืชื™?
01:47
That becomes detritus,
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ื–ื” ื”ื•ืคืš ืœืฉืคื•ื›ืช,
01:48
the base of what we call the brown food chain,
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ื”ื‘ืกื™ืก ืฉืœ ืžื” ืฉืื ื—ื ื• ืงื•ืจืื™ื ืœื• ืฉืจืฉืจืช ื”ืžื–ื•ืŸ ื”ื—ื•ื,
01:51
which looks more like this.
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ืฉื ืจืื” ื™ื•ืชืจ ื›ืžื• ื–ื”.
01:54
What happens to plants
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ืžื” ืฉืงื•ืจื” ืœืฆืžื—ื™ื
01:55
also happens to all other organisms up the food chain:
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ืงื•ืจื” ื’ื ืœื›ืœ ื”ืื•ืจื’ื ื™ื–ืžื™ื ื‘ืžืขืœื” ืฉืจืฉืจืช ื”ืžื–ื•ืŸ:
01:58
some are eaten alive,
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ื›ืžื” ื ืื›ืœื™ื ื—ื™ื™ื,
01:59
but most are eaten only
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ืื‘ืœ ืจื•ื‘ื ื ืื›ืœื™ื ืจืง
02:00
when they're dead and rotting.
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ื›ืฉื”ื ืžืชื™ื ื•ื ืจืงื‘ื™ื.
02:02
And all along this food chain,
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ื•ืœื›ืœ ืื•ืจืš ืฉืจืฉืจืช ื”ืžื–ื•ืŸ,
02:04
living things shed organic matter
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ื“ื‘ืจื™ื ื—ื™ื™ื ืžืฉื™ืจื™ื ื—ื•ืžืจ ืื•ืจื’ื ื™
02:06
and expel digestive waste
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ื•ืคื•ืœื˜ื™ื ืคืกื•ืœืช ืขื™ื›ื•ืœ
02:07
before dying and leaving their remains to decay.
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ืœืคื ื™ ืฉื”ื ืžืชื™ื ื•ืžืฉืื™ืจื™ื ืืช ื”ืฉืืจื™ื•ืช ืฉืœื”ื ืœื”ืจืงื‘.
02:10
All that death sounds grim, right?
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ื›ืœ ื”ืžื•ื•ืช ื”ื–ื” ื”ื•ื ืขื’ื•ื, ื ื›ื•ืŸ?
02:13
But it's not.
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ืื‘ืœ ื”ื•ื ืœื.
02:14
All detritus is ultimately consumed
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ื›ืœ ื”ืฉืืจื™ื•ืช ืžืขื•ื›ืœื•ืช ื‘ืกื•ืคื• ืฉืœ ื“ื‘ืจ
02:16
by microbes and other scavengers,
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ืขืœ ื™ื“ื™ ืžื™ืงืจื•ื‘ื™ื ื•ืื•ื›ืœื™ ืฉืืจื™ื•ืช ืื—ืจื™ื,
02:18
so it actually forms the base of the brown food chain
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ืื– ื–ื” ืœืžืขืฉื” ื™ื•ืฆืจ ืืช ื”ื‘ืกื™ืก ืœืฉืจืฉืจืช ื”ืžื–ื•ืŸ ื”ื—ื•ืžื”
02:21
that supports many other organisms,
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ืฉืชื•ืžื›ืช ื‘ืื•ืจื’ื ื™ื–ืžื™ื ืจื‘ื™ื ืื—ืจื™ื,
02:23
including us.
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ื›ื•ืœืœ ื‘ื ื•.
02:25
Scientists are learning
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ืžื“ืขื ื™ื ืœื•ืžื“ื™ื
02:26
that this detritus
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ืฉื”ืฉืคื•ื›ืช ื”ื–ื•
02:27
is an unexpectedly huge energy source,
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ื”ื™ื ืœืžืขืฉื” ืžืงื•ืจ ืื ืจื’ื™ื” ืขืฆื•ื,
02:29
fueling most natural ecosystems.
