TCSE: Ted Corpus Search Engine

Recorded at	December 07, 2020
Event	TED-Ed
Duration (min:sec)	06:03
Video Type	TED-Ed Original
Words per minute	154.99 slow
Readability (FK)	53.98 medium
Speaker	Alex Rosenthal


1	00:06	This is Goliath, the krill.
2	00:09	Don’t get too attached.
3	00:11	Today this 1 centimeter crustacean
4	00:13	will share the same fate as 40 million of his closest friends:
5	00:18	a life sentence in the belly of the largest blue whale in the world.
6	00:22	Let’s call her Leviatha.
7	00:25	Leviatha weighs something like 150 metric tons,
8	00:29	and she’s the largest animal in the world.
9	00:33	But she’s not even close to being the largest organism by weight,
10	00:38	which is estimated to equal about 40 Leviatha’s.
11	00:41	So where is this behemoth?
12	00:44	Here, in Utah.
13	00:46	Sorry, that’s too close.
14	00:48	Here.
15	00:49	This is Pando, whose name means “I spread out.”
16	00:54	Pando, a quaking aspen, has roughly 47,000 genetically identical clone trunks.
17	01:01	Those all grow from one enormous root system,
18	01:05	which is why scientists consider Pando a single organism.
19	01:09	Pando is the clear winner of world’s largest organism by weight—
20	01:14	an incredible 6 million kilograms.
21	01:18	So how did Pando get to be so huge?
22	01:22	Pando is not an unusual aspen from a genetic standpoint.
23	01:26	Rather, Pando’s size boils down to three main factors:
24	01:30	its age, its location, and aspens’ remarkable evolutionary adaptation
25	01:36	of self-cloning.
26	01:38	So first, Pando is incredibly expansive because it’s incredibly old.
27	01:43	How old exactly?
28	01:45	No one knows.
29	01:47	Dendrochronologist estimates range from 80,000 to 1 million years.
30	01:54	The problem is, there’s no simple way to gauge Pando’s age.
31	01:58	Counting the rings of a single trunk will only account for up to 200 years or so,
32	02:03	as Pando is in a constant cycle of growth, death, and renewal.
33	02:09	On average, each individual tree lives 130 years,
34	02:13	before falling and being replaced by new ones.
35	02:17	Second: location.
36	02:19	During the last ice age, which ended about 12,000 years ago,
37	02:23	glaciers covered much of the North American climate
38	02:26	friendly to aspens.
39	02:28	So if there were other comparably sized clonal colonies,
40	02:32	they may have perished then.
41	02:35	Meanwhile, Pando’s corner of Utah remained glacier-free.
42	02:39	The soil there is rich in nutrients that Pando continuously replenishes;
43	02:44	as it drops leaves and trunks,
44	02:46	the nutrients return to nourish new generations of clones.
45	02:50	Which brings us to the third cause of Pando’s size: cloning.
46	02:55	Aspens are capable of both sexual reproduction—
47	02:59	which produces a new organism—
48	03:01	and asexual reproduction— which creates a clone.
49	03:05	They tend to reproduce sexually when conditions are unfavorable
50	03:10	and the best strategy for survival is to move elsewhere.
51	03:14	Trees aren’t particularly mobile, but their seeds are.
52	03:18	Like the rest of us, sexual reproduction is how Pando came into the world
53	03:23	in the first place all those tens or hundreds of thousands of years ago.
54	03:28	The wind or a pollinator carried pollen from the flower of one of its parents
55	03:32	to the other, where a sperm cell fertilized an egg.
56	03:36	That flower produced fruit, which split open,
57	03:39	releasing hundreds of tiny, light seeds.
58	03:42	The wind carried one to a wet spot of land in what is now Utah,
59	03:46	where it took root and germinated into Pando’s first stem.
60	03:51	A couple of years later, Pando grew mature enough to reproduce asexually.
61	03:56	Asexual reproduction, or cloning,
62	03:59	tends to happen when the environment is favorable to growth.
63	04:03	Aspens have long roots that burrow through the soil.
64	04:08	These can sprout shoots that grow up into new trunks.
65	04:12	And while Pando grew and spread out, so did our ancestors.
66	04:16	As Hunter-gatherers who made cave paintings, survived an ice age,
67	04:20	found their way to North America, built civilizations in Egypt and Mesopotamia,
68	04:26	fought wars, domesticated animals, fought wars, formed nations,
69	04:30	built machines,
70	04:31	and invented the internet, and always newer ways to fight wars.
71	04:37	Pando has survived many millennia of changing climates and encroaching ice.
72	04:42	But it may not survive us.
73	04:45	New stems are growing to maturity much more slowly than they need to
74	04:50	in order to replace the trunks that fall.
75	04:53	Scientists have identified two main reasons for this.
76	04:56	The first is that we’ve deprived Pando of fire.
77	05:00	When a fire clears a patch of forest, Aspen roots survive,
78	05:05	and send shoots bursting up out of the ground by the tens of thousands.
79	05:10	And secondly, grazers like herds of cattle and mule deer—
80	05:14	whose natural predators we’ve hunted to the point of local elimination—
81	05:18	are eating Pando’s fresh growth.
82	05:21	If we lose the world’s largest organism, we’ll lose a scientific treasure trove.
83	05:27	Because Pando’s trunks are genetically identical,
84	05:30	they can serve as a controlled setting for studies
85	05:33	on everything from the tree microbiome
86	05:36	to the influence of climate on tree growth rates.
87	05:39	The good news is, we have a chance to save Pando,
88	05:43	by reducing livestock grazing in the area
89	05:46	and further protecting the vulnerable young saplings.
90	05:50	And the time to act is today.
91	05:53	Because as with so many other marvels of our natural world,
92	05:57	once they’re gone it will be a very, very long time before they return.

Alex Rosenthal: The world's largest organism