Amphibians actually do have lungs. They lack most of the glands
that we humans have.
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amphibians
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amphibians are creatures that can live in water or on land, that does not mean that if we build a dome underwater and live their that we are amphibians.
Amphibians can breathe underwater and on land, and since humans can't breathe underwater without the help of special equipment we are not amphibians.
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Amphibians are part of the kingdom Animal. Same worms and
humans.
To narrow it down, they are part of the Phylum Chordate.