If I'm not mistaken a typical animal in the womb will get oxygen via the umbilical cord from the mother. Thus allowing it to "breathe" in a liquid environment. I thought maybe shells are permeable and allow air to come in through the shell, but then I thought of eggs laid in the ground like turtles do.

  • How do animals in soft/hard shells get their oxygen?
  • $\begingroup$ Both forms are ultimately by diffusion. $\endgroup$
    – kmm
    Sep 1, 2015 at 14:13

1 Answer 1


The key point in both cases is that the eggshell and membrane are permeable to oxygen, as you thought. There are subtleties - for instance, the oxygen-permeability of avian (hard-shelled) eggshells changes during development.

In the case of eggs laid underground, as in sea turtle eggs, the leathery shell is still permeable to oxygen. The sand restricts oxygen flow, but turtles seem to take care to not bury their eggs too deep for oxygen to diffuse to their developing nest.


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