Chicks love air supply.

Temperature. Respiration. Crystals. And how unhatched chicks stay alive in their eggs.


Chicks Get Air in the Egg Because the Shell is Porous

1-Minute NomNom

When an egg is laid, it is warmer than the ambient temperature. As it cools, much like what happens when we boil an egg and cool it down, the membranes inside separate and form an air bubble (read all about it in the 1-Minute NomNom “Eggs-tra Ap-peeling“).

At the same time, the shell is formed mostly of calcium carbonate (CaCO3) crystals, and is porous. The pores allow air from the outside to enter the air bubble, and air and liquids from within the egg to escape or evaporate.

5 days old egg being candled. The air pocket, veins and the chick's eye are clearly visible.

Air pocket is visible at the bottom of the egg

These two phenomena keep the chick in the egg alive before it hatches. According to Scientific American:

“As the developing chick grows it uses the oxygen from the air sack and replaces it with carbon dioxide. The tiny pores in the shell allow the carbon dioxide to escape and fresh air to get in.”


It is no wonder then that chicks, especially those still in their shells, love their air supply.

chick hatching from egg

Isn’t it amazing that a simple shell structure can have so many properties that can be used in so many ways? It not only keeps unhatched chicks alive, but it can also be used to help determine if an egg is fresh (read all about it in the 1-Minute NomNom “Get fresh“). You’ll also want to find out the best way to peel eggshells perfectly.

Feed Me!

Do all types of animal eggs use these same scientific principles? Tell me what you think in the comments below!


Screen Shot 2015-01-10 at 6.02.39 pmLike this? Be my air supply and like me to discover more. All you need is a minute a day to explore the world’s marvels through the phenomenon of food!


photos: in order – istockphoto/PaulMichaelHughes; depositphotos/Klanneketankist276


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