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ืฉืžืชื“ืœืง ืืช ืจื•ื‘ ื”ืžืขืจื›ืช ื”ืืงื•ืœื•ื’ื™ืช.
02:31
But the interactions within an ecosystem
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ืื‘ืœ ื”ืื™ื ื˜ืจืืงืฆื™ื•ืช ื‘ืชื•ืš ื”ืžืขืจื›ืช ื”ืืงื•ืœื•ื’ื™ืช
02:34
are even more complex than that.
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ื”ืŸ ืืคื™ืœื• ื™ื•ืชืจ ืžืกื•ื‘ื›ื•ืช ืžื–ื”.
02:36
What a food chain really represents
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ืžื” ืฉืžืขืจื›ืช ืžื–ื•ืŸ ื‘ืืžืช ืžื™ื™ืฆื’ืช
02:38
is a single pathway of energy flow.
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ื–ื” ื“ืจืš ืื—ืช ืฉืœ ื–ืจื™ืžืช ืื ืจื’ื™ื”.
02:40
And within any ecosystem,
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ื•ื‘ืชื•ืš ื›ืœ ืžืขืจื›ืช ืืงื•ืœื•ื’ื™ืช,
02:42
many of these flows
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ื”ืจื‘ื” ืžื”ื–ืจื™ืžื•ืช ื”ืืœื•
02:43
are linked together
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ืžื—ื•ื‘ืจื•ืช ื™ื—ื“
02:44
to form a rich network of interactions,
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ื›ื“ื™ ืœื™ืฆื•ืจ ืจืฉืชื•ืช ืขืฉื™ืจื•ืช ืฉืœ ืื™ื ื˜ืจืืงืฆื™ื•ืช,
02:46
or food web,
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ืื• ืจืฉืชื•ืช ืื•ื›ืœ,
02:48
with dead matter supporting that network at every step.
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ื›ืฉื—ื•ืžืจ ืžืช ืชื•ืžืš ื‘ืจืฉืช ื”ื–ื• ื‘ื›ืœ ืฉืœื‘.
02:52
The resulting food web
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ืจืฉืช ื”ืžื–ื•ืŸ ื”ื™ื•ืฆืืช ืžื–ื”
02:53
is so connected
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ื”ื™ื ื›ื” ืžืฉื•ืœื‘ืช
02:54
that almost every species
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ืฉื›ืžืขื˜ ื›ืœ ืžื™ืŸ
02:55
is no more than two degrees from detritus,
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ืœื ืจื—ื•ืง ื™ื•ืชืจ ืžืฉืชื™ ื“ืจื’ื•ืช ืžืฉืคื•ื›ืช,
02:58
even us humans.
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ืืคื™ืœื• ืื ื—ื ื• ื‘ื ื™ ื”ืื“ื.
03:00
You probably don't eat rotting things,
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ืืชื ื›ื ืจืื” ืœื ืื•ื›ืœื™ื ื“ื‘ืจื™ื ื ืจืงื‘ื™ื,
03:01
poop, or pond scum directly,
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ืฆื•ืื”, ืื• ืจืคืฉ ืฉืœื•ืœื™ื•ืช ื™ืฉื™ืจื•ืช,
03:03
but your food sources probably do.
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ืื‘ืœ ืžืงื•ืจื•ืช ื”ืื•ื›ืœ ืฉืœื›ื ื›ื ืจืื” ื›ืŸ.
