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  • (Stories from the Sea: How Life Came to Land)

  • Life for my kind wasn't always this way.

  • There was a time when no animals lived on land.

  • All life was in the ocean.

  • The ocean's where all of us animals got our start,

  • more than half a billion years ago,

  • This is where all animal body types -- or phyla, as scientists call them -- first evolved.

  • You know, there are more than 30 animal phyla,

  • but only a handful of major ones had what it took to do something completely daring:

  • step out of the ocean, and on to dry land.

  • So, which of these land-dwelling phyla first invaded the land?

  • Was it me and my mollusc friends, with our amazing mantles and single foot?

  • Perhaps the chordate crowd, with their notochords, segmented muscles and big bony skeletons.

  • Or maybe those lowly annelid worms, with their powerful ringed bodies.

  • Or did the Arthropods first make landfall, with their little flexible suits of armor -- their exoskeleton?

  • Ah, yes. The arthropods.

  • From crustaceans to millipedes, spiders to insects,

  • the arthropods outnumber all animals on land.

  • So what's their secret?

  • Their exoskeleton is key, but here's the real kicker: jointed appendages.

  • They're like little living Swiss army knives:

  • antennae, multiple mouth parts, an obscene number of legs, if you ask me.

  • There's one group of arthropods -- the insects --

  • that really rule the land.

  • Three body parts, six legs, and an annoying tendency to take over.

  • Sure, they have to molt to grow, but that doesn't seem to pose a problem.

  • The insects even invented the first wings, and conquered the skies.

  • Ah, well. So what if arthropods were the first to reach land

  • and invent flight, a hundred million years before the rest of us?

  • So what if they pollinate crops around the world,

  • and make up 75% of all land animal species?

  • And that for every single human, there's 200 million of them?

  • Sure, those leggy arthropods may still be in the lead when it comes to conquering land,

  • but we still rule in the sea.

  • There are more species of molluscs in the ocean than any other animal phylum.

  • We're just getting started up here on land.

  • Besides, the seas are rising. Just give us some time.

  • Who knows who'll end up ruling this ocean planet?

(Stories from the Sea: How Life Came to Land)


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B2 中上級

TED-ED】人生はどのようにして陸に上がってきたのか - ティアニー・ティス (【TED-Ed】How life came to land - Tierney Thys)

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    VoiceTube に公開 2021 年 01 月 14 日