Babies while in the womb are surrounded by fluids, so they cannot breathe. Do they get oxygen through the mother's umbilical cord?
Are we kind of amphibious before coming to the world?
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1 Answer
Why does a foetus not drown?
The foetus gets oxygen through the mother's umbilical cord:
The fetus receives its oxygen supply across the placenta, to which oxygen is delivered by maternal blood. The amount of oxygen delivered to the placental site is determined by the magnitude of blood flow and the oxygen content of uterine arterial blood. Transfer of oxygen from maternal to fetal blood is influenced by the diffusion gradient for oxygen between the maternal uterine blood and fetal umbilical blood.
Oxygen Supply to the Fetus and Fetal Hypoxemia
For further information about the umbilical cord and the placenta, see this Wikipedia image.
Are foetus' amphibious?
No. Although foetuses have pharyngeal arches the "oxygen supply line" is the umbilical cord. A foetus can not live outside the womb due to a lack of oxygen supply (the lungs are not yet working) and general supply of vital molecules. This is why they can not be considered amphibians.
The word "amphibian" is derived from the Ancient Greek term ἀμφίβιος (amphíbios), which means "both kinds of life", ἀμφί meaning "of both kinds" and βιος meaning "life". The term was initially used as a general adjective for animals that could live on land or in water, including seals and otters.
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1Might be worth mentioning the pharyngeal arches to understand where the person is coming from with the amphibious question, and that they can't survive outside the mother, not just in water in general (modern incubation being a separate caveat)– Atl LEDJun 21, 2017 at 18:51
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@AtlLED I couldn't really find any source that the pharyngeal arches aren't used for oxygen intake, but this article is pretty detailed about them. Feel free to post your own answer and focus on the pharyngeal arches.– NarusanJun 21, 2017 at 19:03
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No, I meant they are the reason people have ideas that fetuses are amphibious are pharyngeal arches, and a quick note about why that logic doesn't hold up.– Atl LEDJun 21, 2017 at 19:10
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@AtlLED What about the current version? I haven't found good explanations why the pharyngeal arches aren't a way of oxygen intake but will keep on searching.– NarusanJun 21, 2017 at 19:34
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1Just out of curiosity, would it be possible to provide a human with oxygen through the blood directly, in case for example of asphyxia ?– PablitoJun 22, 2017 at 14:11