03:06
Many animals we eat
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ื”ืจื‘ื” ื—ื™ื•ืช ืฉืื ื—ื ื• ืื•ื›ืœื™ื
03:07
either feed directly on detritus themselves,
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ืื• ื ื™ื–ื•ื ื•ืช ื™ืฉื™ืจื•ืช ืžืฉืคื•ื›ืช ื‘ืขืฆืžืŸ,
03:09
like pork, poultry, mushrooms, shellfish,
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ื›ืžื• ื—ื–ื™ืจื™ื, ืขื•ืคื•ืช, ืคื˜ืจื™ื•ืช, ืฆื“ืคื•ืช,
03:11
or catfish and other bottom feeders,
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ืื• ื˜ืจื™ื’ื•ื ื™ื ื•ื—ื™ื•ืช ืื—ืจื•ืช ืฉื ื™ื–ื•ื ื•ืช ื‘ืชื—ืชื™ืช ื”ื™ื,
03:15
or they are fed animal by-products.
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ืื• ืฉื”ืŸ ืžื•ืื›ืœื•ืช ืœื—ื™ื•ืช ืขืœ ื™ื“ื™ ืžื•ืฆืจื™ื.
03:16
So, if you're thinking nature is full of waste,
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ืื–, ืื ืืชื ื—ื•ืฉื‘ื™ื ืฉื”ื˜ื‘ืข ืžืœื ื‘ืคืกื•ืœืช,
03:19
you're right.
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ืืชื ืฆื•ื“ืงื™ื.
03:20
But one organism's garbage is another's gold,
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ืื‘ืœ ื–ื‘ืœ ืฉืœ ืื•ืจื’ื ื™ื–ื ืื—ื“ ื”ื•ื ื”ื–ื”ื‘ ืฉืœ ืื—ืจ,
03:23
and all that rotting dead stuff
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ื•ื›ืœ ื”ื—ื•ืžืจ ื”ืžืช ื”ื ืจืงื‘
03:25
ultimately provides the energy that nourishes us
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ื‘ืกื•ืคื• ืฉืœ ื“ื‘ืจ ืžืกืคืง ืื ืจื’ื™ื” ืฉืžื–ื™ื ื” ืื•ืชื ื•
03:27
and most of life on Earth,
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ื•ืืช ืจื•ื‘ ื”ื—ื™ื™ื ืขืœ ื›ื“ื•ืจ ื”ืืจืฅ,
03:29
as it passes through the food web.
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ื›ืฉื”ื™ื ืขื•ื‘ืจืช ื“ืจืš ืจืฉืช ื”ืžื–ื•ืŸ.
03:30
Now that's some food for thought.
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ืขื›ืฉื™ื• ื–ื” ืื•ื›ืœ ืœืžื—ืฉื‘ื”.
ืขืœ ืืชืจ ื–ื”

ืืชืจ ื–ื” ื™ืฆื™ื’ ื‘ืคื ื™ื›ื ืกืจื˜ื•ื ื™ YouTube ื”ืžื•ืขื™ืœื™ื ืœืœื™ืžื•ื“ ืื ื’ืœื™ืช. ืชื•ื›ืœื• ืœืจืื•ืช ืฉื™ืขื•ืจื™ ืื ื’ืœื™ืช ื”ืžื•ืขื‘ืจื™ื ืขืœ ื™ื“ื™ ืžื•ืจื™ื ืžื”ืฉื•ืจื” ื”ืจืืฉื•ื ื” ืžืจื—ื‘ื™ ื”ืขื•ืœื. ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ื”ืžื•ืฆื’ื•ืช ื‘ื›ืœ ื“ืฃ ื•ื™ื“ืื• ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ ืžืฉื. ื”ื›ืชื•ื‘ื™ื•ืช ื’ื•ืœืœื•ืช ื‘ืกื ื›ืจื•ืŸ ืขื ื”ืคืขืœืช ื”ื•ื•ื™ื“ืื•. ืื ื™ืฉ ืœืš ื”ืขืจื•ืช ืื• ื‘ืงืฉื•ืช, ืื ื ืฆื•ืจ ืื™ืชื ื• ืงืฉืจ ื‘ืืžืฆืขื•ืช ื˜ื•ืคืก ื™ืฆื™ืจืช ืงืฉืจ ื–ื”.

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