Jellyfish predate dinosaurs. How have they survived so long? - David Gruber
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0:08 - 0:11Some are longer than a blue whale.
-
0:11 - 0:15Others are barely larger
than a grain of sand. -
0:15 - 0:19One species unleashes one of
the most deadly venoms on Earth. -
0:19 - 0:24Another holds a secret that's behind some
of the greatest breakthroughs in biology. -
0:24 - 0:28They've inhabited the ocean for at least
half a billion years, -
0:28 - 0:32and they're still flourishing as the sea
changes around them. -
0:32 - 0:36Jellyfish are soft-bodied sea creatures
that aren't really fish. -
0:36 - 0:40They're part of a diverse team
of gelatinous zooplankton, -
0:40 - 0:44zooplankton being animals that drift
in the ocean. -
0:44 - 0:47There are more than 1,000 species
of jellyfish, -
0:47 - 0:51and many others
that are often mistaken for them. -
0:51 - 0:54A noted feature of jellyfish
is a translucent bell -
0:54 - 0:58made of a soft delicate material
called mesoglea. -
0:58 - 1:01Sandwiched between two layers of skin,
-
1:01 - 1:07the mesoglea is more than 95% water
held together by protein fibers. -
1:07 - 1:12The jellyfish can contract and
relax their bells to propel themselves. -
1:12 - 1:15They don't have a brain or a spinal cord,
-
1:15 - 1:17but a neural net around the bell's
inner margin -
1:17 - 1:20forms a rudimentary nervous system
-
1:20 - 1:25that can sense the ocean's currents
and the touch of other animals. -
1:25 - 1:29Jellyfish don't have typical
digestive systems, either. -
1:29 - 1:34These gelatinous carnivores consume
plankton and other small sea creatures -
1:34 - 1:38through a hole in the underside
of their bells. -
1:38 - 1:41The nutrients are absorbed by
an inner layer of cells -
1:41 - 1:45with waste excreted back through
their mouths. -
1:45 - 1:48But the jellyfish's relatively
simple anatomy -
1:48 - 1:52doesn't prevent it from having
some remarkable abilities. -
1:52 - 1:55One kind of box jellyfish has 24 eyes.
-
1:55 - 2:03Scientists think it can see color and form
images within its simple nervous system. -
2:03 - 2:06Four of its eyes are curved
upward on stalks. -
2:06 - 2:10This allows the jellyfish to peer
through the surface of the water, -
2:10 - 2:15looking for the canopy
of the mangrove trees where it feeds. -
2:15 - 2:17In fact, this may be one
of the only creatures -
2:17 - 2:22with a 360-degree view of its environment.
-
2:22 - 2:26The jellyfish's sting, which helps it
capture prey and defend itself, -
2:26 - 2:29is its most infamous calling card.
-
2:29 - 2:30In the jelly's epidermis,
-
2:30 - 2:36cells called nematocysts
lie coiled like poisonous harpoons. -
2:36 - 2:41When they're triggered by contact,
they shoot with an explosive force. -
2:41 - 2:47It exerts over 550 times the pressure
of Mike Tyson's strongest punch -
2:47 - 2:50to inject venom into the victim.
-
2:50 - 2:52Some jellyfish stings barely tingle,
-
2:52 - 2:56but others cause severe skin damage.
-
2:56 - 3:01The venom of one box jellyfish
can kill a human in under five minutes, -
3:01 - 3:07making it one of the most potent
poisons of any animal in the world. -
3:07 - 3:10Other jellyfish superpowers
are less lethal. -
3:10 - 3:13One species of jellyfish glows green
when it's agitated, -
3:13 - 3:18mostly thanks to a biofluorescent compound
called green fluorescent protein, -
3:18 - 3:20or GFP.
-
3:20 - 3:22Scientists isolated the gene for GFP
-
3:22 - 3:27and figured out how to insert it
into the DNA of other cells. -
3:27 - 3:30There, it acts like a biochemical beacon,
-
3:30 - 3:32marking genetic modifications,
-
3:32 - 3:37or revealing the path
of critical molecules. -
3:37 - 3:42Scientists have used the glow of GFP
to watch cancer cells proliferate, -
3:42 - 3:44track the development of Alzheimer's,
-
3:44 - 3:49and illuminate countless other
biological processes. -
3:49 - 3:51Developing the tools and techniques
from GFP -
3:51 - 3:55has netted three scientists
a Nobel Prize in 2008, -
3:55 - 3:59and another three in 2014.
-
3:59 - 4:04But it's jellyfish who may be the most
successful organisms on Earth. -
4:04 - 4:07Ancient fossils prove that jellyfish
have inhabited the seas -
4:07 - 4:10for at least 500 million years,
-
4:10 - 4:13and maybe go back over 700 million.
-
4:13 - 4:18That's longer than any
other multiorgan animal. -
4:18 - 4:20And as other marine animals
are struggling to survive -
4:20 - 4:23in warmer and more acidic oceans,
-
4:23 - 4:25the jellyfish are thriving,
-
4:25 - 4:29and perhaps getting even more numerous.
-
4:29 - 4:36It doesn't hurt that some can lay
as many as 45,000 eggs in a single night. -
4:36 - 4:38And there's some jellyfish
whose survival strategy -
4:38 - 4:41almost sounds like science fiction.
-
4:41 - 4:44When the immortal jellyfish is sick,
aging, or under stress, -
4:44 - 4:48its struggling cells can change
their identity. -
4:48 - 4:51The tiny bell and tentacles deteriorate
-
4:51 - 4:53and turn into an immature polyp
-
4:53 - 4:57that spawns brand new clones
of the parent. -
4:57 - 5:01As far as we know, these are the only
animals who found a loophole -
5:01 - 5:04when facing mortality.
-
5:04 - 5:08That's pretty sophisticated for species
that are 95% water -
5:08 - 5:10and predate the dinosaurs.
- Title:
- Jellyfish predate dinosaurs. How have they survived so long? - David Gruber
- Description:
-
View full lesson: http://ed.ted.com/lessons/jellyfish-predate-dinosaurs-how-have-they-survived-so-long-david-gruber
Some are longer than a blue whale. Others are barely larger than a grain of sand. One species unleashes one of the most deadly venoms on earth; another holds a secret that’s behind some of the greatest breakthroughs in biology. They’ve inhabited the ocean for at least half a billion years, and they’re still flourishing. David Gruber investigates the secret powers of jellyfish.
Lesson by David Gruber, animation by Silvia Prietov.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 05:26
Jessica Ruby approved English subtitles for Jellyfish predate dinosaurs. How have they survived so long? - David Gruber | ||
Jessica Ruby accepted English subtitles for Jellyfish predate dinosaurs. How have they survived so long? - David Gruber | ||
Jessica Ruby edited English subtitles for Jellyfish predate dinosaurs. How have they survived so long? - David Gruber | ||
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