FLIGHT: The Genius of Birds - Embryonic development

Know Your Eggs!

Eggs and air bubbles

[This is a post taken from this page]

This morning I put some eggs in a pot of warm water and I noticed a faint whistling sound, as though from the worlds tiniest teakettle. When I looked in the pot, I saw tiny streams of bubbles coming from some of the eggs:

This is just one of the bubble streams. Of the five eggs in the pot, I think four had bubbles coming from them, and on one of them, the bubbles came from three spots — literally. These fancy brown organic eggs occasionally have tiny dark spots on them. After a minute or two, the bubbles stopped.

My first thought was that they were nucleation sites for air bubbles to form, like a little scratch in a beer glass, or one of those spots in a pot of boiling water where bubbles keep coming up from. But the water wasn’t even close to boiling — it was a mix of a little leftover water I had just boiled for coffee, and maybe four times as much cold tap water, so it was merely warm.

My second thought was that the fancy organic eggs had tiny little holes that let the air out of the air pocket. On the spotty egg, the bubbles came from the top, bouyant, side of the egg, which seems to confirm this theory. But on the other eggs, like the one in the picture, the bubbles came from the underside, which isn’t where the air pocket is. I also thought that if there were holes so tiny that I couldn’t see them, air bubbles wouldn’t come out that quickly, if at all. But then again, maybe the warm water caused air inside the eggs to expand and push out of any tiny cracks. Still, that wouldn’t explain why they came from the underside of some eggs.

Back to nucleation: maybe it can happen even without boiling water or carbonation, with just aerated water from the tap? After all, there are a lot of little air bubbles visible on the surface of the pot and on the eggs.

One way to test these theories is to take eggs that have “run out” of air bubbles and put them into a fresh pot of water to see if they’ll emit bubbles again: if they do, then that rules out the tiny hole theory, leaving nucleation in aerated water as the best explanation. To be tested another time…

Update: Instead of actually testing this, I used the power of the internet to find out the answer. Eggs do indeed have lots of tiny air holes so the chick inside can breathe. This is probably one of those facts that, as children, we learn, and as adults, we forget.