Name: 【TED-Ed】The game-changing amniotic egg - April Tucker
Uploaded: 2015-01-13T08:02:48.000Z
Duration: 4 min 30 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Steamy swamps and rain forests of horsetails and ferns

Amphibians are the dominant land vertebrates.

And all require water to do their egg laying.

their shell-less, jelly-like eggs will dry out.

a new group of animals named after their revolutionary egg.

While some amphibians can walk around on land

and bury their eggs in wet soil or highly humid areas,

nothing before the amniotes has the ability

with the ability to live a fully terrestrial life.

In fact, the amniotic egg brings the pond with them

by enclosing the aquatic environment within its shell.

The first development is the most obvious:

The shell protects the eggs from predators,

so that the growing amniote inside doesn't suffocate.

The next two developments are two separate membranes

which is the protective layer that oxygen passes through

as the thin skin you peel away on a hard boiled egg.

then the allantois is essentially the lobby of the building.

The chorion and the allantois make sure the embryo

The last and perhaps the most important development

is the amnion, the membrane for which the egg is named.

The amnion is also contained within the chroion

and holds the fluid in which the embryo floats.

Because it has left the watery world of the amphibians,

that allows the amniote to lay the egg on dry land.

like a shock absorber on your bike or car.

Together, the shell and these four membranes

as it explores new land away from the water.

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【TED-Ed】The game-changing amniotic egg - April Tucker

ability

environment

lie

fluid